view tests/test-wireproto-command-manifestdata.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

  $ . $TESTDIR/wireprotohelpers.sh

  $ hg init server
  $ enablehttpv2 server
  $ cd server
  $ echo a0 > a
  $ echo b0 > b
  $ mkdir -p dir0/child0 dir0/child1 dir1
  $ echo c0 > dir0/c
  $ echo d0 > dir0/d
  $ echo e0 > dir0/child0/e
  $ echo f0 > dir0/child1/f
  $ hg -q commit -A -m 'commit 0'

  $ echo a1 > a
  $ echo d1 > dir0/d
  $ hg commit -m 'commit 1'
  $ echo f0 > dir0/child1/f
  $ hg commit -m 'commit 2'
  nothing changed
  [1]

  $ hg -q up -r 0
  $ echo a2 > a
  $ hg commit -m 'commit 3'
  created new head

  $ hg log -G -T '{rev}:{node} {desc}\n'
  @  2:c8757a2ffe552850d1e0dfe60d295ebf64c196d9 commit 3
  |
  | o  1:650165e803375748a94df471e5b58d85763e0b29 commit 1
  |/
  o  0:6d85ca1270b377d320098556ba5bfad34a9ee12d commit 0
  

  $ hg --debug debugindex -m
     rev linkrev nodeid                                   p1                                       p2
       0       0 1b175b595f022cfab5b809cc0ed551bd0b3ff5e4 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000
       1       1 91e0bdbfb0dde0023fa063edc1445f207a22eac7 1b175b595f022cfab5b809cc0ed551bd0b3ff5e4 0000000000000000000000000000000000000000
       2       2 46a6721b5edaf0ea04b79a5cb3218854a4d2aba0 1b175b595f022cfab5b809cc0ed551bd0b3ff5e4 0000000000000000000000000000000000000000

  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
  $ cat hg.pid > $DAEMON_PIDS

Missing arguments is an error

  $ sendhttpv2peer << EOF
  > command manifestdata
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  abort: missing required arguments: nodes, tree
  [255]

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[]
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  abort: missing required arguments: tree
  [255]

Unknown node is an error

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa']
  >     tree eval:b''
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  abort: unknown node: \xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa (esc)
  [255]

Fetching a single revision returns just metadata by default

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0'
    }
  ]

Requesting parents works

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0',
      b'parents': [
        b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

Requesting revision data works
(haveparents defaults to false, so fulltext is emitted)

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  >     fields eval:[b'revision']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          292
        ]
      ],
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0'
    },
    b'a\x000879345e39377229634b420c639454156726c6b6\nb\x00819e258d31a5e1606629f365bb902a1b21ee4216\ndir0/c\x00914445346a0ca0629bd47ceb5dfe07e4d4cf2501\ndir0/child0/e\x00bbba6c06b30f443d34ff841bc985c4d0827c6be4\ndir0/child1/f\x0012fc7dcd773b5a0a929ce195228083c6ddc9cec4\ndir0/d\x00538206dc971e521540d6843abfe6d16032f6d426\n'
  ]

haveparents=False yields same output

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  >     fields eval:[b'revision']
  >     haveparents eval:False
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          292
        ]
      ],
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0'
    },
    b'a\x000879345e39377229634b420c639454156726c6b6\nb\x00819e258d31a5e1606629f365bb902a1b21ee4216\ndir0/c\x00914445346a0ca0629bd47ceb5dfe07e4d4cf2501\ndir0/child0/e\x00bbba6c06b30f443d34ff841bc985c4d0827c6be4\ndir0/child1/f\x0012fc7dcd773b5a0a929ce195228083c6ddc9cec4\ndir0/d\x00538206dc971e521540d6843abfe6d16032f6d426\n'
  ]

haveparents=True will emit delta

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  >     fields eval:[b'revision']
  >     haveparents eval:True
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'deltabasenode': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
      b'fieldsfollowing': [
        [
          b'delta',
          55
        ]
      ],
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0'
    },
    b'\x00\x00\x00\x00\x00\x00\x00+\x00\x00\x00+a\x000879345e39377229634b420c639454156726c6b6\n'
  ]

Requesting multiple revisions works
(haveparents defaults to false, so fulltext is emitted unless a parent
has been emitted)

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x1b\x17\x5b\x59\x5f\x02\x2c\xfa\xb5\xb8\x09\xcc\x0e\xd5\x51\xbd\x0b\x3f\xf5\xe4', b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  >     fields eval:[b'revision']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 2
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          292
        ]
      ],
      b'node': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4'
    },
    b'a\x002b4eb07319bfa077a40a2f04913659aef0da42da\nb\x00819e258d31a5e1606629f365bb902a1b21ee4216\ndir0/c\x00914445346a0ca0629bd47ceb5dfe07e4d4cf2501\ndir0/child0/e\x00bbba6c06b30f443d34ff841bc985c4d0827c6be4\ndir0/child1/f\x0012fc7dcd773b5a0a929ce195228083c6ddc9cec4\ndir0/d\x00538206dc971e521540d6843abfe6d16032f6d426\n',
    {
      b'deltabasenode': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
      b'fieldsfollowing': [
        [
          b'delta',
          55
        ]
      ],
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0'
    },
    b'\x00\x00\x00\x00\x00\x00\x00+\x00\x00\x00+a\x000879345e39377229634b420c639454156726c6b6\n'
  ]

With haveparents=True, first revision is a delta instead of fulltext

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x1b\x17\x5b\x59\x5f\x02\x2c\xfa\xb5\xb8\x09\xcc\x0e\xd5\x51\xbd\x0b\x3f\xf5\xe4', b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  >     fields eval:[b'revision']
  >     haveparents eval:True
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 2
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          292
        ]
      ],
      b'node': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4'
    },
    b'a\x002b4eb07319bfa077a40a2f04913659aef0da42da\nb\x00819e258d31a5e1606629f365bb902a1b21ee4216\ndir0/c\x00914445346a0ca0629bd47ceb5dfe07e4d4cf2501\ndir0/child0/e\x00bbba6c06b30f443d34ff841bc985c4d0827c6be4\ndir0/child1/f\x0012fc7dcd773b5a0a929ce195228083c6ddc9cec4\ndir0/d\x00538206dc971e521540d6843abfe6d16032f6d426\n',
    {
      b'deltabasenode': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
      b'fieldsfollowing': [
        [
          b'delta',
          55
        ]
      ],
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0'
    },
    b'\x00\x00\x00\x00\x00\x00\x00+\x00\x00\x00+a\x000879345e39377229634b420c639454156726c6b6\n'
  ]

Revisions are sorted by DAG order, parents first

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0', b'\x1b\x17\x5b\x59\x5f\x02\x2c\xfa\xb5\xb8\x09\xcc\x0e\xd5\x51\xbd\x0b\x3f\xf5\xe4']
  >     tree eval:b''
  >     fields eval:[b'revision']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 2
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          292
        ]
      ],
      b'node': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4'
    },
    b'a\x002b4eb07319bfa077a40a2f04913659aef0da42da\nb\x00819e258d31a5e1606629f365bb902a1b21ee4216\ndir0/c\x00914445346a0ca0629bd47ceb5dfe07e4d4cf2501\ndir0/child0/e\x00bbba6c06b30f443d34ff841bc985c4d0827c6be4\ndir0/child1/f\x0012fc7dcd773b5a0a929ce195228083c6ddc9cec4\ndir0/d\x00538206dc971e521540d6843abfe6d16032f6d426\n',
    {
      b'deltabasenode': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
      b'fieldsfollowing': [
        [
          b'delta',
          55
        ]
      ],
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0'
    },
    b'\x00\x00\x00\x00\x00\x00\x00+\x00\x00\x00+a\x000879345e39377229634b420c639454156726c6b6\n'
  ]

Requesting parents and revision data works

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x1b\x17\x5b\x59\x5f\x02\x2c\xfa\xb5\xb8\x09\xcc\x0e\xd5\x51\xbd\x0b\x3f\xf5\xe4', b'\x46\xa6\x72\x1b\x5e\xda\xf0\xea\x04\xb7\x9a\x5c\xb3\x21\x88\x54\xa4\xd2\xab\xa0']
  >     tree eval:b''
  >     fields eval:[b'parents', b'revision']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 2
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          292
        ]
      ],
      b'node': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    b'a\x002b4eb07319bfa077a40a2f04913659aef0da42da\nb\x00819e258d31a5e1606629f365bb902a1b21ee4216\ndir0/c\x00914445346a0ca0629bd47ceb5dfe07e4d4cf2501\ndir0/child0/e\x00bbba6c06b30f443d34ff841bc985c4d0827c6be4\ndir0/child1/f\x0012fc7dcd773b5a0a929ce195228083c6ddc9cec4\ndir0/d\x00538206dc971e521540d6843abfe6d16032f6d426\n',
    {
      b'deltabasenode': b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
      b'fieldsfollowing': [
        [
          b'delta',
          55
        ]
      ],
      b'node': b'F\xa6r\x1b^\xda\xf0\xea\x04\xb7\x9a\\\xb3!\x88T\xa4\xd2\xab\xa0',
      b'parents': [
        b'\x1b\x17[Y_\x02,\xfa\xb5\xb8\t\xcc\x0e\xd5Q\xbd\x0b?\xf5\xe4',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    b'\x00\x00\x00\x00\x00\x00\x00+\x00\x00\x00+a\x000879345e39377229634b420c639454156726c6b6\n'
  ]

  $ cat error.log