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[/] [openrisc/] [trunk/] [gnu-src/] [gdb-7.1/] [gdb/] [gnulib/] [m4/] [memmem.m4] - Rev 435
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# memmem.m4 serial 9 dnl Copyright (C) 2002, 2003, 2004, 2007, 2008, 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. 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 $ac_cv_have_decl_memmem = yes; then AC_CACHE_CHECK([whether memmem works in linear time], [gl_cv_func_memmem_works], [AC_RUN_IFELSE([AC_LANG_PROGRAM([ #include <string.h> /* for memmem */ #include <stdlib.h> /* for malloc */ #include <unistd.h> /* for alarm */ ], [[size_t m = 1000000; char *haystack = (char *) malloc (2 * m + 1); char *needle = (char *) malloc (m + 1); void *result = 0; /* Failure to compile this test due to missing alarm is okay, since all such platforms (mingw) also lack memmem. */ alarm (5); /* Check for quadratic performance. */ if (haystack && needle) { memset (haystack, 'A', 2 * m); haystack[2 * m] = 'B'; memset (needle, 'A', m); needle[m] = 'B'; result = memmem (haystack, 2 * m + 1, needle, m + 1); } /* Check for empty needle behavior. */ return !result || !memmem ("a", 1, 0, 0);]])], [gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no], [dnl pessimistically assume the worst, since even glibc 2.6.1 dnl has quadratic complexity in its memmem gl_cv_func_memmem_works="guessing no"])]) if test "$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], [:])
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