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author | dkf <donal.k.fellows@manchester.ac.uk> | 2014-02-03 22:29:31 (GMT) |
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committer | dkf <donal.k.fellows@manchester.ac.uk> | 2014-02-03 22:29:31 (GMT) |
commit | 76a8030f939360bd39bc940842f79175c47ed828 (patch) | |
tree | 2460b8aed34b1dc39f26999cb2294274056a1448 /generic/tclStringObj.c | |
parent | 95a6025facddaf366bf92837026bdcafec4561ec (diff) | |
parent | 9acd6848382529da76b66a3108c7cceb755dcffa (diff) | |
download | tcl-76a8030f939360bd39bc940842f79175c47ed828.zip tcl-76a8030f939360bd39bc940842f79175c47ed828.tar.gz tcl-76a8030f939360bd39bc940842f79175c47ed828.tar.bz2 |
merge trunk
Diffstat (limited to 'generic/tclStringObj.c')
-rw-r--r-- | generic/tclStringObj.c | 42 |
1 files changed, 31 insertions, 11 deletions
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c index e495c2e..dffa38c 100644 --- a/generic/tclStringObj.c +++ b/generic/tclStringObj.c @@ -1281,23 +1281,43 @@ Tcl_AppendObjToObj( if ((TclIsPureByteArray(objPtr) || objPtr->bytes == tclEmptyStringRep) && TclIsPureByteArray(appendObjPtr)) { - unsigned char *bytesSrc; - int lengthSrc, lengthTotal; /* - * We do not assume that objPtr and appendObjPtr must be distinct! - * This makes this code a bit more complex than it otherwise would be, - * but in turn makes it much safer. + * You might expect the code here to be + * + * bytes = Tcl_GetByteArrayFromObj(appendObjPtr, &length); + * TclAppendBytesToByteArray(objPtr, bytes, length); + * + * and essentially all of the time that would be fine. However, + * it would run into trouble in the case where objPtr and + * appendObjPtr point to the same thing. That may never be a + * good idea. It seems to violate Copy On Write, and we don't + * have any tests for the situation, since making any Tcl commands + * that call Tcl_AppendObjToObj() do that appears impossible + * (They honor Copy On Write!). For the sake of extensions that + * go off into that realm, though, here's a more complex approach + * that can handle all the cases. */ + /* Get lengths */ + int lengthSrc; + (void) Tcl_GetByteArrayFromObj(objPtr, &length); (void) Tcl_GetByteArrayFromObj(appendObjPtr, &lengthSrc); - lengthTotal = length + lengthSrc; - if (((length > lengthSrc) ? length : lengthSrc) > lengthTotal) { - Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX); - } - bytesSrc = Tcl_GetByteArrayFromObj(appendObjPtr, NULL); - TclAppendBytesToByteArray(objPtr, bytesSrc, lengthSrc); + + /* Grow buffer enough for the append */ + TclAppendBytesToByteArray(objPtr, NULL, lengthSrc); + + /* Reset objPtr back to the original value */ + Tcl_SetByteArrayLength(objPtr, length); + + /* + * Now do the append knowing that buffer growth cannot cause + * any trouble. + */ + + TclAppendBytesToByteArray(objPtr, + Tcl_GetByteArrayFromObj(appendObjPtr, NULL), lengthSrc); return; } |