Mercurial > gnulib
view m4/memchr.m4 @ 40177:dcd889592b62
dtoastr,ftoastr,ldtoastr: port to c-strtod changes
Decouple these modules from c-strtod. Nowadays it’s reasonable to
assume the C99 signatures for strtod and strtold. Programs that
require stricter adherence to C99 should also use the strtod and
strtold modules as needed, and we no longer need the
HAVE_C99_STRTOLD macro.
* NEWS: Mention this.
* lib/ftoastr.c (STRTOF) [LENGTH == 3]: Assume strtold.
* m4/c-strtod.m4 (gl_C_STRTOLD): Do not define HAVE_C99_STRTOLD.
* modules/dtoastr, modules/ftoastr, modules/ldtoastr:
(Files): Remove m4/c-strtod.m4.
(configure.ac): Do not require gl_C99_STRTOLD, which no longer
exists.
author | Paul Eggert <eggert@cs.ucla.edu> |
---|---|
date | Sat, 02 Feb 2019 13:01:55 -0800 |
parents | f03dfb30b48c |
children |
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# memchr.m4 serial 14 dnl Copyright (C) 2002-2004, 2009-2019 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_DEFUN_ONCE([gl_FUNC_MEMCHR], [ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles dnl Check for prerequisites for memory fence checks. gl_FUNC_MMAP_ANON AC_CHECK_HEADERS_ONCE([sys/mman.h]) AC_CHECK_FUNCS_ONCE([mprotect]) AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) 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 $HAVE_MEMCHR = 1; then # Detect platform-specific bugs in some versions of glibc: # memchr should not dereference anything with length 0 # https://bugzilla.redhat.com/show_bug.cgi?id=499689 # memchr should not dereference overestimated length after a match # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737 # https://sourceware.org/bugzilla/show_bug.cgi?id=10162 # memchr should cast the second argument to 'unsigned char'. # This bug exists in Android 4.3. # Assume that memchr works on platforms that lack mprotect. AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works], [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ #include <string.h> #if HAVE_SYS_MMAN_H # include <fcntl.h> # include <unistd.h> # include <sys/types.h> # include <sys/mman.h> # ifndef MAP_FILE # define MAP_FILE 0 # endif #endif ]], [[ int result = 0; char *fence = NULL; #if HAVE_SYS_MMAN_H && HAVE_MPROTECT # if HAVE_MAP_ANONYMOUS const int flags = MAP_ANONYMOUS | MAP_PRIVATE; const int fd = -1; # else /* !HAVE_MAP_ANONYMOUS */ const int flags = MAP_FILE | MAP_PRIVATE; int fd = open ("/dev/zero", O_RDONLY, 0666); if (fd >= 0) # endif { int pagesize = getpagesize (); char *two_pages = (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE, flags, fd, 0); if (two_pages != (char *)(-1) && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0) fence = two_pages + pagesize; } #endif if (fence) { if (memchr (fence, 0, 0)) result |= 1; strcpy (fence - 9, "12345678"); if (memchr (fence - 9, 0, 79) != fence - 1) result |= 2; if (memchr (fence - 1, 0, 3) != fence - 1) result |= 4; } /* Test against bug on Android 4.3. */ { char input[3]; input[0] = 'a'; input[1] = 'b'; input[2] = 'c'; if (memchr (input, 0x789abc00 | 'b', 3) != input + 1) result |= 8; } return result; ]])], [gl_cv_func_memchr_works=yes], [gl_cv_func_memchr_works=no], [case "$host_os" in # Guess no on Android. linux*-android*) gl_cv_func_memchr_works="guessing no" ;; # Guess yes on native Windows. mingw*) gl_cv_func_memchr_works="guessing yes" ;; # Be pessimistic for now. *) gl_cv_func_memchr_works="guessing no" ;; esac ]) ]) case "$gl_cv_func_memchr_works" in *yes) ;; *) REPLACE_MEMCHR=1 ;; esac fi ]) # Prerequisites of lib/memchr.c. AC_DEFUN([gl_PREREQ_MEMCHR], [ AC_CHECK_HEADERS([bp-sym.h]) ])