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comparison m4/memchr.m4 @ 398:7987ee447833 3.0-beta1

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Added generated files for release
author lost@l-w.ca
date Fri, 23 Jul 2010 17:18:52 -0600
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397:09fe7c40a082 398:7987ee447833
1 # memchr.m4 serial 7
2 dnl Copyright (C) 2002-2004, 2009-2010 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
6
7 AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
8 [
9 dnl Check for prerequisites for memory fence checks.
10 gl_FUNC_MMAP_ANON
11 AC_CHECK_HEADERS_ONCE([sys/mman.h])
12 AC_CHECK_FUNCS_ONCE([mprotect])
13
14 dnl These days, we assume memchr is present. But just in case...
15 AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
16 AC_REPLACE_FUNCS([memchr])
17 if test $ac_cv_func_memchr = no; then
18 gl_PREREQ_MEMCHR
19 REPLACE_MEMCHR=1
20 fi
21
22 if test $ac_cv_func_memchr = yes; then
23 # Detect platform-specific bugs in some versions of glibc:
24 # memchr should not dereference anything with length 0
25 # http://bugzilla.redhat.com/499689
26 # memchr should not dereference overestimated length after a match
27 # http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737
28 # http://sourceware.org/bugzilla/show_bug.cgi?id=10162
29 # Assume that memchr works on platforms that lack mprotect.
30 AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works],
31 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
32 #include <string.h>
33 #if HAVE_SYS_MMAN_H
34 # include <fcntl.h>
35 # include <unistd.h>
36 # include <sys/types.h>
37 # include <sys/mman.h>
38 # ifndef MAP_FILE
39 # define MAP_FILE 0
40 # endif
41 #endif
42 ]], [[
43 char *fence = NULL;
44 #if HAVE_SYS_MMAN_H && HAVE_MPROTECT
45 # if HAVE_MAP_ANONYMOUS
46 const int flags = MAP_ANONYMOUS | MAP_PRIVATE;
47 const int fd = -1;
48 # else /* !HAVE_MAP_ANONYMOUS */
49 const int flags = MAP_FILE | MAP_PRIVATE;
50 int fd = open ("/dev/zero", O_RDONLY, 0666);
51 if (fd >= 0)
52 # endif
53 {
54 int pagesize = getpagesize ();
55 char *two_pages =
56 (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
57 flags, fd, 0);
58 if (two_pages != (char *)(-1)
59 && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0)
60 fence = two_pages + pagesize;
61 }
62 #endif
63 if (fence)
64 {
65 if (memchr (fence, 0, 0))
66 return 1;
67 strcpy (fence - 9, "12345678");
68 if (memchr (fence - 9, 0, 79) != fence - 1)
69 return 2;
70 }
71 return 0;
72 ]])], [gl_cv_func_memchr_works=yes], [gl_cv_func_memchr_works=no],
73 [dnl Be pessimistic for now.
74 gl_cv_func_memchr_works="guessing no"])])
75 if test "$gl_cv_func_memchr_works" != yes; then
76 gl_PREREQ_MEMCHR
77 REPLACE_MEMCHR=1
78 AC_LIBOBJ([memchr])
79 fi
80 fi
81 ])
82
83 # Prerequisites of lib/memchr.c.
84 AC_DEFUN([gl_PREREQ_MEMCHR], [
85 AC_CHECK_HEADERS([bp-sym.h])
86 ])