posix, windows: introduce cachestat
This class contains a stat result, and possibly other file info to reliably
determine between two points in time whether a file has changed.
Uniquely identifying a file gives us that reliability because we either
atomic rename or append. So one of two will happen: the file 'id' will change,
or the size of the file will change.
posix implements it simply by calling os.stat() and checking if the result
has st_ino.
For now on Windows we always assume the path is uncacheable. This can be
improved on NTFS due to file IDs: http://msdn.microsoft.com/en-us/library/
aa363788(v=vs.85).aspx
So we need to find out if a file path is on an NTFS drive, for that we have:
- GetVolumeInformation, which unfortunately only works with a root path (but is available on XP)
- GetVolumeInformationByHandleW, works on a full file path but requires Vista or higher
$ "$TESTDIR/hghave" symlink || exit 80
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ hg qinit
$ hg qnew base.patch
$ echo aaa > a
$ echo bbb > b
$ echo ccc > c
$ hg add a b c
$ hg qrefresh
$ $TESTDIR/readlink.py a
a -> a not a symlink
test replacing a file with a symlink
$ hg qnew symlink.patch
$ rm a
$ ln -s b a
$ hg qrefresh --git
$ $TESTDIR/readlink.py a
a -> b
$ hg qpop
popping symlink.patch
now at: base.patch
$ hg qpush
applying symlink.patch
now at: symlink.patch
$ $TESTDIR/readlink.py a
a -> b
test updating a symlink
$ rm a
$ ln -s c a
$ hg qnew --git -f updatelink
$ $TESTDIR/readlink.py a
a -> c
$ hg qpop
popping updatelink
now at: symlink.patch
$ hg qpush --debug
applying updatelink
patching file a
a
now at: updatelink
$ $TESTDIR/readlink.py a
a -> c
$ hg st
test replacing a symlink with a file
$ ln -s c s
$ hg add s
$ hg qnew --git -f addlink
$ rm s
$ echo sss > s
$ hg qnew --git -f replacelinkwithfile
$ hg qpop
popping replacelinkwithfile
now at: addlink
$ hg qpush
applying replacelinkwithfile
now at: replacelinkwithfile
$ cat s
sss
$ hg st
test symlink removal
$ hg qnew removesl.patch
$ hg rm a
$ hg qrefresh --git
$ hg qpop
popping removesl.patch
now at: replacelinkwithfile
$ hg qpush
applying removesl.patch
now at: removesl.patch
$ hg st -c
C b
C c
C s
replace broken symlink with another broken symlink
$ ln -s linka linka
$ hg add linka
$ hg qnew link
$ hg mv linka linkb
$ rm linkb
$ ln -s linkb linkb
$ hg qnew movelink
$ hg qpop
popping movelink
now at: link
$ hg qpush
applying movelink
now at: movelink
$ $TESTDIR/readlink.py linkb
linkb -> linkb