Fix [Bug 1675116] in a way suitable for 8.4.

3 files changed, 25 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index e82d508..06a6e5c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2007-03-10  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
+
+	* generic/tclCmdIL.c (Tcl_LsortObjCmd): Handle tricky case with loss
+	* tests/cmdIL.test (cmdIL-1.29):of list rep during sorting due
+	to shimmering. [Bug 1675116]
+
 2007-03-07  Daniel Steffen  <das@users.sourceforge.net>
 
 	* macosx/tclMacOSXNotify.c: add spinlock debugging and sanity checks.
diff --git a/generic/tclCmdIL.c b/generic/tclCmdIL.c
index d44ba7a..85e51d0 100644
--- a/generic/tclCmdIL.c
+++ b/generic/tclCmdIL.c
@@ -15,7 +15,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclCmdIL.c,v 1.47.2.10 2006/11/28 22:20:00 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclCmdIL.c,v 1.47.2.11 2007/03/10 14:57:38 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -3799,6 +3799,15 @@ Tcl_LsortObjCmd(clientData, interp, objc, objv)
 	elementArray[i].objPtr = listObjPtrs[i];
 	elementArray[i].count = 0;
 	elementArray[i].nextPtr = &elementArray[i+1];
+
+	/*
+	 * When sorting using a command, we are reentrant and therefore might
+	 * have the representation of the list being sorted shimmered out from
+	 * underneath our feet. Increment the reference counts of the elements
+	 * to sort to prevent this. [Bug 1675116]
+	 */
+
+	Tcl_IncrRefCount(elementArray[i].objPtr);
     }
     elementArray[length-1].nextPtr = NULL;
     elementPtr = MergeSort(elementArray, &sortInfo);
@@ -3824,6 +3833,9 @@ Tcl_LsortObjCmd(clientData, interp, objc, objv)
 	    }
 	}
     }
+    for (i=0; i<length; i++) {
+	Tcl_DecrRefCount(elementArray[i].objPtr);
+    }
     ckfree((char*) elementArray);
 
     done:
diff --git a/tests/cmdIL.test b/tests/cmdIL.test
index 6376a12..2148dd1 100644
--- a/tests/cmdIL.test
+++ b/tests/cmdIL.test
@@ -8,7 +8,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: cmdIL.test,v 1.14.6.1 2003/07/15 15:44:52 dkf Exp $
+# RCS: @(#) $Id: cmdIL.test,v 1.14.6.2 2007/03/10 14:57:38 dkf Exp $
 
 if {[lsearch [namespace children] ::tcltest] == -1} {
     package require tcltest
@@ -104,6 +104,11 @@ test cmdIL-1.25 {Tcl_LsortObjCmd procedure, order of -index and -command} {
 test cmdIL-1.26 {Tcl_LsortObjCmd procedure, offset indexing from end} {
     lsort -index end-1 {{a 1 e i} {b 2 3 f g} {c 4 5 6 d h}}
 } {{c 4 5 6 d h} {a 1 e i} {b 2 3 f g}}
+test cmdIL-1.29 {Tcl_LsortObjCmd procedure, loss of list rep during sorting} {
+    set l {1 2 3}
+    proc testcmp args {string length $::l}
+    string length [lsort -command testcmp $l]
+} 5
 
 # Can't think of any good tests for the MergeSort and MergeLists
 # procedures, except a bunch of random lists to sort.