dirfd: Avoid link error on AIX 7.1.

[gnulib.git] / m4 / strsignal.m4

diff --git a/m4/strsignal.m4 b/m4/strsignal.m4
index 9bcd374..be3c733 100644 (file)
--- a/m4/strsignal.m4
+++ b/m4/strsignal.m4
@@ -1,5 +1,5 @@
-# strsignal.m4 serial 1
-dnl Copyright (C) 2008 Free Software Foundation, Inc.
+# strsignal.m4 serial 3
+dnl Copyright (C) 2008, 2009, 2010 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.
@@ -9,16 +9,47 @@ AC_DEFUN([gl_FUNC_STRSIGNAL],
   dnl Persuade glibc <string.h> to declare strsignal().
   AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
 
-  AC_REQUIRE([AC_DECL_SYS_SIGLIST])
-
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
-  AC_REPLACE_FUNCS([strsignal])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
   AC_CHECK_DECLS_ONCE([strsignal])
   if test $ac_cv_have_decl_strsignal = no; then
     HAVE_DECL_STRSIGNAL=0
+  fi
+
+  AC_CHECK_FUNCS([strsignal])
+  if test $ac_cv_func_strsignal = yes; then
+    dnl Check if strsignal behaves reasonably for out-of-range signal numbers.
+    dnl On Solaris it returns NULL; on AIX 5.1 it returns (char *) -1.
+    AC_CACHE_CHECK([whether strsignal always returns a string],
+      [gl_cv_func_working_strsignal],
+      [AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <string.h>
+            ]],
+            [[char *s = strsignal (-1);
+              return !(s != (char *) 0 && s != (char *) -1);]])],
+         [gl_cv_func_working_strsignal=yes],
+         [gl_cv_func_working_strsignal=no],
+         [case "$host_os" in
+            solaris* | aix*) gl_cv_func_working_strsignal=no;;
+            *)               gl_cv_func_working_strsignal="guessing yes";;
+          esac])])
+  else
+    gl_cv_func_working_strsignal=no
+  fi
+
+  if test "$gl_cv_func_working_strsignal" = no; then
+    if test $ac_cv_func_strsignal = yes; then
+      REPLACE_STRSIGNAL=1
+    fi
+    AC_LIBOBJ([strsignal])
     gl_PREREQ_STRSIGNAL
   fi
 ])
 
 # Prerequisites of lib/strsignal.c.
-AC_DEFUN([gl_PREREQ_STRSIGNAL], [:])
+AC_DEFUN([gl_PREREQ_STRSIGNAL], [
+  AC_REQUIRE([AC_DECL_SYS_SIGLIST])
+  AC_CHECK_DECLS([_sys_siglist], [], [], [#include <signal.h>])
+])