To redirect messages, instead of assigning stderr to stdout, use dup2

4 files changed, 83 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index e5d3399..c939750 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,11 @@
 	* Makefile.in (GETOPT_H): Include subdirectory (gl/lib/) when
 	using the gnulib version.
 
+	* src/patch.c: When sending output to stdout, use dup2 to redirect
+	messages to stderr; simply assigning stderr to stdout doesn't work on
+	some platforms.
+	* gl/lib/dup2.c, gl/m4/dup2.m4: Import from gnulib.
+
 2009-05-12  Andreas Gruenbacher  <agruen@suse.de>
 
 	* src/merge.c (locate_merge): Make sure to return a line number
diff --git a/gl/lib/dup2.c b/gl/lib/dup2.c
new file mode 100644
index 0000000..0999082
--- /dev/null
+++ b/gl/lib/dup2.c
@@ -0,0 +1,57 @@
+/* Duplicate an open file descriptor to a specified file descriptor.
+
+   Copyright (C) 1999, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* written by Paul Eggert */
+
+#include <config.h>
+
+/* Specification.  */
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+
+#ifndef F_DUPFD
+static int
+dupfd (int fd, int desired_fd)
+{
+  int duplicated_fd = dup (fd);
+  if (duplicated_fd < 0 || duplicated_fd == desired_fd)
+    return duplicated_fd;
+  else
+    {
+      int r = dupfd (fd, desired_fd);
+      int e = errno;
+      close (duplicated_fd);
+      errno = e;
+      return r;
+    }
+}
+#endif
+
+int
+dup2 (int fd, int desired_fd)
+{
+  if (fd == desired_fd)
+    return fd;
+  close (desired_fd);
+#ifdef F_DUPFD
+  return fcntl (fd, F_DUPFD, desired_fd);
+#else
+  return dupfd (fd, desired_fd);
+#endif
+}
diff --git a/gl/m4/dup2.m4 b/gl/m4/dup2.m4
new file mode 100644
index 0000000..0549823
--- /dev/null
+++ b/gl/m4/dup2.m4
@@ -0,0 +1,15 @@
+#serial 5
+dnl Copyright (C) 2002, 2005, 2007 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_DUP2],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_CHECK_FUNCS_ONCE([dup2])
+  if test $ac_cv_func_dup2 = no; then
+    HAVE_DUP2=0
+    AC_LIBOBJ([dup2])
+  fi
+])
diff --git a/src/patch.c b/src/patch.c
index 79718a7..897e796 100644
--- a/src/patch.c
+++ b/src/patch.c
@@ -1349,8 +1349,12 @@ init_output (char const *name, int open_flags, struct outstate *outstate)
     outstate->ofp = create_output_file (name, open_flags);
   else
     {
-      outstate->ofp = stdout;
-      stdout = stderr;
+      int stdout_dup = dup (fileno (stdout));
+      outstate->ofp = fdopen (stdout_dup, "a");
+      if (stdout_dup == -1 || ! outstate->ofp)
+	pfatal ("Failed to duplicate standard output");
+      if (dup2 (fileno (stderr), fileno (stdout)) == -1)
+	pfatal ("Failed to redirect messages to standard error");
     }
 
   outstate->after_newline = true;