view tests/test-eol-hook.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 EOL hook

  $ hg init main
  $ cat > main/.hg/hgrc <<EOF
  > [hooks]
  > pretxnchangegroup = python:hgext.eol.hook
  > EOF
  $ hg clone main fork
  updating to branch default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd fork

Create repo
  $ cat > .hgeol <<EOF
  > [patterns]
  > mixed.txt = BIN
  > crlf.txt = CRLF
  > **.txt = native
  > EOF
  $ hg add .hgeol
  $ hg commit -m 'Commit .hgeol'

  $ printf "first\nsecond\nthird\n" > a.txt
  $ hg add a.txt
  $ hg commit -m 'LF a.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files

  $ printf "first\r\nsecond\r\nthird\n" > a.txt
  $ hg commit -m 'CRLF a.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  error: pretxnchangegroup hook failed: end-of-line check failed:
    a.txt in a8ee6548cd86 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    a.txt in a8ee6548cd86 should not have CRLF line endings
  [255]

  $ printf "first\nsecond\nthird\n" > a.txt
  $ hg commit -m 'LF a.txt (fixed)'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files

  $ printf "first\nsecond\nthird\n" > crlf.txt
  $ hg add crlf.txt
  $ hg commit -m 'LF crlf.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  error: pretxnchangegroup hook failed: end-of-line check failed:
    crlf.txt in 004ba2132725 should not have LF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    crlf.txt in 004ba2132725 should not have LF line endings
  [255]

  $ printf "first\r\nsecond\r\nthird\r\n" > crlf.txt
  $ hg commit -m 'CRLF crlf.txt (fixed)'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files

  $ printf "first\r\nsecond" > b.txt
  $ hg add b.txt
  $ hg commit -m 'CRLF b.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

  $ hg up -r -2
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ printf "some\nother\nfile" > c.txt
  $ hg add c.txt
  $ hg commit -m "LF c.txt, b.txt doesn't exist here"
  created new head
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

Test checkheadshook alias

  $ cat > ../main/.hg/hgrc <<EOF
  > [hooks]
  > pretxnchangegroup = python:hgext.eol.checkheadshook
  > EOF
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

We can fix the head and push again

  $ hg up 6
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ printf "first\nsecond" > b.txt
  $ hg ci -m "remove CRLF from b.txt"
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  $ hg -R ../main rollback
  repository tip rolled back to revision 5 (undo push)

Test it still fails with checkallhook

  $ cat > ../main/.hg/hgrc <<EOF
  > [hooks]
  > pretxnchangegroup = python:hgext.eol.checkallhook
  > EOF
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

But we can push the clean head

  $ hg push -r7 -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

Test multiple files/revisions output

  $ printf "another\r\nbad\r\none" > d.txt
  $ hg add d.txt
  $ hg ci -m "add d.txt"
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
    d.txt in a7040e68714f should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
    d.txt in a7040e68714f should not have CRLF line endings
  [255]

  $ cd ..