-# memchr.m4 serial 7
-dnl Copyright (C) 2002, 2003, 2004, 2009 Free Software Foundation, Inc.
+# memchr.m4 serial 12
+dnl Copyright (C) 2002-2004, 2009-2013 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.
AC_CHECK_HEADERS_ONCE([sys/mman.h])
AC_CHECK_FUNCS_ONCE([mprotect])
- dnl These days, we assume memchr is present. But just in case...
AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
- AC_REPLACE_FUNCS([memchr])
- if test $ac_cv_func_memchr = no; then
- gl_PREREQ_MEMCHR
- REPLACE_MEMCHR=1
- fi
-
- if test $ac_cv_func_memchr = yes; then
+ m4_ifdef([gl_FUNC_MEMCHR_OBSOLETE], [
+ dnl These days, we assume memchr is present. But if support for old
+ dnl platforms is desired:
+ AC_CHECK_FUNCS_ONCE([memchr])
+ if test $ac_cv_func_memchr = no; then
+ HAVE_MEMCHR=0
+ fi
+ ])
+ if test $HAVE_MEMCHR = 1; then
# Detect platform-specific bugs in some versions of glibc:
# memchr should not dereference anything with length 0
# http://bugzilla.redhat.com/499689
# endif
#endif
]], [[
+ int result = 0;
char *fence = NULL;
#if HAVE_SYS_MMAN_H && HAVE_MPROTECT
# if HAVE_MAP_ANONYMOUS
{
int pagesize = getpagesize ();
char *two_pages =
- (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
- flags, fd, 0);
+ (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
+ flags, fd, 0);
if (two_pages != (char *)(-1)
- && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0)
- fence = two_pages + pagesize;
+ && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0)
+ fence = two_pages + pagesize;
}
#endif
if (fence)
{
if (memchr (fence, 0, 0))
- return 1;
+ result |= 1;
strcpy (fence - 9, "12345678");
if (memchr (fence - 9, 0, 79) != fence - 1)
- return 2;
+ result |= 2;
+ if (memchr (fence - 1, 0, 3) != fence - 1)
+ result |= 4;
}
- return 0;
+ return result;
]])], [gl_cv_func_memchr_works=yes], [gl_cv_func_memchr_works=no],
[dnl Be pessimistic for now.
gl_cv_func_memchr_works="guessing no"])])
if test "$gl_cv_func_memchr_works" != yes; then
- gl_PREREQ_MEMCHR
REPLACE_MEMCHR=1
- AC_LIBOBJ([memchr])
fi
fi
])