Fix a race condition in TexManager.make_dvi. #30426
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Previously, a race condition could occur if, while a process had called make_tex (generating the tex file in the global cache) and was going to call the latex subprocess (to generate the dvi file), another process also called make_tex for the same tex string and started rewriting the tex source. In that case, the latex subprocess could see a partially written (invalid) tex source. Fix that by generating the tex source in a process-private temporary directory, where the latex process is already going to run anyways. (This is cheap compared to the latex subprocess invocation.)
tacaswell
reviewed
Aug 14, 2025
| @@ -296,12 +298,12 @@ def make_dvi(cls, tex, fontsize): | |||
| # will be blocked when `openin_any = p` in texmf.cnf). | |||
| cwd = Path(dvifile).parent | |||
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I don't think we need this any more?
tacaswell
approved these changes
Aug 14, 2025
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Previously, a race condition could occur if, while a process had called make_tex (generating the tex file in the global cache) and was going to call the latex subprocess (to generate the dvi file), another process also called make_tex for the same tex string and started rewriting the tex source. In that case, the latex subprocess could see a partially written (invalid) tex source.
Fix that by generating the tex source in a process-private temporary directory, where the latex process is already going to run anyways. (This is cheap compared to the latex subprocess invocation.)
See #30420 (comment) (point (2)).
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