* 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.

1 files changed, 18 insertions, 1 deletions

diff --git a/unix/tclUnixPipe.c b/unix/tclUnixPipe.c
index 8a20bcc..c177f67 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 1.34 2006/07/20 06:17:39 das Exp $
+ * RCS: @(#) $Id: tclUnixPipe.c,v 1.35 2006/08/02 20:04:11 das Exp $
  */
 
 #include "tclInt.h"
@@ -428,6 +428,23 @@ TclpCreateProcess(
 	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);