kc3-lang/gnulib/m4/snprintf.m4
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Hash : c3153d2c
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Date : 2011-07-01T08:20:06
snprintf: guarantee %1$d, for libintl Newer mingw (but not yet mingw64) provides two flavors of snprintf: _snprintf defers straight to msvcrt, which has broken return value and does not understand %llu or %zu; and snprintf, which fixes these two bugs but does not understand %1$s. Libintl specifically favors _snprintf, with broken return value, even when compiled on mingw with a fixed snprintf, because the only behavior which it wants to fix is %1$s handling. But this means that the replacement libintl_snprintf has a broken return. If one uses the 'snprintf-posix' module, then the gnulib replacement kicks in, and does everything that libintl needs, so on mingw, <libintl.h> specifically avoids overriding snprintf if it detected that gnulib replaced snprintf. However, if one only uses the 'snprintf' module and also uses libintl, this means there are two problems: 1. The gnulib 'snprintf' module does not replace the mingw snprintf function, because it has proper return values, while the libintl.h header knows that %1$d is broken so snprintf must be replaced, with the end result that the application gets the libintl replacement snprintf with broken return values in spite of the gnulib module. 2. Conversely, if the application did '#define snprintf snprintf', that would be enough to make libintl avoid installing its own replacement because libintl would see the define as a sign that gnulib is happy with snprintf. However, if gnulib didn't enforce %1$s, users can end up with translated strings that break when passed to the native snprintf. Happily, the gnulib snprintf replacement already guarantees %1$s without needing any further preprocessor macros defined, and without dragging in the LGPLv3+ bulk of snprintf-posix, so the problem boils down to guaranteeing that gnulib will replace snprintf if it lacks %1$s support. Basically, gnulib must replace snprintf under all the same conditions as libintl, as well as any other conditions of its own, if the libintl trick of deferring to gnulib is to work correctly. * m4/snprintf.m4 (gl_FUNC_SNPRINTF): Require %1$d support. * m4/vsnprintf.m4 (gl_FUNC_VSNPRINTF): Likewise. * doc/posix-functions/snprintf.texi (snprintf): Update. * doc/posix-functions/vsnprintf.texi (vsnprintf): Likewise. * tests/test-snprintf.c (main): Enhance test. * tests/test-vsnprintf.c (main): Likewise. Signed-off-by: Eric Blake <eblake@redhat.com>
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m4/snprintf.m4
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# snprintf.m4 serial 6 dnl Copyright (C) 2002-2004, 2007-2011 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. dnl Libintl 0.17 will replace snprintf only if it does not support %1$s, dnl but defers to any gnulib snprintf replacements. Therefore, gnulib dnl must guarantee that the decision for replacing snprintf is a superset dnl of the reasons checked by libintl. AC_DEFUN([gl_FUNC_SNPRINTF], [ AC_REQUIRE([gl_STDIO_H_DEFAULTS]) gl_cv_func_snprintf_usable=no AC_CHECK_FUNCS([snprintf]) if test $ac_cv_func_snprintf = yes; then gl_SNPRINTF_SIZE1 case "$gl_cv_func_snprintf_size1" in *yes) gl_SNPRINTF_RETVAL_C99 case "$gl_cv_func_snprintf_retval_c99" in *yes) gl_PRINTF_POSITIONS case "$gl_cv_func_printf_positions" in *yes) gl_cv_func_snprintf_usable=yes ;; esac ;; esac ;; esac fi if test $gl_cv_func_snprintf_usable = no; then gl_REPLACE_SNPRINTF fi AC_CHECK_DECLS_ONCE([snprintf]) if test $ac_cv_have_decl_snprintf = no; then HAVE_DECL_SNPRINTF=0 fi ]) AC_DEFUN([gl_REPLACE_SNPRINTF], [ AC_REQUIRE([gl_STDIO_H_DEFAULTS]) AC_LIBOBJ([snprintf]) if test $ac_cv_func_snprintf = yes; then REPLACE_SNPRINTF=1 fi gl_PREREQ_SNPRINTF ]) # Prerequisites of lib/snprintf.c. AC_DEFUN([gl_PREREQ_SNPRINTF], [:])