1 files changed, 63 insertions, 0 deletions
diff --git a/m4/perror.m4 b/m4/perror.m4
new file mode 100644
index 0000000..743ab7a
--- /dev/null
+++ b/m4/perror.m4
@@ -0,0 +1,63 @@
+# perror.m4 serial 6
+dnl Copyright (C) 2008-2016 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_PERROR],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  AC_REQUIRE([gl_HEADER_ERRNO_H])
+  AC_REQUIRE([gl_FUNC_STRERROR_R])
+  AC_REQUIRE([gl_FUNC_STRERROR_0])
+  dnl We intentionally do not check for the broader REPLACE_STRERROR_R,
+  dnl since on glibc systems, strerror_r is replaced only for signature
+  dnl issues, and perror is just fine.  Rather, we only want to
+  dnl replace perror if strerror_r was replaced for a content fix.
+  if test "$ERRNO_H:$REPLACE_STRERROR_0" != :0; then
+    dnl The system's perror() cannot know about the new errno values we add
+    dnl to <errno.h>, or any fix for strerror(0). Replace it.
+    REPLACE_PERROR=1
+  fi
+  case ${gl_cv_func_strerror_r_works-unset} in
+    unset|*yes)
+      AC_CACHE_CHECK([whether perror matches strerror],
+        [gl_cv_func_perror_works],
+        [AC_RUN_IFELSE(
+           [AC_LANG_PROGRAM(
+              [[#include <errno.h>
+                #include <stdio.h>
+                #include <stdlib.h>
+                #include <string.h>
+              ]],
+              [[char *str = strerror (-1);
+                if (!getenv("CONFTEST_OUTPUT")) return 0;
+                if (!str) str = "";
+                puts (str);
+                errno = -1;
+                perror ("");
+                return 0;
+              ]])],
+           [if CONFTEST_OUTPUT=1 ./conftest$EXEEXT >conftest.txt1 2>conftest.txt2 \
+               && cmp conftest.txt1 conftest.txt2 >/dev/null; then
+              gl_cv_func_perror_works=yes
+            else
+              gl_cv_func_perror_works=no
+            fi
+            rm -rf conftest.txt1 conftest.txt2],
+           [gl_cv_func_perror_works=no],
+           [dnl Guess no when cross-compiling.
+            gl_cv_func_perror_works="guessing no"
+           ])
+        ])
+      if test "$gl_cv_func_perror_works" != yes; then
+        REPLACE_PERROR=1
+      fi
+      ;;
+    *)
+      dnl The system's perror() probably inherits the bugs in the
+      dnl system's strerror_r(). Replace it.
+      REPLACE_PERROR=1
+      ;;
+  esac
+])