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view tests/test-basic.t @ 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
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 05 Apr 2022 10:55:28 +0200 |
parents | e845537f6adb |
children | 5aafc3c5bdec |
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Create a repository: #if no-extraextensions $ hg config chgserver.idletimeout=60 devel.all-warnings=true devel.default-date=0 0 extensions.fsmonitor= (fsmonitor !) format.use-dirstate-v2=1 (dirstate-v2 !) largefiles.usercache=$TESTTMP/.cache/largefiles lfs.usercache=$TESTTMP/.cache/lfs ui.slash=True ui.interactive=False ui.detailed-exit-code=True ui.merge=internal:merge ui.mergemarkers=detailed ui.promptecho=True ui.ssh=* (glob) ui.timeout.warn=15 web.address=localhost web\.ipv6=(?:True|False) (re) web.server-header=testing stub value #endif $ hg init t $ cd t Prepare a changeset: $ echo a > a $ hg add a $ hg status A a Writes to stdio succeed and fail appropriately #if devfull $ hg status 2>/dev/full A a $ hg status >/dev/full abort: No space left on device* (glob) [255] #endif #if devfull $ hg status >/dev/full 2>&1 [255] $ hg status ENOENT 2>/dev/full [255] #endif On Python 3, stdio may be None: $ hg debuguiprompt --config ui.interactive=true 0<&- abort: Bad file descriptor (no-rhg !) abort: response expected (rhg !) [255] $ hg version -q 0<&- Mercurial Distributed SCM * (glob) #if py3 no-rhg $ hg version -q 1>&- abort: Bad file descriptor [255] #else $ hg version -q 1>&- #endif $ hg unknown -q 1>&- hg: unknown command 'unknown' (did you mean debugknown?) [10] $ hg version -q 2>&- Mercurial Distributed SCM * (glob) $ hg unknown -q 2>&- [10] $ hg commit -m test This command is ancient: $ hg history changeset: 0:acb14030fe0a tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: test Verify that updating to revision 0 via commands.update() works properly $ cat <<EOF > update_to_rev0.py > from mercurial import commands, hg, ui as uimod > myui = uimod.ui.load() > repo = hg.repository(myui, path=b'.') > commands.update(myui, repo, rev=b"0") > EOF $ hg up null 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ "$PYTHON" ./update_to_rev0.py 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg identify -n 0 Poke around at hashes: $ hg manifest --debug b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644 a $ hg cat a a Verify should succeed: $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 1 changesets with 1 changes to 1 files Repository root: $ hg root $TESTTMP/t $ hg log -l1 -T '{reporoot}\n' $TESTTMP/t $ hg root -Tjson | sed 's|\\\\|\\|g' [ { "hgpath": "$TESTTMP/t/.hg", "reporoot": "$TESTTMP/t", "storepath": "$TESTTMP/t/.hg/store" } ] At the end... $ cd .. Status message redirection: $ hg init empty status messages are sent to stdout by default: $ hg outgoing -R t empty -Tjson 2>/dev/null comparing with empty searching for changes [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] which can be configured to send to stderr, so the output wouldn't be interleaved: $ cat <<'EOF' >> "$HGRCPATH" > [ui] > message-output = stderr > EOF $ hg outgoing -R t empty -Tjson 2>/dev/null [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] $ hg outgoing -R t empty -Tjson >/dev/null comparing with empty searching for changes this option should be turned off by HGPLAIN= since it may break scripting use: $ HGPLAIN= hg outgoing -R t empty -Tjson 2>/dev/null comparing with empty searching for changes [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] but still overridden by --config: $ HGPLAIN= hg outgoing -R t empty -Tjson --config ui.message-output=stderr \ > 2>/dev/null [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] Invalid ui.message-output option: $ hg log -R t --config ui.message-output=bad abort: invalid ui.message-output destination: bad [255] Underlying message streams should be updated when ui.fout/ferr are set: $ cat <<'EOF' > capui.py > from mercurial import pycompat, registrar > cmdtable = {} > command = registrar.command(cmdtable) > @command(b'capui', norepo=True) > def capui(ui): > out = ui.fout > ui.fout = pycompat.bytesio() > ui.status(b'status\n') > ui.ferr = pycompat.bytesio() > ui.warn(b'warn\n') > out.write(b'stdout: %s' % ui.fout.getvalue()) > out.write(b'stderr: %s' % ui.ferr.getvalue()) > EOF $ hg --config extensions.capui=capui.py --config ui.message-output=stdio capui stdout: status stderr: warn