# strndup.m4 serial 22

dnl Copyright (C) 2002-2003, 2005-2020 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.

AC_DEFUN([gl_FUNC_STRNDUP],

[

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

  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])

  AC_CHECK_DECLS_ONCE([strndup])

  AC_CHECK_FUNCS_ONCE([strndup])

  if test $ac_cv_have_decl_strndup = no; then

    HAVE_DECL_STRNDUP=0

  fi

  if test $ac_cv_func_strndup = yes; then

    HAVE_STRNDUP=1

    # AIX 4.3.3, AIX 5.1 have a function that fails to add the terminating '\0'.

    AC_CACHE_CHECK([for working strndup], [gl_cv_func_strndup_works],

      [AC_RUN_IFELSE([

         AC_LANG_PROGRAM([[#include <string.h>

                           #include <stdlib.h>]], [[

#if !HAVE_DECL_STRNDUP

  extern

  #ifdef __cplusplus

  "C"

  #endif

  char *strndup (const char *, size_t);

#endif

  int result;

  char *s;

  s = strndup ("some longer string", 15);

  free (s);

  s = strndup ("shorter string", 13);

  result = s[13] != '\0';

  free (s);

  return result;]])],

         [gl_cv_func_strndup_works=yes],

         [gl_cv_func_strndup_works=no],

         [

changequote(,)dnl

          case $host_os in

            aix | aix[3-6]*) gl_cv_func_strndup_works="guessing no";;

            *)               gl_cv_func_strndup_works="guessing yes";;

          esac

changequote([,])dnl

         ])])

    case $gl_cv_func_strndup_works in

      *no) REPLACE_STRNDUP=1 ;;

    esac

  else

    HAVE_STRNDUP=0

  fi

])