1 files changed, 35 insertions, 11 deletions

diff --git a/generic/tclEncoding.c b/generic/tclEncoding.c
index 95c59c0..2a766d1 100644
--- a/generic/tclEncoding.c
+++ b/generic/tclEncoding.c
@@ -1206,7 +1206,10 @@ Tcl_ExternalToUtf(
 				 * output buffer. */
 {
     const Encoding *encodingPtr;
-    int result, srcRead, dstWrote, dstChars;
+    int result, srcRead, dstWrote, dstChars = 0;
+    int noTerminate = flags & TCL_ENCODING_NO_TERMINATE;
+    int charLimited = (flags & TCL_ENCODING_CHAR_LIMIT) && dstCharsPtr;
+    int maxChars = INT_MAX;
     Tcl_EncodingState state;
 
     if (encoding == NULL) {
@@ -1231,19 +1234,40 @@ Tcl_ExternalToUtf(
     }
     if (dstCharsPtr == NULL) {
 	dstCharsPtr = &dstChars;
+	flags &= ~TCL_ENCODING_CHAR_LIMIT;
+    } else if (charLimited) {
+	maxChars = *dstCharsPtr;
     }
 
-    /*
-     * If there are any null characters in the middle of the buffer, they will
-     * converted to the UTF-8 null character (\xC080). To get the actual \0 at
-     * the end of the destination buffer, we need to append it manually.
-     */
+    if (!noTerminate) {
+	/*
+	 * If there are any null characters in the middle of the buffer,
+	 * they will converted to the UTF-8 null character (\xC080). To get
+	 * the actual \0 at the end of the destination buffer, we need to
+	 * append it manually.  First make room for it...
+	 */
 
-    dstLen--;
-    result = encodingPtr->toUtfProc(encodingPtr->clientData, src, srcLen,
-	    flags, statePtr, dst, dstLen, srcReadPtr, dstWrotePtr,
-	    dstCharsPtr);
-    dst[*dstWrotePtr] = '\0';
+	dstLen--;
+    }
+    do {
+	int savedFlags = flags;
+	Tcl_EncodingState savedState = *statePtr;
+
+	result = encodingPtr->toUtfProc(encodingPtr->clientData, src, srcLen,
+		flags, statePtr, dst, dstLen, srcReadPtr, dstWrotePtr,
+		dstCharsPtr);
+	if (*dstCharsPtr <= maxChars) {
+	    break;
+	}
+	dstLen = Tcl_UtfAtIndex(dst, maxChars) - 1 - dst + TCL_UTF_MAX;
+	flags = savedFlags;
+	*statePtr = savedState;
+    } while (1);
+    if (!noTerminate) {
+	/* ...and then append it */
+
+	dst[*dstWrotePtr] = '\0';
+    }
 
     return result;
 }