Ensure tmpdir usage internally is always the realpath #870
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As it turns out os.tmpdir can point to a symlink, which can introduce path ambiguity. Some of our algorithms are sensitive to path equality, and introducing a path with indirection via a symlink can confuse the system. For example shared-internal’s explicit-relative algorithm fails to create the expected relative paths for externals as it attempts to compare /private/var/folders/… with /var/folders/… The algorithms in question are currently not coupled to the state of the filesystem, and most likely should remain decoupled, this then implies the inputs should be carefully considered and we should not introduce spurious ambiguity where the state enters the system. Given that, ensuring a stable + realpath’d tmpdir is appropriate.
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thoov
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Jun 23, 2021
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As it turns out os.tmpdir can point to a symlink, which can introduce path ambiguity. Some of our algorithms are sensitive to path equality, and introducing a path with indirection via a symlink can confuse the system. For example shared-internal’s explicit-relative algorithm fails to create the expected relative paths for externals as it attempts to compare /private/var/folders/… with /var/folders/…
The algorithms in question are currently not coupled to the state of the filesystem, and most likely should remain decoupled, this then implies the inputs should be carefully considered and we should not introduce spurious ambiguity where the state enters the system. Given that, ensuring a stable + realpath’d tmpdir is appropriate.