[Bug 2947783]: Ensure that result is an unshared object before appending to it.

2 files changed, 26 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index ce3e2dc..e82b91a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-02-08  Donal K. Fellows  <dkf@users.sf.net>
+
+	* generic/tclZlib.c (Tcl_ZlibDeflate, Tcl_ZlibInflate): [Bug 2947783]:
+	Make sure that the result is an unshared object before appending to it
+	so that nothing crashes if it is shared (use in Tcl code was not
+	affected by this, but use from C was an issue).
+
 2010-02-06  Donal K. Fellows  <dkf@users.sf.net>
 
 	* generic/tclHash.c (HashStringKey):	Replace Tcl's crusty old hash
diff --git a/generic/tclZlib.c b/generic/tclZlib.c
index 2ae12c0..f43f704 100644
--- a/generic/tclZlib.c
+++ b/generic/tclZlib.c
@@ -13,7 +13,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclZlib.c,v 1.32 2009/11/18 21:59:51 nijtmans Exp $
+ * RCS: @(#) $Id: tclZlib.c,v 1.33 2010/02/08 13:21:42 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -1316,6 +1316,15 @@ Tcl_ZlibDeflate(
     obj = Tcl_GetObjResult(interp);
 
     /*
+     * Make sure that the result is an unshared object. [Bug 2947783]
+     */
+
+    if (Tcl_IsShared(obj)) {
+	obj = Tcl_DuplicateObj(obj);
+	Tcl_SetObjResult(interp, obj);
+    }
+
+    /*
      * Compressed format is specified by the wbits parameter. See zlib.h for
      * details.
      */
@@ -1469,6 +1478,15 @@ Tcl_ZlibInflate(
     obj = Tcl_GetObjResult(interp);
 
     /*
+     * Make sure that the result is an unshared object. [Bug 2947783]
+     */
+
+    if (Tcl_IsShared(obj)) {
+	obj = Tcl_DuplicateObj(obj);
+	Tcl_SetObjResult(interp, obj);
+    }
+
+    /*
      * Compressed format is specified by the wbits parameter. See zlib.h for
      * details.
      */