view tests/test-identify.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

#require serve

#if no-outer-repo

no repo

  $ hg id
  abort: there is no Mercurial repository here (.hg not found)
  [10]

#endif

create repo

  $ hg init test
  $ cd test
  $ echo a > a
  $ hg ci -Ama
  adding a

basic id usage

  $ hg id
  cb9a9f314b8b tip
  $ hg id --debug
  cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b tip
  $ hg id -q
  cb9a9f314b8b
  $ hg id -v
  cb9a9f314b8b tip

with options

  $ hg id -r.
  cb9a9f314b8b tip
  $ hg id -n
  0
  $ hg id -t
  tip
  $ hg id -b
  default
  $ hg id -i
  cb9a9f314b8b
  $ hg id -n -t -b -i
  cb9a9f314b8b 0 default tip
  $ hg id -Tjson
  [
   {
    "bookmarks": [],
    "branch": "default",
    "dirty": "",
    "id": "cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b",
    "node": "ffffffffffffffffffffffffffffffffffffffff",
    "parents": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"],
    "tags": ["tip"]
   }
  ]

test template keywords and functions which require changectx:

  $ hg id -T '{rev} {node|shortest}\n'
  2147483647 ffff
  $ hg id -T '{parents % "{rev} {node|shortest} {desc}\n"}'
  0 cb9a a
  $ hg id -T '{parents}\n'
  cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b

test nested template: '{tags}'/'{node}' constants shouldn't override the
default keywords, but '{id}' persists because there's no default keyword
for '{id}' (issue5612)

  $ hg id -T '{tags}\n'
  tip
  $ hg id -T '{revset("null:.") % "{rev}:{node|short} {tags} {id|short}\n"}'
  -1:000000000000  cb9a9f314b8b
  0:cb9a9f314b8b tip cb9a9f314b8b

with modifications

  $ echo b > a
  $ hg id -n -t -b -i
  cb9a9f314b8b+ 0+ default tip
  $ hg id -Tjson
  [
   {
    "bookmarks": [],
    "branch": "default",
    "dirty": "+",
    "id": "cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b+",
    "node": "ffffffffffffffffffffffffffffffffffffffff",
    "parents": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"],
    "tags": ["tip"]
   }
  ]

other local repo

  $ cd ..
  $ hg -R test id
  cb9a9f314b8b+ tip
#if no-outer-repo
  $ hg id test
  cb9a9f314b8b+ tip
#endif

with remote http repo

  $ cd test
  $ hg serve -p $HGPORT1 -d --pid-file=hg.pid
  $ cat hg.pid >> $DAEMON_PIDS
  $ hg id http://localhost:$HGPORT1/
  cb9a9f314b8b

remote with rev number?

  $ hg id -n http://localhost:$HGPORT1/
  abort: can't query remote revision number, branch, or tags
  [10]

remote with tags?

  $ hg id -t http://localhost:$HGPORT1/
  abort: can't query remote revision number, branch, or tags
  [10]

remote with branch?

  $ hg id -b http://localhost:$HGPORT1/
  abort: can't query remote revision number, branch, or tags
  [10]

test bookmark support

  $ hg bookmark Y
  $ hg bookmark Z
  $ hg bookmarks
     Y                         0:cb9a9f314b8b
   * Z                         0:cb9a9f314b8b
  $ hg id
  cb9a9f314b8b+ tip Y/Z
  $ hg id --bookmarks
  Y Z

test remote identify with bookmarks

  $ hg id http://localhost:$HGPORT1/
  cb9a9f314b8b Y/Z
  $ hg id --bookmarks http://localhost:$HGPORT1/
  Y Z
  $ hg id -r . http://localhost:$HGPORT1/
  cb9a9f314b8b Y/Z
  $ hg id --bookmarks -r . http://localhost:$HGPORT1/
  Y Z

test invalid lookup

  $ hg id -r noNoNO http://localhost:$HGPORT1/
  abort: unknown revision 'noNoNO'
  [255]

Make sure we do not obscure unknown requires file entries (issue2649)

  $ echo fake >> .hg/requires
  $ hg id
  abort: repository requires features unknown to this Mercurial: fake
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]

  $ cd ..
#if no-outer-repo
  $ hg id test
  abort: repository requires features unknown to this Mercurial: fake
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]
#endif