+ else
+ dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
+ dnl Also check that we handle empty needles correctly.
+ AC_CACHE_CHECK([whether memmem works],
+ [gl_cv_func_memmem_works_always],
+ [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <string.h> /* for memmem */
+#define P "_EF_BF_BD"
+#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
+#define NEEDLE P P P P P
+]], [[
+ int result = 0;
+ if (memmem (HAYSTACK, strlen (HAYSTACK), NEEDLE, strlen (NEEDLE)))
+ result |= 1;
+ /* Check for empty needle behavior. */
+ {
+ const char *haystack = "AAA";
+ if (memmem (haystack, 3, NULL, 0) != haystack)
+ result |= 2;
+ }
+ return result;
+ ]])],
+ [gl_cv_func_memmem_works_always=yes],
+ [gl_cv_func_memmem_works_always=no],
+ [dnl glibc 2.9..2.12 and cygwin 1.7.7 have issue #12092 above.
+ dnl Also empty needles work on glibc >= 2.1 and cygwin >= 1.7.0.
+ dnl uClibc is not affected, since it uses different source code.
+ dnl Assume that it works on all other platforms (even if not linear).
+ AC_EGREP_CPP([Lucky user],
+ [
+#ifdef __GNU_LIBRARY__
+ #include <features.h>
+ #if ((__GLIBC__ == 2 && ((__GLIBC_MINOR > 0 && __GLIBC_MINOR__ < 9) \
+ || __GLIBC_MINOR__ > 12)) \
+ || (__GLIBC__ > 2)) \
+ || defined __UCLIBC__
+ Lucky user
+ #endif
+#elif defined __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
+ Lucky user
+ #endif
+#else
+ Lucky user
+#endif
+ ],
+ [gl_cv_func_memmem_works_always=yes],
+ [gl_cv_func_memmem_works_always="guessing no"])
+ ])
+ ])
+ if test "$gl_cv_func_memmem_works_always" != yes; then
+ REPLACE_MEMMEM=1
+ AC_LIBOBJ([memmem])
+ fi