* unix/tclUnixPipe.c (TclpCreateProcess): for USE_VFORK: ensure standard

    channels are initialized before vfork() so that the child doesn't
    potentially corrupt global state in the parent's address space.

2 files changed, 24 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 5e138d1..9e9a23c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2006-08-03  Daniel Steffen  <das@users.sourceforge.net>
+
+	* unix/tclUnixPipe.c (TclpCreateProcess): for USE_VFORK: ensure standard
+	channels are initialized before vfork() so that the child doesn't
+	potentially corrupt global state in the parent's address space.
+
 2006-07-30  Kevin Kenny  <kennykb@acm.org>
 
 	* tests/clock.test: Allowed UTC as a synonym for GMT in two
diff --git a/unix/tclUnixPipe.c b/unix/tclUnixPipe.c
index de92407..6825f24 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 1.23.2.6 2006/07/20 06:21:46 das Exp $
+ * RCS: @(#) $Id: tclUnixPipe.c,v 1.23.2.7 2006/08/02 20:04:40 das Exp $
  */
 
 #include "tclInt.h"
@@ -430,6 +430,23 @@ TclpCreateProcess(interp, argc, argv, inputFile, outputFile, errorFile,
 	newArgv[i] = Tcl_UtfToExternalDString(NULL, argv[i], -1, &dsArray[i]);
     }
 
+#ifdef USE_VFORK
+    /*
+     * After vfork(), do not call code in the child that changes global state,
+     * because it is using the parent's memory space at that point and writes
+     * might corrupt the parent: so ensure standard channels are initialized in
+     * the parent, otherwise SetupStdFile() might initialize them in the child.
+     */
+    if (!inputFile) {
+	Tcl_GetStdChannel(TCL_STDIN);
+    }
+    if (!outputFile) {
+        Tcl_GetStdChannel(TCL_STDOUT);
+    }
+    if (!errorFile) {
+        Tcl_GetStdChannel(TCL_STDERR);
+    }
+#endif
     pid = fork();
     if (pid == 0) {
 	int joinThisError = errorFile && (errorFile == outputFile);