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Re: [Gcl-devel] Re: ACL2 Version 4.0


From: Camm Maguire
Subject: Re: [Gcl-devel] Re: ACL2 Version 4.0
Date: Tue, 27 Jul 2010 13:24:44 -0400
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux)

Greetings!

Matt Kaufmann <address@hidden> writes:

> Hi, Camm --
>
> ACL2 expected that a call of pathname-device on
> #pZ:/home/camm/debian/acl2/acl2-4.0/ would return the string "Z".
> Here, that path was the value of (truename "").  I confess that I
> don't think much about pathname-device or Windows, and whatever
> thinking I did, I didn't document well.
>

Me too!

> What do you get when evaluating (pathname-device (truename "")) in
> that same directory?
>

(pathname-device (truename ""))

("Z:")

>

Why this is a list (like pathname-directory, I guess) I do not really
know.  I can't find anything in the lisp standard that really says
what this should be. 

Take care,

> Thanks --
> -- Matt
>    Cc: address@hidden
>    From: Camm Maguire <address@hidden>
>    Date: Tue, 27 Jul 2010 12:27:07 -0400
>    X-SpamAssassin-Status: No, hits=-2.2 required=5.0
>    X-UTCS-Spam-Status: No, hits=-242 required=165
>
>    Greetings, and thanks!  I should have an updated file for you to try
>    soon.
>
>    Running acl2 under wine emulation for windows, I successfully built
>    saved_acl2, but run into this when executing:
>
>    GCL (GNU Common Lisp)  2.6.8 CLtL1    Jul 26 2010 22:47:17
>    Source License: LGPL(gcl,gmp), GPL(unexec,bfd,xgcl)
>    Binary License:  GPL due to GPL'ed components: (UNEXEC)
>    Modifications of this banner must retain notice of a compatible license
>    Dedicated to the memory of W. Schelter
>
>    Use (help) to get some basic information on how to use GCL.
>    Temporary directory for compiler files set to 
> /home/camm/debian/gcl/gcl8mac2/unixport/
>
>     ACL2 Version 4.0 built July 27, 2010  15:56:04.
>     Copyright (C) 2010  University of Texas at Austin
>     ACL2 comes with ABSOLUTELY NO WARRANTY.  This is free software and you
>     are welcome to redistribute it under certain conditions.  For details,
>     see the GNU General Public License.
>
>     Initialized with (INITIALIZE-ACL2 'INCLUDE-BOOK *ACL2-PASS-2-FILES*).
>     See the documentation topic note-4-0 for recent changes.
>     Note: We have modified the prompt in some underlying Lisps to further
>     distinguish it from the ACL2 prompt.
>
>
>    ACL2 Error in LP:  The value of 
>    (SUBSEQ "Z:/home/camm/debian/acl2/acl2-4.0/" 0 1) is "Z" while the
>    value of (PATHNAME-DEVICE 
>    Error: Prin1$ called on an illegal object 
> #pZ:/home/camm/debian/acl2/acl2-4.0/
>
>         .
>    Fast links are on: do (si::use-fast-links nil) for debugging
>    Error signalled by LISP:LAMBDA-CLOSURE.
>    Backtrace: funcall > system:top-level > lisp:lambda-closure > lp > 
> system:universal-error-handler > system::break-level-for-acl2 > let* > UNLESS
>
>    ...
>
>    Just typing (lp) at the ACL2> prompt and :q (si::save-syste "...")
>    gives me a binary that starts cleanly, but cannot certify anything:
>
>       | HARD ACL2 ERROR in CBD:  The connected book directory has apparently
>       | not yet been set.  This could be a sign that the top-level ACL2 loop,
>       | generally entered using (LP), has not yet been entered.
>       | 
>
>
>    Can you point out to me the problem?  There is an obvious difficulty
>    in this environment interpolating between windows and unix pathnames.
>
>    Take care,
>
>
>    Matt Kaufmann <address@hidden> writes:
>
>    > Hi, Camm --
>    >
>    > I've attached a log showing those files (on my Intel-based Mac running
>    > Mac OS 10.6.4).
>    >
>    > -- Matt
>    >    Cc: Matt Kaufmann <address@hidden>, address@hidden
>    >    From: Camm Maguire <address@hidden>
>    >    Date: Tue, 27 Jul 2010 10:00:52 -0400
>    >    X-SpamAssassin-Status: No, hits=-0.4 required=5.0
>    >    X-UTCS-Spam-Status: No, hits=-189 required=165
>    >
>    >    Thank you so much!  But after reviewing the below, it appears I now
>    >    need:
>    >
>    >    /usr/include/mach-o/nlist.h
>    >    /usr/include/nlist.h
>    >
>    >    Take care,
>    >
>    >    "George W. Dinolt" <address@hidden> writes:
>    >
>    >    > Camm:
>    >    > I have been a lurker on the list for several years.  Time for a 
> small
>    >    > contribution.
>    >    >
>    >    > I tried the same test as Matt on a Snow Leopard MAC and got the same
>    >    > result.  I also have access to a Mac running Leopard.  I was able to
>    >    > compile gcl on that (after making sure that tcl/tk was not in the
>    >    > path). I checked the differences between Leopard and Snow Leopard 
> with
>    >    > the files you suggested we look at, they are in /usr/include.
>    >    >
>    >    > The one that is different in Snow Leopard is "loader.h".  It is
>    >    > included below.
>    >    >
>    >    > Unfortunately, I am unable to make a machine available to you.  My
>    >    > machines are relatively hidden behind U.S. gov't firewalls.
>    >    >
>    >    > I hope this will be of some help.
>    >    >
>    >    > Regards,
>    >    > George Dinolt
>    >    > ----------------------------------------
>    >    > loader.h from Snow Leopard
>    >    > ----------------------------------------
>    >    > /*
>    >    >  * Copyright (c) 1999-2008 Apple Inc.  All Rights Reserved.
>    >    >  *
>    >    >  * @APPLE_LICENSE_HEADER_START@
>    >    >  *
>    >    >  * This file contains Original Code and/or Modifications of 
> Original Code
>    >    >  * as defined in and that are subject to the Apple Public Source 
> License
>    >    >  * Version 2.0 (the 'License'). You may not use this file except in
>    >    >  * compliance with the License. Please obtain a copy of the License 
> at
>    >    >  * http://www.opensource.apple.com/apsl/ and read it before using 
> this
>    >    >  * file.
>    >    >  *
>    >    >  * The Original Code and all software distributed under the License 
> are
>    >    >  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, 
> EITHER
>    >    >  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH 
> WARRANTIES,
>    >    >  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
>    >    >  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR 
> NON-INFRINGEMENT.
>    >    >  * Please see the License for the specific language governing 
> rights and
>    >    >  * limitations under the License.
>    >    >  *
>    >    >  * @APPLE_LICENSE_HEADER_END@
>    >    >  */
>    >    > #ifndef _MACHO_LOADER_H_
>    >    > #define _MACHO_LOADER_H_
>    >    >
>    >    > /*
>    >    >  * This file describes the format of mach object files.
>    >    >  */
>    >    > #include <stdint.h>
>    >    >
>    >    > /*
>    >    >  * <mach/machine.h> is needed here for the cpu_type_t and
>    >    > cpu_subtype_t types
>    >    >  * and contains the constants for the possible values of these 
> types.
>    >    >  */
>    >    > #include <mach/machine.h>
>    >    >
>    >    > /*
>    >    >  * <mach/vm_prot.h> is needed here for the vm_prot_t type and 
> contains the
>    >    >  * constants that are or'ed together for the possible values of 
> this type.
>    >    >  */
>    >    > #include <mach/vm_prot.h>
>    >    >
>    >    > /*
>    >    >  * <machine/thread_status.h> is expected to define the flavors of 
> the
>    >    > thread
>    >    >  * states and the structures of those flavors for each machine.
>    >    >  */
>    >    > #include <mach/machine/thread_status.h>
>    >    > #include <architecture/byte_order.h>
>    >    >
>    >    > /*
>    >    >  * The 32-bit mach header appears at the very beginning of the 
> object
>    >    > file for
>    >    >  * 32-bit architectures.
>    >    >  */
>    >    > struct mach_header {
>    >    >     uint32_t    magic;        /* mach magic number identifier */
>    >    >     cpu_type_t    cputype;    /* cpu specifier */
>    >    >     cpu_subtype_t    cpusubtype;    /* machine specifier */
>    >    >     uint32_t    filetype;    /* type of file */
>    >    >     uint32_t    ncmds;        /* number of load commands */
>    >    >     uint32_t    sizeofcmds;    /* the size of all the load commands 
> */
>    >    >     uint32_t    flags;        /* flags */
>    >    > };
>    >    >
>    >    > /* Constant for the magic field of the mach_header (32-bit 
> architectures) */
>    >    > #define    MH_MAGIC    0xfeedface    /* the mach magic number */
>    >    > #define MH_CIGAM    0xcefaedfe    /* NXSwapInt(MH_MAGIC) */
>    >    >
>    >    > /*
>    >    >  * The 64-bit mach header appears at the very beginning of object 
> files for
>    >    >  * 64-bit architectures.
>    >    >  */
>    >    > struct mach_header_64 {
>    >    >     uint32_t    magic;        /* mach magic number identifier */
>    >    >     cpu_type_t    cputype;    /* cpu specifier */
>    >    >     cpu_subtype_t    cpusubtype;    /* machine specifier */
>    >    >     uint32_t    filetype;    /* type of file */
>    >    >     uint32_t    ncmds;        /* number of load commands */
>    >    >     uint32_t    sizeofcmds;    /* the size of all the load commands 
> */
>    >    >     uint32_t    flags;        /* flags */
>    >    >     uint32_t    reserved;    /* reserved */
>    >    > };
>    >    >
>    >    > /* Constant for the magic field of the mach_header_64 (64-bit
>    >    > architectures) */
>    >    > #define MH_MAGIC_64 0xfeedfacf /* the 64-bit mach magic number */
>    >    > #define MH_CIGAM_64 0xcffaedfe /* NXSwapInt(MH_MAGIC_64) */
>    >    >
>    >    > /*
>    >    >  * The layout of the file depends on the filetype.  For all but the
>    >    > MH_OBJECT
>    >    >  * file type the segments are padded out and aligned on a segment 
> alignment
>    >    >  * boundary for efficient demand pageing.  The MH_EXECUTE, 
> MH_FVMLIB,
>    >    > MH_DYLIB,
>    >    >  * MH_DYLINKER and MH_BUNDLE file types also have the headers 
> included
>    >    > as part
>    >    >  * of their first segment.
>    >    >  *
>    >    >  * The file type MH_OBJECT is a compact format intended as output 
> of the
>    >    >  * assembler and input (and possibly output) of the link editor 
> (the .o
>    >    >  * format).  All sections are in one unnamed segment with no segment
>    >    > padding.
>    >    >  * This format is used as an executable format when the file is so
>    >    > small the
>    >    >  * segment padding greatly increases its size.
>    >    >  *
>    >    >  * The file type MH_PRELOAD is an executable format intended for
>    >    > things that
>    >    >  * are not executed under the kernel (proms, stand alones, kernels,
>    >    > etc).  The
>    >    >  * format can be executed under the kernel but may demand paged it 
> and not
>    >    >  * preload it before execution.
>    >    >  *
>    >    >  * A core file is in MH_CORE format and can be any in an arbritray 
> legal
>    >    >  * Mach-O file.
>    >    >  *
>    >    >  * Constants for the filetype field of the mach_header
>    >    >  */
>    >    > #define    MH_OBJECT    0x1        /* relocatable object file */
>    >    > #define    MH_EXECUTE    0x2        /* demand paged executable file 
> */
>    >    > #define    MH_FVMLIB    0x3        /* fixed VM shared library file 
> */
>    >    > #define    MH_CORE        0x4        /* core file */
>    >    > #define    MH_PRELOAD    0x5        /* preloaded executable file */
>    >    > #define    MH_DYLIB    0x6        /* dynamically bound shared 
> library */
>    >    > #define    MH_DYLINKER    0x7        /* dynamic link editor */
>    >    > #define    MH_BUNDLE    0x8        /* dynamically bound bundle file 
> */
>    >    > #define    MH_DYLIB_STUB    0x9        /* shared library stub for 
> static */
>    >    >                     /*  linking only, no section contents */
>    >    > #define    MH_DSYM        0xa        /* companion file with only 
> debug */
>    >    >                     /*  sections */
>    >    > #define    MH_KEXT_BUNDLE    0xb        /* x86_64 kexts */
>    >    >
>    >    > /* Constants for the flags field of the mach_header */
>    >    > #define    MH_NOUNDEFS    0x1        /* the object file has no 
> undefined
>    >    >                        references */
>    >    > #define    MH_INCRLINK    0x2        /* the object file is the 
> output of an
>    >    >                        incremental link against a base file
>    >    >                        and can't be link edited again */
>    >    > #define MH_DYLDLINK    0x4        /* the object file is input for 
> the
>    >    >                        dynamic linker and can't be staticly
>    >    >                        link edited again */
>    >    > #define MH_BINDATLOAD    0x8        /* the object file's undefined
>    >    >                        references are bound by the dynamic
>    >    >                        linker when loaded. */
>    >    > #define MH_PREBOUND    0x10        /* the file has its dynamic 
> undefined
>    >    >                        references prebound. */
>    >    > #define MH_SPLIT_SEGS    0x20        /* the file has its read-only 
> and
>    >    >                        read-write segments split */
>    >    > #define MH_LAZY_INIT    0x40        /* the shared library init 
> routine is
>    >    >                        to be run lazily via catching memory
>    >    >                        faults to its writeable segments
>    >    >                        (obsolete) */
>    >    > #define MH_TWOLEVEL    0x80        /* the image is using two-level 
> name
>    >    >                        space bindings */
>    >    > #define MH_FORCE_FLAT    0x100        /* the executable is forcing 
> all
>    >    > images
>    >    >                        to use flat name space bindings */
>    >    > #define MH_NOMULTIDEFS    0x200        /* this umbrella guarantees 
> no
>    >    > multiple
>    >    >                        defintions of symbols in its
>    >    >                        sub-images so the two-level namespace
>    >    >                        hints can always be used. */
>    >    > #define MH_NOFIXPREBINDING 0x400    /* do not have dyld notify the
>    >    >                        prebinding agent about this
>    >    >                        executable */
>    >    > #define MH_PREBINDABLE  0x800           /* the binary is not 
> prebound
>    >    > but can
>    >    >                        have its prebinding redone. only used
>    >    >                                            when MH_PREBOUND is not 
> set. */
>    >    > #define MH_ALLMODSBOUND 0x1000        /* indicates that this binary 
> binds to
>    >    >                                            all two-level namespace
>    >    > modules of
>    >    >                        its dependent libraries. only used
>    >    >                        when MH_PREBINDABLE and MH_TWOLEVEL
>    >    >                        are both set. */
>    >    > #define MH_SUBSECTIONS_VIA_SYMBOLS 0x2000/* safe to divide up the
>    >    > sections into
>    >    >                         sub-sections via symbols for dead
>    >    >                         code stripping */
>    >    > #define MH_CANONICAL    0x4000        /* the binary has been 
> canonicalized
>    >    >                        via the unprebind operation */
>    >    > #define MH_WEAK_DEFINES    0x8000        /* the final linked image 
> contains
>    >    >                        external weak symbols */
>    >    > #define MH_BINDS_TO_WEAK 0x10000    /* the final linked image uses
>    >    >                        weak symbols */
>    >    >
>    >    > #define MH_ALLOW_STACK_EXECUTION 0x20000/* When this bit is set, 
> all stacks
>    >    >                        in the task will be given stack
>    >    >                        execution privilege.  Only used in
>    >    >                        MH_EXECUTE filetypes. */
>    >    > #define    MH_DEAD_STRIPPABLE_DYLIB 0x400000 /* Only for use on
>    >    > dylibs.  When
>    >    >                          linking against a dylib that
>    >    >                          has this bit set, the static linker
>    >    >                          will automatically not create a
>    >    >                          LC_LOAD_DYLIB load command to the
>    >    >                          dylib if no symbols are being
>    >    >                          referenced from the dylib. */
>    >    > #define MH_ROOT_SAFE 0x40000           /* When this bit is set, the 
> binary
>    >    >                       declares it is safe for use in
>    >    >                       processes with uid zero */
>    >    >
>    >    > #define MH_SETUID_SAFE 0x80000         /* When this bit is set, the 
> binary
>    >    >                       declares it is safe for use in
>    >    >                       processes when issetugid() is true */
>    >    >
>    >    > #define MH_NO_REEXPORTED_DYLIBS 0x100000 /* When this bit is set on 
> a
>    >    > dylib,
>    >    >                       the static linker does not need to
>    >    >                       examine dependent dylibs to see
>    >    >                       if any are re-exported */
>    >    > #define    MH_PIE 0x200000            /* When this bit is set, the 
> OS will
>    >    >                        load the main executable at a
>    >    >                        random address.  Only used in
>    >    >                        MH_EXECUTE filetypes. */
>    >    >
>    >    > /*
>    >    >  * The load commands directly follow the mach_header.  The total 
> size
>    >    > of all
>    >    >  * of the commands is given by the sizeofcmds field in the
>    >    > mach_header.  All
>    >    >  * load commands must have as their first two fields cmd and 
> cmdsize.
>    >    > The cmd
>    >    >  * field is filled in with a constant for that command type.  Each
>    >    > command type
>    >    >  * has a structure specifically for it.  The cmdsize field is the 
> size
>    >    > in bytes
>    >    >  * of the particular load command structure plus anything that 
> follows
>    >    > it that
>    >    >  * is a part of the load command (i.e. section structures, strings,
>    >    > etc.).  To
>    >    >  * advance to the next load command the cmdsize can be added to the
>    >    > offset or
>    >    >  * pointer of the current load command.  The cmdsize for 32-bit
>    >    > architectures
>    >    >  * MUST be a multiple of 4 bytes and for 64-bit architectures MUST 
> be
>    >    > a multiple
>    >    >  * of 8 bytes (these are forever the maximum alignment of any load
>    >    > commands).
>    >    >  * The padded bytes must be zero.  All tables in the object file 
> must also
>    >    >  * follow these rules so the file can be memory mapped.  Otherwise 
> the
>    >    > pointers
>    >    >  * to these tables will not work well or at all on some machines.  
> With all
>    >    >  * padding zeroed like objects will compare byte for byte.
>    >    >  */
>    >    > struct load_command {
>    >    >     uint32_t cmd;        /* type of load command */
>    >    >     uint32_t cmdsize;    /* total size of command in bytes */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * After MacOS X 10.1 when a new load command is added that is
>    >    > required to be
>    >    >  * understood by the dynamic linker for the image to execute 
> properly the
>    >    >  * LC_REQ_DYLD bit will be or'ed into the load command constant.  If
>    >    > the dynamic
>    >    >  * linker sees such a load command it it does not understand will 
> issue a
>    >    >  * "unknown load command required for execution" error and refuse to
>    >    > use the
>    >    >  * image.  Other load commands without this bit that are not
>    >    > understood will
>    >    >  * simply be ignored.
>    >    >  */
>    >    > #define LC_REQ_DYLD 0x80000000
>    >    >
>    >    > /* Constants for the cmd field of all load commands, the type */
>    >    > #define    LC_SEGMENT    0x1    /* segment of this file to be 
> mapped */
>    >    > #define    LC_SYMTAB    0x2    /* link-edit stab symbol table info 
> */
>    >    > #define    LC_SYMSEG    0x3    /* link-edit gdb symbol table info
>    >    > (obsolete) */
>    >    > #define    LC_THREAD    0x4    /* thread */
>    >    > #define    LC_UNIXTHREAD    0x5    /* unix thread (includes a 
> stack) */
>    >    > #define    LC_LOADFVMLIB    0x6    /* load a specified fixed VM 
> shared
>    >    > library */
>    >    > #define    LC_IDFVMLIB    0x7    /* fixed VM shared library
>    >    > identification */
>    >    > #define    LC_IDENT    0x8    /* object identification info 
> (obsolete) */
>    >    > #define LC_FVMFILE    0x9    /* fixed VM file inclusion (internal 
> use) */
>    >    > #define LC_PREPAGE      0xa     /* prepage command (internal use) */
>    >    > #define    LC_DYSYMTAB    0xb    /* dynamic link-edit symbol table 
> info */
>    >    > #define    LC_LOAD_DYLIB    0xc    /* load a dynamically linked 
> shared
>    >    > library */
>    >    > #define    LC_ID_DYLIB    0xd    /* dynamically linked shared lib 
> ident */
>    >    > #define LC_LOAD_DYLINKER 0xe    /* load a dynamic linker */
>    >    > #define LC_ID_DYLINKER    0xf    /* dynamic linker identification */
>    >    > #define    LC_PREBOUND_DYLIB 0x10    /* modules prebound for a
>    >    > dynamically */
>    >    >                 /*  linked shared library */
>    >    > #define    LC_ROUTINES    0x11    /* image routines */
>    >    > #define    LC_SUB_FRAMEWORK 0x12    /* sub framework */
>    >    > #define    LC_SUB_UMBRELLA 0x13    /* sub umbrella */
>    >    > #define    LC_SUB_CLIENT    0x14    /* sub client */
>    >    > #define    LC_SUB_LIBRARY  0x15    /* sub library */
>    >    > #define    LC_TWOLEVEL_HINTS 0x16    /* two-level namespace lookup 
> hints */
>    >    > #define    LC_PREBIND_CKSUM  0x17    /* prebind checksum */
>    >    >
>    >    > /*
>    >    >  * load a dynamically linked shared library that is allowed to be 
> missing
>    >    >  * (all symbols are weak imported).
>    >    >  */
>    >    > #define    LC_LOAD_WEAK_DYLIB (0x18 | LC_REQ_DYLD)
>    >    >
>    >    > #define    LC_SEGMENT_64    0x19    /* 64-bit segment of this file 
> to be
>    >    >                    mapped */
>    >    > #define    LC_ROUTINES_64    0x1a    /* 64-bit image routines */
>    >    > #define LC_UUID        0x1b    /* the uuid */
>    >    > #define LC_RPATH       (0x1c | LC_REQ_DYLD)    /* runpath additions 
> */
>    >    > #define LC_CODE_SIGNATURE 0x1d    /* local of code signature */
>    >    > #define LC_SEGMENT_SPLIT_INFO 0x1e /* local of info to split 
> segments */
>    >    > #define LC_REEXPORT_DYLIB (0x1f | LC_REQ_DYLD) /* load and re-export
>    >    > dylib */
>    >    > #define    LC_LAZY_LOAD_DYLIB 0x20    /* delay load of dylib until
>    >    > first use */
>    >    > #define    LC_ENCRYPTION_INFO 0x21    /* encrypted segment 
> information */
>    >    > #define    LC_DYLD_INFO     0x22    /* compressed dyld information 
> */
>    >    > #define    LC_DYLD_INFO_ONLY (0x22|LC_REQ_DYLD)    /* compressed 
> dyld
>    >    > information only */
>    >    >
>    >    > /*
>    >    >  * A variable length string in a load command is represented by an 
> lc_str
>    >    >  * union.  The strings are stored just after the load command 
> structure and
>    >    >  * the offset is from the start of the load command structure.  The 
> size
>    >    >  * of the string is reflected in the cmdsize field of the load 
> command.
>    >    >  * Once again any padded bytes to bring the cmdsize field to a 
> multiple
>    >    >  * of 4 bytes must be zero.
>    >    >  */
>    >    > union lc_str {
>    >    >     uint32_t    offset;    /* offset to the string */
>    >    > #ifndef __LP64__
>    >    >     char        *ptr;    /* pointer to the string */
>    >    > #endif
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The segment load command indicates that a part of this file is 
> to be
>    >    >  * mapped into the task's address space.  The size of this segment 
> in
>    >    > memory,
>    >    >  * vmsize, maybe equal to or larger than the amount to map from 
> this file,
>    >    >  * filesize.  The file is mapped starting at fileoff to the 
> beginning of
>    >    >  * the segment in memory, vmaddr.  The rest of the memory of the 
> segment,
>    >    >  * if any, is allocated zero fill on demand.  The segment's maximum 
> virtual
>    >    >  * memory protection and initial virtual memory protection are 
> specified
>    >    >  * by the maxprot and initprot fields.  If the segment has sections
>    >    > then the
>    >    >  * section structures directly follow the segment command and their 
> size is
>    >    >  * reflected in cmdsize.
>    >    >  */
>    >    > struct segment_command { /* for 32-bit architectures */
>    >    >     uint32_t    cmd;        /* LC_SEGMENT */
>    >    >     uint32_t    cmdsize;    /* includes sizeof section structs */
>    >    >     char        segname[16];    /* segment name */
>    >    >     uint32_t    vmaddr;        /* memory address of this segment */
>    >    >     uint32_t    vmsize;        /* memory size of this segment */
>    >    >     uint32_t    fileoff;    /* file offset of this segment */
>    >    >     uint32_t    filesize;    /* amount to map from the file */
>    >    >     vm_prot_t    maxprot;    /* maximum VM protection */
>    >    >     vm_prot_t    initprot;    /* initial VM protection */
>    >    >     uint32_t    nsects;        /* number of sections in segment */
>    >    >     uint32_t    flags;        /* flags */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The 64-bit segment load command indicates that a part of this 
> file
>    >    > is to be
>    >    >  * mapped into a 64-bit task's address space.  If the 64-bit 
> segment has
>    >    >  * sections then section_64 structures directly follow the 64-bit 
> segment
>    >    >  * command and their size is reflected in cmdsize.
>    >    >  */
>    >    > struct segment_command_64 { /* for 64-bit architectures */
>    >    >     uint32_t    cmd;        /* LC_SEGMENT_64 */
>    >    >     uint32_t    cmdsize;    /* includes sizeof section_64 structs */
>    >    >     char        segname[16];    /* segment name */
>    >    >     uint64_t    vmaddr;        /* memory address of this segment */
>    >    >     uint64_t    vmsize;        /* memory size of this segment */
>    >    >     uint64_t    fileoff;    /* file offset of this segment */
>    >    >     uint64_t    filesize;    /* amount to map from the file */
>    >    >     vm_prot_t    maxprot;    /* maximum VM protection */
>    >    >     vm_prot_t    initprot;    /* initial VM protection */
>    >    >     uint32_t    nsects;        /* number of sections in segment */
>    >    >     uint32_t    flags;        /* flags */
>    >    > };
>    >    >
>    >    > /* Constants for the flags field of the segment_command */
>    >    > #define    SG_HIGHVM    0x1    /* the file contents for this 
> segment is for
>    >    >                    the high part of the VM space, the low part
>    >    >                    is zero filled (for stacks in core files) */
>    >    > #define    SG_FVMLIB    0x2    /* this segment is the VM that is
>    >    > allocated by
>    >    >                    a fixed VM library, for overlap checking in
>    >    >                    the link editor */
>    >    > #define    SG_NORELOC    0x4    /* this segment has nothing that was
>    >    > relocated
>    >    >                    in it and nothing relocated to it, that is
>    >    >                    it maybe safely replaced without relocation*/
>    >    > #define SG_PROTECTED_VERSION_1    0x8 /* This segment is protected. 
>  If the
>    >    >                        segment starts at file offset 0, the
>    >    >                        first page of the segment is not
>    >    >                        protected.  All other pages of the
>    >    >                        segment are protected. */
>    >    >
>    >    > /*
>    >    >  * A segment is made up of zero or more sections.  Non-MH_OBJECT 
> files have
>    >    >  * all of their segments with the proper sections in each, and 
> padded
>    >    > to the
>    >    >  * specified segment alignment when produced by the link editor.  
> The first
>    >    >  * segment of a MH_EXECUTE and MH_FVMLIB format file contains the
>    >    > mach_header
>    >    >  * and load commands of the object file before its first section.  
> The zero
>    >    >  * fill sections are always last in their segment (in all formats). 
>  This
>    >    >  * allows the zeroed segment padding to be mapped into memory where
>    >    > zero fill
>    >    >  * sections might be. The gigabyte zero fill sections, those with 
> the
>    >    > section
>    >    >  * type S_GB_ZEROFILL, can only be in a segment with sections of 
> this type.
>    >    >  * These segments are then placed after all other segments.
>    >    >  *
>    >    >  * The MH_OBJECT format has all of its sections in one segment for
>    >    >  * compactness.  There is no padding to a specified segment boundary
>    >    > and the
>    >    >  * mach_header and load commands are not part of the segment.
>    >    >  *
>    >    >  * Sections with the same section name, sectname, going into the 
> same
>    >    > segment,
>    >    >  * segname, are combined by the link editor.  The resulting section 
> is
>    >    > aligned
>    >    >  * to the maximum alignment of the combined sections and is the new
>    >    > section's
>    >    >  * alignment.  The combined sections are aligned to their original
>    >    > alignment in
>    >    >  * the combined section.  Any padded bytes to get the specified
>    >    > alignment are
>    >    >  * zeroed.
>    >    >  *
>    >    >  * The format of the relocation entries referenced by the reloff 
> and nreloc
>    >    >  * fields of the section structure for mach object files is 
> described
>    >    > in the
>    >    >  * header file <reloc.h>.
>    >    >  */
>    >    > struct section { /* for 32-bit architectures */
>    >    >     char        sectname[16];    /* name of this section */
>    >    >     char        segname[16];    /* segment this section goes in */
>    >    >     uint32_t    addr;        /* memory address of this section */
>    >    >     uint32_t    size;        /* size in bytes of this section */
>    >    >     uint32_t    offset;        /* file offset of this section */
>    >    >     uint32_t    align;        /* section alignment (power of 2) */
>    >    >     uint32_t    reloff;        /* file offset of relocation entries 
> */
>    >    >     uint32_t    nreloc;        /* number of relocation entries */
>    >    >     uint32_t    flags;        /* flags (section type and 
> attributes)*/
>    >    >     uint32_t    reserved1;    /* reserved (for offset or index) */
>    >    >     uint32_t    reserved2;    /* reserved (for count or sizeof) */
>    >    > };
>    >    >
>    >    > struct section_64 { /* for 64-bit architectures */
>    >    >     char        sectname[16];    /* name of this section */
>    >    >     char        segname[16];    /* segment this section goes in */
>    >    >     uint64_t    addr;        /* memory address of this section */
>    >    >     uint64_t    size;        /* size in bytes of this section */
>    >    >     uint32_t    offset;        /* file offset of this section */
>    >    >     uint32_t    align;        /* section alignment (power of 2) */
>    >    >     uint32_t    reloff;        /* file offset of relocation entries 
> */
>    >    >     uint32_t    nreloc;        /* number of relocation entries */
>    >    >     uint32_t    flags;        /* flags (section type and 
> attributes)*/
>    >    >     uint32_t    reserved1;    /* reserved (for offset or index) */
>    >    >     uint32_t    reserved2;    /* reserved (for count or sizeof) */
>    >    >     uint32_t    reserved3;    /* reserved */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The flags field of a section structure is separated into two 
> parts
>    >    > a section
>    >    >  * type and section attributes.  The section types are mutually
>    >    > exclusive (it
>    >    >  * can only have one type) but the section attributes are not (it 
> may
>    >    > have more
>    >    >  * than one attribute).
>    >    >  */
>    >    > #define SECTION_TYPE         0x000000ff    /* 256 section types */
>    >    > #define SECTION_ATTRIBUTES     0xffffff00    /*  24 section 
> attributes */
>    >    >
>    >    > /* Constants for the type of a section */
>    >    > #define    S_REGULAR        0x0    /* regular section */
>    >    > #define    S_ZEROFILL        0x1    /* zero fill on demand section 
> */
>    >    > #define    S_CSTRING_LITERALS    0x2    /* section with only 
> literal C
>    >    > strings*/
>    >    > #define    S_4BYTE_LITERALS    0x3    /* section with only 4 byte
>    >    > literals */
>    >    > #define    S_8BYTE_LITERALS    0x4    /* section with only 8 byte
>    >    > literals */
>    >    > #define    S_LITERAL_POINTERS    0x5    /* section with only 
> pointers to */
>    >    >                     /*  literals */
>    >    > /*
>    >    >  * For the two types of symbol pointers sections and the symbol 
> stubs
>    >    > section
>    >    >  * they have indirect symbol table entries.  For each of the 
> entries in the
>    >    >  * section the indirect symbol table entries, in corresponding 
> order in the
>    >    >  * indirect symbol table, start at the index stored in the 
> reserved1 field
>    >    >  * of the section structure.  Since the indirect symbol table 
> entries
>    >    >  * correspond to the entries in the section the number of indirect
>    >    > symbol table
>    >    >  * entries is inferred from the size of the section divided by the
>    >    > size of the
>    >    >  * entries in the section.  For symbol pointers sections the size of
>    >    > the entries
>    >    >  * in the section is 4 bytes and for symbol stubs sections the byte
>    >    > size of the
>    >    >  * stubs is stored in the reserved2 field of the section structure.
>    >    >  */
>    >    > #define    S_NON_LAZY_SYMBOL_POINTERS    0x6    /* section with only
>    >    > non-lazy
>    >    >                            symbol pointers */
>    >    > #define    S_LAZY_SYMBOL_POINTERS        0x7    /* section with only
>    >    > lazy symbol
>    >    >                            pointers */
>    >    > #define    S_SYMBOL_STUBS            0x8    /* section with only 
> symbol
>    >    >                            stubs, byte size of stub in
>    >    >                            the reserved2 field */
>    >    > #define    S_MOD_INIT_FUNC_POINTERS    0x9    /* section with only 
> function
>    >    >                            pointers for initialization*/
>    >    > #define    S_MOD_TERM_FUNC_POINTERS    0xa    /* section with only 
> function
>    >    >                            pointers for termination */
>    >    > #define    S_COALESCED            0xb    /* section contains 
> symbols that
>    >    >                            are to be coalesced */
>    >    > #define    S_GB_ZEROFILL            0xc    /* zero fill on demand 
> section
>    >    >                            (that can be larger than 4
>    >    >                            gigabytes) */
>    >    > #define    S_INTERPOSING            0xd    /* section with only 
> pairs of
>    >    >                            function pointers for
>    >    >                            interposing */
>    >    > #define    S_16BYTE_LITERALS        0xe    /* section with only 16 
> byte
>    >    >                            literals */
>    >    > #define    S_DTRACE_DOF            0xf    /* section contains
>    >    >                            DTrace Object Format */
>    >    > #define    S_LAZY_DYLIB_SYMBOL_POINTERS    0x10    /* section with 
> only lazy
>    >    >                            symbol pointers to lazy
>    >    >                            loaded dylibs */
>    >    > /*
>    >    >  * Constants for the section attributes part of the flags field of a
>    >    > section
>    >    >  * structure.
>    >    >  */
>    >    > #define SECTION_ATTRIBUTES_USR     0xff000000    /* User setable
>    >    > attributes */
>    >    > #define S_ATTR_PURE_INSTRUCTIONS 0x80000000    /* section contains 
> only true
>    >    >                            machine instructions */
>    >    > #define S_ATTR_NO_TOC          0x40000000    /* section contains 
> coalesced
>    >    >                            symbols that are not to be
>    >    >                            in a ranlib table of
>    >    >                            contents */
>    >    > #define S_ATTR_STRIP_STATIC_SYMS 0x20000000    /* ok to strip 
> static symbols
>    >    >                            in this section in files
>    >    >                            with the MH_DYLDLINK flag */
>    >    > #define S_ATTR_NO_DEAD_STRIP     0x10000000    /* no dead stripping 
> */
>    >    > #define S_ATTR_LIVE_SUPPORT     0x08000000    /* blocks are live if 
> they
>    >    >                            reference live blocks */
>    >    > #define S_ATTR_SELF_MODIFYING_CODE 0x04000000    /* Used with i386
>    >    > code stubs
>    >    >                            written on by dyld */
>    >    > /*
>    >    >  * If a segment contains any sections marked with S_ATTR_DEBUG then 
> all
>    >    >  * sections in that segment must have this attribute.  No section
>    >    > other than
>    >    >  * a section marked with this attribute may reference the contents 
> of this
>    >    >  * section.  A section with this attribute may contain no symbols 
> and
>    >    > must have
>    >    >  * a section type S_REGULAR.  The static linker will not copy 
> section
>    >    > contents
>    >    >  * from sections with this attribute into its output file.  These 
> sections
>    >    >  * generally contain DWARF debugging info.
>    >    >  */
>    >    > #define    S_ATTR_DEBUG         0x02000000    /* a debug section */
>    >    > #define SECTION_ATTRIBUTES_SYS     0x00ffff00    /* system setable
>    >    > attributes */
>    >    > #define S_ATTR_SOME_INSTRUCTIONS 0x00000400    /* section contains 
> some
>    >    >                            machine instructions */
>    >    > #define S_ATTR_EXT_RELOC     0x00000200    /* section has external
>    >    >                            relocation entries */
>    >    > #define S_ATTR_LOC_RELOC     0x00000100    /* section has local
>    >    >                            relocation entries */
>    >    >
>    >    >
>    >    > /*
>    >    >  * The names of segments and sections in them are mostly 
> meaningless to the
>    >    >  * link-editor.  But there are few things to support traditional 
> UNIX
>    >    >  * executables that require the link-editor and assembler to use 
> some names
>    >    >  * agreed upon by convention.
>    >    >  *
>    >    >  * The initial protection of the "__TEXT" segment has write 
> protection
>    >    > turned
>    >    >  * off (not writeable).
>    >    >  *
>    >    >  * The link-editor will allocate common symbols at the end of the
>    >    > "__common"
>    >    >  * section in the "__DATA" segment.  It will create the section and 
> segment
>    >    >  * if needed.
>    >    >  */
>    >    >
>    >    > /* The currently known segment names and the section names in those
>    >    > segments */
>    >    >
>    >    > #define    SEG_PAGEZERO    "__PAGEZERO"    /* the pagezero segment
>    >    > which has no */
>    >    >                     /* protections and catches NULL */
>    >    >                     /* references for MH_EXECUTE files */
>    >    >
>    >    >
>    >    > #define    SEG_TEXT    "__TEXT"    /* the tradition UNIX text 
> segment */
>    >    > #define    SECT_TEXT    "__text"    /* the real text part of the 
> text */
>    >    >                     /* section no headers, and no padding */
>    >    > #define SECT_FVMLIB_INIT0 "__fvmlib_init0"    /* the fvmlib
>    >    > initialization */
>    >    >                         /*  section */
>    >    > #define SECT_FVMLIB_INIT1 "__fvmlib_init1"    /* the section 
> following
>    >    > the */
>    >    >                             /*  fvmlib initialization */
>    >    >                         /*  section */
>    >    >
>    >    > #define    SEG_DATA    "__DATA"    /* the tradition UNIX data 
> segment */
>    >    > #define    SECT_DATA    "__data"    /* the real initialized data 
> section */
>    >    >                     /* no padding, no bss overlap */
>    >    > #define    SECT_BSS    "__bss"        /* the real uninitialized data
>    >    > section*/
>    >    >                     /* no padding */
>    >    > #define SECT_COMMON    "__common"    /* the section common symbols 
> are */
>    >    >                     /* allocated in by the link editor */
>    >    >
>    >    > #define    SEG_OBJC    "__OBJC"    /* objective-C runtime segment */
>    >    > #define SECT_OBJC_SYMBOLS "__symbol_table"    /* symbol table */
>    >    > #define SECT_OBJC_MODULES "__module_info"    /* module information 
> */
>    >    > #define SECT_OBJC_STRINGS "__selector_strs"    /* string table */
>    >    > #define SECT_OBJC_REFS "__selector_refs"    /* string table */
>    >    >
>    >    > #define    SEG_ICON     "__ICON"    /* the icon segment */
>    >    > #define    SECT_ICON_HEADER "__header"    /* the icon headers */
>    >    > #define    SECT_ICON_TIFF   "__tiff"    /* the icons in tiff format 
> */
>    >    >
>    >    > #define    SEG_LINKEDIT    "__LINKEDIT"    /* the segment containing
>    >    > all structs */
>    >    >                     /* created and maintained by the link */
>    >    >                     /* editor.  Created with -seglinkedit */
>    >    >                     /* option to ld(1) for MH_EXECUTE and */
>    >    >                     /* FVMLIB file types only */
>    >    >
>    >    > #define SEG_UNIXSTACK    "__UNIXSTACK"    /* the unix stack segment 
> */
>    >    >
>    >    > #define SEG_IMPORT    "__IMPORT"    /* the segment for the self 
> (dyld) */
>    >    >                     /* modifing code stubs that has read, */
>    >    >                     /* write and execute permissions */
>    >    >
>    >    > /*
>    >    >  * Fixed virtual memory shared libraries are identified by two 
> things.  The
>    >    >  * target pathname (the name of the library as found for execution),
>    >    > and the
>    >    >  * minor version number.  The address of where the headers are 
> loaded is in
>    >    >  * header_addr. (THIS IS OBSOLETE and no longer supported).
>    >    >  */
>    >    > struct fvmlib {
>    >    >     union lc_str    name;        /* library's target pathname */
>    >    >     uint32_t    minor_version;    /* library's minor version number 
> */
>    >    >     uint32_t    header_addr;    /* library's header address */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * A fixed virtual shared library (filetype == MH_FVMLIB in the mach
>    >    > header)
>    >    >  * contains a fvmlib_command (cmd == LC_IDFVMLIB) to identify the 
> library.
>    >    >  * An object that uses a fixed virtual shared library also contains 
> a
>    >    >  * fvmlib_command (cmd == LC_LOADFVMLIB) for each library it uses.
>    >    >  * (THIS IS OBSOLETE and no longer supported).
>    >    >  */
>    >    > struct fvmlib_command {
>    >    >     uint32_t    cmd;        /* LC_IDFVMLIB or LC_LOADFVMLIB */
>    >    >     uint32_t    cmdsize;    /* includes pathname string */
>    >    >     struct fvmlib    fvmlib;        /* the library identification */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * Dynamicly linked shared libraries are identified by two things.  
> The
>    >    >  * pathname (the name of the library as found for execution), and 
> the
>    >    >  * compatibility version number.  The pathname must match and the
>    >    > compatibility
>    >    >  * number in the user of the library must be greater than or equal 
> to the
>    >    >  * library being used.  The time stamp is used to record the time a
>    >    > library was
>    >    >  * built and copied into user so it can be use to determined if the
>    >    > library used
>    >    >  * at runtime is exactly the same as used to built the program.
>    >    >  */
>    >    > struct dylib {
>    >    >     union lc_str  name;            /* library's path name */
>    >    >     uint32_t timestamp;            /* library's build time stamp */
>    >    >     uint32_t current_version;        /* library's current version 
> number */
>    >    >     uint32_t compatibility_version;    /* library's compatibility 
> vers
>    >    > number*/
>    >    > };
>    >    >
>    >    > /*
>    >    >  * A dynamically linked shared library (filetype == MH_DYLIB in the
>    >    > mach header)
>    >    >  * contains a dylib_command (cmd == LC_ID_DYLIB) to identify the 
> library.
>    >    >  * An object that uses a dynamically linked shared library also 
> contains a
>    >    >  * dylib_command (cmd == LC_LOAD_DYLIB, LC_LOAD_WEAK_DYLIB, or
>    >    >  * LC_REEXPORT_DYLIB) for each library it uses.
>    >    >  */
>    >    > struct dylib_command {
>    >    >     uint32_t    cmd;        /* LC_ID_DYLIB, LC_LOAD_{,WEAK_}DYLIB,
>    >    >                        LC_REEXPORT_DYLIB */
>    >    >     uint32_t    cmdsize;    /* includes pathname string */
>    >    >     struct dylib    dylib;        /* the library identification */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * A dynamically linked shared library may be a subframework of an 
> umbrella
>    >    >  * framework.  If so it will be linked with "-umbrella 
> umbrella_name" where
>    >    >  * Where "umbrella_name" is the name of the umbrella framework. A
>    >    > subframework
>    >    >  * can only be linked against by its umbrella framework or other
>    >    > subframeworks
>    >    >  * that are part of the same umbrella framework.  Otherwise the 
> static link
>    >    >  * editor produces an error and states to link against the umbrella
>    >    > framework.
>    >    >  * The name of the umbrella framework for subframeworks is recorded 
> in the
>    >    >  * following structure.
>    >    >  */
>    >    > struct sub_framework_command {
>    >    >     uint32_t    cmd;        /* LC_SUB_FRAMEWORK */
>    >    >     uint32_t    cmdsize;    /* includes umbrella string */
>    >    >     union lc_str     umbrella;    /* the umbrella framework name */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * For dynamically linked shared libraries that are subframework of 
> an
>    >    > umbrella
>    >    >  * framework they can allow clients other than the umbrella 
> framework
>    >    > or other
>    >    >  * subframeworks in the same umbrella framework.  To do this the
>    >    > subframework
>    >    >  * is built with "-allowable_client client_name" and an 
> LC_SUB_CLIENT load
>    >    >  * command is created for each -allowable_client flag.  The 
> client_name is
>    >    >  * usually a framework name.  It can also be a name used for bundles
>    >    > clients
>    >    >  * where the bundle is built with "-client_name client_name".
>    >    >  */
>    >    > struct sub_client_command {
>    >    >     uint32_t    cmd;        /* LC_SUB_CLIENT */
>    >    >     uint32_t    cmdsize;    /* includes client string */
>    >    >     union lc_str     client;        /* the client name */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * A dynamically linked shared library may be a sub_umbrella of an 
> umbrella
>    >    >  * framework.  If so it will be linked with "-sub_umbrella
>    >    > umbrella_name" where
>    >    >  * Where "umbrella_name" is the name of the sub_umbrella framework. 
>  When
>    >    >  * staticly linking when -twolevel_namespace is in effect a twolevel
>    >    > namespace
>    >    >  * umbrella framework will only cause its subframeworks and those
>    >    > frameworks
>    >    >  * listed as sub_umbrella frameworks to be implicited linked in.  
> Any other
>    >    >  * dependent dynamic libraries will not be linked it when
>    >    > -twolevel_namespace
>    >    >  * is in effect.  The primary library recorded by the static linker 
> when
>    >    >  * resolving a symbol in these libraries will be the umbrella 
> framework.
>    >    >  * Zero or more sub_umbrella frameworks may be use by an umbrella
>    >    > framework.
>    >    >  * The name of a sub_umbrella framework is recorded in the following
>    >    > structure.
>    >    >  */
>    >    > struct sub_umbrella_command {
>    >    >     uint32_t    cmd;        /* LC_SUB_UMBRELLA */
>    >    >     uint32_t    cmdsize;    /* includes sub_umbrella string */
>    >    >     union lc_str     sub_umbrella;    /* the sub_umbrella framework 
> name */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * A dynamically linked shared library may be a sub_library of 
> another
>    >    > shared
>    >    >  * library.  If so it will be linked with "-sub_library 
> library_name" where
>    >    >  * Where "library_name" is the name of the sub_library shared 
> library.
>    >    > When
>    >    >  * staticly linking when -twolevel_namespace is in effect a twolevel
>    >    > namespace
>    >    >  * shared library will only cause its subframeworks and those 
> frameworks
>    >    >  * listed as sub_umbrella frameworks and libraries listed as
>    >    > sub_libraries to
>    >    >  * be implicited linked in.  Any other dependent dynamic libraries
>    >    > will not be
>    >    >  * linked it when -twolevel_namespace is in effect.  The primary 
> library
>    >    >  * recorded by the static linker when resolving a symbol in these 
> libraries
>    >    >  * will be the umbrella framework (or dynamic library). Zero or more
>    >    > sub_library
>    >    >  * shared libraries may be use by an umbrella framework or (or 
> dynamic
>    >    > library).
>    >    >  * The name of a sub_library framework is recorded in the following
>    >    > structure.
>    >    >  * For example /usr/lib/libobjc_profile.A.dylib would be recorded as
>    >    > "libobjc".
>    >    >  */
>    >    > struct sub_library_command {
>    >    >     uint32_t    cmd;        /* LC_SUB_LIBRARY */
>    >    >     uint32_t    cmdsize;    /* includes sub_library string */
>    >    >     union lc_str     sub_library;    /* the sub_library name */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * A program (filetype == MH_EXECUTE) that is
>    >    >  * prebound to its dynamic libraries has one of these for each 
> library that
>    >    >  * the static linker used in prebinding.  It contains a bit vector 
> for the
>    >    >  * modules in the library.  The bits indicate which modules are 
> bound
>    >    > (1) and
>    >    >  * which are not (0) from the library.  The bit for module 0 is the 
> low bit
>    >    >  * of the first byte.  So the bit for the Nth module is:
>    >    >  * (linked_modules[N/8] >> N%8) & 1
>    >    >  */
>    >    > struct prebound_dylib_command {
>    >    >     uint32_t    cmd;        /* LC_PREBOUND_DYLIB */
>    >    >     uint32_t    cmdsize;    /* includes strings */
>    >    >     union lc_str    name;        /* library's path name */
>    >    >     uint32_t    nmodules;    /* number of modules in library */
>    >    >     union lc_str    linked_modules;    /* bit vector of linked 
> modules */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * A program that uses a dynamic linker contains a dylinker_command 
> to
>    >    > identify
>    >    >  * the name of the dynamic linker (LC_LOAD_DYLINKER).  And a 
> dynamic linker
>    >    >  * contains a dylinker_command to identify the dynamic linker
>    >    > (LC_ID_DYLINKER).
>    >    >  * A file can have at most one of these.
>    >    >  */
>    >    > struct dylinker_command {
>    >    >     uint32_t    cmd;        /* LC_ID_DYLINKER or LC_LOAD_DYLINKER */
>    >    >     uint32_t    cmdsize;    /* includes pathname string */
>    >    >     union lc_str    name;        /* dynamic linker's path name */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * Thread commands contain machine-specific data structures 
> suitable for
>    >    >  * use in the thread state primitives.  The machine specific data
>    >    > structures
>    >    >  * follow the struct thread_command as follows.
>    >    >  * Each flavor of machine specific data structure is preceded by an
>    >    > unsigned
>    >    >  * long constant for the flavor of that data structure, an uint32_t
>    >    >  * that is the count of longs of the size of the state data 
> structure
>    >    > and then
>    >    >  * the state data structure follows.  This triple may be repeated 
> for many
>    >    >  * flavors.  The constants for the flavors, counts and state data 
> structure
>    >    >  * definitions are expected to be in the header file
>    >    > <machine/thread_status.h>.
>    >    >  * These machine specific data structures sizes must be multiples of
>    >    >  * 4 bytes  The cmdsize reflects the total size of the 
> thread_command
>    >    >  * and all of the sizes of the constants for the flavors, counts 
> and state
>    >    >  * data structures.
>    >    >  *
>    >    >  * For executable objects that are unix processes there will be one
>    >    >  * thread_command (cmd == LC_UNIXTHREAD) created for it by the 
> link-editor.
>    >    >  * This is the same as a LC_THREAD, except that a stack is 
> automatically
>    >    >  * created (based on the shell's limit for the stack size).  Command
>    >    > arguments
>    >    >  * and environment variables are copied onto that stack.
>    >    >  */
>    >    > struct thread_command {
>    >    >     uint32_t    cmd;        /* LC_THREAD or  LC_UNIXTHREAD */
>    >    >     uint32_t    cmdsize;    /* total size of this command */
>    >    >     /* uint32_t flavor           flavor of thread state */
>    >    >     /* uint32_t count           count of longs in thread state */
>    >    >     /* struct XXX_thread_state state   thread state for this flavor 
> */
>    >    >     /* ... */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The routines command contains the address of the dynamic shared 
> library
>    >    >  * initialization routine and an index into the module table for 
> the module
>    >    >  * that defines the routine.  Before any modules are used from the
>    >    > library the
>    >    >  * dynamic linker fully binds the module that defines the
>    >    > initialization routine
>    >    >  * and then calls it.  This gets called before any module 
> initialization
>    >    >  * routines (used for C++ static constructors) in the library.
>    >    >  */
>    >    > struct routines_command { /* for 32-bit architectures */
>    >    >     uint32_t    cmd;        /* LC_ROUTINES */
>    >    >     uint32_t    cmdsize;    /* total size of this command */
>    >    >     uint32_t    init_address;    /* address of initialization 
> routine */
>    >    >     uint32_t    init_module;    /* index into the module table that 
> */
>    >    >                         /*  the init routine is defined in */
>    >    >     uint32_t    reserved1;
>    >    >     uint32_t    reserved2;
>    >    >     uint32_t    reserved3;
>    >    >     uint32_t    reserved4;
>    >    >     uint32_t    reserved5;
>    >    >     uint32_t    reserved6;
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The 64-bit routines command.  Same use as above.
>    >    >  */
>    >    > struct routines_command_64 { /* for 64-bit architectures */
>    >    >     uint32_t    cmd;        /* LC_ROUTINES_64 */
>    >    >     uint32_t    cmdsize;    /* total size of this command */
>    >    >     uint64_t    init_address;    /* address of initialization 
> routine */
>    >    >     uint64_t    init_module;    /* index into the module table that 
> */
>    >    >                     /*  the init routine is defined in */
>    >    >     uint64_t    reserved1;
>    >    >     uint64_t    reserved2;
>    >    >     uint64_t    reserved3;
>    >    >     uint64_t    reserved4;
>    >    >     uint64_t    reserved5;
>    >    >     uint64_t    reserved6;
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The symtab_command contains the offsets and sizes of the 
> link-edit
>    >    > 4.3BSD
>    >    >  * "stab" style symbol table information as described in the header 
> files
>    >    >  * <nlist.h> and <stab.h>.
>    >    >  */
>    >    > struct symtab_command {
>    >    >     uint32_t    cmd;        /* LC_SYMTAB */
>    >    >     uint32_t    cmdsize;    /* sizeof(struct symtab_command) */
>    >    >     uint32_t    symoff;        /* symbol table offset */
>    >    >     uint32_t    nsyms;        /* number of symbol table entries */
>    >    >     uint32_t    stroff;        /* string table offset */
>    >    >     uint32_t    strsize;    /* string table size in bytes */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * This is the second set of the symbolic information which is used 
> to
>    >    > support
>    >    >  * the data structures for the dynamically link editor.
>    >    >  *
>    >    >  * The original set of symbolic information in the symtab_command
>    >    > which contains
>    >    >  * the symbol and string tables must also be present when this load
>    >    > command is
>    >    >  * present.  When this load command is present the symbol table is
>    >    > organized
>    >    >  * into three groups of symbols:
>    >    >  *    local symbols (static and debugging symbols) - grouped by 
> module
>    >    >  *    defined external symbols - grouped by module (sorted by name 
> if
>    >    > not lib)
>    >    >  *    undefined external symbols (sorted by name if MH_BINDATLOAD is
>    >    > not set,
>    >    >  *                         and in order the were seen by the static
>    >    >  *                    linker if MH_BINDATLOAD is set)
>    >    >  * In this load command there are offsets and counts to each of the
>    >    > three groups
>    >    >  * of symbols.
>    >    >  *
>    >    >  * This load command contains a the offsets and sizes of the 
> following new
>    >    >  * symbolic information tables:
>    >    >  *    table of contents
>    >    >  *    module table
>    >    >  *    reference symbol table
>    >    >  *    indirect symbol table
>    >    >  * The first three tables above (the table of contents, module 
> table and
>    >    >  * reference symbol table) are only present if the file is a
>    >    > dynamically linked
>    >    >  * shared library.  For executable and object modules, which are 
> files
>    >    >  * containing only one module, the information that would be in 
> these three
>    >    >  * tables is determined as follows:
>    >    >  *     table of contents - the defined external symbols are sorted 
> by name
>    >    >  *    module table - the file contains only one module so 
> everything in the
>    >    >  *               file is part of the module.
>    >    >  *    reference symbol table - is the defined and undefined external
>    >    > symbols
>    >    >  *
>    >    >  * For dynamically linked shared library files this load command 
> also
>    >    > contains
>    >    >  * offsets and sizes to the pool of relocation entries for all 
> sections
>    >    >  * separated into two groups:
>    >    >  *    external relocation entries
>    >    >  *    local relocation entries
>    >    >  * For executable and object modules the relocation entries continue
>    >    > to hang
>    >    >  * off the section structures.
>    >    >  */
>    >    > struct dysymtab_command {
>    >    >     uint32_t cmd;    /* LC_DYSYMTAB */
>    >    >     uint32_t cmdsize;    /* sizeof(struct dysymtab_command) */
>    >    >
>    >    >     /*
>    >    >      * The symbols indicated by symoff and nsyms of the LC_SYMTAB 
> load
>    >    > command
>    >    >      * are grouped into the following three groups:
>    >    >      *    local symbols (further grouped by the module they are 
> from)
>    >    >      *    defined external symbols (further grouped by the module 
> they
>    >    > are from)
>    >    >      *    undefined symbols
>    >    >      *
>    >    >      * The local symbols are used only for debugging.  The dynamic 
> binding
>    >    >      * process may have to use them to indicate to the debugger the 
> local
>    >    >      * symbols for a module that is being bound.
>    >    >      *
>    >    >      * The last two groups are used by the dynamic binding process 
> to
>    >    > do the
>    >    >      * binding (indirectly through the module table and the 
> reference
>    >    > symbol
>    >    >      * table when this is a dynamically linked shared library file).
>    >    >      */
>    >    >     uint32_t ilocalsym;    /* index to local symbols */
>    >    >     uint32_t nlocalsym;    /* number of local symbols */
>    >    >
>    >    >     uint32_t iextdefsym;/* index to externally defined symbols */
>    >    >     uint32_t nextdefsym;/* number of externally defined symbols */
>    >    >
>    >    >     uint32_t iundefsym;    /* index to undefined symbols */
>    >    >     uint32_t nundefsym;    /* number of undefined symbols */
>    >    >
>    >    >     /*
>    >    >      * For the for the dynamic binding process to find which module 
> a
>    >    > symbol
>    >    >      * is defined in the table of contents is used (analogous to 
> the ranlib
>    >    >      * structure in an archive) which maps defined external symbols 
> to
>    >    > modules
>    >    >      * they are defined in.  This exists only in a dynamically 
> linked
>    >    > shared
>    >    >      * library file.  For executable and object modules the defined
>    >    > external
>    >    >      * symbols are sorted by name and is use as the table of 
> contents.
>    >    >      */
>    >    >     uint32_t tocoff;    /* file offset to table of contents */
>    >    >     uint32_t ntoc;    /* number of entries in table of contents */
>    >    >
>    >    >     /*
>    >    >      * To support dynamic binding of "modules" (whole object files)
>    >    > the symbol
>    >    >      * table must reflect the modules that the file was created 
> from.
>    >    > This is
>    >    >      * done by having a module table that has indexes and counts 
> into
>    >    > the merged
>    >    >      * tables for each module.  The module structure that these two 
> entries
>    >    >      * refer to is described below.  This exists only in a 
> dynamically
>    >    > linked
>    >    >      * shared library file.  For executable and object modules the
>    >    > file only
>    >    >      * contains one module so everything in the file belongs to the 
> module.
>    >    >      */
>    >    >     uint32_t modtaboff;    /* file offset to module table */
>    >    >     uint32_t nmodtab;    /* number of module table entries */
>    >    >
>    >    >     /*
>    >    >      * To support dynamic module binding the module structure for 
> each
>    >    > module
>    >    >      * indicates the external references (defined and undefined) 
> each
>    >    > module
>    >    >      * makes.  For each module there is an offset and a count into 
> the
>    >    >      * reference symbol table for the symbols that the module 
> references.
>    >    >      * This exists only in a dynamically linked shared library 
> file.  For
>    >    >      * executable and object modules the defined external symbols 
> and the
>    >    >      * undefined external symbols indicates the external references.
>    >    >      */
>    >    >     uint32_t extrefsymoff;    /* offset to referenced symbol table 
> */
>    >    >     uint32_t nextrefsyms;    /* number of referenced symbol table
>    >    > entries */
>    >    >
>    >    >     /*
>    >    >      * The sections that contain "symbol pointers" and "routine 
> stubs" have
>    >    >      * indexes and (implied counts based on the size of the section
>    >    > and fixed
>    >    >      * size of the entry) into the "indirect symbol" table for each 
> pointer
>    >    >      * and stub.  For every section of these two types the index 
> into the
>    >    >      * indirect symbol table is stored in the section header in the 
> field
>    >    >      * reserved1.  An indirect symbol table entry is simply a 32bit
>    >    > index into
>    >    >      * the symbol table to the symbol that the pointer or stub is
>    >    > referring to.
>    >    >      * The indirect symbol table is ordered to match the entries in
>    >    > the section.
>    >    >      */
>    >    >     uint32_t indirectsymoff; /* file offset to the indirect symbol 
> table */
>    >    >     uint32_t nindirectsyms;  /* number of indirect symbol table 
> entries */
>    >    >
>    >    >     /*
>    >    >      * To support relocating an individual module in a library file
>    >    > quickly the
>    >    >      * external relocation entries for each module in the library 
> need
>    >    > to be
>    >    >      * accessed efficiently.  Since the relocation entries can't be
>    >    > accessed
>    >    >      * through the section headers for a library file they are
>    >    > separated into
>    >    >      * groups of local and external entries further grouped by 
> module.
>    >    > In this
>    >    >      * case the presents of this load command who's extreloff, 
> nextrel,
>    >    >      * locreloff and nlocrel fields are non-zero indicates that the
>    >    > relocation
>    >    >      * entries of non-merged sections are not referenced through the
>    >    > section
>    >    >      * structures (and the reloff and nreloc fields in the section
>    >    > headers are
>    >    >      * set to zero).
>    >    >      *
>    >    >      * Since the relocation entries are not accessed through the
>    >    > section headers
>    >    >      * this requires the r_address field to be something other than 
> a
>    >    > section
>    >    >      * offset to identify the item to be relocated.  In this case
>    >    > r_address is
>    >    >      * set to the offset from the vmaddr of the first LC_SEGMENT 
> command.
>    >    >      * For MH_SPLIT_SEGS images r_address is set to the the offset 
> from the
>    >    >      * vmaddr of the first read-write LC_SEGMENT command.
>    >    >      *
>    >    >      * The relocation entries are grouped by module and the module 
> table
>    >    >      * entries have indexes and counts into them for the group of 
> external
>    >    >      * relocation entries for that the module.
>    >    >      *
>    >    >      * For sections that are merged across modules there must not 
> be any
>    >    >      * remaining external relocation entries for them (for merged 
> sections
>    >    >      * remaining relocation entries must be local).
>    >    >      */
>    >    >     uint32_t extreloff;    /* offset to external relocation entries 
> */
>    >    >     uint32_t nextrel;    /* number of external relocation entries */
>    >    >
>    >    >     /*
>    >    >      * All the local relocation entries are grouped together (they 
> are not
>    >    >      * grouped by their module since they are only used if the 
> object
>    >    > is moved
>    >    >      * from it staticly link edited address).
>    >    >      */
>    >    >     uint32_t locreloff;    /* offset to local relocation entries */
>    >    >     uint32_t nlocrel;    /* number of local relocation entries */
>    >    >
>    >    > };
>    >    >
>    >    > /*
>    >    >  * An indirect symbol table entry is simply a 32bit index into the
>    >    > symbol table
>    >    >  * to the symbol that the pointer or stub is refering to.  Unless it
>    >    > is for a
>    >    >  * non-lazy symbol pointer section for a defined symbol which 
> strip(1) as
>    >    >  * removed.  In which case it has the value INDIRECT_SYMBOL_LOCAL.  
> If the
>    >    >  * symbol was also absolute INDIRECT_SYMBOL_ABS is or'ed with that.
>    >    >  */
>    >    > #define INDIRECT_SYMBOL_LOCAL    0x80000000
>    >    > #define INDIRECT_SYMBOL_ABS    0x40000000
>    >    >
>    >    >
>    >    > /* a table of contents entry */
>    >    > struct dylib_table_of_contents {
>    >    >     uint32_t symbol_index;    /* the defined external symbol
>    >    >                    (index into the symbol table) */
>    >    >     uint32_t module_index;    /* index into the module table this 
> symbol
>    >    >                    is defined in */
>    >    > };
>    >    >
>    >    > /* a module table entry */
>    >    > struct dylib_module {
>    >    >     uint32_t module_name;    /* the module name (index into string
>    >    > table) */
>    >    >
>    >    >     uint32_t iextdefsym;    /* index into externally defined 
> symbols */
>    >    >     uint32_t nextdefsym;    /* number of externally defined symbols 
> */
>    >    >     uint32_t irefsym;        /* index into reference symbol table */
>    >    >     uint32_t nrefsym;        /* number of reference symbol table 
> entries */
>    >    >     uint32_t ilocalsym;        /* index into symbols for local 
> symbols */
>    >    >     uint32_t nlocalsym;        /* number of local symbols */
>    >    >
>    >    >     uint32_t iextrel;        /* index into external relocation 
> entries */
>    >    >     uint32_t nextrel;        /* number of external relocation 
> entries */
>    >    >
>    >    >     uint32_t iinit_iterm;    /* low 16 bits are the index into the 
> init
>    >    >                    section, high 16 bits are the index into
>    >    >                        the term section */
>    >    >     uint32_t ninit_nterm;    /* low 16 bits are the number of init 
> section
>    >    >                    entries, high 16 bits are the number of
>    >    >                    term section entries */
>    >    >
>    >    >     uint32_t            /* for this module address of the start of 
> */
>    >    >     objc_module_info_addr;  /*  the (__OBJC,__module_info) section 
> */
>    >    >     uint32_t            /* for this module size of */
>    >    >     objc_module_info_size;    /*  the (__OBJC,__module_info) 
> section */
>    >    > };
>    >    >
>    >    > /* a 64-bit module table entry */
>    >    > struct dylib_module_64 {
>    >    >     uint32_t module_name;    /* the module name (index into string
>    >    > table) */
>    >    >
>    >    >     uint32_t iextdefsym;    /* index into externally defined 
> symbols */
>    >    >     uint32_t nextdefsym;    /* number of externally defined symbols 
> */
>    >    >     uint32_t irefsym;        /* index into reference symbol table */
>    >    >     uint32_t nrefsym;        /* number of reference symbol table 
> entries */
>    >    >     uint32_t ilocalsym;        /* index into symbols for local 
> symbols */
>    >    >     uint32_t nlocalsym;        /* number of local symbols */
>    >    >
>    >    >     uint32_t iextrel;        /* index into external relocation 
> entries */
>    >    >     uint32_t nextrel;        /* number of external relocation 
> entries */
>    >    >
>    >    >     uint32_t iinit_iterm;    /* low 16 bits are the index into the 
> init
>    >    >                    section, high 16 bits are the index into
>    >    >                    the term section */
>    >    >     uint32_t ninit_nterm;      /* low 16 bits are the number of init
>    >    > section
>    >    >                   entries, high 16 bits are the number of
>    >    >                   term section entries */
>    >    >
>    >    >     uint32_t            /* for this module size of */
>    >    >         objc_module_info_size;    /*  the (__OBJC,__module_info) 
> section */
>    >    >     uint64_t            /* for this module address of the start of 
> */
>    >    >         objc_module_info_addr;    /*  the (__OBJC,__module_info) 
> section */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The entries in the reference symbol table are used when loading 
> the
>    >    > module
>    >    >  * (both by the static and dynamic link editors) and if the module 
> is
>    >    > unloaded
>    >    >  * or replaced.  Therefore all external symbols (defined and 
> undefined) are
>    >    >  * listed in the module's reference table.  The flags describe the 
> type of
>    >    >  * reference that is being made.  The constants for the flags are
>    >    > defined in
>    >    >  * <mach-o/nlist.h> as they are also used for symbol table entries.
>    >    >  */
>    >    > struct dylib_reference {
>    >    >     uint32_t isym:24,        /* index into the symbol table */
>    >    >               flags:8;    /* flags to indicate the type of 
> reference */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The twolevel_hints_command contains the offset and number of 
> hints
>    >    > in the
>    >    >  * two-level namespace lookup hints table.
>    >    >  */
>    >    > struct twolevel_hints_command {
>    >    >     uint32_t cmd;    /* LC_TWOLEVEL_HINTS */
>    >    >     uint32_t cmdsize;    /* sizeof(struct twolevel_hints_command) */
>    >    >     uint32_t offset;    /* offset to the hint table */
>    >    >     uint32_t nhints;    /* number of hints in the hint table */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The entries in the two-level namespace lookup hints table are
>    >    > twolevel_hint
>    >    >  * structs.  These provide hints to the dynamic link editor where 
> to start
>    >    >  * looking for an undefined symbol in a two-level namespace image.  
> The
>    >    >  * isub_image field is an index into the sub-images (sub-frameworks 
> and
>    >    >  * sub-umbrellas list) that made up the two-level image that the 
> undefined
>    >    >  * symbol was found in when it was built by the static link editor. 
>  If
>    >    >  * isub-image is 0 the the symbol is expected to be defined in 
> library
>    >    > and not
>    >    >  * in the sub-images.  If isub-image is non-zero it is an index into
>    >    > the array
>    >    >  * of sub-images for the umbrella with the first index in the
>    >    > sub-images being
>    >    >  * 1. The array of sub-images is the ordered list of sub-images of 
> the
>    >    > umbrella
>    >    >  * that would be searched for a symbol that has the umbrella 
> recorded
>    >    > as its
>    >    >  * primary library.  The table of contents index is an index into 
> the
>    >    >  * library's table of contents.  This is used as the starting point 
> of the
>    >    >  * binary search or a directed linear search.
>    >    >  */
>    >    > struct twolevel_hint {
>    >    >     uint32_t
>    >    >     isub_image:8,    /* index into the sub images */
>    >    >     itoc:24;    /* index into the table of contents */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The prebind_cksum_command contains the value of the original 
> check
>    >    > sum for
>    >    >  * prebound files or zero.  When a prebound file is first created or
>    >    > modified
>    >    >  * for other than updating its prebinding information the value of 
> the
>    >    > check sum
>    >    >  * is set to zero.  When the file has it prebinding re-done and if 
> the
>    >    > value of
>    >    >  * the check sum is zero the original check sum is calculated and 
> stored in
>    >    >  * cksum field of this load command in the output file.  If when the
>    >    > prebinding
>    >    >  * is re-done and the cksum field is non-zero it is left unchanged 
> from the
>    >    >  * input file.
>    >    >  */
>    >    > struct prebind_cksum_command {
>    >    >     uint32_t cmd;    /* LC_PREBIND_CKSUM */
>    >    >     uint32_t cmdsize;    /* sizeof(struct prebind_cksum_command) */
>    >    >     uint32_t cksum;    /* the check sum or zero */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The uuid load command contains a single 128-bit unique random
>    >    > number that
>    >    >  * identifies an object produced by the static link editor.
>    >    >  */
>    >    > struct uuid_command {
>    >    >     uint32_t    cmd;        /* LC_UUID */
>    >    >     uint32_t    cmdsize;    /* sizeof(struct uuid_command) */
>    >    >     uint8_t    uuid[16];    /* the 128-bit uuid */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The rpath_command contains a path which at runtime should be 
> added to
>    >    >  * the current run path used to find @rpath prefixed dylibs.
>    >    >  */
>    >    > struct rpath_command {
>    >    >     uint32_t     cmd;        /* LC_RPATH */
>    >    >     uint32_t     cmdsize;    /* includes string */
>    >    >     union lc_str path;        /* path to add to run path */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The linkedit_data_command contains the offsets and sizes of a 
> blob
>    >    >  * of data in the __LINKEDIT segment.
>    >    >  */
>    >    > struct linkedit_data_command {
>    >    >     uint32_t    cmd;        /* LC_CODE_SIGNATURE or
>    >    > LC_SEGMENT_SPLIT_INFO */
>    >    >     uint32_t    cmdsize;    /* sizeof(struct linkedit_data_command) 
> */
>    >    >     uint32_t    dataoff;    /* file offset of data in __LINKEDIT 
> segment */
>    >    >     uint32_t    datasize;    /* file size of data in __LINKEDIT 
> segment  */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The encryption_info_command contains the file offset and size of 
> an
>    >    >  * of an encrypted segment.
>    >    >  */
>    >    > struct encryption_info_command {
>    >    >    uint32_t    cmd;        /* LC_ENCRYPTION_INFO */
>    >    >    uint32_t    cmdsize;    /* sizeof(struct 
> encryption_info_command) */
>    >    >    uint32_t    cryptoff;    /* file offset of encrypted range */
>    >    >    uint32_t    cryptsize;    /* file size of encrypted range */
>    >    >    uint32_t    cryptid;    /* which enryption system,
>    >    >                    0 means not-encrypted yet */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The dyld_info_command contains the file offsets and sizes of
>    >    >  * the new compressed form of the information dyld needs to
>    >    >  * load the image.  This information is used by dyld on Mac OS X
>    >    >  * 10.6 and later.  All information pointed to by this command
>    >    >  * is encoded using byte streams, so no endian swapping is needed
>    >    >  * to interpret it.
>    >    >  */
>    >    > struct dyld_info_command {
>    >    >    uint32_t   cmd;        /* LC_DYLD_INFO or LC_DYLD_INFO_ONLY */
>    >    >    uint32_t   cmdsize;        /* sizeof(struct dyld_info_command) */
>    >    >
>    >    >     /*
>    >    >      * Dyld rebases an image whenever dyld loads it at an address 
> different
>    >    >      * from its preferred address.  The rebase information is a 
> stream
>    >    >      * of byte sized opcodes whose symbolic names start with
>    >    > REBASE_OPCODE_.
>    >    >      * Conceptually the rebase information is a table of tuples:
>    >    >      * <seg-index, seg-offset, type>
>    >    >      * The opcodes are a compressed way to encode the table by only
>    >    >      * encoding when a column changes.  In addition simple patterns
>    >    >      * like "every n'th offset for m times" can be encoded in a few
>    >    >      * bytes.
>    >    >      */
>    >    >     uint32_t   rebase_off;    /* file offset to rebase info  */
>    >    >     uint32_t   rebase_size;    /* size of rebase info   */
>    >    >
>    >    >     /*
>    >    >      * Dyld binds an image during the loading process, if the image
>    >    >      * requires any pointers to be initialized to symbols in other 
> images.
>    >    >      * The rebase information is a stream of byte sized
>    >    >      * opcodes whose symbolic names start with BIND_OPCODE_.
>    >    >      * Conceptually the bind information is a table of tuples:
>    >    >      * <seg-index, seg-offset, type, symbol-library-ordinal,
>    >    > symbol-name, addend>
>    >    >      * The opcodes are a compressed way to encode the table by only
>    >    >      * encoding when a column changes.  In addition simple patterns
>    >    >      * like for runs of pointers initialzed to the same value can be
>    >    >      * encoded in a few bytes.
>    >    >      */
>    >    >     uint32_t   bind_off;    /* file offset to binding info   */
>    >    >     uint32_t   bind_size;    /* size of binding info  */
>    >    >
>    >    >     /*
>    >    >      * Some C++ programs require dyld to unique symbols so that all
>    >    >      * images in the process use the same copy of some code/data.
>    >    >      * This step is done after binding. The content of the weak_bind
>    >    >      * info is an opcode stream like the bind_info.  But it is 
> sorted
>    >    >      * alphabetically by symbol name.  This enable dyld to walk
>    >    >      * all images with weak binding information in order and look
>    >    >      * for collisions.  If there are no collisions, dyld does
>    >    >      * no updating.  That means that some fixups are also encoded
>    >    >      * in the bind_info.  For instance, all calls to "operator new"
>    >    >      * are first bound to libstdc++.dylib using the information
>    >    >      * in bind_info.  Then if some image overrides operator new
>    >    >      * that is detected when the weak_bind information is processed
>    >    >      * and the call to operator new is then rebound.
>    >    >      */
>    >    >     uint32_t   weak_bind_off;    /* file offset to weak binding 
> info   */
>    >    >     uint32_t   weak_bind_size;  /* size of weak binding info  */
>    >    >
>    >    >     /*
>    >    >      * Some uses of external symbols do not need to be bound 
> immediately.
>    >    >      * Instead they can be lazily bound on first use.  The lazy_bind
>    >    >      * are contains a stream of BIND opcodes to bind all lazy 
> symbols.
>    >    >      * Normal use is that dyld ignores the lazy_bind section when
>    >    >      * loading an image.  Instead the static linker arranged for the
>    >    >      * lazy pointer to initially point to a helper function which
>    >    >      * pushes the offset into the lazy_bind area for the symbol
>    >    >      * needing to be bound, then jumps to dyld which simply adds
>    >    >      * the offset to lazy_bind_off to get the information on what
>    >    >      * to bind.
>    >    >      */
>    >    >     uint32_t   lazy_bind_off;    /* file offset to lazy binding 
> info */
>    >    >     uint32_t   lazy_bind_size;  /* size of lazy binding infs */
>    >    >
>    >    >     /*
>    >    >      * The symbols exported by a dylib are encoded in a trie.  This
>    >    >      * is a compact representation that factors out common prefixes.
>    >    >      * It also reduces LINKEDIT pages in RAM because it encodes all
>    >    >      * information (name, address, flags) in one small, contiguous 
> range.
>    >    >      * The export area is a stream of nodes.  The first node 
> sequentially
>    >    >      * is the start node for the trie.
>    >    >      *
>    >    >      * Nodes for a symbol start with a byte that is the length of
>    >    >      * the exported symbol information for the string so far.
>    >    >      * If there is no exported symbol, the byte is zero. If there
>    >    >      * is exported info, it follows the length byte.  The exported
>    >    >      * info normally consists of a flags and offset both encoded
>    >    >      * in uleb128.  The offset is location of the content named
>    >    >      * by the symbol.  It is the offset from the mach_header for
>    >    >      * the image.
>    >    >      *
>    >    >      * After the initial byte and optional exported symbol 
> information
>    >    >      * is a byte of how many edges (0-255) that this node has 
> leaving
>    >    >      * it, followed by each edge.
>    >    >      * Each edge is a zero terminated cstring of the addition chars
>    >    >      * in the symbol, followed by a uleb128 offset for the node that
>    >    >      * edge points to.
>    >    >      *
>    >    >      */
>    >    >     uint32_t   export_off;    /* file offset to lazy binding info */
>    >    >     uint32_t   export_size;    /* size of lazy binding infs */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The following are used to encode rebasing information
>    >    >  */
>    >    > #define REBASE_TYPE_POINTER                    1
>    >    > #define REBASE_TYPE_TEXT_ABSOLUTE32                2
>    >    > #define REBASE_TYPE_TEXT_PCREL32                3
>    >    >
>    >    > #define REBASE_OPCODE_MASK                    0xF0
>    >    > #define REBASE_IMMEDIATE_MASK                    0x0F
>    >    > #define REBASE_OPCODE_DONE                    0x00
>    >    > #define REBASE_OPCODE_SET_TYPE_IMM                0x10
>    >    > #define REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB        0x20
>    >    > #define REBASE_OPCODE_ADD_ADDR_ULEB                0x30
>    >    > #define REBASE_OPCODE_ADD_ADDR_IMM_SCALED            0x40
>    >    > #define REBASE_OPCODE_DO_REBASE_IMM_TIMES            0x50
>    >    > #define REBASE_OPCODE_DO_REBASE_ULEB_TIMES            0x60
>    >    > #define REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB            0x70
>    >    > #define REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB    0x80
>    >    >
>    >    >
>    >    > /*
>    >    >  * The following are used to encode binding information
>    >    >  */
>    >    > #define BIND_TYPE_POINTER                    1
>    >    > #define BIND_TYPE_TEXT_ABSOLUTE32                2
>    >    > #define BIND_TYPE_TEXT_PCREL32                    3
>    >    >
>    >    > #define BIND_SPECIAL_DYLIB_SELF                     0
>    >    > #define BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE            -1
>    >    > #define BIND_SPECIAL_DYLIB_FLAT_LOOKUP                -2
>    >    >
>    >    > #define BIND_SYMBOL_FLAGS_WEAK_IMPORT                0x1
>    >    > #define BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION            0x8
>    >    >
>    >    > #define BIND_OPCODE_MASK                    0xF0
>    >    > #define BIND_IMMEDIATE_MASK                    0x0F
>    >    > #define BIND_OPCODE_DONE                    0x00
>    >    > #define BIND_OPCODE_SET_DYLIB_ORDINAL_IMM            0x10
>    >    > #define BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB            0x20
>    >    > #define BIND_OPCODE_SET_DYLIB_SPECIAL_IMM            0x30
>    >    > #define BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM        0x40
>    >    > #define BIND_OPCODE_SET_TYPE_IMM                0x50
>    >    > #define BIND_OPCODE_SET_ADDEND_SLEB                0x60
>    >    > #define BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB            0x70
>    >    > #define BIND_OPCODE_ADD_ADDR_ULEB                0x80
>    >    > #define BIND_OPCODE_DO_BIND                    0x90
>    >    > #define BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB            0xA0
>    >    > #define BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED            0xB0
>    >    > #define BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB        0xC0
>    >    >
>    >    >
>    >    > /*
>    >    >  * The following are used on the flags byte of a terminal node
>    >    >  * in the export information.
>    >    >  */
>    >    > #define EXPORT_SYMBOL_FLAGS_KIND_MASK                0x03
>    >    > #define EXPORT_SYMBOL_FLAGS_KIND_REGULAR            0x00
>    >    > #define EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL            0x01
>    >    > #define EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION            0x04
>    >    > #define EXPORT_SYMBOL_FLAGS_INDIRECT_DEFINITION            0x08
>    >    > #define EXPORT_SYMBOL_FLAGS_HAS_SPECIALIZATIONS            0x10
>    >    >
>    >    > /*
>    >    >  * The symseg_command contains the offset and size of the GNU style
>    >    >  * symbol table information as described in the header file 
> <symseg.h>.
>    >    >  * The symbol roots of the symbol segments must also be aligned 
> properly
>    >    >  * in the file.  So the requirement of keeping the offsets aligned 
> to a
>    >    >  * multiple of a 4 bytes translates to the length field of the 
> symbol
>    >    >  * roots also being a multiple of a long.  Also the padding must 
> again be
>    >    >  * zeroed. (THIS IS OBSOLETE and no longer supported).
>    >    >  */
>    >    > struct symseg_command {
>    >    >     uint32_t    cmd;        /* LC_SYMSEG */
>    >    >     uint32_t    cmdsize;    /* sizeof(struct symseg_command) */
>    >    >     uint32_t    offset;        /* symbol segment offset */
>    >    >     uint32_t    size;        /* symbol segment size in bytes */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The ident_command contains a free format string table following 
> the
>    >    >  * ident_command structure.  The strings are null terminated and the
>    >    > size of
>    >    >  * the command is padded out with zero bytes to a multiple of 4 
> bytes/
>    >    >  * (THIS IS OBSOLETE and no longer supported).
>    >    >  */
>    >    > struct ident_command {
>    >    >     uint32_t cmd;        /* LC_IDENT */
>    >    >     uint32_t cmdsize;    /* strings that follow this command */
>    >    > };
>    >    >
>    >    > /*
>    >    >  * The fvmfile_command contains a reference to a file to be loaded 
> at the
>    >    >  * specified virtual address.  (Presently, this command is reserved 
> for
>    >    >  * internal use.  The kernel ignores this command when loading a
>    >    > program into
>    >    >  * memory).
>    >    >  */
>    >    > struct fvmfile_command {
>    >    >     uint32_t cmd;            /* LC_FVMFILE */
>    >    >     uint32_t cmdsize;        /* includes pathname string */
>    >    >     union lc_str    name;        /* files pathname */
>    >    >     uint32_t    header_addr;    /* files virtual address */
>    >    > };
>    >    >
>    >    > #endif /* _MACHO_LOADER_H_ */
>    >    >
>    >    >
>    >    > On 07/26/10 15:21, Camm Maguire wrote:
>    >    >> Greetings1
>    >    >>
>    >    >> Matt Kaufmann<address@hidden>  writes:
>    >    >>
>    >    >>    
>    >    >>> Hi, Camm --
>    >    >>>
>    >    >>> I'd be very happy to give you access to my laptop, which is the 
> Intel
>    >    >>> box in question (which is running Mac OS 10.6.4, by the way).  
> But I
>    >    >>> don't know how to do it.  I think could create an account, but 
> how do
>    >    >>>      
>    >    >> Well, this looks difficult.  It would be great if you could send me
>    >    >> these files:
>    >    >>
>    >    >> #include<mach-o/loader.h>
>    >    >> #include<mach-o/nlist.h>
>    >    >>
>    >    >> #include<mach/mach.h>
>    >    >>
>    >    >> Separately, if you are interested, I can send you a small patch 
> that
>    >    >> steps around rsym_macosx all together.  Of course, if you are 
> still on
>    >    >> vacation, please don't bother about this until you get home!  If 
> there
>    >    >> is a machine at ut you could point me to, that of course would be
>    >    >> great, but if you'd have to ask David Ranger, perhaps I could just
>    >    >> email him myself.
>    >    >>
>    >    >> Last update, gcl can now run cross compiled for windows on Linux 
> under
>    >    >> wine.  maxima just passed all its tests.  Checking acl2 ....  The 
> idea
>    >    >> being to get one tree verified on both these seldom used machines 
> (mac
>    >    >> and windows) and then finalize gcl 2.6.8.
>    >    >>
>    >    >> Take care,
>    >    >>
>    >    >>    
>    >    >>> -- Matt
>    >    >>>     From: Camm Maguire<address@hidden>
>    >    >>>     Date: Mon, 26 Jul 2010 11:07:47 -0400
>    >    >>>     X-SpamAssassin-Status: No, hits=0.2 required=5.0
>    >    >>>     X-UTCS-Spam-Status: No, hits=-180 required=165
>    >    >>>
>    >    >>>     Greetings!  Sigh.  I was afraid of this.  There are multiple 
> versions
>    >    >>>     of mac os x out there which apparently differ in significant 
> ways.
>    >    >>>     Not sure of the versioning system, but 10.4, 10.5, and 10.6 
> sound
>    >    >>>     familiar.  This code was well tested on the axiom intel mac 
> box. Could
>    >    >>>     you please provide access to the box in question?
>    >    >>>
>    >    >>>     Take care,
>    >    >>>     --
>    >    >>>     Camm Maguire                                      
> address@hidden
>    >    >>>     
> ==========================================================================
>    >    >>>     "The earth is but one country, and mankind its citizens."  -- 
>  Baha'u'llah
>    >    >>>
>    >    >>>
>    >    >>>
>    >    >>>
>    >    >>>      
>    >    >>    
>    >    >
>    >    >
>    >    >
>    >    >
>    >
>    >    -- 
>    >    Camm Maguire                                      address@hidden
>    >    
> ==========================================================================
>    >    "The earth is but one country, and mankind its citizens."  --  
> Baha'u'llah/$ cat /usr/include/mach-o/nlist.h
>    > /*
>    >  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
>    >  * 
>    >  * @APPLE_LICENSE_HEADER_START@
>    >  * 
>    >  * This file contains Original Code and/or Modifications of Original Code
>    >  * as defined in and that are subject to the Apple Public Source License
>    >  * Version 2.0 (the 'License'). You may not use this file except in
>    >  * compliance with the License. Please obtain a copy of the License at
>    >  * http://www.opensource.apple.com/apsl/ and read it before using this
>    >  * file.
>    >  * 
>    >  * The Original Code and all software distributed under the License are
>    >  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
>    >  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
>    >  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
>    >  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
>    >  * Please see the License for the specific language governing rights and
>    >  * limitations under the License.
>    >  * 
>    >  * @APPLE_LICENSE_HEADER_END@
>    >  */
>    > #ifndef _MACHO_NLIST_H_
>    > #define _MACHO_NLIST_H_
>    > /*       $NetBSD: nlist.h,v 1.5 1994/10/26 00:56:11 cgd Exp $    */
>    >
>    > /*-
>    >  * Copyright (c) 1991, 1993
>    >  *       The Regents of the University of California.  All rights 
> reserved.
>    >  * (c) UNIX System Laboratories, Inc.
>    >  * All or some portions of this file are derived from material licensed
>    >  * to the University of California by American Telephone and Telegraph
>    >  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
>    >  * the permission of UNIX System Laboratories, Inc.
>    >  *
>    >  * Redistribution and use in source and binary forms, with or without
>    >  * modification, are permitted provided that the following conditions
>    >  * are met:
>    >  * 1. Redistributions of source code must retain the above copyright
>    >  *    notice, this list of conditions and the following disclaimer.
>    >  * 2. Redistributions in binary form must reproduce the above copyright
>    >  *    notice, this list of conditions and the following disclaimer in the
>    >  *    documentation and/or other materials provided with the 
> distribution.
>    >  * 3. All advertising materials mentioning features or use of this 
> software
>    >  *    must display the following acknowledgement:
>    >  *       This product includes software developed by the University of
>    >  *       California, Berkeley and its contributors.
>    >  * 4. Neither the name of the University nor the names of its 
> contributors
>    >  *    may be used to endorse or promote products derived from this 
> software
>    >  *    without specific prior written permission.
>    >  *
>    >  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' 
> AND
>    >  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
>    >  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
> PURPOSE
>    >  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE 
> LIABLE
>    >  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
> CONSEQUENTIAL
>    >  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE 
> GOODS
>    >  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
>    >  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
> STRICT
>    >  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY 
> WAY
>    >  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
>    >  * SUCH DAMAGE.
>    >  *
>    >  *       @(#)nlist.h     8.2 (Berkeley) 1/21/94
>    >  */
>    > #include <stdint.h>
>    >
>    > /*
>    >  * Format of a symbol table entry of a Mach-O file for 32-bit 
> architectures.
>    >  * Modified from the BSD format.  The modifications from the original 
> format
>    >  * were changing n_other (an unused field) to n_sect and the addition of 
> the
>    >  * N_SECT type.  These modifications are required to support symbols in 
> a larger
>    >  * number of sections not just the three sections (text, data and bss) 
> in a BSD
>    >  * file.
>    >  */
>    > struct nlist {
>    >  union {
>    > #ifndef __LP64__
>    >          char *n_name;   /* for use when in-core */
>    > #endif
>    >          int32_t n_strx; /* index into the string table */
>    >  } n_un;
>    >  uint8_t n_type;         /* type flag, see below */
>    >  uint8_t n_sect;         /* section number or NO_SECT */
>    >  int16_t n_desc;         /* see <mach-o/stab.h> */
>    >  uint32_t n_value;       /* value of this symbol (or stab offset) */
>    > };
>    >
>    > /*
>    >  * This is the symbol table entry structure for 64-bit architectures.
>    >  */
>    > struct nlist_64 {
>    >     union {
>    >         uint32_t  n_strx; /* index into the string table */
>    >     } n_un;
>    >     uint8_t n_type;        /* type flag, see below */
>    >     uint8_t n_sect;        /* section number or NO_SECT */
>    >     uint16_t n_desc;       /* see <mach-o/stab.h> */
>    >     uint64_t n_value;      /* value of this symbol (or stab offset) */
>    > };
>    >
>    > /*
>    >  * Symbols with a index into the string table of zero (n_un.n_strx == 0) 
> are
>    >  * defined to have a null, "", name.  Therefore all string indexes to 
> non null
>    >  * names must not have a zero string index.  This is bit historical 
> information
>    >  * that has never been well documented.
>    >  */
>    >
>    > /*
>    >  * The n_type field really contains four fields:
>    >  *       unsigned char N_STAB:3,
>    >  *                     N_PEXT:1,
>    >  *                     N_TYPE:3,
>    >  *                     N_EXT:1;
>    >  * which are used via the following masks.
>    >  */
>    > #define  N_STAB  0xe0  /* if any of these bits set, a symbolic debugging 
> entry */
>    > #define  N_PEXT  0x10  /* private external symbol bit */
>    > #define  N_TYPE  0x0e  /* mask for the type bits */
>    > #define  N_EXT   0x01  /* external symbol bit, set for external symbols 
> */
>    >
>    > /*
>    >  * Only symbolic debugging entries have some of the N_STAB bits set and 
> if any
>    >  * of these bits are set then it is a symbolic debugging entry (a stab). 
>  In
>    >  * which case then the values of the n_type field (the entire field) are 
> given
>    >  * in <mach-o/stab.h>
>    >  */
>    >
>    > /*
>    >  * Values for N_TYPE bits of the n_type field.
>    >  */
>    > #define  N_UNDF  0x0             /* undefined, n_sect == NO_SECT */
>    > #define  N_ABS   0x2             /* absolute, n_sect == NO_SECT */
>    > #define  N_SECT  0xe             /* defined in section number n_sect */
>    > #define  N_PBUD  0xc             /* prebound undefined (defined in a 
> dylib) */
>    > #define N_INDR   0xa             /* indirect */
>    >
>    > /* 
>    >  * If the type is N_INDR then the symbol is defined to be the same as 
> another
>    >  * symbol.  In this case the n_value field is an index into the string 
> table
>    >  * of the other symbol's name.  When the other symbol is defined then 
> they both
>    >  * take on the defined type and value.
>    >  */
>    >
>    > /*
>    >  * If the type is N_SECT then the n_sect field contains an ordinal of the
>    >  * section the symbol is defined in.  The sections are numbered from 1 
> and 
>    >  * refer to sections in order they appear in the load commands for the 
> file
>    >  * they are in.  This means the same ordinal may very well refer to 
> different
>    >  * sections in different files.
>    >  *
>    >  * The n_value field for all symbol table entries (including N_STAB's) 
> gets
>    >  * updated by the link editor based on the value of it's n_sect field 
> and where
>    >  * the section n_sect references gets relocated.  If the value of the 
> n_sect 
>    >  * field is NO_SECT then it's n_value field is not changed by the link 
> editor.
>    >  */
>    > #define  NO_SECT         0       /* symbol is not in any section */
>    > #define MAX_SECT 255     /* 1 thru 255 inclusive */
>    >
>    > /*
>    >  * Common symbols are represented by undefined (N_UNDF) external (N_EXT) 
> types
>    >  * who's values (n_value) are non-zero.  In which case the value of the 
> n_value
>    >  * field is the size (in bytes) of the common symbol.  The n_sect field 
> is set
>    >  * to NO_SECT.  The alignment of a common symbol may be set as a power 
> of 2
>    >  * between 2^1 and 2^15 as part of the n_desc field using the macros 
> below. If
>    >  * the alignment is not set (a value of zero) then natural alignment 
> based on
>    >  * the size is used.
>    >  */
>    > #define GET_COMM_ALIGN(n_desc) (((n_desc) >> 8) & 0x0f)
>    > #define SET_COMM_ALIGN(n_desc,align) \
>    >     (n_desc) = (((n_desc) & 0xf0ff) | (((align) & 0x0f) << 8))
>    >
>    > /*
>    >  * To support the lazy binding of undefined symbols in the dynamic 
> link-editor,
>    >  * the undefined symbols in the symbol table (the nlist structures) are 
> marked
>    >  * with the indication if the undefined reference is a lazy reference or
>    >  * non-lazy reference.  If both a non-lazy reference and a lazy 
> reference is
>    >  * made to the same symbol the non-lazy reference takes precedence.  A 
> reference
>    >  * is lazy only when all references to that symbol are made through a 
> symbol
>    >  * pointer in a lazy symbol pointer section.
>    >  *
>    >  * The implementation of marking nlist structures in the symbol table for
>    >  * undefined symbols will be to use some of the bits of the n_desc field 
> as a
>    >  * reference type.  The mask REFERENCE_TYPE will be applied to the 
> n_desc field
>    >  * of an nlist structure for an undefined symbol to determine the type of
>    >  * undefined reference (lazy or non-lazy).
>    >  *
>    >  * The constants for the REFERENCE FLAGS are propagated to the reference 
> table
>    >  * in a shared library file.  In that case the constant for a defined 
> symbol,
>    >  * REFERENCE_FLAG_DEFINED, is also used.
>    >  */
>    > /* Reference type bits of the n_desc field of undefined symbols */
>    > #define REFERENCE_TYPE                           0x7
>    > /* types of references */
>    > #define REFERENCE_FLAG_UNDEFINED_NON_LAZY                0
>    > #define REFERENCE_FLAG_UNDEFINED_LAZY                    1
>    > #define REFERENCE_FLAG_DEFINED                           2
>    > #define REFERENCE_FLAG_PRIVATE_DEFINED                   3
>    > #define REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY        4
>    > #define REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY            5
>    >
>    > /*
>    >  * To simplify stripping of objects that use are used with the dynamic 
> link
>    >  * editor, the static link editor marks the symbols defined an object 
> that are
>    >  * referenced by a dynamicly bound object (dynamic shared libraries, 
> bundles).
>    >  * With this marking strip knows not to strip these symbols.
>    >  */
>    > #define REFERENCED_DYNAMICALLY   0x0010
>    >
>    > /*
>    >  * For images created by the static link editor with the 
> -twolevel_namespace
>    >  * option in effect the flags field of the mach header is marked with
>    >  * MH_TWOLEVEL.  And the binding of the undefined references of the 
> image are
>    >  * determined by the static link editor.  Which library an undefined 
> symbol is
>    >  * bound to is recorded by the static linker in the high 8 bits of the 
> n_desc
>    >  * field using the SET_LIBRARY_ORDINAL macro below.  The ordinal recorded
>    >  * references the libraries listed in the Mach-O's LC_LOAD_DYLIB load 
> commands
>    >  * in the order they appear in the headers.   The library ordinals start 
> from 1.
>    >  * For a dynamic library that is built as a two-level namespace image the
>    >  * undefined references from module defined in another use the same 
> nlist struct
>    >  * an in that case SELF_LIBRARY_ORDINAL is used as the library ordinal.  
> For
>    >  * defined symbols in all images they also must have the library ordinal 
> set to
>    >  * SELF_LIBRARY_ORDINAL.  The EXECUTABLE_ORDINAL refers to the executable
>    >  * image for references from plugins that refer to the executable that 
> loads
>    >  * them.
>    >  * 
>    >  * The DYNAMIC_LOOKUP_ORDINAL is for undefined symbols in a two-level 
> namespace
>    >  * image that are looked up by the dynamic linker with flat namespace 
> semantics.
>    >  * This ordinal was added as a feature in Mac OS X 10.3 by reducing the
>    >  * value of MAX_LIBRARY_ORDINAL by one.  So it is legal for existing 
> binaries
>    >  * or binaries built with older tools to have 0xfe (254) dynamic 
> libraries.  In
>    >  * this case the ordinal value 0xfe (254) must be treated as a library 
> ordinal
>    >  * for compatibility. 
>    >  */
>    > #define GET_LIBRARY_ORDINAL(n_desc) (((n_desc) >> 8) & 0xff)
>    > #define SET_LIBRARY_ORDINAL(n_desc,ordinal) \
>    >  (n_desc) = (((n_desc) & 0x00ff) | (((ordinal) & 0xff) << 8))
>    > #define SELF_LIBRARY_ORDINAL 0x0
>    > #define MAX_LIBRARY_ORDINAL 0xfd
>    > #define DYNAMIC_LOOKUP_ORDINAL 0xfe
>    > #define EXECUTABLE_ORDINAL 0xff
>    >
>    > /*
>    >  * The bit 0x0020 of the n_desc field is used for two non-overlapping 
> purposes
>    >  * and has two different symbolic names, N_NO_DEAD_STRIP and 
> N_DESC_DISCARDED.
>    >  */
>    >
>    > /*
>    >  * The N_NO_DEAD_STRIP bit of the n_desc field only ever appears in a 
>    >  * relocatable .o file (MH_OBJECT filetype). And is used to indicate to 
> the
>    >  * static link editor it is never to dead strip the symbol.
>    >  */
>    > #define N_NO_DEAD_STRIP 0x0020 /* symbol is not to be dead stripped */
>    >
>    > /*
>    >  * The N_DESC_DISCARDED bit of the n_desc field never appears in linked 
> image.
>    >  * But is used in very rare cases by the dynamic link editor to mark an 
> in
>    >  * memory symbol as discared and longer used for linking.
>    >  */
>    > #define N_DESC_DISCARDED 0x0020  /* symbol is discarded */
>    >
>    > /*
>    >  * The N_WEAK_REF bit of the n_desc field indicates to the dynamic 
> linker that
>    >  * the undefined symbol is allowed to be missing and is to have the 
> address of
>    >  * zero when missing.
>    >  */
>    > #define N_WEAK_REF       0x0040 /* symbol is weak referenced */
>    >
>    > /*
>    >  * The N_WEAK_DEF bit of the n_desc field indicates to the static and 
> dynamic
>    >  * linkers that the symbol definition is weak, allowing a non-weak 
> symbol to
>    >  * also be used which causes the weak definition to be discared.  
> Currently this
>    >  * is only supported for symbols in coalesed sections.
>    >  */
>    > #define N_WEAK_DEF       0x0080 /* coalesed symbol is a weak definition 
> */
>    >
>    > /*
>    >  * The N_REF_TO_WEAK bit of the n_desc field indicates to the dynamic 
> linker
>    >  * that the undefined symbol should be resolved using flat namespace 
> searching.
>    >  */
>    > #define  N_REF_TO_WEAK   0x0080 /* reference to a weak symbol */
>    >
>    > /*
>    >  * The N_ARM_THUMB_DEF bit of the n_desc field indicates that the symbol 
> is
>    >  * a defintion of a Thumb function.
>    >  */
>    > #define N_ARM_THUMB_DEF  0x0008 /* symbol is a Thumb function (ARM) */
>    >
>    > #ifndef __STRICT_BSD__
>    > #if __cplusplus
>    > extern "C" {
>    > #endif /* __cplusplus */
>    > /*
>    >  * The function nlist(3) from the C library.
>    >  */
>    > extern int nlist (const char *filename, struct nlist *list);
>    > #if __cplusplus
>    > }
>    > #endif /* __cplusplus */
>    > #endif /* __STRICT_BSD__ */
>    >
>    > #endif /* _MACHO_LIST_H_ */
>    > /$ cat /usr/include/nlist.h
>    > /*-
>    >  * Copyright (c) 1991, 1993
>    >  *       The Regents of the University of California.  All rights 
> reserved.
>    >  * (c) UNIX System Laboratories, Inc.
>    >  * All or some portions of this file are derived from material licensed
>    >  * to the University of California by American Telephone and Telegraph
>    >  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
>    >  * the permission of UNIX System Laboratories, Inc.
>    >  *
>    >  * Redistribution and use in source and binary forms, with or without
>    >  * modification, are permitted provided that the following conditions
>    >  * are met:
>    >  * 1. Redistributions of source code must retain the above copyright
>    >  *    notice, this list of conditions and the following disclaimer.
>    >  * 2. Redistributions in binary form must reproduce the above copyright
>    >  *    notice, this list of conditions and the following disclaimer in the
>    >  *    documentation and/or other materials provided with the 
> distribution.
>    >  * 3. All advertising materials mentioning features or use of this 
> software
>    >  *    must display the following acknowledgement:
>    >  *       This product includes software developed by the University of
>    >  *       California, Berkeley and its contributors.
>    >  * 4. Neither the name of the University nor the names of its 
> contributors
>    >  *    may be used to endorse or promote products derived from this 
> software
>    >  *    without specific prior written permission.
>    >  *
>    >  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' 
> AND
>    >  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
>    >  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
> PURPOSE
>    >  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE 
> LIABLE
>    >  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
> CONSEQUENTIAL
>    >  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE 
> GOODS
>    >  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
>    >  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
> STRICT
>    >  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY 
> WAY
>    >  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
>    >  * SUCH DAMAGE.
>    >  *
>    >  *       @(#)nlist.h     8.2 (Berkeley) 1/21/94
>    >  */
>    >
>    > #ifndef _NLIST_H_
>    > #define  _NLIST_H_
>    >
>    > /*
>    >  * Symbol table entry format.  The #ifdef's are so that programs 
> including
>    >  * nlist.h can initialize nlist structures statically.
>    >  */
>    > struct nlist {
>    > #ifdef _AOUT_INCLUDE_
>    >  union {
>    >          char *n_name;   /* symbol name (in memory) */
>    >          long n_strx;    /* file string table offset (on disk) */
>    >  } n_un;
>    > #else
>    >  char *n_name;           /* symbol name (in memory) */
>    > #endif
>    >
>    > #define  N_UNDF  0x00            /* undefined */
>    > #define  N_ABS   0x02            /* absolute address */
>    > #define  N_TEXT  0x04            /* text segment */
>    > #define  N_DATA  0x06            /* data segment */
>    > #define  N_BSS   0x08            /* bss segment */
>    > #define  N_COMM  0x12            /* common reference */
>    > #define  N_FN    0x1e            /* file name */
>    >
>    > #define  N_EXT   0x01            /* external (global) bit, OR'ed in */
>    > #define  N_TYPE  0x1e            /* mask for all the type bits */
>    >  unsigned char n_type;   /* type defines */
>    >
>    >  char n_other;           /* spare */
>    > #define  n_hash  n_desc          /* used internally by ld(1); XXX */
>    >  short n_desc;           /* used by stab entries */
>    >  unsigned long n_value;  /* address/value of the symbol */
>    > };
>    >
>    > #define  N_FORMAT        "%08x"  /* namelist value format; XXX */
>    > #define  N_STAB          0x0e0   /* mask for debugger symbols -- stab(5) 
> */
>    >
>    > #include <sys/cdefs.h>
>    >
>    > __BEGIN_DECLS
>    > int nlist(const char *, struct nlist *);
>    > __END_DECLS
>    >
>    > #endif /* !_NLIST_H_ */
>    > /$ =
>
>    -- 
>    Camm Maguire                                           address@hidden
>    ==========================================================================
>    "The earth is but one country, and mankind its citizens."  --  Baha'u'llah
>
>
>
>

-- 
Camm Maguire                                        address@hidden
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah



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