* generic/tkImgPNG.c (ReadIDAT, DecodePNG): Move the check for overall

	termination of the compressed stream until after the final IDAT has
	been read, so that multi-segment images will work right. Reported by
	Andy Goth on the Wiki.

1 files changed, 15 insertions, 12 deletions

diff --git a/generic/tkImgPNG.c b/generic/tkImgPNG.c
index c138b78..ec84a1c 100644
--- a/generic/tkImgPNG.c
+++ b/generic/tkImgPNG.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tkImgPNG.c,v 1.6 2010/04/12 08:40:15 dkf Exp $
+ * RCS: @(#) $Id: tkImgPNG.c,v 1.7 2010/04/25 18:23:52 dkf Exp $
  */
 
 #include "tkInt.h"
@@ -2130,26 +2130,18 @@ ReadIDAT(
     }
 
     /*
-     * Ensure that when we've got to the end of the compressed data, we've
+     * Ensure that if we've got to the end of the compressed data, we've
      * also got to the end of the compressed stream. This sanity check is
      * enforced by most PNG readers.
      */
 
-    if (!Tcl_ZlibStreamEof(pngPtr->stream)) {
-	Tcl_AppendResult(interp, "unfinalized data stream in PNG data", NULL);
-	return TCL_ERROR;
-    }
     if (chunkSz != 0) {
 	Tcl_AppendResult(interp,
 		"compressed data after stream finalize in PNG data", NULL);
 	return TCL_ERROR;
     }
 
-    if (CheckCRC(interp, pngPtr, crc) == TCL_ERROR) {
-	return TCL_ERROR;
-    }
-
-    return TCL_OK;
+    return CheckCRC(interp, pngPtr, crc);
 }
 
 /*
@@ -2456,9 +2448,9 @@ DecodePNG(
     Tcl_IncrRefCount(pngPtr->lastLineObj);
     pngPtr->thisLineObj = Tcl_NewObj();
     Tcl_IncrRefCount(pngPtr->thisLineObj);
+
     pngPtr->block.pixelPtr = (unsigned char *)
 	    attemptckalloc(pngPtr->blockLen);
-
     if (!pngPtr->block.pixelPtr) {
 	Tcl_SetResult(interp, "Memory allocation failed", TCL_STATIC);
 	return TCL_ERROR;
@@ -2504,6 +2496,17 @@ DecodePNG(
     }
 
     /*
+     * Ensure that we've got to the end of the compressed stream now that
+     * there are no more IDAT segments. This sanity check is enforced by most
+     * PNG readers.
+     */
+
+    if (!Tcl_ZlibStreamEof(pngPtr->stream)) {
+	Tcl_AppendResult(interp, "unfinalized data stream in PNG data", NULL);
+	return TCL_ERROR;
+    }
+
+    /*
      * Now skip the remaining chunks which we're also not interested in.
      */