[PD-dev] [ pure-data-Patches-3420484 ] Invalid memory access in s_utf8.c

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Patches item #3420484, was opened at 2011-10-07 20:10
Message generated for change (Tracker Item Submitted) made by creamygoodness
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Category: puredata
Group: bugfix
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Marvin Humphrey (creamygoodness)
Assigned to: Nobody/Anonymous (nobody)
Summary: Invalid memory access in s_utf8.c

Initial Comment:
After hearing on IRC that segfaults could be produced while editing text in an
Object box under gdb, I tried running the Vanilla main git branch under
Valgrind:

    valgrind ./src/pd

Valgrind reported many "invalid read" memory errors, which on inspection, all 
arose from the same root cause: these strings are not NULL-terminated, but the 
UTF-8 handling code in s_utf8.c assumes NULL-termination and malfunctions in
its absence.

The attached patch suffices to eliminate the read errors. However, it does not 
address all the problems in s_utf8.c; other functions will require similar
treatment.

I have attempted make the new code as compatible with the old code as
possible, for instance preserving its dubious algorithm for handling missing
or excess continuation bytes.  Hopefully I got everything right, though it is
hard to be certain with bit-twiddling code like this in the absence of 
thorough unit tests.

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