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Diffstat (limited to 'gl/m4/strstr.m4')
-rw-r--r-- | gl/m4/strstr.m4 | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/gl/m4/strstr.m4 b/gl/m4/strstr.m4 new file mode 100644 index 00000000..779957aa --- /dev/null +++ b/gl/m4/strstr.m4 | |||
@@ -0,0 +1,79 @@ | |||
1 | # strstr.m4 serial 7 | ||
2 | dnl Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc. | ||
3 | dnl This file is free software; the Free Software Foundation | ||
4 | dnl gives unlimited permission to copy and/or distribute it, | ||
5 | dnl with or without modifications, as long as this notice is preserved. | ||
6 | |||
7 | dnl Check that strstr works. | ||
8 | AC_DEFUN([gl_FUNC_STRSTR_SIMPLE], | ||
9 | [ | ||
10 | AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) | ||
11 | AC_REQUIRE([gl_FUNC_MEMCHR]) | ||
12 | if test "$gl_cv_func_memchr_works" != yes; then | ||
13 | REPLACE_STRSTR=1 | ||
14 | AC_LIBOBJ([strstr]) | ||
15 | fi | ||
16 | ]) # gl_FUNC_STRSTR_SIMPLE | ||
17 | |||
18 | dnl Additionally, check that strstr is efficient. | ||
19 | AC_DEFUN([gl_FUNC_STRSTR], | ||
20 | [ | ||
21 | AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE]) | ||
22 | if test $REPLACE_STRSTR = 0; then | ||
23 | AC_CACHE_CHECK([whether strstr works in linear time], | ||
24 | [gl_cv_func_strstr_linear], | ||
25 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ | ||
26 | #include <signal.h> /* for signal */ | ||
27 | #include <string.h> /* for memmem */ | ||
28 | #include <stdlib.h> /* for malloc */ | ||
29 | #include <unistd.h> /* for alarm */ | ||
30 | ]], [[size_t m = 1000000; | ||
31 | char *haystack = (char *) malloc (2 * m + 2); | ||
32 | char *needle = (char *) malloc (m + 2); | ||
33 | void *result = 0; | ||
34 | /* Failure to compile this test due to missing alarm is okay, | ||
35 | since all such platforms (mingw) also have quadratic strstr. */ | ||
36 | signal (SIGALRM, SIG_DFL); | ||
37 | alarm (5); | ||
38 | /* Check for quadratic performance. */ | ||
39 | if (haystack && needle) | ||
40 | { | ||
41 | memset (haystack, 'A', 2 * m); | ||
42 | haystack[2 * m] = 'B'; | ||
43 | haystack[2 * m + 1] = 0; | ||
44 | memset (needle, 'A', m); | ||
45 | needle[m] = 'B'; | ||
46 | needle[m + 1] = 0; | ||
47 | result = strstr (haystack, needle); | ||
48 | } | ||
49 | return !result;]])], | ||
50 | [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no], | ||
51 | [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a | ||
52 | dnl strstr that works in linear time. | ||
53 | AC_EGREP_CPP([Lucky user], | ||
54 | [ | ||
55 | #include <features.h> | ||
56 | #ifdef __GNU_LIBRARY__ | ||
57 | #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2) | ||
58 | Lucky user | ||
59 | #endif | ||
60 | #endif | ||
61 | #ifdef __CYGWIN__ | ||
62 | #include <cygwin/version.h> | ||
63 | #if CYGWIN_VERSION_DLL_MAJOR >= 1007 | ||
64 | Lucky user | ||
65 | #endif | ||
66 | #endif | ||
67 | ], | ||
68 | [gl_cv_func_strstr_linear=yes], | ||
69 | [gl_cv_func_strstr_linear="guessing no"]) | ||
70 | ]) | ||
71 | ]) | ||
72 | if test "$gl_cv_func_strstr_linear" != yes; then | ||
73 | REPLACE_STRSTR=1 | ||
74 | fi | ||
75 | fi | ||
76 | if test $REPLACE_STRSTR = 1; then | ||
77 | AC_LIBOBJ([strstr]) | ||
78 | fi | ||
79 | ]) # gl_FUNC_STRSTR | ||