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view tests/test-issue3084.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 | 9d5c27890790 |
children |
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$ echo "[extensions]" >> $HGRCPATH $ echo "largefiles =" >> $HGRCPATH Create the repository outside $HOME since largefiles write to $HOME/.cache/largefiles. $ hg init test $ cd test $ echo "root" > root $ hg add root $ hg commit -m "Root commit" --config extensions.largefiles=! Ensure that .hg/largefiles isn't created before largefiles are added #if unix-permissions $ chmod 555 .hg #endif $ hg status #if unix-permissions $ chmod 755 .hg #endif $ test -f .hg/largefiles [1] $ echo "large" > foo $ hg add --large foo $ hg commit -m "Add foo as a largefile" $ hg update -r 0 getting changed largefiles 0 largefiles updated, 1 removed 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ echo "normal" > foo $ hg add foo $ hg commit -m "Add foo as normal file" created new head Normal file in the working copy, keeping the normal version: $ echo "n" | hg merge --config ui.interactive=Yes remote turned local normal file foo into a largefile use (l)argefile or keep (n)ormal file? n 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status $ cat foo normal Normal file in the working copy, keeping the largefile version: $ hg update -q -C $ echo "l" | hg merge --config ui.interactive=Yes remote turned local normal file foo into a largefile use (l)argefile or keep (n)ormal file? l getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status M foo $ hg diff --nodates diff -r fa129ab6b5a7 .hglf/foo --- /dev/null +++ b/.hglf/foo @@ -0,0 +1,1 @@ +7f7097b041ccf68cc5561e9600da4655d21c6d18 diff -r fa129ab6b5a7 foo --- a/foo +++ /dev/null @@ -1,1 +0,0 @@ -normal $ cat foo large Largefile in the working copy, keeping the normal version: $ hg update -q -C -r 1 $ echo "n" | hg merge --config ui.interactive=Yes remote turned local largefile foo into a normal file keep (l)argefile or use (n)ormal file? n getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status M foo $ hg diff --nodates diff -r ff521236428a .hglf/foo --- a/.hglf/foo +++ /dev/null @@ -1,1 +0,0 @@ -7f7097b041ccf68cc5561e9600da4655d21c6d18 diff -r ff521236428a foo --- /dev/null +++ b/foo @@ -0,0 +1,1 @@ +normal $ cat foo normal Largefile in the working copy, keeping the largefile version: $ hg update -q -C -r 1 $ echo "l" | hg merge --config ui.interactive=Yes remote turned local largefile foo into a normal file keep (l)argefile or use (n)ormal file? l 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status $ cat foo large Whatever ... commit something so we can invoke merge when updating $ hg commit -m '3: Merge' Updating from largefile to normal - no reason to prompt $ hg up -r 2 getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ cat foo normal (the update above used to leave the working dir in a very weird state - clean it $ hg up -qr null $ hg up -qr 2 ) Updating from normal to largefile - no reason to prompt $ hg up -r 3 getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ cat foo large $ cd .. Systematic testing of merges involving largefiles: Ancestor: normal Parent: normal-id Parent: large result: large Ancestor: normal Parent: normal2 Parent: large result: ? Ancestor: large Parent: large-id Parent: normal result: normal Ancestor: large Parent: large2 Parent: normal result: ? All cases should try merging both ways. Prepare test repo: $ hg init merges $ cd merges prepare cases with "normal" ancestor: $ hg up -qr null $ echo normal > f $ hg ci -Aqm "normal-ancestor" $ hg tag -l "normal-ancestor" $ touch f2 $ hg ci -Aqm "normal-id" $ hg tag -l "normal-id" $ echo normal2 > f $ hg ci -m "normal2" $ hg tag -l "normal2" $ echo normal > f $ hg ci -Aqm "normal-same" $ hg tag -l "normal-same" $ hg up -qr "normal-ancestor" $ hg rm f $ echo large > f $ hg add --large f $ hg ci -qm "large" $ hg tag -l "large" prepare cases with "large" ancestor: $ hg up -qr null $ echo large > f $ hg add --large f $ hg ci -qm "large-ancestor" $ hg tag -l "large-ancestor" $ touch f2 $ hg ci -Aqm "large-id" $ hg tag -l "large-id" $ echo large2 > f $ hg ci -m "large2" $ hg tag -l "large2" $ echo large > f $ hg ci -Aqm "large-same" $ hg tag -l "large-same" $ hg up -qr "large-ancestor" $ hg rm f $ echo normal > f $ hg ci -qAm "normal" $ hg tag -l "normal" $ hg log -GT '{tags}' @ normal tip | | o large-same | | | o large2 | | | o large-id |/ o large-ancestor o large | | o normal-same | | | o normal2 | | | o normal-id |/ o normal-ancestor Ancestor: normal Parent: normal-id Parent: large result: large $ hg up -Cqr normal-id $ hg merge -r large getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large swap $ hg up -Cqr large $ hg merge -r normal-id 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large Ancestor: normal Parent: normal-same Parent: large result: large $ hg up -Cqr normal-same $ hg merge -r large getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large swap $ hg up -Cqr large $ hg merge -r normal-same 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large Ancestor: normal Parent: normal2 Parent: large result: ? (annoying extra prompt ... but it do not do any serious harm) $ hg up -Cqr normal2 $ hg merge -r large remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? l getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large $ hg up -Cqr normal2 $ echo n | hg merge -r large --config ui.interactive=Yes remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? n 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal2 swap $ hg up -Cqr large $ hg merge -r normal2 remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? l 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large $ hg up -Cqr large $ echo n | hg merge -r normal2 --config ui.interactive=Yes remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? n getting changed largefiles 0 largefiles updated, 0 removed 2 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal2 Ancestor: large Parent: large-id Parent: normal result: normal $ hg up -Cqr large-id $ hg merge -r normal getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal swap $ hg up -Cqr normal $ hg merge -r large-id 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal Ancestor: large Parent: large-same Parent: normal result: normal $ hg up -Cqr large-same $ hg merge -r normal getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal swap $ hg up -Cqr normal $ hg merge -r large-same 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal Ancestor: large Parent: large2 Parent: normal result: ? (annoying extra prompt ... but it do not do any serious harm) $ hg up -Cqr large2 $ hg merge -r normal remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? l 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large2 $ hg up -Cqr large2 $ echo n | hg merge -r normal --config ui.interactive=Yes remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? n getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal swap $ hg up -Cqr normal $ hg merge -r large2 remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? l getting changed largefiles 1 largefiles updated, 0 removed 2 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large2 $ hg up -Cqr normal $ echo n | hg merge -r large2 --config ui.interactive=Yes remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? n 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal $ cd ..