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std: sys: fs: uefi: Implement File::seek #150918

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Merged
rust-bors merged 1 commit into from
Jan 11, 2026
Merged

std: sys: fs: uefi: Implement File::seek #150918

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26 changes: 24 additions & 2 deletions library/std/src/sys/fs/uefi.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -352,8 +352,24 @@ impl File {
unsupported()
}

pub fn seek(&self, _pos: SeekFrom) -> io::Result<u64> {
unsupported()
pub fn seek(&self, pos: SeekFrom) -> io::Result<u64> {
const NEG_OFF_ERR: io::Error =
io::const_error!(io::ErrorKind::InvalidInput, "cannot seek to negative offset.");

let off = match pos {
SeekFrom::Start(p) => p,
SeekFrom::End(p) => {
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@joboet joboet Jan 10, 2026

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You could special-case SeekFrom::End(0) here and use 0xFFFFFFFFFFFFFFFF as offset, since that causes the position to be set to the end of the file without having to look up the length.

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@Ayush1325 Ayush1325 Jan 10, 2026

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Added

// Seeking to position 0xFFFFFFFFFFFFFFFF causes the current position to be set to the end of the file.
if p == 0 {
0xFFFFFFFFFFFFFFFF
} else {
self.file_attr()?.size().checked_add_signed(p).ok_or(NEG_OFF_ERR)?
}
}
SeekFrom::Current(p) => self.tell()?.checked_add_signed(p).ok_or(NEG_OFF_ERR)?,
};

self.0.set_position(off).map(|_| off)
}

pub fn size(&self) -> Option<io::Result<u64>> {
Expand Down Expand Up @@ -755,6 +771,12 @@ mod uefi_fs {
if r.is_error() { Err(io::Error::from_raw_os_error(r.as_usize())) } else { Ok(pos) }
}

pub(crate) fn set_position(&self, pos: u64) -> io::Result<()> {
let file_ptr = self.protocol.as_ptr();
let r = unsafe { ((*file_ptr).set_position)(file_ptr, pos) };
if r.is_error() { Err(io::Error::from_raw_os_error(r.as_usize())) } else { Ok(()) }
}

pub(crate) fn delete(self) -> io::Result<()> {
let file_ptr = self.protocol.as_ptr();
let r = unsafe { ((*file_ptr).delete)(file_ptr) };
Expand Down
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