diff: don't use pathname-based diff drivers for symlinks
authorJeff King <peff@peff.net>
Tue, 21 Sep 2010 21:01:24 +0000 (17:01 -0400)
committerJunio C Hamano <gitster@pobox.com>
Fri, 24 Sep 2010 01:32:32 +0000 (18:32 -0700)
commitd391c0ff94e1b314b0664db0e8eb5bd92934f9cb
tree917615d9622c3c4958048e40b3fbef2d57c07c49
parente22148f406a7a31a25ebda01d21d9a4646ce82ea
diff: don't use pathname-based diff drivers for symlinks

When we're diffing symlinks, we consider the contents to be
the pathname that the symlink points to. When a user sets up
a userdiff driver like "*.pdf diff=pdf", their "diff.pdf.*"
config generally tells us what to do with the content of
pdf files.

With the current code, we will actually process a symlink
like "link.pdf" using a configured pdf driver, meaning we
are using contents which consist of a pathname with
configuration that is expecting contents that consist of an
actual pdf file.

The most noticeable example of this would have been
textconv; however, it was already protected in its own
textconv-specific code path. We can still see the breakage
with something like "diff.*.binary", though. You could
also see it with diff.*.funcname, though it is a bit harder
to trigger accidentally there.

This patch adds a check for S_ISREG lower in the callstack
than the textconv-specific check, which should block use of
any userdiff config for non-regular files. We can drop the
check in the textconv code, which is now redundant.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff.c
t/t4011-diff-symlink.sh