projects / deliverable / binutils-gdb.git / blame
| Commit | Line | Data |
|---|---|---|
| f6ea5628 | 1 | # memmem.m4 serial 9 |
| 4c38e0a4 | 2 | dnl Copyright (C) 2002, 2003, 2004, 2007, 2008, 2009, 2010 |
| 0fb0cc75 | 3 | Free Software Foundation, Inc. |
| f6ea5628 DJ |
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 $ac_cv_have_decl_memmem = yes; then | |
| 28 | AC_CACHE_CHECK([whether memmem works in linear time], | |
| 29 | [gl_cv_func_memmem_works], | |
| 30 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([ | |
| 31 | #include <string.h> /* for memmem */ | |
| 32 | #include <stdlib.h> /* for malloc */ | |
| 33 | #include <unistd.h> /* for alarm */ | |
| 34 | ], [[size_t m = 1000000; | |
| 35 | char *haystack = (char *) malloc (2 * m + 1); | |
| 36 | char *needle = (char *) malloc (m + 1); | |
| 37 | void *result = 0; | |
| 38 | /* Failure to compile this test due to missing alarm is okay, | |
| 39 | since all such platforms (mingw) also lack memmem. */ | |
| 40 | alarm (5); | |
| 41 | /* Check for quadratic performance. */ | |
| 42 | if (haystack && needle) | |
| 43 | { | |
| 44 | memset (haystack, 'A', 2 * m); | |
| 45 | haystack[2 * m] = 'B'; | |
| 46 | memset (needle, 'A', m); | |
| 47 | needle[m] = 'B'; | |
| 48 | result = memmem (haystack, 2 * m + 1, needle, m + 1); | |
| 49 | } | |
| 50 | /* Check for empty needle behavior. */ | |
| 51 | return !result || !memmem ("a", 1, 0, 0);]])], | |
| 52 | [gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no], | |
| 53 | [dnl pessimistically assume the worst, since even glibc 2.6.1 | |
| 54 | dnl has quadratic complexity in its memmem | |
| 55 | gl_cv_func_memmem_works="guessing no"])]) | |
| 56 | if test "$gl_cv_func_memmem_works" != yes; then | |
| 57 | REPLACE_MEMMEM=1 | |
| 58 | AC_LIBOBJ([memmem]) | |
| 59 | fi | |
| 60 | fi | |
| 61 | ]) # gl_FUNC_MEMMEM | |
| 62 | ||
| 63 | # Prerequisites of lib/memmem.c. | |
| 64 | AC_DEFUN([gl_PREREQ_MEMMEM], [:]) |