Mercurial > hg
view tests/test-symlink-os-yes-fs-no.py @ 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 | ca6cebd8734e |
children | cd3032437064 |
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import os, sys, time from mercurial import hg, ui, commands TESTDIR = os.environ["TESTDIR"] # only makes sense to test on os which supports symlinks if not hasattr(os, "symlink"): sys.exit(80) # SKIPPED_STATUS defined in run-tests.py # clone with symlink support u = ui.ui() hg.clone(u, os.path.join(TESTDIR, 'test-no-symlinks.hg'), 'test0') repo = hg.repository(u, 'test0') # wait a bit, or the status call wont update the dirstate time.sleep(1) commands.status(u, repo) # now disable symlink support -- this is what os.symlink would do on a # non-symlink file system def symlink_failure(src, dst): raise OSError, (1, "Operation not permitted") os.symlink = symlink_failure # dereference links as if a Samba server has exported this to a # Windows client for f in 'test0/a.lnk', 'test0/d/b.lnk': os.unlink(f) fp = open(f, 'wb') fp.write(open(f[:-4]).read()) fp.close() # reload repository u = ui.ui() repo = hg.repository(u, 'test0') commands.status(u, repo) # try cloning a repo which contains symlinks u = ui.ui() hg.clone(u, os.path.join(TESTDIR, 'test-no-symlinks.hg'), 'test1')