Bug [a173f922]: fix bug: fcopy does not write leading correct chars on later encoding error.

1 files changed, 18 insertions, 0 deletions

diff --git a/generic/tclIO.c b/generic/tclIO.c
index bc1b1c6..884f4a8 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -9802,6 +9802,7 @@ CopyData(
     ChannelState *inStatePtr, *outStatePtr;
     int result = TCL_OK;
     Tcl_Size sizeb;
+    Tcl_Size sizePart;
     Tcl_WideInt total;
     int size;
     const char *buffer;
@@ -9888,6 +9889,23 @@ CopyData(
 		size = DoReadChars(inStatePtr->topChanPtr, bufObj, sizeb,
 			!GotFlag(inStatePtr, CHANNEL_NONBLOCKING)
 			,0 /* No append */);
+		/*
+		 * In case of a recoverable encoding error, any data before
+		 * the error should be written. This data is in the bufObj.
+		 * Program flow for this case:
+		 * - Check, if there are any remaining bytes to write
+		 * - If yes, simulate a successful read to write them out
+		 * - Come back here by the outer loop and read again
+		 * - Do not enter in the if below, as there are no pending
+		 *  writes
+		 * - Fail below with a read error
+		 */
+		if (size < 0 && Tcl_GetErrno() == EILSEQ) {
+		    Tcl_GetStringFromObj(bufObj, &sizePart);
+		    if (sizePart > 0) {
+			size = sizePart;
+		    }
+		}
 	    }
 	    underflow = (size >= 0) && (size < sizeb);	/* Input underflow */
 	}