HCoop / bpt / guile.git / blame
| Commit | Line | Data |
|---|---|---|
| c4b681fd LC |
1 | # memchr.m4 serial 7 |
| 2 | dnl Copyright (C) 2002, 2003, 2004, 2009 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 | ]) |