autoupdate

[gnulib.git] / m4 / strerror.m4

diff --git a/m4/strerror.m4 b/m4/strerror.m4
index 9cb5769..ca05be6 100644 (file)
--- a/m4/strerror.m4
+++ b/m4/strerror.m4
@@ -1,46 +1,78 @@
-# strerror.m4 serial 6
-dnl Copyright (C) 2002, 2007 Free Software Foundation, Inc.
+# strerror.m4 serial 16
+dnl Copyright (C) 2002, 2007-2011 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_STRERROR],
 [
-  AC_REQUIRE([gl_FUNC_STRERROR_SEPARATE])
-  if test $gl_cv_func_working_strerror = no; then
-    AC_LIBOBJ([strerror])
-    AC_DEFINE_UNQUOTED([REPLACE_STRERROR], [$REPLACE_STRERROR],
-      [Define this to 1 if strerror is broken.])
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_REQUIRE([gl_HEADER_ERRNO_H])
+  AC_REQUIRE([gl_FUNC_STRERROR_0])
+  m4_ifdef([gl_FUNC_STRERROR_R_WORKS], [
+    AC_REQUIRE([gl_FUNC_STRERROR_R_WORKS])
+  ])
+  if test "$ERRNO_H:$REPLACE_STRERROR_0" = :0; then
+    AC_CACHE_CHECK([for working strerror function],
+     [gl_cv_func_working_strerror],
+     [AC_RUN_IFELSE(
+        [AC_LANG_PROGRAM(
+           [[#include <string.h>
+           ]],
+           [[if (!*strerror (-2)) return 1;]])],
+        [gl_cv_func_working_strerror=yes],
+        [gl_cv_func_working_strerror=no],
+        [dnl Be pessimistic on cross-compiles for now.
+         gl_cv_func_working_strerror="guessing no"])
+    ])
+    if test "$gl_cv_func_working_strerror" != yes; then
+      dnl The system's strerror() fails to return a string for out-of-range
+      dnl integers. Replace it.
+      REPLACE_STRERROR=1
+    fi
+    m4_ifdef([gl_FUNC_STRERROR_R_WORKS], [
+      dnl If the system's strerror_r or __xpg_strerror_r clobbers strerror's
+      dnl buffer, we must replace strerror.
+      case "$gl_cv_func_strerror_r_works" in
+        *no) REPLACE_STRERROR=1 ;;
+      esac
+    ])
+  else
+    dnl The system's strerror() cannot know about the new errno values we add
+    dnl to <errno.h>, or any fix for strerror(0). Replace it.
+    REPLACE_STRERROR=1
   fi
 ])
 
-# Like gl_FUNC_STRERROR, except prepare for separate compilation (no AC_LIBOBJ).
-AC_DEFUN([gl_FUNC_STRERROR_SEPARATE],
+dnl Detect if strerror(0) passes (that is, does not set errno, and does not
+dnl return a string that matches strerror(-1)).
+AC_DEFUN([gl_FUNC_STRERROR_0],
 [
-  AC_CACHE_CHECK([for working strerror function],
-   [gl_cv_func_working_strerror],
+  REPLACE_STRERROR_0=0
+  AC_CACHE_CHECK([whether strerror(0) succeeds],
+   [gl_cv_func_strerror_0_works],
    [AC_RUN_IFELSE(
       [AC_LANG_PROGRAM(
-        [#include <string.h>
-        ],
-        [return !*strerror (-2);])],
-      [gl_cv_func_working_strerror=yes],
-      [gl_cv_func_working_strerror=no],
-      [dnl Assume crossbuild works if it compiles.
-       AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM(
-           [#include <string.h>
-           ],
-           [return !*strerror (-2);])],
-        [gl_cv_func_working_strerror=yes],
-        [gl_cv_func_working_strerror=no])])])
-  if test $gl_cv_func_working_strerror = no ; then
-    REPLACE_STRERROR=1
-    gl_PREREQ_STRERROR
+         [[#include <string.h>
+           #include <errno.h>
+         ]],
+         [[int result = 0;
+           char *str;
+           errno = 0;
+           str = strerror (0);
+           if (!*str) result |= 1;
+           if (errno) result |= 2;
+           if (strstr (str, "nknown") || strstr (str, "ndefined"))
+             result |= 4;
+           return result;]])],
+      [gl_cv_func_strerror_0_works=yes],
+      [gl_cv_func_strerror_0_works=no],
+      [dnl Be pessimistic on cross-compiles for now.
+       gl_cv_func_strerror_0_works="guessing no"])
+  ])
+  if test "$gl_cv_func_strerror_0_works" != yes; then
+    REPLACE_STRERROR_0=1
+    AC_DEFINE([REPLACE_STRERROR_0], [1], [Define to 1 if strerror(0)
+      does not return a message implying success.])
   fi
 ])
-
-# Prerequisites of lib/strerror.c.
-AC_DEFUN([gl_PREREQ_STRERROR], [
-  AC_CHECK_DECLS([strerror])
-])