view tests/test-storage.py @ 49000:dd6b67d5c256 stable

rust: fix unsound `OwningDirstateMap`

As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.

The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.

I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.

In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.

Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.

Differential Revision: https://phab.mercurial-scm.org/D12429

# This test verifies the conformance of various classes to various
# storage interfaces.
from __future__ import absolute_import

import silenttestrunner

from mercurial import (
    error,
    filelog,
    revlog,
    transaction,
    ui as uimod,
    vfs as vfsmod,
)

from mercurial.testing import storage as storagetesting

try:
    from hgext import sqlitestore
except ImportError:
    sqlitestore = None

try:
    import sqlite3

    if sqlite3.sqlite_version_info < (3, 8, 3):
        # WITH clause not supported
        sqlitestore = None
except ImportError:
    pass

try:
    from mercurial import zstd

    zstd.__version__
except ImportError:
    zstd = None

STATE = {
    'lastindex': 0,
    'ui': uimod.ui(),
    'vfs': vfsmod.vfs(b'.', realpath=True),
}


def makefilefn(self):
    """Factory for filelog instances."""
    fl = filelog.filelog(STATE['vfs'], b'filelog-%d' % STATE['lastindex'])
    STATE['lastindex'] += 1
    return fl


def maketransaction(self):
    vfsmap = {b'plain': STATE['vfs'], b'store': STATE['vfs']}

    return transaction.transaction(
        STATE['ui'].warn, STATE['vfs'], vfsmap, b'journal', b'undo'
    )


def addrawrevision(
    self,
    fl,
    tr,
    node,
    p1,
    p2,
    linkrev,
    rawtext=None,
    delta=None,
    censored=False,
    ellipsis=False,
    extstored=False,
):
    flags = 0

    if censored:
        flags |= revlog.REVIDX_ISCENSORED
    if ellipsis:
        flags |= revlog.REVIDX_ELLIPSIS
    if extstored:
        flags |= revlog.REVIDX_EXTSTORED

    if rawtext is not None:
        fl._revlog.addrawrevision(rawtext, tr, linkrev, p1, p2, node, flags)
    elif delta is not None:
        fl._revlog.addrawrevision(
            rawtext, tr, linkrev, p1, p2, node, flags, cachedelta=delta
        )
    else:
        raise error.Abort('must supply rawtext or delta arguments')

    # We may insert bad data. Clear caches to prevent e.g. cache hits to
    # bypass hash verification.
    fl._revlog.clearcaches()


# Assigning module-level attributes that inherit from unittest.TestCase
# is all that is needed to register tests.
filelogindextests = storagetesting.makeifileindextests(
    makefilefn, maketransaction, addrawrevision
)
filelogdatatests = storagetesting.makeifiledatatests(
    makefilefn, maketransaction, addrawrevision
)
filelogmutationtests = storagetesting.makeifilemutationtests(
    makefilefn, maketransaction, addrawrevision
)


def makesqlitefile(self):
    path = STATE['vfs'].join(b'db-%d.db' % STATE['lastindex'])
    STATE['lastindex'] += 1

    db = sqlitestore.makedb(path)

    compression = b'zstd' if zstd else b'zlib'

    return sqlitestore.sqlitefilestore(db, b'dummy-path', compression)


def addrawrevisionsqlite(
    self,
    fl,
    tr,
    node,
    p1,
    p2,
    linkrev,
    rawtext=None,
    delta=None,
    censored=False,
    ellipsis=False,
    extstored=False,
):
    flags = 0

    if censored:
        flags |= sqlitestore.FLAG_CENSORED

    if ellipsis | extstored:
        raise error.Abort(
            b'support for ellipsis and extstored flags not ' b'supported'
        )

    if rawtext is not None:
        fl._addrawrevision(node, rawtext, tr, linkrev, p1, p2, flags=flags)
    elif delta is not None:
        fl._addrawrevision(
            node, rawtext, tr, linkrev, p1, p2, storedelta=delta, flags=flags
        )
    else:
        raise error.Abort(b'must supply rawtext or delta arguments')


if sqlitestore is not None:
    sqlitefileindextests = storagetesting.makeifileindextests(
        makesqlitefile, maketransaction, addrawrevisionsqlite
    )
    sqlitefiledatatests = storagetesting.makeifiledatatests(
        makesqlitefile, maketransaction, addrawrevisionsqlite
    )
    sqlitefilemutationtests = storagetesting.makeifilemutationtests(
        makesqlitefile, maketransaction, addrawrevisionsqlite
    )

if __name__ == '__main__':
    silenttestrunner.main(__name__)