Johannes Schindelin f899957fa7 diff_populate_filespec: NUL-terminate buffers ...

While the xdiff machinery is quite capable of working with strings given
as pointer and size, Git's add-on functionality simply assumes that we
are operating on NUL-terminated strings, e.g. y running regexec() on the
provided pointer, with no way to pass the size, too.

In general, this assumption is wrong.

It is true that many code paths populate the mmfile_t structure silently
appending a NUL, e.g. when running textconv on a temporary file and
reading the results back into an strbuf.

The assumption is most definitely wrong, however, when mmap()ing a file.

Practically, we seemed to be lucky that the bytes after mmap()ed memory
were 1) accessible and 2) somehow contained NUL bytes *somewhere*.

In a use case reported by Chris Sidi, it turned out that the mmap()ed
file had the precise size of a memory page, and on Windows the bytes
after memory-mapped pages are in general not valid.

This patch works around that issue, giving us time to discuss the best
course how to fix this problem more generally.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

2016-09-05 17:22:53 +02:00

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