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1 # memchr.m4 serial 8 | 1 # memchr.m4 serial 12 |
2 dnl Copyright (C) 2002-2004, 2009-2011 Free Software Foundation, Inc. | 2 dnl Copyright (C) 2002-2004, 2009-2012 Free Software Foundation, Inc. |
3 dnl This file is free software; the Free Software Foundation | 3 dnl This file is free software; the Free Software Foundation |
4 dnl gives unlimited permission to copy and/or distribute it, | 4 dnl gives unlimited permission to copy and/or distribute it, |
5 dnl with or without modifications, as long as this notice is preserved. | 5 dnl with or without modifications, as long as this notice is preserved. |
6 | 6 |
7 AC_DEFUN_ONCE([gl_FUNC_MEMCHR], | 7 AC_DEFUN_ONCE([gl_FUNC_MEMCHR], |
8 [ | 8 [ |
9 dnl Check for prerequisites for memory fence checks. | 9 dnl Check for prerequisites for memory fence checks. |
10 gl_FUNC_MMAP_ANON | 10 gl_FUNC_MMAP_ANON |
11 AC_CHECK_HEADERS_ONCE([sys/mman.h]) | 11 AC_CHECK_HEADERS_ONCE([sys/mman.h]) |
12 AC_CHECK_FUNCS_ONCE([mprotect]) | 12 AC_CHECK_FUNCS_ONCE([mprotect]) |
13 | 13 |
14 dnl These days, we assume memchr is present. But just in case... | |
15 AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) | 14 AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) |
16 AC_CHECK_FUNCS_ONCE([memchr]) | 15 m4_ifdef([gl_FUNC_MEMCHR_OBSOLETE], [ |
17 if test $ac_cv_func_memchr = yes; then | 16 dnl These days, we assume memchr is present. But if support for old |
| 17 dnl platforms is desired: |
| 18 AC_CHECK_FUNCS_ONCE([memchr]) |
| 19 if test $ac_cv_func_memchr = no; then |
| 20 HAVE_MEMCHR=0 |
| 21 fi |
| 22 ]) |
| 23 if test $HAVE_MEMCHR = 1; then |
18 # Detect platform-specific bugs in some versions of glibc: | 24 # Detect platform-specific bugs in some versions of glibc: |
19 # memchr should not dereference anything with length 0 | 25 # memchr should not dereference anything with length 0 |
20 # http://bugzilla.redhat.com/499689 | 26 # http://bugzilla.redhat.com/499689 |
21 # memchr should not dereference overestimated length after a match | 27 # memchr should not dereference overestimated length after a match |
22 # http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737 | 28 # http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737 |
23 # http://sourceware.org/bugzilla/show_bug.cgi?id=10162 | 29 # http://sourceware.org/bugzilla/show_bug.cgi?id=10162 |
24 # Assume that memchr works on platforms that lack mprotect. | 30 # Assume that memchr works on platforms that lack mprotect. |
25 AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works], | 31 AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works], |
26 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ | 32 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ |
27 #include <string.h> | 33 #include <string.h> |
28 #if HAVE_SYS_MMAN_H | 34 #if HAVE_SYS_MMAN_H |
29 # include <fcntl.h> | 35 # include <fcntl.h> |
30 # include <unistd.h> | 36 # include <unistd.h> |
31 # include <sys/types.h> | 37 # include <sys/types.h> |
32 # include <sys/mman.h> | 38 # include <sys/mman.h> |
33 # ifndef MAP_FILE | 39 # ifndef MAP_FILE |
34 # define MAP_FILE 0 | 40 # define MAP_FILE 0 |
35 # endif | 41 # endif |
36 #endif | 42 #endif |
37 ]], [[ | 43 ]], [[ |
| 44 int result = 0; |
38 char *fence = NULL; | 45 char *fence = NULL; |
39 #if HAVE_SYS_MMAN_H && HAVE_MPROTECT | 46 #if HAVE_SYS_MMAN_H && HAVE_MPROTECT |
40 # if HAVE_MAP_ANONYMOUS | 47 # if HAVE_MAP_ANONYMOUS |
41 const int flags = MAP_ANONYMOUS | MAP_PRIVATE; | 48 const int flags = MAP_ANONYMOUS | MAP_PRIVATE; |
42 const int fd = -1; | 49 const int fd = -1; |
43 # else /* !HAVE_MAP_ANONYMOUS */ | 50 # else /* !HAVE_MAP_ANONYMOUS */ |
44 const int flags = MAP_FILE | MAP_PRIVATE; | 51 const int flags = MAP_FILE | MAP_PRIVATE; |
45 int fd = open ("/dev/zero", O_RDONLY, 0666); | 52 int fd = open ("/dev/zero", O_RDONLY, 0666); |
46 if (fd >= 0) | 53 if (fd >= 0) |
47 # endif | 54 # endif |
48 { | 55 { |
49 int pagesize = getpagesize (); | 56 int pagesize = getpagesize (); |
50 char *two_pages = | 57 char *two_pages = |
51 (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE, | 58 (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE, |
52 flags, fd, 0); | 59 flags, fd, 0); |
53 if (two_pages != (char *)(-1) | 60 if (two_pages != (char *)(-1) |
54 && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0) | 61 && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0) |
55 fence = two_pages + pagesize; | 62 fence = two_pages + pagesize; |
56 } | 63 } |
57 #endif | 64 #endif |
58 if (fence) | 65 if (fence) |
59 { | 66 { |
60 if (memchr (fence, 0, 0)) | 67 if (memchr (fence, 0, 0)) |
61 return 1; | 68 result |= 1; |
62 strcpy (fence - 9, "12345678"); | 69 strcpy (fence - 9, "12345678"); |
63 if (memchr (fence - 9, 0, 79) != fence - 1) | 70 if (memchr (fence - 9, 0, 79) != fence - 1) |
64 return 2; | 71 result |= 2; |
| 72 if (memchr (fence - 1, 0, 3) != fence - 1) |
| 73 result |= 4; |
65 } | 74 } |
66 return 0; | 75 return result; |
67 ]])], [gl_cv_func_memchr_works=yes], [gl_cv_func_memchr_works=no], | 76 ]])], [gl_cv_func_memchr_works=yes], [gl_cv_func_memchr_works=no], |
68 [dnl Be pessimistic for now. | 77 [dnl Be pessimistic for now. |
69 gl_cv_func_memchr_works="guessing no"])]) | 78 gl_cv_func_memchr_works="guessing no"])]) |
70 if test "$gl_cv_func_memchr_works" != yes; then | 79 if test "$gl_cv_func_memchr_works" != yes; then |
71 REPLACE_MEMCHR=1 | 80 REPLACE_MEMCHR=1 |
72 fi | 81 fi |
73 else | |
74 HAVE_MEMCHR=0 | |
75 fi | |
76 if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then | |
77 AC_LIBOBJ([memchr]) | |
78 gl_PREREQ_MEMCHR | |
79 fi | 82 fi |
80 ]) | 83 ]) |
81 | 84 |
82 # Prerequisites of lib/memchr.c. | 85 # Prerequisites of lib/memchr.c. |
83 AC_DEFUN([gl_PREREQ_MEMCHR], [ | 86 AC_DEFUN([gl_PREREQ_MEMCHR], [ |
84 AC_CHECK_HEADERS([bp-sym.h]) | 87 AC_CHECK_HEADERS([bp-sym.h]) |
85 ]) | 88 ]) |
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