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


From: Matt Kaufmann
Subject: Re: [Gcl-devel] Re: ACL2 Version 4.0
Date: Tue, 27 Jul 2010 09:06:12 -0500

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_ */
/$ 

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