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Auto merge of #134722 - ChrisDenton:trunc, r=Amanieu

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Windows: Use FILE_ALLOCATION_INFO for truncation

We use `FILE_END_OF_FILE_INFO` here only because WINE does not support `FILE_ALLOCATION_INFO`. Instead of going with the one with broadest support, let's just use that as fallback only.
This commit is contained in:
bors 2024-12-24 22:00:05 +00:00
commit a92c3cf04d
1 changed files with 20 additions and 8 deletions
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28
library/std/src/sys/pal/windows/fs.rs
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@ -316,19 +316,31 @@ impl File {
&& api::get_last_error() == WinError::ALREADY_EXISTS
{
unsafe {
// This originally used `FileAllocationInfo` instead of
// `FileEndOfFileInfo` but that wasn't supported by WINE.
// It's arguable which fits the semantics of `OpenOptions`
// better so let's just use the more widely supported method.
let eof = c::FILE_END_OF_FILE_INFO { EndOfFile: 0 };
// This first tries `FileAllocationInfo` but falls back to
// `FileEndOfFileInfo` in order to support WINE.
// If WINE gains support for FileAllocationInfo, we should
// remove the fallback.
let alloc = c::FILE_ALLOCATION_INFO { AllocationSize: 0 };
let result = c::SetFileInformationByHandle(
handle.as_raw_handle(),
c::FileEndOfFileInfo,
(&raw const eof).cast::<c_void>(),
mem::size_of::<c::FILE_END_OF_FILE_INFO>() as u32,
(&raw const alloc).cast::<c_void>(),
mem::size_of::<c::FILE_ALLOCATION_INFO>() as u32,
);
if result == 0 {
return Err(io::Error::last_os_error());
if api::get_last_error().code != 0 {
panic!("FILE_ALLOCATION_INFO failed!!!");
}
let eof = c::FILE_END_OF_FILE_INFO { EndOfFile: 0 };
let result = c::SetFileInformationByHandle(
handle.as_raw_handle(),
c::FileEndOfFileInfo,
(&raw const eof).cast::<c_void>(),
mem::size_of::<c::FILE_END_OF_FILE_INFO>() as u32,
);
if result == 0 {
return Err(io::Error::last_os_error());
}
}
}
}