diff options
Diffstat (limited to 'gnulib/m4/memmem.m4')
| -rw-r--r-- | gnulib/m4/memmem.m4 | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/gnulib/m4/memmem.m4 b/gnulib/m4/memmem.m4 new file mode 100644 index 0000000..87ab663 --- /dev/null +++ b/gnulib/m4/memmem.m4 @@ -0,0 +1,83 @@ +# memmem.m4 serial 13 +dnl Copyright (C) 2002, 2003, 2004, 2007, 2008 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. + +dnl Check that memmem is present. +AC_DEFUN([gl_FUNC_MEMMEM_SIMPLE], +[ + dnl Persuade glibc <string.h> to declare memmem(). + AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) + + AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) + AC_REPLACE_FUNCS(memmem) + AC_CHECK_DECLS_ONCE(memmem) + if test $ac_cv_have_decl_memmem = no; then + HAVE_DECL_MEMMEM=0 + fi + gl_PREREQ_MEMMEM +]) # gl_FUNC_MEMMEM_SIMPLE + +dnl Additionally, check that memmem is efficient and handles empty needles. +AC_DEFUN([gl_FUNC_MEMMEM], +[ + AC_REQUIRE([gl_FUNC_MEMMEM_SIMPLE]) + if test $ac_cv_have_decl_memmem = yes; then + AC_CACHE_CHECK([whether memmem works in linear time], + [gl_cv_func_memmem_works], + [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ +#include <signal.h> /* for signal */ +#include <string.h> /* for memmem */ +#include <stdlib.h> /* for malloc */ +#include <unistd.h> /* for alarm */ +]], [[size_t m = 1000000; + char *haystack = (char *) malloc (2 * m + 1); + char *needle = (char *) malloc (m + 1); + void *result = 0; + /* Failure to compile this test due to missing alarm is okay, + since all such platforms (mingw) also lack memmem. */ + signal (SIGALRM, SIG_DFL); + alarm (5); + /* Check for quadratic performance. */ + if (haystack && needle) + { + memset (haystack, 'A', 2 * m); + haystack[2 * m] = 'B'; + memset (needle, 'A', m); + needle[m] = 'B'; + result = memmem (haystack, 2 * m + 1, needle, m + 1); + } + /* Check for empty needle behavior. */ + return !result || !memmem ("a", 1, 0, 0);]])], + [gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no], + [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a + dnl memmem that works in linear time. + AC_EGREP_CPP([Lucky user], + [ +#include <features.h> +#ifdef __GNU_LIBRARY__ + #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2) + Lucky user + #endif +#endif +#ifdef __CYGWIN__ + #include <cygwin/version.h> + #if CYGWIN_VERSION_DLL_MAJOR >= 1007 + Lucky user + #endif +#endif + ], + [gl_cv_func_memmem_works=yes], + [gl_cv_func_memmem_works="guessing no"]) + ]) + ]) + if test "$gl_cv_func_memmem_works" != yes; then + REPLACE_MEMMEM=1 + AC_LIBOBJ([memmem]) + fi + fi +]) # gl_FUNC_MEMMEM + +# Prerequisites of lib/memmem.c. +AC_DEFUN([gl_PREREQ_MEMMEM], [:]) |