doc about some workarounds

[Bruno Haible]

Some of the problems that are worked around by gnulib on glibc/Linux
systems are not documented. People then wonder why gnulib creates
overrides (such as printf.o, glob.o, linkat.o).

This fixes it. I got the info about the problems from the *.m4 files.


2012-04-22  Bruno Haible  <address@hidden>

        doc: Mention reason for replacement on glibc/Linux systems.
        * doc/posix-functions/dprintf.texi: Mention the problem with special
        'long double' values.
        * doc/posix-functions/fprintf.texi: Likewise.
        * doc/posix-functions/printf.texi: Likewise.
        * doc/posix-functions/snprintf.texi: Likewise.
        * doc/posix-functions/sprintf.texi: Likewise.
        * doc/posix-functions/vdprintf.texi: Likewise.
        * doc/posix-functions/vfprintf.texi: Likewise.
        * doc/posix-functions/vprintf.texi: Likewise.
        * doc/posix-functions/vsnprintf.texi: Likewise.
        * doc/posix-functions/vsprintf.texi: Likewise.
        * doc/posix-functions/fcntl.texi: Add glibc/Linux to the list of
        platforms with F_DUPFD_CLOEXEC problems.
        * doc/posix-functions/glob.texi: Mention which platforms are affected
        by the problem with symbolic links.
        * doc/posix-functions/linkat.texi: Mention the problem with
        AT_SYMLINK_FOLLOW on Linux.

--- doc/posix-functions/dprintf.texi.orig       Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/dprintf.texi    Sun Apr 22 16:21:51 2012
@@ -17,6 +17,10 @@
 Portability problems fixed by Gnulib module @code{dprintf-posix}:
 @itemize
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6.
--- doc/posix-functions/fcntl.texi.orig Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/fcntl.texi      Sun Apr 22 16:04:48 2012
@@ -15,6 +15,7 @@
 @item
 This function does not support @code{F_DUPFD_CLOEXEC} on some
 platforms:
+glibc with Linux kernels before 2.6.24,
 MacOS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, AIX 5.1, HP-UX 11,
 IRIX 6.5, OSF/1 5.1, Solaris 11 2010-11, Cygwin 1.7.1, Interix 3.5,
 BeOS.
--- doc/posix-functions/fprintf.texi.orig       Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/fprintf.texi    Sun Apr 22 16:22:03 2012
@@ -20,6 +20,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
--- doc/posix-functions/glob.texi.orig  Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/glob.texi       Sun Apr 22 16:36:57 2012
@@ -12,8 +12,9 @@
 This function is missing on some platforms:
 IRIX 5.3, mingw, MSVC 9, BeOS.
 @item
-This function may list symbolic links to nonexistent files among the results,
-on some platforms.
+This function does not list symbolic links to nonexistent files among the 
results,
+on some platforms:
+glibc 2.14, AIX 7.1, HP-UX 11, Solaris 11 2011-11.
 @item
 On platforms where @code{off_t} is a 32-bit type, this function may not
 work correctly on huge directories larger than 2 GB.
--- doc/posix-functions/linkat.texi.orig        Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/linkat.texi     Sun Apr 22 16:09:01 2012
@@ -17,6 +17,9 @@
 This function fails to reject trailing slashes on non-directories on
 some platforms:
 AIX 7.1, Solaris 11 2011-11.
address@hidden
+This functions does not support @code{AT_SYMLINK_FOLLOW} on some platforms:
+Linux kernel 2.6.17.
 @end itemize
 
 Portability problems not fixed by Gnulib:
--- doc/posix-functions/printf.texi.orig        Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/printf.texi     Sun Apr 22 16:21:49 2012
@@ -20,6 +20,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
--- doc/posix-functions/snprintf.texi.orig      Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/snprintf.texi   Sun Apr 22 16:22:00 2012
@@ -39,6 +39,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
--- doc/posix-functions/sprintf.texi.orig       Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/sprintf.texi    Sun Apr 22 16:21:58 2012
@@ -20,6 +20,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
--- doc/posix-functions/vdprintf.texi.orig      Sun Apr 22 16:37:36 2012
+++ doc/posix-functions/vdprintf.texi   Sun Apr 22 16:21:56 2012
@@ -24,6 +24,10 @@
 printf of @samp{long double} numbers is unsupported on some platforms:
 BeOS.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, BeOS.
--- doc/posix-functions/vfprintf.texi.orig      Sun Apr 22 16:37:37 2012
+++ doc/posix-functions/vfprintf.texi   Sun Apr 22 16:21:53 2012
@@ -20,6 +20,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
--- doc/posix-functions/vprintf.texi.orig       Sun Apr 22 16:37:37 2012
+++ doc/posix-functions/vprintf.texi    Sun Apr 22 16:22:12 2012
@@ -20,6 +20,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
--- doc/posix-functions/vsnprintf.texi.orig     Sun Apr 22 16:37:37 2012
+++ doc/posix-functions/vsnprintf.texi  Sun Apr 22 16:22:07 2012
@@ -39,6 +39,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
--- doc/posix-functions/vsprintf.texi.orig      Sun Apr 22 16:37:37 2012
+++ doc/posix-functions/vsprintf.texi   Sun Apr 22 16:22:05 2012
@@ -20,6 +20,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
address@hidden
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,