diff options
| -rw-r--r-- | generic/tclIO.c | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/generic/tclIO.c b/generic/tclIO.c index b7135e9..e414668 100644 --- a/generic/tclIO.c +++ b/generic/tclIO.c @@ -5596,9 +5596,27 @@ ReadChars( /* * We read more chars than allowed. Reset limits to * prevent that and try again. + * + * Note how we are adding back TCL_UTF_MAX to ensure that the + * Tcl_External2Utf invoked by the next round will have enough + * space in the destination for at least one multi-byte + * character. Without that nothing will be copied and the system + * will try to consolidate the entire current and next buffer, + * likely triggering the "Buffer Underflow" panic. */ - dstLimit = Tcl_UtfAtIndex(dst, charsToRead + 1) - dst; + int newLimit = Tcl_UtfAtIndex(dst, charsToRead + 1) - dst + TCL_UTF_MAX; + + if (newLimit >= dstLimit) { + dstLimit --; + } else { + dstLimit = newLimit; + } + + if (dstLimit <= TCL_UTF_MAX) { + Tcl_Panic ("Not enough space left for a single multi-byte character."); + } + statePtr->flags = savedFlags; statePtr->inputEncodingFlags = savedIEFlags; statePtr->inputEncodingState = savedState; @@ -5661,7 +5679,8 @@ ReadChars( */ if (nextPtr->nextRemoved - srcLen < 0) { - Tcl_Panic("Buffer Underflow, BUFFER_PADDING not enough"); + Tcl_Panic("Buffer Underflow, BUFFER_PADDING not enough (%d < %d)", + nextPtr->nextRemoved, srcLen); } nextPtr->nextRemoved -= srcLen; |