Compile for WASI #50
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Compile for WASI #50
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vitiral
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Dec 19, 2020
vitiral
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Dec 20, 2020
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Actually, wait, this PR is wrong. The file descriptor in the API is supposed to be a preopen directory descriptor, not the descriptor for the target file. |
This was referenced Jan 30, 2021
RReverser
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Jan 30, 2021
As described in rust-lang#68574, the currently exposed API for symlinks is, in fact, a thin wrapper around the corresponding syscall, and not suitable for public usage. The reason is that the 2nd param in the call is expected to be a handle of a "preopened directory" (a WASI concept for exposing dirs), and the only way to retrieve such handle right now is by tinkering with a private `__wasilibc_find_relpath` API, which is an implementation detail and definitely not something we want users to call directly. Making matters worse, the semantics of this param aren't obvious from its name (`fd`), and easy to misinterpret, resulting in people trying to pass a handle of the target file itself (as in vitiral/path_abs#50), which doesn't work as expected. I did a codesearch among open-source repos, and the usage above is so far the only usage of this API at all, but we should fix it before more people start using it incorrectly. While this is technically a breaking API change, I believe it's a justified one, as 1) it's OS-specific and 2) there was strictly no way to correctly use the previous form of the API, and if someone does use it, they're likely doing it wrong like in the example above. The new API does not lead to the same confusion, as it mirrors `std::os::unix::fs::symlink` and `std::os::windows::fs::symlink_{file,dir}` variants by accepting source/target paths. Fixes rust-lang#68574.
Dylan-DPC-zz
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Feb 3, 2021
Expose correct symlink API on WASI As described in rust-lang#68574, the currently exposed API for symlinks is, in fact, a thin wrapper around the corresponding syscall, and not suitable for public usage. The reason is that the 2nd param in the call is expected to be a handle of a "preopened directory" (a WASI concept for exposing dirs), and the only way to retrieve such handle right now is by tinkering with a private `__wasilibc_find_relpath` API, which is an implementation detail and definitely not something we want users to call directly. Making matters worse, the semantics of this param aren't obvious from its name (`fd`), and easy to misinterpret, resulting in people trying to pass a handle of the target file itself (as in vitiral/path_abs#50), which doesn't work as expected. I did a [codesearch among open-source repos](https://sourcegraph.com/search?q=std%3A%3Aos%3A%3Awasi%3A%3Afs%3A%3Asymlink&patternType=literal), and the usage above is so far the only usage of this API at all, but we should fix it before more people start using it incorrectly. While this is technically a breaking API change, I believe it's a justified one, as 1) it's OS-specific and 2) there was strictly no way to correctly use the previous form of the API, and if someone does use it, they're likely doing it wrong like in the example above. The new API does not lead to the same confusion, as it mirrors `std::os::unix::fs::symlink` and `std::os::windows::fs::symlink_{file,dir}` variants by accepting source/target paths. Fixes rust-lang#68574. r? `@alexcrichton`
m-ou-se
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Feb 5, 2021
Expose correct symlink API on WASI As described in rust-lang#68574, the currently exposed API for symlinks is, in fact, a thin wrapper around the corresponding syscall, and not suitable for public usage. The reason is that the 2nd param in the call is expected to be a handle of a "preopened directory" (a WASI concept for exposing dirs), and the only way to retrieve such handle right now is by tinkering with a private `__wasilibc_find_relpath` API, which is an implementation detail and definitely not something we want users to call directly. Making matters worse, the semantics of this param aren't obvious from its name (`fd`), and easy to misinterpret, resulting in people trying to pass a handle of the target file itself (as in vitiral/path_abs#50), which doesn't work as expected. I did a [codesearch among open-source repos](https://sourcegraph.com/search?q=std%3A%3Aos%3A%3Awasi%3A%3Afs%3A%3Asymlink&patternType=literal), and the usage above is so far the only usage of this API at all, but we should fix it before more people start using it incorrectly. While this is technically a breaking API change, I believe it's a justified one, as 1) it's OS-specific and 2) there was strictly no way to correctly use the previous form of the API, and if someone does use it, they're likely doing it wrong like in the example above. The new API does not lead to the same confusion, as it mirrors `std::os::unix::fs::symlink` and `std::os::windows::fs::symlink_{file,dir}` variants by accepting source/target paths. Fixes rust-lang#68574. r? `@alexcrichton`
m-ou-se
added a commit
to m-ou-se/rust
that referenced
this pull request
Feb 5, 2021
Expose correct symlink API on WASI As described in rust-lang#68574, the currently exposed API for symlinks is, in fact, a thin wrapper around the corresponding syscall, and not suitable for public usage. The reason is that the 2nd param in the call is expected to be a handle of a "preopened directory" (a WASI concept for exposing dirs), and the only way to retrieve such handle right now is by tinkering with a private `__wasilibc_find_relpath` API, which is an implementation detail and definitely not something we want users to call directly. Making matters worse, the semantics of this param aren't obvious from its name (`fd`), and easy to misinterpret, resulting in people trying to pass a handle of the target file itself (as in vitiral/path_abs#50), which doesn't work as expected. I did a [codesearch among open-source repos](https://sourcegraph.com/search?q=std%3A%3Aos%3A%3Awasi%3A%3Afs%3A%3Asymlink&patternType=literal), and the usage above is so far the only usage of this API at all, but we should fix it before more people start using it incorrectly. While this is technically a breaking API change, I believe it's a justified one, as 1) it's OS-specific and 2) there was strictly no way to correctly use the previous form of the API, and if someone does use it, they're likely doing it wrong like in the example above. The new API does not lead to the same confusion, as it mirrors `std::os::unix::fs::symlink` and `std::os::windows::fs::symlink_{file,dir}` variants by accepting source/target paths. Fixes rust-lang#68574. r? ``@alexcrichton``
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Fixes #49.