manifest: fix possible SEGV caused by uninitialized lazymanifest fields
Before, uninitialized self->pydata would be passed to lazymanifest_dealloc()
on OOM, and Py_DECREF(self->pydata) would crash if we were unlucky.
It's still wrong to do malloc() thingy in tp_init because __init__() may be
called more than once [1], but I don't want to go a step further in stable
branch.
[1]: https://docs.python.org/2/c-api/typeobj.html#c.PyTypeObject.tp_new
"The tp_new function should ... do only as much further initialization as
is absolutely necessary. Initialization that can safely be ignored or
repeated should be placed in the tp_init handler."
https://bz.mercurial-scm.org/2137
Setup:
create a little extension that has 3 side-effects:
1) ensure changelog data is not inlined
2) make revlog to use lazyparser
3) test that repo.lookup() works
1 and 2 are preconditions for the bug; 3 is the bug.
$ cat > commitwrapper.py <<EOF
> from mercurial import extensions, node, revlog
>
> def reposetup(ui, repo):
> class wraprepo(repo.__class__):
> def commit(self, *args, **kwargs):
> result = super(wraprepo, self).commit(*args, **kwargs)
> tip1 = node.short(repo.changelog.tip())
> tip2 = node.short(repo.lookup(tip1))
> assert tip1 == tip2
> ui.write(b'new tip: %s\n' % tip1)
> return result
> repo.__class__ = wraprepo
>
> def extsetup(ui):
> revlog._maxinline = 8 # split out 00changelog.d early
> revlog._prereadsize = 8 # use revlog.lazyparser
> EOF
$ cat >> $HGRCPATH <<EOF
> [extensions]
> commitwrapper = `pwd`/commitwrapper.py
> EOF
$ hg init repo1
$ cd repo1
$ echo a > a
$ hg commit -A -m'add a with a long commit message to make the changelog a bit bigger'
adding a
new tip: 553596fad57b
Test that new changesets are visible to repo.lookup():
$ echo a >> a
$ hg commit -m'one more commit to demonstrate the bug'
new tip: 799ae3599e0e
$ hg tip
changeset: 1:799ae3599e0e
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: one more commit to demonstrate the bug
$ cd ..