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Windows: don't error if access_mode is set on OpenOptions #162984

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Merged
rust-bors merged 3 commits into from
Sep 21, 2026
Merged

Windows: don't error if access_mode is set on OpenOptions #162984

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21d6920
Test windows `access_mode` override
ChrisDenton Sep 20, 2026
ac5ff45
Windows: don't error if `access_mode` is set
ChrisDenton Sep 20, 2026
39f76c9
Refactor access_mode case out of match
ChrisDenton Sep 20, 2026
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8 changes: 8 additions & 0 deletions library/std/src/fs/tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1640,6 +1640,14 @@ fn open_flavors() {
assert_eq!(check!(fs::metadata(&tmpdir.join("h"))).len(), 9);
}

#[test]
#[cfg(windows)]
fn windows_access_mode_override() {
// ensure that using access_mode negates the need for using write or append
use crate::os::windows::fs::OpenOptionsExt;
File::options().create(true).access_mode(0).open(tmpdir().join("foo.txt")).unwrap();
}

#[test]
fn _assert_send_sync() {
fn _assert_send_sync<T: Send + Sync>() {}
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66 changes: 23 additions & 43 deletions library/std/src/sys/fs/windows.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -263,54 +263,34 @@ impl OpenOptions {
}

fn get_access_mode(&self) -> io::Result<u32> {
match (self.read, self.write, self.append, self.access_mode) {
(.., Some(mode)) => Ok(mode),
(true, false, false, None) => Ok(c::GENERIC_READ),
(false, true, false, None) => Ok(c::GENERIC_WRITE),
(true, true, false, None) => Ok(c::GENERIC_READ | c::GENERIC_WRITE),
(false, _, true, None) => Ok(c::FILE_GENERIC_WRITE & !c::FILE_WRITE_DATA),
(true, _, true, None) => {
Ok(c::GENERIC_READ | (c::FILE_GENERIC_WRITE & !c::FILE_WRITE_DATA))
}
(false, false, false, None) => {
// If no access mode is set, check if any creation flags are set
// to provide a more descriptive error message
if self.create || self.create_new || self.truncate {
Err(io::Error::new(
io::ErrorKind::InvalidInput,
"creating or truncating a file requires write or append access",
))
} else {
Err(io::Error::new(
io::ErrorKind::InvalidInput,
"must specify at least one of read, write, or append access",
))
}
}
if let Some(access) = self.access_mode {
return Ok(access);
}
}

fn get_cmode_disposition(&self) -> io::Result<(u32, u32)> {
match (self.write, self.append) {
(true, false) => {}
(false, false) => {
if self.truncate || self.create || self.create_new {
return Err(io::Error::new(
io::ErrorKind::InvalidInput,
"creating or truncating a file requires write or append access",
));
}
}
(_, true) => {
if self.truncate && !self.create_new {
return Err(io::Error::new(
io::ErrorKind::InvalidInput,
"append and truncate cannot both be enabled",
));
}
match (self.read, self.write, self.append) {
(_, false, false) if self.truncate || self.create || self.create_new => {
Err(io::Error::new(
io::ErrorKind::InvalidInput,
"creating or truncating a file requires write or append access",
))
}
(_, _, true) if self.truncate && !self.create_new => Err(io::Error::new(
io::ErrorKind::InvalidInput,
"append and truncate cannot both be enabled",
)),
(true, false, false) => Ok(c::GENERIC_READ),
(false, true, false) => Ok(c::GENERIC_WRITE),
(true, true, false) => Ok(c::GENERIC_READ | c::GENERIC_WRITE),
(false, _, true) => Ok(c::FILE_GENERIC_WRITE & !c::FILE_WRITE_DATA),
(true, _, true) => Ok(c::GENERIC_READ | (c::FILE_GENERIC_WRITE & !c::FILE_WRITE_DATA)),
(false, false, false) => Err(io::Error::new(
io::ErrorKind::InvalidInput,
"must specify at least one of read, write, or append access",
)),
}
}

fn get_cmode_disposition(&self) -> io::Result<(u32, u32)> {
Ok(match (self.create, self.truncate, self.create_new) {
(false, false, false) => (c::OPEN_EXISTING, c::FILE_OPEN),
(true, false, false) => (c::OPEN_ALWAYS, c::FILE_OPEN_IF),
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