Race condition with runfiles tree creation on Windows #12033
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area-Windows
Windows-specific issues and feature requests.
P3
We're not considering working on this, but happy to review a PR. (No assignee)
team-Rules-Server
Issues for serverside rules included with Bazel
type: bug
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benjaminp
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Sep 1, 2020
…tifacts. Windows distinguishes between symlinks to files and symlinks to directories. The code to create symlink trees on Windows thus inspects the targets of the links to learn what kind of symlink to make. Unfortunately, the symlinking code did not depend on the link targets actually being created. This race could lead to non-deterministic and non-functional symlink trees. Fix this problem by depending on runfiles artifacts in the SymtreeTreeAction when the host platform is Windows. It's certainly possible to avoid this os-dependent input dependency—by using in-memory Artifact state for the in-process implementation and extending the runfiles manifest format to indicate target type for build-runfiles-windows—but this commit is the most straightforward change that remediates the serious correctness issue represented by the previous state. This topic has a long history. When Windows runfiles trees were actually copies of artifacts, the "symlink" action obviously had to depend on the origin artifacts (41f4456). That code was removed in an interregnum period where runfiles trees weren't supported at all on Windows (0885abd). However, the dependency was not added back when Windows symlinked runfiles trees support was finally added (b592dbd). Fixes bazelbuild#12033.
oquenchil
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area-Windows
lberki
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P3
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Description of the problem / feature request:
There is a race condition on Windows where Bazel can create the runfiles tree before the runfiles dependencies, leading to runfiles containing file symlinks even when the actual dependency is a directory (and a directory symlink is expected).
This manifests when running with
--experimental_enable_runfiles.This prevents reliable use of directories in runfiles trees.
Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.
Needs some custom rules, so I've created this repository, which should be usable out of the box. Please see the README in the repository for details steps to reproduce.
https://github.com/nikhilm/demo-runfiles-dir/
What operating system are you running Bazel on?
Windows 10
What's the output of
bazel info release?release 3.4.1
Have you found anything relevant by searching the web?
No
Any other information, logs, or outputs that you want to share?
Please see the README in the repository.
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