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[/] [openrisc/] [tags/] [gnu-src/] [gdb-7.2/] [gdb-7.2-or32-1.0rc1/] [gdb/] [gnulib/] [m4/] [memchr.m4] - Rev 330
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# memchr.m4 serial 8 dnl Copyright (C) 2002-2004, 2009-2010 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], [ dnl Check for prerequisites for memory fence checks. gl_FUNC_MMAP_ANON 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_CHECK_FUNCS_ONCE([memchr]) if test $ac_cv_func_memchr = yes; then # Detect platform-specific bugs in some versions of glibc: # memchr should not dereference anything with length 0 # http://bugzilla.redhat.com/499689 # memchr should not dereference overestimated length after a match # http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737 # http://sourceware.org/bugzilla/show_bug.cgi?id=10162 # Assume that memchr works on platforms that lack mprotect. AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works], [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ #include <string.h> #if HAVE_SYS_MMAN_H # include <fcntl.h> # include <unistd.h> # include <sys/types.h> # include <sys/mman.h> # ifndef MAP_FILE # define MAP_FILE 0 # endif #endif ]], [[ char *fence = NULL; #if HAVE_SYS_MMAN_H && HAVE_MPROTECT # if HAVE_MAP_ANONYMOUS const int flags = MAP_ANONYMOUS | MAP_PRIVATE; const int fd = -1; # else /* !HAVE_MAP_ANONYMOUS */ const int flags = MAP_FILE | MAP_PRIVATE; int fd = open ("/dev/zero", O_RDONLY, 0666); if (fd >= 0) # endif { int pagesize = getpagesize (); char *two_pages = (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE, flags, fd, 0); if (two_pages != (char *)(-1) && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0) fence = two_pages + pagesize; } #endif if (fence) { if (memchr (fence, 0, 0)) return 1; strcpy (fence - 9, "12345678"); if (memchr (fence - 9, 0, 79) != fence - 1) return 2; } return 0; ]])], [gl_cv_func_memchr_works=yes], [gl_cv_func_memchr_works=no], [dnl Be pessimistic for now. gl_cv_func_memchr_works="guessing no"])]) if test "$gl_cv_func_memchr_works" != yes; then REPLACE_MEMCHR=1 fi else HAVE_MEMCHR=0 fi if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then AC_LIBOBJ([memchr]) gl_PREREQ_MEMCHR fi ]) # Prerequisites of lib/memchr.c. AC_DEFUN([gl_PREREQ_MEMCHR], [ AC_CHECK_HEADERS([bp-sym.h]) ])
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