view tests/test-contrib-check-commit.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

Test the 'check-commit' script
==============================

A fine patch:

  $ cat > patch-with-long-header.diff << EOF
  > # HG changeset patch
  > # User timeless <[e-mail]>
  > # Date 1448911706 0
  > #      Mon Nov 30 19:28:26 2015 +0000
  > # Node ID c41cb6d2b7dbd62b1033727f8606b8c09fc4aa88
  > # Parent  42aa0e570eaa364a622bc4443b0bcb79b1100a58
  > # ClownJoke This is a veryly long header that should not be warned about because its not the description
  > bundle2: use Oxford comma (issue123) (BC)
  > 
  > diff --git a/hgext/transplant.py b/hgext/transplant.py
  > --- a/hgext/transplant.py
  > +++ b/hgext/transplant.py
  > @@ -599,7 +599,7 @@
  >              return
  >          if not (opts.get('source') or revs or
  >                  opts.get('merge') or opts.get('branch')):
  > -            raise error.Abort(_('no source URL, branch revision or revision '
  > +            raise error.Abort(_('no source URL, branch revision, or revision '
  >                                 'list provided'))
  >          if opts.get('all'):
  > 
  > + def blahblah(x):
  > +     pass
  > EOF
  $ cat patch-with-long-header.diff | $TESTDIR/../contrib/check-commit

This would normally be against the rules, but it's okay because that's
what tagging and signing looks like:

  $ cat > creates-a-tag.diff << EOF
  > # HG changeset patch
  > # User Augie Fackler <[e-mail]>
  > # Date 1484787778 18000
  > #      Wed Jan 18 20:02:58 2017 -0500
  > # Branch stable
  > # Node ID c177635e4acf52923bc3aa9f72a5b1ad1197b173
  > # Parent  a1dd2c0c479e0550040542e392e87bc91262517e
  > Added tag 4.1-rc for changeset a1dd2c0c479e
  > 
  > diff --git a/.hgtags b/.hgtags
  > --- a/.hgtags
  > +++ b/.hgtags
  > @@ -150,3 +150,4 @@ 438173c415874f6ac653efc1099dec9c9150e90f
  >  eab27446995210c334c3d06f1a659e3b9b5da769 4.0
  >  b3b1ae98f6a0e14c1e1ba806a6c18e193b6dae5c 4.0.1
  >  e69874dc1f4e142746ff3df91e678a09c6fc208c 4.0.2
  > +a1dd2c0c479e0550040542e392e87bc91262517e 4.1-rc
  > EOF
  $ $TESTDIR/../contrib/check-commit < creates-a-tag.diff

A patch with lots of errors:

  $ cat > patch-with-long-header.diff << EOF
  > # HG changeset patch
  > # User timeless
  > # Date 1448911706 0
  > #      Mon Nov 30 19:28:26 2015 +0000
  > # Node ID c41cb6d2b7dbd62b1033727f8606b8c09fc4aa88
  > # Parent  42aa0e570eaa364a622bc4443b0bcb79b1100a58
  > # ClownJoke This is a veryly long header that should not be warned about because its not the description
  > transplant/foo: this summary is way too long use Oxford comma (bc) (bug123) (issue 244)
  > 
  > diff --git a/hgext/transplant.py b/hgext/transplant.py
  > --- a/hgext/transplant.py
  > +++ b/hgext/transplant.py
  > @@ -599,7 +599,7 @@
  >              return
  >          if not (opts.get('source') or revs or
  >                  opts.get('merge') or opts.get('branch')):
  > -            raise error.Abort(_('no source URL, branch revision or revision '
  > +            raise error.Abort(_('no source URL, branch revision, or revision '
  >                                 'list provided'))
  >          if opts.get('all'):
  > EOF
  $ cat patch-with-long-header.diff | $TESTDIR/../contrib/check-commit
  1: username is not an email address
   # User timeless
  7: summary keyword should be most user-relevant one-word command or topic
   transplant/foo: this summary is way too long use Oxford comma (bc) (bug123) (issue 244)
  7: (BC) needs to be uppercase
   transplant/foo: this summary is way too long use Oxford comma (bc) (bug123) (issue 244)
  7: use (issueDDDD) instead of bug
   transplant/foo: this summary is way too long use Oxford comma (bc) (bug123) (issue 244)
  7: no space allowed between issue and number
   transplant/foo: this summary is way too long use Oxford comma (bc) (bug123) (issue 244)
  7: summary line too long (limit is 78)
   transplant/foo: this summary is way too long use Oxford comma (bc) (bug123) (issue 244)
  [1]

A patch with other errors:

  $ cat > patch-with-long-header.diff << EOF
  > # HG changeset patch
  > # User timeless
  > # Date 1448911706 0
  > #      Mon Nov 30 19:28:26 2015 +0000
  > # Node ID c41cb6d2b7dbd62b1033727f8606b8c09fc4aa88
  > # Parent  42aa0e570eaa364a622bc4443b0bcb79b1100a58
  > # ClownJoke This is a veryly long header that should not be warned about because its not the description
  > This has no topic and ends with a period.
  > 
  > diff --git a/hgext/transplant.py b/hgext/transplant.py
  > --- a/hgext/transplant.py
  > +++ b/hgext/transplant.py
  > @@ -599,7 +599,7 @@
  >          if opts.get('all'):
  >  
  > 
  > +
  > + some = otherjunk
  > +
  > +
  > + def blah_blah(x):
  > +     pass
  > +
  >  
  > EOF
  $ cat patch-with-long-header.diff | $TESTDIR/../contrib/check-commit
  1: username is not an email address
   # User timeless
  7: don't capitalize summary lines
   This has no topic and ends with a period.
  7: summary line doesn't start with 'topic: '
   This has no topic and ends with a period.
  7: don't add trailing period on summary line
   This has no topic and ends with a period.
  [1]