Hash :
c924151b
Author :
Date :
2018-11-29T13:33:28
docs: mention printf %m considerations
gcc -Wformat does NOT flag printf("%m") on a BSD system, even though
it prints only "m" instead of the desired GNU/Linux behavior of the
current errno value (you have to use -Wpedantic to flag it, but that's
a rather heavy hammer). Still, it's easy enough (even if verbose)
to write out strerror() usage directly, to the point that gnulib will
probably never provide a module to guarantee %m everywhere.
See also https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88270
* doc/glibc-functions/asprintf.texi (asprintf): Document that %m
is not portable, and is easy enough to work around.
* doc/glibc-functions/obstack_printf.texi (obstack_printf): Likewise.
* doc/glibc-functions/obstack_vprintf.texi (obstack_vprintf): Likewise.
* doc/glibc-functions/vasprintf.texi (vasprintf): Likewise.
* doc/posix-functions/dprintf.texi (dprintf): Likewise.
* doc/posix-functions/fprintf.texi (fprintf): Likewise.
* doc/posix-functions/fwprintf.texi (fwprintf): Likewise.
* doc/posix-functions/printf.texi (printf): Likewise.
* doc/posix-functions/snprintf.texi (snprintf): Likewise.
* doc/posix-functions/sprintf.texi (sprintf): Likewise.
* doc/posix-functions/swprintf.texi (swprintf): Likewise.
* doc/posix-functions/vdprintf.texi (vdprintf): Likewise.
* doc/posix-functions/vfprintf.texi (vfprintf): Likewise.
* doc/posix-functions/vfwprintf.texi (vfwprintf): Likewise.
* doc/posix-functions/vprintf.texi (vprintf): Likewise.
* doc/posix-functions/vsnprintf.texi (vsnprintf): Likewise.
* doc/posix-functions/vsprintf.texi (vsprintf): Likewise.
* doc/posix-functions/vswprintf.texi (vswprintf): Likewise.
* doc/posix-functions/vwprintf.texi (vwprintf): Likewise.
* doc/posix-functions/wprintf.texi (wprintf): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
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@node obstack_printf
@subsection @code{obstack_printf}
@findex obstack_printf
Gnulib module: obstack-printf or obstack-printf-posix
Portability problems fixed by either Gnulib module
@code{obstack-printf} or @code{obstack-printf-posix}:
@itemize
@item
This function is missing on all non-glibc platforms:
Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
@end itemize
Portability problems fixed by Gnulib module @code{ostack-printf-posix}:
@itemize
@item
This function does not support size specifiers as in C99 (@code{hh}, @code{ll},
@code{j}, @code{t}, @code{z}) on some platforms:
AIX 5.1, HP-UX 11.23, IRIX 6.5, OSF/1 5.1, Solaris 9, Cygwin 1.5.24, mingw, MSVC 14, BeOS.
@item
printf of @samp{long double} numbers is unsupported on some platforms:
mingw, MSVC 14, BeOS.
@item
printf @code{"%f"}, @code{"%e"}, @code{"%g"} of Infinity and NaN yields an
incorrect result on some platforms:
AIX 5.2, OSF/1 5.1, Solaris 11.0, mingw, MSVC 14.
@item
This function does not support the @samp{a} and @samp{A} directives on some
platforms:
glibc-2.3.6, Mac OS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,
IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin 1.5.x, mingw, MSVC 14, BeOS.
@item
This function does not support the @samp{F} directive on some platforms:
NetBSD 3.0, AIX 5.1, HP-UX 11.23, IRIX 6.5, OSF/1 5.1, Solaris 9,
Cygwin 1.5.x, mingw, MSVC 14, BeOS.
@item
This function does not support the @samp{n} directive on some platforms:
MSVC 14.
@item
This function does not support the @samp{ls} directive on some platforms:
OpenBSD 4.0, IRIX 6.5, Solaris 2.6, Cygwin 1.5.x, Haiku.
@item
This function does not support precisions in the @samp{ls} directive correctly
on some platforms:
Solaris 11.4.
@item
This function does not support format directives that access arguments in an
arbitrary order, such as @code{"%2$s"}, on some platforms:
NetBSD 3.0, mingw, MSVC 14, BeOS.
@item
This function doesn't support the @code{'} flag on some platforms:
NetBSD 3.0, Cygwin 1.5.24, mingw, MSVC 14.
@item
This function does not round the argument of the @samp{a} directive correctly
on some platforms:
Mac OS X 10.12, FreeBSD 6.1.
@item
This function behaves incorrectly when a @samp{-} flag and a negative width
are specified together, on some platforms:
HP-UX 10.20.
@item
printf @code{"%010f"} of NaN and Infinity yields an incorrect result (padded
with zeroes) on some platforms:
Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, AIX 5.2, IRIX 6.5, OSF/1 5.1, Solaris 11.0, Cygwin 1.5.x, mingw, MSVC 14.
@item
This function does not support precisions larger than 512 or 1024 in integer,
floating-point and pointer output on some platforms:
Solaris 10/x86, mingw, MSVC 14, BeOS.
@item
This function can crash in out-of-memory conditions on some platforms:
Mac OS X 10.3, FreeBSD 6.0, NetBSD 5.0.
@item
This function does not fully support the @samp{n} directive on some platforms:
HP-UX 11, mingw, MSVC 14.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
@item
The @code{%m} directive is not portable, use @code{%s} mapped to an
argument of @code{strerror(errno)} (or a version of @code{strerror_r})
instead.
@end itemize