Added comments to try to tame the file attributes guts, while trying to simplify

things enough that I can puzzle out AK's TclVFS problems. I suspect this is not
a real fix though; just an attempt to make the problem tractable.

2 files changed, 34 insertions, 20 deletions

diff --git a/ChangeLog b/ChangeLog
index d04c05e..13aa14a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,9 +1,15 @@
+2011-04-16  Donal K. Fellows  <dkf@users.sf.net>
+
+	* generic/tclFCmd.c (TclFileAttrsCmd): Add comments to make this code
+	easier to understand. Added a panic to handle the case where the VFS
+	layer does something odd.
+
 2011-04-13  Don Porter  <dgp@users.sourceforge.net>
 
-	* generic/tclUtil.c:	Rewrite of Tcl_Concat*() routines to 
-	prevent segfaults on buffer overflow.  Build them out of existing
-	primitives already coded to handle overflow properly.  Uses the
-	new TclTrim*() routines. [Bug 3285375]
+	* generic/tclUtil.c:	[Bug 3285375]: Rewrite of Tcl_Concat*()
+	routines to prevent segfaults on buffer overflow.  Build them out of
+	existing primitives already coded to handle overflow properly.  Uses
+	the new TclTrim*() routines.
 
 	* generic/tclCmdMZ.c:	New internal utility routines TclTrimLeft()
 	* generic/tclInt.h:	and TclTrimRight().  Refactor the
@@ -11,8 +17,8 @@
 
 2011-04-13  Miguel Sofer  <msofer@users.sf.net>
 
-	* generic/tclVar.c: fix for [Bug 2662380], crash caused by
-	appending to a variable with a write trace that unsets it.
+	* generic/tclVar.c: [Bug 2662380]: Fix crash caused by appending to a
+	variable with a write trace that unsets it.
 
 2011-04-13  Donal K. Fellows  <dkf@users.sf.net>
 
diff --git a/generic/tclFCmd.c b/generic/tclFCmd.c
index e9176ca..048fa57 100644
--- a/generic/tclFCmd.c
+++ b/generic/tclFCmd.c
@@ -966,6 +966,10 @@ TclFileAttrsCmd(
     result = TCL_ERROR;
     Tcl_SetErrno(0);
 
+    /*
+     * Get the set of attribute names from the filesystem.
+     */
+
     attributeStrings = Tcl_FSFileAttrStrings(filePtr, &objStrings);
     if (attributeStrings == NULL) {
 	int index;
@@ -980,9 +984,8 @@ TclFileAttrsCmd(
 		Tcl_AppendResult(interp, "could not read \"",
 			TclGetString(filePtr), "\": ", Tcl_PosixError(interp),
 			NULL);
-		return TCL_ERROR;
 	    }
-	    goto end;
+	    return TCL_ERROR;
 	}
 
 	/*
@@ -1006,7 +1009,16 @@ TclFileAttrsCmd(
 	}
 	attributeStringsAllocated[index] = NULL;
 	attributeStrings = attributeStringsAllocated;
+    } else if (objStrings != NULL) {
+	Tcl_Panic("must not update objPtrRef's variable and return non-NULL");
     }
+
+    /*
+     * Process the attributes to produce a list of all of them, the value of a
+     * particular attribute, or to set one or more attributes (depending on
+     * the number of arguments).
+     */
+
     if (objc == 0) {
 	/*
 	 * Get all attributes.
@@ -1114,21 +1126,17 @@ TclFileAttrsCmd(
     }
     result = TCL_OK;
 
+    /*
+     * Free up the array we allocated and drop our reference to any list of
+     * attribute names issued by the filesystem.
+     */
+
   end:
     if (attributeStringsAllocated != NULL) {
-	/*
-	 * Free up the array we allocated.
-	 */
-
 	TclStackFree(interp, (void *) attributeStringsAllocated);
-
-	/*
-	 * We don't need this object that was passed to us any more.
-	 */
-
-	if (objStrings != NULL) {
-	    Tcl_DecrRefCount(objStrings);
-	}
+    }
+    if (objStrings != NULL) {
+	Tcl_DecrRefCount(objStrings);
     }
     return result;
 }