Mercurial hook to disallow committing large binary files - mercurial

Question

I want to have a Mercurial hook that will run before committing a transaction that will abort the transaction if a binary file being committed is greater than 1 megabyte. I found the following code which works fine except for one problem. If my changeset involves removing a file, this hook will throw an exception.
The hook (I'm using pretxncommit = python:checksize.newbinsize):
from mercurial import context, util
from mercurial.i18n import _
import mercurial.node as dpynode
'''hooks to forbid adding binary file over a given size
Ensure the PYTHONPATH is pointing where hg_checksize.py is and setup your
repo .hg/hgrc like this:
[hooks]
pretxncommit = python:checksize.newbinsize
pretxnchangegroup = python:checksize.newbinsize
preoutgoing = python:checksize.nopull
[limits]
maxnewbinsize = 10240
'''
def newbinsize(ui, repo, node=None, **kwargs):
'''forbid to add binary files over a given size'''
forbid = False
# default limit is 10 MB
limit = int(ui.config('limits', 'maxnewbinsize', 10000000))
tip = context.changectx(repo, 'tip').rev()
ctx = context.changectx(repo, node)
for rev in range(ctx.rev(), tip+1):
ctx = context.changectx(repo, rev)
print ctx.files()
for f in ctx.files():
fctx = ctx.filectx(f)
filecontent = fctx.data()
# check only for new files
if not fctx.parents():
if len(filecontent) > limit and util.binary(filecontent):
msg = 'new binary file %s of %s is too large: %ld > %ld\n'
hname = dpynode.short(ctx.node())
ui.write(_(msg) % (f, hname, len(filecontent), limit))
forbid = True
return forbid
The exception:
$ hg commit -m 'commit message'
error: pretxncommit hook raised an exception: apps/helpers/templatetags/include_extends.py#bced6272d8f4: not found in manifest
transaction abort!
rollback completed
abort: apps/helpers/templatetags/include_extends.py#bced6272d8f4: not found in manifest!
I'm not familiar with writing Mercurial hooks, so I'm pretty confused about what's going on. Why does the hook care that a file was removed if hg already knows about it? Is there a way to fix this hook so that it works all the time?
Update (solved):
I modified the hook to filter out files that were removed in the changeset.
def newbinsize(ui, repo, node=None, **kwargs):
'''forbid to add binary files over a given size'''
forbid = False
# default limit is 10 MB
limit = int(ui.config('limits', 'maxnewbinsize', 10000000))
ctx = repo[node]
for rev in xrange(ctx.rev(), len(repo)):
ctx = context.changectx(repo, rev)
# do not check the size of files that have been removed
# files that have been removed do not have filecontexts
# to test for whether a file was removed, test for the existence of a filecontext
filecontexts = list(ctx)
def file_was_removed(f):
"""Returns True if the file was removed"""
if f not in filecontexts:
return True
else:
return False
for f in itertools.ifilterfalse(file_was_removed, ctx.files()):
fctx = ctx.filectx(f)
filecontent = fctx.data()
# check only for new files
if not fctx.parents():
if len(filecontent) > limit and util.binary(filecontent):
msg = 'new binary file %s of %s is too large: %ld > %ld\n'
hname = dpynode.short(ctx.node())
ui.write(_(msg) % (f, hname, len(filecontent), limit))
forbid = True
return forbid

Answer 1

This is really easy to do in a shell hook in recent Mercurial:
if hg locate -r tip "set:(added() or modified()) and binary() and size('>100k')"; then
echo "bad files!"
exit 1
else
exit 0
fi
What's going on here? First we have a fileset to find all the changed files that are problematic (see 'hg help filesets' in hg 1.9). The 'locate' command is like status, except it just lists files and returns 0 if it finds anything. And we specify '-r tip' to look at the pending commit.

Answer 2

for f in ctx.files() will include removed files, you need to filter those out.
(and you can replace for rev in range(ctx.rev(), tip+1): by for rev in xrange(ctx.rev(), len(repo)):, and remove tip = ...)
If you're using a modern hg, you don't do ctx = context.changectx(repo, node) but ctx = repo[node] instead.