# strcasestr.m4 serial 23

dnl Copyright (C) 2005, 2007-2018 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 strcasestr is present and works.

AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE],

[

  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])

  dnl Persuade glibc <string.h> to declare strcasestr().

  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

  AC_REQUIRE([gl_FUNC_MEMCHR])

  AC_CHECK_FUNCS([strcasestr])

  if test $ac_cv_func_strcasestr = no; then

    HAVE_STRCASESTR=0

  else

    if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then

      REPLACE_STRCASESTR=1

    else

      dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092.

      AC_CACHE_CHECK([whether strcasestr works],

        [gl_cv_func_strcasestr_works_always],

        [AC_RUN_IFELSE([AC_LANG_PROGRAM([[

#include <string.h> /* for strcasestr */

#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

]], [[return !!strcasestr (HAYSTACK, NEEDLE);

      ]])],

          [gl_cv_func_strcasestr_works_always=yes],

          [gl_cv_func_strcasestr_works_always=no],

          [dnl glibc 2.12 and cygwin 1.7.7 have a known bug.  uClibc is not

           dnl affected, since it uses different source code for strcasestr

           dnl than glibc.

           dnl Assume that it works on all other platforms, even if it is not

           dnl linear.

           AC_EGREP_CPP([Lucky user],

             [

#ifdef __GNU_LIBRARY__

 #include <features.h>

 #if ((__GLIBC__ == 2 && __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_strcasestr_works_always="guessing yes"],

             [gl_cv_func_strcasestr_works_always="guessing no"])

          ])

        ])

      case "$gl_cv_func_strcasestr_works_always" in

        *yes) ;;

        *)

          REPLACE_STRCASESTR=1

          ;;

      esac

    fi

  fi

]) # gl_FUNC_STRCASESTR_SIMPLE

dnl Additionally, check that strcasestr is efficient.

AC_DEFUN([gl_FUNC_STRCASESTR],

[

  AC_REQUIRE([gl_FUNC_STRCASESTR_SIMPLE])

  if test $HAVE_STRCASESTR = 1 && test $REPLACE_STRCASESTR = 0; then

    AC_CACHE_CHECK([whether strcasestr works in linear time],

      [gl_cv_func_strcasestr_linear],

      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[

#include <signal.h> /* for signal */

#include <string.h> /* for strcasestr */

#include <stdlib.h> /* for malloc */

#include <unistd.h> /* for alarm */

static void quit (int sig) { _exit (sig + 128); }

]], [[

    int result = 0;

    size_t m = 1000000;

    char *haystack = (char *) malloc (2 * m + 2);

    char *needle = (char *) malloc (m + 2);

    /* Failure to compile this test due to missing alarm is okay,

       since all such platforms (mingw) also lack strcasestr.  */

    signal (SIGALRM, quit);

    alarm (5);

    /* Check for quadratic performance.  */

    if (haystack && needle)

      {

        memset (haystack, 'A', 2 * m);

        haystack[2 * m] = 'B';

        haystack[2 * m + 1] = 0;

        memset (needle, 'A', m);

        needle[m] = 'B';

        needle[m + 1] = 0;

        if (!strcasestr (haystack, needle))

          result |= 1;

      }

    /* Free allocated memory, in case some sanitizer is watching.  */

    free (haystack);

    free (needle);

    return result;

    ]])],

        [gl_cv_func_strcasestr_linear=yes], [gl_cv_func_strcasestr_linear=no],

        [dnl Only glibc > 2.12 and cygwin > 1.7.7 are known to have a

         dnl strcasestr that works in linear time.

         AC_EGREP_CPP([Lucky user],

           [

#include <features.h>

#ifdef __GNU_LIBRARY__

 #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \

     && !defined __UCLIBC__

  Lucky user

 #endif

#endif

#ifdef __CYGWIN__

 #include <cygwin/version.h>

 #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)

  Lucky user

 #endif

#endif

           ],

           [gl_cv_func_strcasestr_linear="guessing yes"],

           [gl_cv_func_strcasestr_linear="guessing no"])

        ])

      ])

    case "$gl_cv_func_strcasestr_linear" in

      *yes) ;;

      *)

        REPLACE_STRCASESTR=1

        ;;

    esac

  fi

]) # gl_FUNC_STRCASESTR

# Prerequisites of lib/strcasestr.c.

AC_DEFUN([gl_PREREQ_STRCASESTR], [

  :

])