dd: detect closed stderr

* src/dd.c (maybe_close_stdout): Always flush stderr; regression
introduced in commit 381e69ea.
* tests/misc/close-stdout (p): Use consistent style.
* tests/dd/stderr: New test, borrowing from misc/close-stdout.
* tests/Makefile.am (TESTS): Run it.
* NEWS: Mention this.

5 files changed, 61 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index c125b3194..c3b2e989b 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,11 @@ GNU coreutils NEWS                                    -*- outline -*-
   cp, mv now ignore failure to preserve a symlink time stamp, when it is
   due to their running on a kernel older than what was implied by headers
   and libraries tested at configure time.
+  [bug introduced in coreutils-7.5]
+
+  dd now returns non-zero status if it encountered a write error while
+  printing a summary to stderr.
+  [bug introduced in coreutils-6.11]
 
 
 * Noteworthy changes in release 7.5 (2009-08-20) [stable]
diff --git a/src/dd.c b/src/dd.c
index dc15cfdf1..d2f566eac 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -25,6 +25,7 @@
 #include <getopt.h>
 
 #include "system.h"
+#include "close-stream.h"
 #include "error.h"
 #include "fd-reopen.h"
 #include "gethrxtime.h"
@@ -444,12 +445,16 @@ static bool close_stdout_required = true;
    close_stdout function call "fclose (stdout)" would result in a
    harmless failure of the close syscall (with errno EBADF).
    This function serves solely to avoid the unnecessary close_stdout
-   call, once parse_long_options has succeeded.  */
+   call, once parse_long_options has succeeded.
+   Meanwhile, we guarantee that the standard error stream is flushed,
+   by inlining the last half of close_stdout as needed.  */
 static void
 maybe_close_stdout (void)
 {
   if (close_stdout_required)
     close_stdout ();
+  else if (close_stream (stderr) != 0)
+    _exit (EXIT_FAILURE);
 }
 
 void
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 6ad61331c..c88dd9c44 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -305,6 +305,7 @@ TESTS =						\
   dd/skip-seek					\
   dd/skip-seek2					\
   dd/skip-seek-past-file			\
+  dd/stderr					\
   dd/unblock-sync				\
   df/total-verify				\
   du/2g						\
diff --git a/tests/dd/stderr b/tests/dd/stderr
new file mode 100755
index 000000000..a6c8fba4e
--- /dev/null
+++ b/tests/dd/stderr
@@ -0,0 +1,48 @@
+#!/bin/sh
+# Ensure dd recognizes failure to write to stderr.
+
+# Copyright (C) 2009 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/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  dd --version
+fi
+
+. $srcdir/test-lib.sh
+
+p=$abs_top_builddir
+
+fail=0
+
+# Ensure this exits successfully, even though stderr is closed,
+# because it generates no stderr output.
+dd --help >/dev/null 2>&- || fail=1
+
+# If 2>&- works, ensure this fails, because stderr is closed and it
+# *does* generate output.  2>&- apparently does not work in HP-UX 11.23.
+# This test is ineffective unless /dev/stderr also works.
+# This exposes a failure present in 6.11 through 7.5.
+if "$p/src/test" -w /dev/stderr 2>/dev/null &&
+   "$p/src/test" ! -w /dev/stderr 2>&-; then
+  : | dd 2>&- && fail=1
+fi
+
+# Likewise for /dev/full, if /dev/full works.
+if test -w /dev/full && test -c /dev/full; then
+  : | dd 2>/dev/full && fail=1
+fi
+
+Exit $fail
diff --git a/tests/misc/close-stdout b/tests/misc/close-stdout
index d5fdbb9d4..fe911d8a9 100755
--- a/tests/misc/close-stdout
+++ b/tests/misc/close-stdout
@@ -24,7 +24,7 @@ fi
 
 . $srcdir/test-lib.sh
 
-p="$abs_top_builddir"
+p=$abs_top_builddir
 
 fail=0