cat: Fix immediate output of processed data

Introduced by commit 790892db, 2006-06-08 "Ensure that cat works ...".
* NEWS: Mention the bugfix.
* src/cat.c (cat): Fix the typo which stopped the writing
of processed data before a blocking read() is done.
* tests/misc/cat-buf: Add to ensure processed data is not buffered.
* tests/Makefile.am: Reference the new test.

NEWS

@@ -4,6 +4,11 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Bug fixes
 
+  cat once again immediately outputs data it has processed.
+  Previously it would have been buffered and only output if enough
+  data was read, or on process exit.
+  [bug introduced in coreutils-6.0]
+
   comm's new --check-order option would fail to detect disorder on any pair
   of lines where one was a prefix of the other.  For example, this would
   fail to report the disorder: printf 'Xb\nX\n'>k; comm --check-order k k

src/cat.c

@@ -333,7 +333,7 @@ cat (
 		input_pending = true;
 #endif
 
-	      if (input_pending)
+	      if (!input_pending)
 		write_pending (outbuf, &bpout);
 
 	      /* Read more input into INBUF.  */

tests/Makefile.am

@@ -149,6 +149,7 @@ TESTS =						\
   misc/wc-files0-from				\
   misc/wc-files0				\
   misc/cat-proc					\
+  misc/cat-buf					\
   misc/base64					\
   misc/basename					\
   misc/close-stdout				\

tests/misc/cat-buf

@@ -0,0 +1,41 @@
+#!/bin/sh
+# Ensure that cat outputs processed data immediately.
+
+# 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
+  cat --version
+fi
+
+. $srcdir/test-lib.sh
+
+# Use a fifo rather than a pipe in the tests below
+# so that the producer (cat) will wait until the
+# consumer (dd) opens the fifo therefore increasing
+# the chance that dd will read the data from each
+# write separately.
+mkfifo fifo || framework_failure
+
+echo '1' > exp
+
+dd count=1 if=fifo > out 2> err&
+(echo '1'; sleep .2; echo '2') | cat -v > fifo
+wait #for dd to complete
+
+compare out exp || fail=1
+
+Exit $fail