Backport of fix for [Bug 1245953]

5 files changed, 50 insertions, 7 deletions

diff --git a/ChangeLog b/ChangeLog
index 0efc97f..7d5a0f5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2005-07-28  Donal K. Fellows  <dkf@users.sf.net>
+
+	* generic/tclPipe.c (TclCreatePipeline): Arrange for POSIX systems to
+	* unix/tclUnixPipe.c (TclpOpenFile):	 use the O_APPEND flag for
+	* tests/exec.test (exec-19.1):		 files opened in a pipeline
+	like ">>this".  Note that Windows cannot support such access; there is
+	no equivalent flag on the handle that can be set at the kernel-call
+	level. The test is unix-specific in every way. [Bug 1245953]
+
 2005-07-26  Mo DeJong  <mdejong@users.sourceforge.net>
 
 	* unix/configure: Regen.
diff --git a/generic/tclPipe.c b/generic/tclPipe.c
index 7339926..fc0e6c0 100644
--- a/generic/tclPipe.c
+++ b/generic/tclPipe.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclPipe.c,v 1.7.2.1 2004/07/02 23:37:31 hobbs Exp $
+ * RCS: @(#) $Id: tclPipe.c,v 1.7.2.2 2005/07/28 15:27:58 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -605,7 +605,13 @@ TclCreatePipeline(interp, argc, argv, pidArrayPtr, inPipePtr,
 	    if (*p == '>') {
 		p++;
 		atOK = 0;
-		flags = O_WRONLY | O_CREAT;
+
+		/*
+		 * Note that the O_APPEND flag only has an effect on POSIX
+		 * platforms. On Windows, we just have to carry on regardless.
+		 */
+
+		flags = O_WRONLY | O_CREAT | O_APPEND;
 	    }
 	    if (*p == '&') {
 		if (errorClose != 0) {
diff --git a/tests/exec.test b/tests/exec.test
index 3613cba..bb6ecd4 100644
--- a/tests/exec.test
+++ b/tests/exec.test
@@ -11,7 +11,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: exec.test,v 1.16.2.4 2004/10/28 00:01:06 dgp Exp $
+# RCS: @(#) $Id: exec.test,v 1.16.2.5 2005/07/28 15:27:59 dkf Exp $
 
 package require tcltest 2
 namespace import -force ::tcltest::*
@@ -600,6 +600,34 @@ test exec-18.1 { exec cat deals with weird file names} {exec tempNotWin} {
     set res
 } {0 contents}
 
+# Note that this test cannot be adapted to work on Windows; that platform has
+# no kernel support for an analog of O_APPEND.
+test exec-19.1 {exec >> uses O_APPEND} {
+    -constraints {exec unix}
+    -setup {
+	set tmpfile [makeFile {0} tmpfile.exec-19.1]
+    }
+    -body {
+	# Note that we have to allow for the current contents of the
+	# temporary file, which is why the result is 14 and not 12
+	exec /bin/sh -c \
+	    {for a in 1 2 3; do sleep 1; echo $a; done} >>$tmpfile &
+	exec /bin/sh -c \
+	    {for a in a b c; do sleep 1; echo $a; done} >>$tmpfile &
+	# The above two shell invokations take about 3 seconds to
+	# finish, so allow 5s (in case the machine is busy)
+	after 5000
+	# Check that no bytes have got lost through mixups with
+	# overlapping appends, which is only guaranteed to work when
+	# we set O_APPEND on the file descriptor in the [exec >>...]
+	file size $tmpfile
+    }
+    -cleanup {
+	removeFile $tmpfile
+    }
+    -result 14
+}
+
 # cleanup
 
 foreach file {script gorp.file gorp.file2 echo cat wc sh sleep exit err} {
diff --git a/unix/tclUnixPipe.c b/unix/tclUnixPipe.c
index dd9bc1c..0d3bd0b 100644
--- a/unix/tclUnixPipe.c
+++ b/unix/tclUnixPipe.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclUnixPipe.c,v 1.23.2.4 2005/06/22 19:36:35 kennykb Exp $
+ * RCS: @(#) $Id: tclUnixPipe.c,v 1.23.2.5 2005/07/28 15:27:59 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -156,7 +156,7 @@ TclpOpenFile(fname, mode)
 	 * so we can append to any data already in the file.
 	 */
 
-	if (mode & O_WRONLY) {
+	if ((mode & O_WRONLY) && !(mode & O_APPEND)) {
 	    TclOSseek(fd, (Tcl_SeekOffset) 0, SEEK_END);
 	}
 
diff --git a/win/tclWinPipe.c b/win/tclWinPipe.c
index 323302a..dc9a917 100644
--- a/win/tclWinPipe.c
+++ b/win/tclWinPipe.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclWinPipe.c,v 1.33.2.13 2005/06/22 21:30:20 kennykb Exp $
+ * RCS: @(#) $Id: tclWinPipe.c,v 1.33.2.14 2005/07/28 15:27:59 dkf Exp $
  */
 
 #include "tclWinInt.h"
@@ -670,7 +670,7 @@ TclpOpenFile(path, mode)
      * Seek to the end of file if we are writing.
      */
 
-    if (mode & O_WRONLY) {
+    if (mode & (O_WRONLY|O_APPEND)) {
 	SetFilePointer(handle, 0, NULL, FILE_END);
     }