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view tests/test-hgweb-removed.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 | 82ae4f471254 |
| children |
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#require serve setting up repo $ hg init test $ cd test $ echo a > a $ hg ci -Ama adding a $ hg rm a $ hg ci -mdel set up hgweb $ hg serve -n test -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log $ cat hg.pid >> $DAEMON_PIDS revision $ get-with-headers.py localhost:$HGPORT 'rev/tip' 200 Script output follows <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US"> <head> <link rel="icon" href="/static/hgicon.png" type="image/png" /> <meta name="robots" content="index, nofollow" /> <link rel="stylesheet" href="/static/style-paper.css" type="text/css" /> <script type="text/javascript" src="/static/mercurial.js"></script> <title>test: c78f6c5cbea9</title> </head> <body> <div class="container"> <div class="menu"> <div class="logo"> <a href="https://mercurial-scm.org/"> <img src="/static/hglogo.png" alt="mercurial" /></a> </div> <ul> <li><a href="/shortlog/tip">log</a></li> <li><a href="/graph/tip">graph</a></li> <li><a href="/tags">tags</a></li> <li><a href="/bookmarks">bookmarks</a></li> <li><a href="/branches">branches</a></li> </ul> <ul> <li class="active">changeset</li> <li><a href="/raw-rev/tip">raw</a></li> <li><a href="/file/tip">browse</a></li> </ul> <ul> </ul> <ul> <li><a href="/help">help</a></li> </ul> </div> <div class="main"> <h2 class="breadcrumb"><a href="/">Mercurial</a> </h2> <h3> changeset 1:<a href="/rev/c78f6c5cbea9">c78f6c5cbea9</a> <span class="phase">draft</span> <span class="branchhead">default</span> <span class="tag">tip</span> </h3> <form class="search" action="/log"> <p><input name="rev" id="search1" type="text" size="30" value="" /></p> <div id="hint">Find changesets by keywords (author, files, the commit message), revision number or hash, or <a href="/help/revsets">revset expression</a>.</div> </form> <div class="description">del</div> <table id="changesetEntry"> <tr> <th class="author">author</th> <td class="author">test</td> </tr> <tr> <th class="date">date</th> <td class="date age">Thu, 01 Jan 1970 00:00:00 +0000</td> </tr> <tr> <th class="author">parents</th> <td class="author"><a href="/rev/cb9a9f314b8b">cb9a9f314b8b</a> </td> </tr> <tr> <th class="author">children</th> <td class="author"></td> </tr> <tr> <th class="files">files</th> <td class="files">a </td> </tr> <tr> <th class="diffstat">diffstat</th> <td class="diffstat"> 1 files changed, 0 insertions(+), 1 deletions(-) <a id="diffstatexpand" class="diffstattoggle" href="#">[<tt>+</tt>]</a> <div id="diffstatdetails" style="display:none;"> <a class="diffstattoggle" href="#">[<tt>-</tt>]</a> <table class="diffstat-table stripes2"> <tr> <td class="diffstat-file"><a href="#l1.1">a</a></td> <td class="diffstat-total" align="right">1</td> <td class="diffstat-graph"> <span class="diffstat-add" style="width:0.0%;"> </span> <span class="diffstat-remove" style="width:100.0%;"> </span> </td> </tr> </table> </div> </td> </tr> </table> <div class="overflow"> <div class="sourcefirst linewraptoggle">line wrap: <a class="linewraplink" href="#">on</a></div> <div class="sourcefirst"> line diff</div> <div class="stripes2 diffblocks"> <div class="bottomline inc-lineno"><pre class="sourcelines wrap"> <span id="l1.1" class="minusline">--- a/a Thu Jan 01 00:00:00 1970 +0000</span><a href="#l1.1"></a> <span id="l1.2" class="plusline">+++ /dev/null Thu Jan 01 00:00:00 1970 +0000</span><a href="#l1.2"></a> <span id="l1.3" class="atline">@@ -1,1 +0,0 @@</span><a href="#l1.3"></a> <span id="l1.4" class="minusline">-a</span><a href="#l1.4"></a></pre></div> </div> </div> </div> </div> </body> </html> diff removed file $ get-with-headers.py localhost:$HGPORT 'diff/tip/a' 200 Script output follows <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US"> <head> <link rel="icon" href="/static/hgicon.png" type="image/png" /> <meta name="robots" content="index, nofollow" /> <link rel="stylesheet" href="/static/style-paper.css" type="text/css" /> <script type="text/javascript" src="/static/mercurial.js"></script> <title>test: a diff</title> </head> <body> <div class="container"> <div class="menu"> <div class="logo"> <a href="https://mercurial-scm.org/"> <img src="/static/hglogo.png" alt="mercurial" /></a> </div> <ul> <li><a href="/shortlog/tip">log</a></li> <li><a href="/graph/tip">graph</a></li> <li><a href="/tags">tags</a></li> <li><a href="/bookmarks">bookmarks</a></li> <li><a href="/branches">branches</a></li> </ul> <ul> <li><a href="/rev/tip">changeset</a></li> <li><a href="/file/tip">browse</a></li> </ul> <ul> <li><a href="/file/tip/a">file</a></li> <li><a href="/file/tip/a">latest</a></li> <li class="active">diff</li> <li><a href="/comparison/tip/a">comparison</a></li> <li><a href="/annotate/tip/a">annotate</a></li> <li><a href="/log/tip/a">file log</a></li> <li><a href="/raw-file/tip/a">raw</a></li> </ul> <ul> <li><a href="/help">help</a></li> </ul> </div> <div class="main"> <h2 class="breadcrumb"><a href="/">Mercurial</a> </h2> <h3> diff a @ 1:<a href="/rev/c78f6c5cbea9">c78f6c5cbea9</a> <span class="phase">draft</span> <span class="branchhead">default</span> <span class="tag">tip</span> </h3> <form class="search" action="/log"> <p><input name="rev" id="search1" type="text" size="30" value="" /></p> <div id="hint">Find changesets by keywords (author, files, the commit message), revision number or hash, or <a href="/help/revsets">revset expression</a>.</div> </form> <div class="description">del</div> <table id="changesetEntry"> <tr> <th>author</th> <td>test</td> </tr> <tr> <th>date</th> <td class="date age">Thu, 01 Jan 1970 00:00:00 +0000</td> </tr> <tr> <th>parents</th> <td><a href="/file/cb9a9f314b8b/a">cb9a9f314b8b</a> </td> </tr> <tr> <th>children</th> <td></td> </tr> </table> <div class="overflow"> <div class="sourcefirst linewraptoggle">line wrap: <a class="linewraplink" href="#">on</a></div> <div class="sourcefirst"> line diff</div> <div class="stripes2 diffblocks"> <div class="bottomline inc-lineno"><pre class="sourcelines wrap"> <span id="l1.1" class="minusline">--- a/a Thu Jan 01 00:00:00 1970 +0000</span><a href="#l1.1"></a> <span id="l1.2" class="plusline">+++ /dev/null Thu Jan 01 00:00:00 1970 +0000</span><a href="#l1.2"></a> <span id="l1.3" class="atline">@@ -1,1 +0,0 @@</span><a href="#l1.3"></a> <span id="l1.4" class="minusline">-a</span><a href="#l1.4"></a></pre></div> </div> </div> </div> </div> </body> </html> $ cd ..