Mercurial > hg
view tests/test-mq-missingfiles.t @ 46607:e9901d01d135
revlog: add a mechanism to verify expected file position before appending
If someone uses `hg debuglocks`, or some non-hg process writes to the .hg
directory without respecting the locks, or if the repo's on a networked
filesystem, it's possible for the revlog code to write out corrupted data.
The form of this corruption can vary depending on what data was written and how
that happened. We are in the "networked filesystem" case (though I've had users
also do this to themselves with the "`hg debuglocks`" scenario), and most often
see this with the changelog. What ends up happening is we produce two items
(let's call them rev1 and rev2) in the .i file that have the same linkrev,
baserev, and offset into the .d file, while the data in the .d file is appended
properly. rev2's compressed_size is accurate for rev2, but when we go to
decompress the data in the .d file, we use the offset that's recorded in the
index file, which is the same as rev1, and attempt to decompress
rev2.compressed_size bytes of rev1's data. This usually does not succeed. :)
When using inline data, this also fails, though I haven't investigated why too
closely. This shows up as a "patch decode" error. I believe what's happening
there is that we're basically ignoring the offset field, getting the data
properly, but since baserev != rev, it thinks this is a delta based on rev
(instead of a full text) and can't actually apply it as such.
For now, I'm going to make this an optional component and default it to entirely
off. I may increase the default severity of this in the future, once I've
enabled it for my users and we gain more experience with it. Luckily, most of my
users have a versioned filesystem and can roll back to before the corruption has
been written, it's just a hassle to do so and not everyone knows how (so it's a
support burden). Users on other filesystems will not have that luxury, and this
can cause them to have a corrupted repository that they are unlikely to know how
to resolve, and they'll see this as a data-loss event. Refusing to create the
corruption is a much better user experience.
This mechanism is not perfect. There may be false-negatives (racy writes that
are not detected). There should not be any false-positives (non-racy writes that
are detected as such). This is not a mechanism that makes putting a repo on a
networked filesystem "safe" or "supported", just *less* likely to cause
corruption.
Differential Revision: https://phab.mercurial-scm.org/D9952
author | Kyle Lippincott <spectral@google.com> |
---|---|
date | Wed, 03 Feb 2021 16:33:10 -0800 |
parents | c70bdd222dcd |
children | fe3303436b79 |
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Issue835: qpush fails immediately when patching a missing file, but remaining added files are still created empty which will trick a future qrefresh. $ cat > writelines.py <<EOF > import sys > if sys.version_info[0] >= 3: > encode = lambda x: x.encode('utf-8').decode('unicode_escape').encode('utf-8') > else: > encode = lambda x: x.decode('string_escape') > path = sys.argv[1] > args = sys.argv[2:] > assert (len(args) % 2) == 0 > > f = open(path, 'wb') > for i in range(len(args) // 2): > count, s = args[2 * i:2 * i + 2] > count = int(count) > s = encode(s) > f.write(s * count) > f.close() > EOF $ echo "[extensions]" >> $HGRCPATH $ echo "mq=" >> $HGRCPATH $ hg init normal $ cd normal $ "$PYTHON" ../writelines.py b 10 'a\n' $ hg ci -Am addb adding b $ echo a > a $ "$PYTHON" ../writelines.py b 2 'b\n' 10 'a\n' 2 'c\n' $ echo c > c $ hg add a c $ hg qnew -f changeb $ hg qpop popping changeb patch queue now empty $ hg rm b $ hg ci -Am rmb Push patch with missing target: $ hg qpush applying changeb unable to find 'b' for patching (use '--prefix' to apply patch relative to the current directory) 2 out of 2 hunks FAILED -- saving rejects to file b.rej patch failed, unable to continue (try -v) patch failed, rejects left in working directory errors during apply, please fix and qrefresh changeb [2] Display added files: $ cat a a $ cat c c Display rejections: $ cat b.rej --- b +++ b @@ -1,3 +1,5 @@ +b +b a a a @@ -8,3 +10,5 @@ a a a +c +c Test missing renamed file $ hg qpop popping changeb patch queue now empty $ hg up -qC 0 $ echo a > a $ hg mv b bb $ "$PYTHON" ../writelines.py bb 2 'b\n' 10 'a\n' 2 'c\n' $ echo c > c $ hg add a c $ hg qnew changebb $ hg qpop popping changebb patch queue now empty $ hg up -qC 1 $ hg qpush applying changebb patching file bb Hunk #1 FAILED at 0 Hunk #2 FAILED at 7 2 out of 2 hunks FAILED -- saving rejects to file bb.rej b not tracked! patch failed, unable to continue (try -v) patch failed, rejects left in working directory errors during apply, please fix and qrefresh changebb [2] $ cat a a $ cat c c $ cat bb.rej --- bb +++ bb @@ -1,3 +1,5 @@ +b +b a a a @@ -8,3 +10,5 @@ a a a +c +c $ cd .. $ echo "[diff]" >> $HGRCPATH $ echo "git=1" >> $HGRCPATH $ hg init git $ cd git $ "$PYTHON" ../writelines.py b 1 '\x00' $ hg ci -Am addb adding b $ echo a > a $ "$PYTHON" ../writelines.py b 1 '\x01' 1 '\x00' $ echo c > c $ hg add a c $ hg qnew -f changeb $ hg qpop popping changeb patch queue now empty $ hg rm b $ hg ci -Am rmb Push git patch with missing target: $ hg qpush applying changeb unable to find 'b' for patching (use '--prefix' to apply patch relative to the current directory) 1 out of 1 hunks FAILED -- saving rejects to file b.rej patch failed, unable to continue (try -v) patch failed, rejects left in working directory errors during apply, please fix and qrefresh changeb [2] $ hg st ? b.rej Display added files: $ cat a a $ cat c c Display rejections: $ cat b.rej --- b +++ b GIT binary patch literal 2 Jc${No0000400IC2 $ cd .. Test push creating directory during git copy or rename: $ hg init missingdir $ cd missingdir $ echo a > a $ hg ci -Am adda adding a $ mkdir d $ hg copy a d/a2 $ hg mv a d/a $ hg qnew -g -f patch $ hg qpop popping patch patch queue now empty $ hg qpush applying patch now at: patch $ cd ..