dirstate: ignore symlinks when fs cannot handle them (issue1888)
When the filesystem cannot handle the executable bit, we currently
ignore it completely when looking for modified files. Similarly, it is
impossible to set or clear the bit when the filesystem ignores it.
This patch makes Mercurial treat symbolic links the same way.
Symlinks are a little different since they manifest themselves as
small files containing a filename (the symlink target). On Windows,
these files show up as regular files, and on Linux and Mac they show
up as real symlinks.
Issue1888 presents a case where the symlink files are better ignored
from the Windows side. A Linux client creates symlinks in a working
copy which is shared over a network between Linux and Windows clients.
The Samba server is helpful and defererences the symlink when the
Windows client looks at it. This means that Mercurial on the Windows
side sees file content instead of a file name in the symlink, and
hence flags the link as modified. Ignoring the change would be much
more helpful, similarly to how Mercurial does not report any changes
when executable bits are ignored in a checkout on Windows.
An initial checkout of a symbolic link on a file system that cannot
handle symbolic links will still result in a regular file containing
the target file name as its content. Sharing such a checkout with a
Linux client will not turn the file into a symlink automatically, but
'hg revert' can fix that. After the revert, the Windows client will
see the correct file content (provided by the Samba server when it
follows the link on the Linux side) and otherwise ignore the change.
Running 'hg perfstatus' 10 times gives these results:
Before: After:
min: 0.544703 min: 0.546549
med: 0.547592 med: 0.548881
avg: 0.549146 avg: 0.548549
max: 0.564112 max: 0.551504
The median time is increased about 0.24%.
#!/bin/sh
hg init repo
cd repo
cat > a <<EOF
c
c
a
a
b
a
a
c
c
EOF
hg ci -Am adda
cat > a <<EOF
c
c
a
a
dd
a
a
c
c
EOF
echo '% default context'
hg diff --nodates
echo '% invalid --unified'
hg diff --nodates -U foo
echo '% --unified=2'
hg diff --nodates -U 2
echo '% diff.unified=2'
hg --config diff.unified=2 diff --nodates
echo '% diff.unified=2 --unified=1'
hg diff --nodates -U 1
echo '% invalid diff.unified'
hg --config diff.unified=foo diff --nodates
echo % test off-by-one error with diff -p
hg init diffp
cd diffp
echo a > a
hg ci -Ama
rm a
echo b > a
echo a >> a
echo c >> a
hg diff -U0 -p --nodates
exit 0