view m4/free.m4 @ 15308:a3ba680ad389

strerror_r: fix OpenBSD behavior on 0 OpenBSD treats strerror_r(0,,) as a success, but with a message "Undefined error: 0"; while this is distinct from strerror_r(-1,,) returning "Unknown error: -1", it does not imply success. Meanwhile, if buf is short enough for ERANGE, then we can't use strstr to look for "Unknown" or "Undefined" in the resulting message, like we had been doing for strerror(). Fix this by shifting the burden - now the strerror-override code guarantees that 0 will have an override when needed. * lib/strerror-override.c (strerror_override): Also override 0 when needed. * lib/strerror-override.h (strerror_override): Likewise. * lib/strerror.c (strerror): Simplify, now that 0 override is done earlier. * lib/strerror_r.c (strerror_r): Likewise. * m4/strerror.m4 (gl_FUNC_STRERROR): Split detection of 0 behavior... (gl_FUNC_STRERROR_0): ...into new macro. * m4/strerror_r.m4 (gl_FUNC_STRERROR_R): Replace strerror_r if 0 is overridden. (gl_FUNC_STRERROR_R_WORKS): Avoid extra tests if 0 is broken. * modules/strerror-override (Files): Add strerror.m4. (configure.ac): Also provide override for 0 when needed. * doc/posix-functions/strerror.texi (strerror): Document this. * doc/posix-functions/perror.texi (perror): Likewise. Signed-off-by: Eric Blake <eblake@redhat.com>
author Eric Blake <eblake@redhat.com>
date Tue, 21 Jun 2011 08:50:51 -0600
parents fff577282e62
children f62f29997e98
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# Check whether free (NULL) is supposed to work.

# Copyright (C) 2003-2005, 2009-2011 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.

# Written by Paul Eggert.

# We can't test for free (NULL) even at runtime, since it might
# happen to "work" for our test program, but not in general.  So, be
# conservative and use feature tests for relatively modern hosts,
# where free (NULL) is known to work.  This costs a bit of
# performance on some older hosts, but we can fix that later if
# needed.

AC_DEFUN([gl_FUNC_FREE],
[
  AC_CACHE_CHECK([whether free (NULL) is known to work],
    [gl_cv_func_free],
    [AC_COMPILE_IFELSE(
       [AC_LANG_PROGRAM(
          [[@%:@include <unistd.h>]],
          [[@%:@if _POSIX_VERSION < 199009L && \
                (defined unix || defined _unix || defined _unix_ \
                 || defined __unix || defined __unix__)
              @%:@error "'free (NULL)' is not known to work"
            @%:@endif]])],
       [gl_cv_func_free=yes],
       [gl_cv_func_free=no])])

  if test $gl_cv_func_free = no; then
    AC_DEFINE([free], [rpl_free],
      [Define to rpl_free if the replacement function should be used.])
  fi
])

# Prerequisites of lib/free.c.
AC_DEFUN([gl_PREREQ_FREE], [:])