| 1 |
330 |
jeremybenn |
# memmem.m4 serial 14
|
| 2 |
|
|
dnl Copyright (C) 2002, 2003, 2004, 2007, 2008, 2009, 2010 Free Software
|
| 3 |
|
|
dnl Foundation, Inc.
|
| 4 |
|
|
dnl This file is free software; the Free Software Foundation
|
| 5 |
|
|
dnl gives unlimited permission to copy and/or distribute it,
|
| 6 |
|
|
dnl with or without modifications, as long as this notice is preserved.
|
| 7 |
|
|
|
| 8 |
|
|
dnl Check that memmem is present.
|
| 9 |
|
|
AC_DEFUN([gl_FUNC_MEMMEM_SIMPLE],
|
| 10 |
|
|
[
|
| 11 |
|
|
dnl Persuade glibc <string.h> to declare memmem().
|
| 12 |
|
|
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
|
| 13 |
|
|
|
| 14 |
|
|
AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
|
| 15 |
|
|
AC_REPLACE_FUNCS([memmem])
|
| 16 |
|
|
AC_CHECK_DECLS_ONCE([memmem])
|
| 17 |
|
|
if test $ac_cv_have_decl_memmem = no; then
|
| 18 |
|
|
HAVE_DECL_MEMMEM=0
|
| 19 |
|
|
fi
|
| 20 |
|
|
gl_PREREQ_MEMMEM
|
| 21 |
|
|
]) # gl_FUNC_MEMMEM_SIMPLE
|
| 22 |
|
|
|
| 23 |
|
|
dnl Additionally, check that memmem is efficient and handles empty needles.
|
| 24 |
|
|
AC_DEFUN([gl_FUNC_MEMMEM],
|
| 25 |
|
|
[
|
| 26 |
|
|
AC_REQUIRE([gl_FUNC_MEMMEM_SIMPLE])
|
| 27 |
|
|
if test $ac_cv_have_decl_memmem = yes; then
|
| 28 |
|
|
AC_CACHE_CHECK([whether memmem works in linear time],
|
| 29 |
|
|
[gl_cv_func_memmem_works],
|
| 30 |
|
|
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
|
| 31 |
|
|
#include <signal.h> /* for signal */
|
| 32 |
|
|
#include <string.h> /* for memmem */
|
| 33 |
|
|
#include <stdlib.h> /* for malloc */
|
| 34 |
|
|
#include <unistd.h> /* for alarm */
|
| 35 |
|
|
]], [[size_t m = 1000000;
|
| 36 |
|
|
char *haystack = (char *) malloc (2 * m + 1);
|
| 37 |
|
|
char *needle = (char *) malloc (m + 1);
|
| 38 |
|
|
void *result = 0;
|
| 39 |
|
|
/* Failure to compile this test due to missing alarm is okay,
|
| 40 |
|
|
since all such platforms (mingw) also lack memmem. */
|
| 41 |
|
|
signal (SIGALRM, SIG_DFL);
|
| 42 |
|
|
alarm (5);
|
| 43 |
|
|
/* Check for quadratic performance. */
|
| 44 |
|
|
if (haystack && needle)
|
| 45 |
|
|
{
|
| 46 |
|
|
memset (haystack, 'A', 2 * m);
|
| 47 |
|
|
haystack[2 * m] = 'B';
|
| 48 |
|
|
memset (needle, 'A', m);
|
| 49 |
|
|
needle[m] = 'B';
|
| 50 |
|
|
result = memmem (haystack, 2 * m + 1, needle, m + 1);
|
| 51 |
|
|
}
|
| 52 |
|
|
/* Check for empty needle behavior. */
|
| 53 |
|
|
return !result || !memmem ("a", 1, 0, 0);]])],
|
| 54 |
|
|
[gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no],
|
| 55 |
|
|
[dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a
|
| 56 |
|
|
dnl memmem that works in linear time.
|
| 57 |
|
|
AC_EGREP_CPP([Lucky user],
|
| 58 |
|
|
[
|
| 59 |
|
|
#include <features.h>
|
| 60 |
|
|
#ifdef __GNU_LIBRARY__
|
| 61 |
|
|
#if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)
|
| 62 |
|
|
Lucky user
|
| 63 |
|
|
#endif
|
| 64 |
|
|
#endif
|
| 65 |
|
|
#ifdef __CYGWIN__
|
| 66 |
|
|
#include <cygwin/version.h>
|
| 67 |
|
|
#if CYGWIN_VERSION_DLL_MAJOR >= 1007
|
| 68 |
|
|
Lucky user
|
| 69 |
|
|
#endif
|
| 70 |
|
|
#endif
|
| 71 |
|
|
],
|
| 72 |
|
|
[gl_cv_func_memmem_works=yes],
|
| 73 |
|
|
[gl_cv_func_memmem_works="guessing no"])
|
| 74 |
|
|
])
|
| 75 |
|
|
])
|
| 76 |
|
|
if test "$gl_cv_func_memmem_works" != yes; then
|
| 77 |
|
|
REPLACE_MEMMEM=1
|
| 78 |
|
|
AC_LIBOBJ([memmem])
|
| 79 |
|
|
fi
|
| 80 |
|
|
fi
|
| 81 |
|
|
]) # gl_FUNC_MEMMEM
|
| 82 |
|
|
|
| 83 |
|
|
# Prerequisites of lib/memmem.c.
|
| 84 |
|
|
AC_DEFUN([gl_PREREQ_MEMMEM], [:])
|
