Mercurial > hg
view tests/test-mq-symlinks.t @ 14007:d764463b433e
atomictempfile: avoid infinite recursion in __del__().
The problem is that a programmer using atomictempfile directly can
make an innocent everyday mistake -- not enough args to the
constructor -- which escalates badly. You would expect a simple
TypeError crash in that case, but you actually get an infinite
recursion that is surprisingly difficult to kill: it happens between
__del__() and __getattr__(), and Python does not handle infinite
recursion from __del__() well.
The fix is to not implement __getattr__(), but instead assign instance
attributes for the methods we wish to delegate to the builtin file
type: write() and fileno(). I've audited mercurial.* and hgext.* and
found no users of atomictempfile using methods other than write() and
rename(). I audited third-party extensions and found one (snap)
passing an atomictempfile to util.fstat(), so I also threw in
fileno().
The last time I submitted a similar patch, Matt proposed that we make
atomictempfile a subclass of file instead of wrapping it. Rejected on
grounds of unnecessary complexity: for one thing, it would make the
Windows implementation of posixfile quite a bit more complex. It would
have to become a subclass of file rather than a simple function -- but
since it's written in C, this is non-obvious and non-trivial.
Furthermore, there's nothing wrong with wrapping objects and
delegating methods: it's a well-established pattern that works just
fine in many cases. Subclassing is not the answer to all of life's
problems.
author | Greg Ward <greg@gerg.ca> |
---|---|
date | Sun, 24 Apr 2011 19:25:10 -0400 |
parents | 2bc926ad65c2 |
children | ee574cfd0c32 |
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$ "$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 check patch does not overwrite untracked symlinks $ hg qpop popping movelink now at: link $ ln -s linkbb linkb $ hg qpush applying movelink patch failed, unable to continue (try -v) patch failed, rejects left in working dir errors during apply, please fix and refresh movelink [2]