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Windows: std::fs::read_dir returns NotFound for empty volume #120040

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ChrisDenton opened this issue Jan 17, 2024 · 2 comments · Fixed by #120373
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Windows: std::fs::read_dir returns NotFound for empty volume #120040

ChrisDenton opened this issue Jan 17, 2024 · 2 comments · Fixed by #120373
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O-windows Operating system: Windows T-libs Relevant to the library team, which will review and decide on the PR/issue.

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@ChrisDenton
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ChrisDenton commented Jan 17, 2024

This was reported on discord by @Fulgen301 who pointed out that the C++ STL has a similar issue.

Example:

// where `path` is a path to an empty volume.
let path = r"\\?\Volume{e6d42597-fcdc-4856-b3c2-482fe652f1df}\";
std::fs::read_dir(path).unwrap();

prints:

called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "The system cannot find the file specified." }

It should return success but the returned iterator will have no items.

Basically if you use FindFirstFileW on a completely empty volume then it will return ERROR_FILE_NOT_FOUND. Rust should interpret this as being an empty iteration and not return an error to the user. Note that empty directories do not return an error so this behaviour was overlooked.

We need to add some extra logic to this else:

} else {
Err(Error::last_os_error())
}

@ChrisDenton ChrisDenton added O-windows Operating system: Windows T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jan 17, 2024
@rustbot rustbot added the needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. label Jan 17, 2024
@ChrisDenton ChrisDenton removed the needs-triage This issue may need triage. Remove it if it has been sufficiently triaged. label Jan 17, 2024
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This is fixed in C++ STL after this PR: microsoft/STL#4311

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Jan 27, 2024
…120040, r=ChrisDenton

Adjust Behaviour of `read_dir` and `ReadDir` in Windows Implementation: Check Whether Path to Search In Exists

This pull request changes the `read_dir` function's and the `ReadDir` structure's internal implementations for the Windows operating system to make its behaviour more accurate.

It should be noted that `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function when *no matching files can be found*, not necessarily that the path to search in does not exist in the first place. Therefore, directly returning the "The system cannot find the file specified." may not be accurate.

An extra check for whether the path to search in exists is added, returning a constructed `ReadDir` iterator with its handle being an `INVALID_HANDLE_VALUE` returned by the `FindFirstFileW` function if `ERROR_FILE_NOT_FOUND` is indeed the last OS error. The `ReadDir` implementation for the Windows operating system is correspondingly updated to always return `None` if the handle it has is an `INVALID_HANDLE_VALUE` which can only be the case if and only if specifically constructed by the `read_dir` function in the aforementioned conditions.

It should also be noted that `FindFirstFileW` would have returned `ERROR_PATH_NOT_FOUND` if the path to search in does not exist in the first place.

Presumably fixes rust-lang#120040.
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Jan 27, 2024
…120040, r=ChrisDenton

Adjust Behaviour of `read_dir` and `ReadDir` in Windows Implementation: Check Whether Path to Search In Exists

This pull request changes the `read_dir` function's and the `ReadDir` structure's internal implementations for the Windows operating system to make its behaviour more accurate.

It should be noted that `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function when *no matching files can be found*, not necessarily that the path to search in does not exist in the first place. Therefore, directly returning the "The system cannot find the file specified." may not be accurate.

An extra check for whether the path to search in exists is added, returning a constructed `ReadDir` iterator with its handle being an `INVALID_HANDLE_VALUE` returned by the `FindFirstFileW` function if `ERROR_FILE_NOT_FOUND` is indeed the last OS error. The `ReadDir` implementation for the Windows operating system is correspondingly updated to always return `None` if the handle it has is an `INVALID_HANDLE_VALUE` which can only be the case if and only if specifically constructed by the `read_dir` function in the aforementioned conditions.

It should also be noted that `FindFirstFileW` would have returned `ERROR_PATH_NOT_FOUND` if the path to search in does not exist in the first place.

Presumably fixes rust-lang#120040.
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Jan 27, 2024
…120040, r=ChrisDenton

Adjust Behaviour of `read_dir` and `ReadDir` in Windows Implementation: Check Whether Path to Search In Exists

This pull request changes the `read_dir` function's and the `ReadDir` structure's internal implementations for the Windows operating system to make its behaviour more accurate.

It should be noted that `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function when *no matching files can be found*, not necessarily that the path to search in does not exist in the first place. Therefore, directly returning the "The system cannot find the file specified." may not be accurate.

An extra check for whether the path to search in exists is added, returning a constructed `ReadDir` iterator with its handle being an `INVALID_HANDLE_VALUE` returned by the `FindFirstFileW` function if `ERROR_FILE_NOT_FOUND` is indeed the last OS error. The `ReadDir` implementation for the Windows operating system is correspondingly updated to always return `None` if the handle it has is an `INVALID_HANDLE_VALUE` which can only be the case if and only if specifically constructed by the `read_dir` function in the aforementioned conditions.

It should also be noted that `FindFirstFileW` would have returned `ERROR_PATH_NOT_FOUND` if the path to search in does not exist in the first place.

Presumably fixes rust-lang#120040.
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Jan 28, 2024
…120040, r=ChrisDenton

Adjust Behaviour of `read_dir` and `ReadDir` in Windows Implementation: Check Whether Path to Search In Exists

This pull request changes the `read_dir` function's and the `ReadDir` structure's internal implementations for the Windows operating system to make its behaviour more accurate.

It should be noted that `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function when *no matching files can be found*, not necessarily that the path to search in does not exist in the first place. Therefore, directly returning the "The system cannot find the file specified." may not be accurate.

An extra check for whether the path to search in exists is added, returning a constructed `ReadDir` iterator with its handle being an `INVALID_HANDLE_VALUE` returned by the `FindFirstFileW` function if `ERROR_FILE_NOT_FOUND` is indeed the last OS error. The `ReadDir` implementation for the Windows operating system is correspondingly updated to always return `None` if the handle it has is an `INVALID_HANDLE_VALUE` which can only be the case if and only if specifically constructed by the `read_dir` function in the aforementioned conditions.

It should also be noted that `FindFirstFileW` would have returned `ERROR_PATH_NOT_FOUND` if the path to search in does not exist in the first place.

Presumably fixes rust-lang#120040.
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Jan 28, 2024
…120040, r=ChrisDenton

Adjust Behaviour of `read_dir` and `ReadDir` in Windows Implementation: Check Whether Path to Search In Exists

This pull request changes the `read_dir` function's and the `ReadDir` structure's internal implementations for the Windows operating system to make its behaviour more accurate.

It should be noted that `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function when *no matching files can be found*, not necessarily that the path to search in does not exist in the first place. Therefore, directly returning the "The system cannot find the file specified." may not be accurate.

An extra check for whether the path to search in exists is added, returning a constructed `ReadDir` iterator with its handle being an `INVALID_HANDLE_VALUE` returned by the `FindFirstFileW` function if `ERROR_FILE_NOT_FOUND` is indeed the last OS error. The `ReadDir` implementation for the Windows operating system is correspondingly updated to always return `None` if the handle it has is an `INVALID_HANDLE_VALUE` which can only be the case if and only if specifically constructed by the `read_dir` function in the aforementioned conditions.

It should also be noted that `FindFirstFileW` would have returned `ERROR_PATH_NOT_FOUND` if the path to search in does not exist in the first place.

Presumably fixes rust-lang#120040.
@bors bors closed this as completed in d04bede Jan 29, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Jan 29, 2024
Rollup merge of rust-lang#120373 - HTGAzureX1212:HTGAzureX1212/issue-120040, r=ChrisDenton

Adjust Behaviour of `read_dir` and `ReadDir` in Windows Implementation: Check Whether Path to Search In Exists

This pull request changes the `read_dir` function's and the `ReadDir` structure's internal implementations for the Windows operating system to make its behaviour more accurate.

It should be noted that `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function when *no matching files can be found*, not necessarily that the path to search in does not exist in the first place. Therefore, directly returning the "The system cannot find the file specified." may not be accurate.

An extra check for whether the path to search in exists is added, returning a constructed `ReadDir` iterator with its handle being an `INVALID_HANDLE_VALUE` returned by the `FindFirstFileW` function if `ERROR_FILE_NOT_FOUND` is indeed the last OS error. The `ReadDir` implementation for the Windows operating system is correspondingly updated to always return `None` if the handle it has is an `INVALID_HANDLE_VALUE` which can only be the case if and only if specifically constructed by the `read_dir` function in the aforementioned conditions.

It should also be noted that `FindFirstFileW` would have returned `ERROR_PATH_NOT_FOUND` if the path to search in does not exist in the first place.

Presumably fixes rust-lang#120040.
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