- [gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no],
- [dnl pessimistically assume the worst, since even glibc 2.6.1
- dnl has quadratic complexity in its memmem
- gl_cv_func_memmem_works="guessing no"])])
+ [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"])
+ ])
+ ])