[PATCH] Fix OOB access due to multiple backspaces Commit 419ca82d57 (Fix m17n backspace handling causes out-of-bounds write in checkType) introduced an incomplete fix.
In function checkType we store the length of the previous multi-char character in a buffer plens_buffer with pointer plens pointing to the current position inside the buffer. When encountering a backspace plens is set to the previous position without a bounds check. This will lead to plens being out of bounds if we get more backspaces than we have processed multi-char characters before.
If we are at the beginning of the buffer do not decrement and set plen (the current length) to 0.
This also fixes GH Issue #270 [BUG] Out of bound read in Strnew_size , Str.c:61
If the above explanation does sound weird it's because I didn't fully grok that function. :-)
