Struct OpenFlags

pub struct OpenFlags(/* private fields */);

Wrapper for the underlying libc’s O_* flags.

The flag values and their meaning is identical to the description in the open(2) man page.

Caveats

For historical reasons, the first three bits of open(2)’s flags are for the access mode and are actually treated as a 2-bit number. So, it is incorrect to attempt to do any checks on the access mode without masking it correctly. So some helpers were added to make usage more ergonomic.

// Using .contains() can lead to confusing behaviour:
OpenFlags::O_WRONLY.contains(OpenFlags::O_RDONLY); // returns true!
OpenFlags::O_RDWR.contains(OpenFlags::O_RDONLY); // returns true!
OpenFlags::O_RDWR.contains(OpenFlags::O_WRONLY); // returns false!
// But using the .wants_write() and .wants_read() helpers works:
assert_eq!(OpenFlags::O_WRONLY.wants_read(), false);
assert_eq!(OpenFlags::O_RDONLY.wants_read(), true);
assert_eq!(OpenFlags::O_RDWR.wants_write(), true);
// And we also correctly handle O_PATH as being "neither read nor write".
assert_eq!((OpenFlags::O_PATH | OpenFlags::O_RDWR).access_mode(), None);
assert_eq!((OpenFlags::O_PATH | OpenFlags::O_RDWR).wants_read(), false);
assert_eq!((OpenFlags::O_PATH | OpenFlags::O_RDWR).wants_write(), false);
// As well as the sneaky "implied write" cases.
assert_eq!((OpenFlags::O_CREAT|OpenFlags::O_RDONLY).wants_write(), true);
assert_eq!((OpenFlags::O_TRUNC|OpenFlags::O_RDONLY).wants_write(), true);

Also, if you wish to check for O_TMPFILE, make sure to use contains. O_TMPFILE includes O_DIRECTORY, so doing intersection will match O_DIRECTORY as well.

// O_TMPFILE contains O_DIRECTORY (as a kernel implementation detail).
OpenFlags::O_DIRECTORY.intersection(OpenFlags::O_TMPFILE).is_empty(); // returns false!
// Instead, use contains:
assert_eq!(OpenFlags::O_DIRECTORY.contains(OpenFlags::O_TMPFILE), false);

Implementations

impl OpenFlags

pub const O_RDWR: Self

pub const O_RDONLY: Self

pub const O_WRONLY: Self

pub const O_PATH: Self

pub const O_CLOEXEC: Self

pub const O_NOFOLLOW: Self

pub const O_DIRECTORY: Self

pub const O_NOCTTY: Self

pub const O_TMPFILE: Self

pub const O_CREAT: Self

pub const O_EXCL: Self

pub const O_TRUNC: Self

pub const O_APPEND: Self

pub const O_SYNC: Self

pub const O_ASYNC: Self

pub const O_DSYNC: Self

pub const O_FSYNC: Self

pub const O_RSYNC: Self

pub const O_DIRECT: Self

pub const O_NDELAY: Self

pub const O_NOATIME: Self

pub const O_NONBLOCK: Self

impl OpenFlags

pub const fn empty() -> Self

Get a flags value with all bits unset.

pub const fn all() -> Self

Get a flags value with all known bits set.

pub const fn bits(&self) -> c_int

Get the underlying bits value.

The returned value is exactly the bits set in this flags value.

pub const fn from_bits(bits: c_int) -> Option<Self>

Convert from a bits value.

This method will return None if any unknown bits are set.

pub const fn from_bits_truncate(bits: c_int) -> Self

Convert from a bits value, unsetting any unknown bits.

pub const fn from_bits_retain(bits: c_int) -> Self

Convert from a bits value exactly.

pub fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

This method will return None if name is empty or doesn’t correspond to any named flag.

pub const fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

pub const fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

pub const fn intersects(&self, other: Self) -> bool

Whether any set bits in a source flags value are also set in a target flags value.

pub const fn contains(&self, other: Self) -> bool

Whether all set bits in a source flags value are also set in a target flags value.

pub fn insert(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

pub fn remove(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. remove won’t truncate other, but the ! operator will.

pub fn toggle(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

pub fn set(&mut self, other: Self, value: bool)

Call insert when value is true or remove when value is false.

pub const fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

pub const fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

pub const fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

pub const fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

pub const fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl OpenFlags

pub const fn iter(&self) -> Iter<OpenFlags>

Yield a set of contained flags values.

Each yielded flags value will correspond to a defined named flag. Any unknown bits will be yielded together as a final flags value.

pub const fn iter_names(&self) -> IterNames<OpenFlags>

Yield a set of contained named flags values.

This method is like iter, except only yields bits in contained named flags. Any unknown bits, or bits not corresponding to a contained flag will not be yielded.

impl OpenFlags

pub fn access_mode(self) -> Option<c_int>

Grab the access mode bits from the flags.

If the flags contain O_PATH, this returns None.

pub fn wants_read(self) -> bool

Does the access mode imply read access?

Returns false for O_PATH.

pub fn wants_write(self) -> bool

Does the access mode imply write access? Note that there are several other bits in OpenFlags that imply write access other than O_WRONLY and O_RDWR. This function checks those bits as well.

Returns false for O_PATH.

Trait Implementations

impl Binary for OpenFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl BitAnd for OpenFlags

fn bitand(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

type Output = OpenFlags

The resulting type after applying the & operator.

impl BitAndAssign for OpenFlags

fn bitand_assign(&mut self, other: Self)

The bitwise and (&) of the bits in two flags values.

impl BitOr for OpenFlags

fn bitor(self, other: OpenFlags) -> Self

The bitwise or (|) of the bits in two flags values.

type Output = OpenFlags

The resulting type after applying the | operator.

impl BitOrAssign for OpenFlags

fn bitor_assign(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

impl BitXor for OpenFlags

fn bitxor(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

type Output = OpenFlags

The resulting type after applying the ^ operator.

impl BitXorAssign for OpenFlags

fn bitxor_assign(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

impl Clone for OpenFlags

fn clone(&self) -> OpenFlags

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for OpenFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for OpenFlags

fn default() -> OpenFlags

Returns the “default value” for a type.

impl Extend<OpenFlags> for OpenFlags

fn extend<T: IntoIterator<Item = Self>>(&mut self, iterator: T)

The bitwise or (|) of the bits in each flags value.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl Flags for OpenFlags

const FLAGS: &'static [Flag<OpenFlags>]

The set of defined flags.

type Bits = i32

The underlying bits type.

fn bits(&self) -> c_int

Get the underlying bits value.

fn from_bits_retain(bits: c_int) -> OpenFlags

Convert from a bits value exactly.

fn empty() -> Self

Get a flags value with all bits unset.

fn all() -> Self

Get a flags value with all known bits set.

fn contains_unknown_bits(&self) -> bool

This method will return true if any unknown bits are set.

fn from_bits(bits: Self::Bits) -> Option<Self>

Convert from a bits value.

fn from_bits_truncate(bits: Self::Bits) -> Self

Convert from a bits value, unsetting any unknown bits.

fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

fn iter(&self) -> Iter<Self>

Yield a set of contained flags values.

fn iter_names(&self) -> IterNames<Self>

Yield a set of contained named flags values.

fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

fn intersects(&self, other: Self) -> bool

where Self: Sized,

Whether any set bits in a source flags value are also set in a target flags value.

fn contains(&self, other: Self) -> bool

where Self: Sized,

Whether all set bits in a source flags value are also set in a target flags value.

fn truncate(&mut self)

where Self: Sized,

Remove any unknown bits from the flags.

fn insert(&mut self, other: Self)

where Self: Sized,

The bitwise or (|) of the bits in two flags values.

fn remove(&mut self, other: Self)

where Self: Sized,

The intersection of a source flags value with the complement of a target flags value (&!).

fn toggle(&mut self, other: Self)

where Self: Sized,

The bitwise exclusive-or (^) of the bits in two flags values.

fn set(&mut self, other: Self, value: bool)

where Self: Sized,

Call Flags::insert when value is true or Flags::remove when value is false.

fn clear(&mut self)

where Self: Sized,

Unsets all bits in the flags.

fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl FromIterator<OpenFlags> for OpenFlags

fn from_iter<T: IntoIterator<Item = Self>>(iterator: T) -> Self

The bitwise or (|) of the bits in each flags value.

impl IntoIterator for OpenFlags

type Item = OpenFlags

The type of the elements being iterated over.

type IntoIter = Iter<OpenFlags>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl LowerHex for OpenFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Not for OpenFlags

fn not(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

type Output = OpenFlags

The resulting type after applying the ! operator.

impl Octal for OpenFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for OpenFlags

fn eq(&self, other: &OpenFlags) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PublicFlags for OpenFlags

type Primitive = i32

The type of the underlying storage.

type Internal = InternalBitFlags

The type of the internal field on the generated flags type.

impl Sub for OpenFlags

fn sub(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

type Output = OpenFlags

The resulting type after applying the - operator.

impl SubAssign for OpenFlags

fn sub_assign(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

impl UpperHex for OpenFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for OpenFlags

impl Eq for OpenFlags

impl StructuralPartialEq for OpenFlags