Struct LocalFile

pub struct LocalFile { /* private fields */ }

Wraps the kernel’s struct file. Not thread safe.

This type represents a file that is not known to be safe to transfer across thread boundaries. To obtain a thread-safe File, use the assume_no_fdget_pos conversion.

See the documentation for File for more information.

Invariants

• All instances of this type are refcounted using the f_count field.
• If there is an active call to fdget_pos that did not take the f_pos_lock mutex, then it must be on the same thread as this file.

Implementations

impl LocalFile

pub fn fget(fd: u32) -> Result<ARef<LocalFile>, BadFdError>

Constructs a new struct file wrapper from a file descriptor.

The file descriptor belongs to the current process, and there might be active local calls to fdget_pos on the same file.

To obtain an ARef<File>, use the assume_no_fdget_pos function to convert.

pub unsafe fn from_raw_file<'a>(ptr: *const file) -> &'a LocalFile

Creates a reference to a LocalFile from a valid pointer.

Safety

• The caller must ensure that ptr points at a valid file and that the file’s refcount is positive for the duration of ’a.
• The caller must ensure that if there is an active call to fdget_pos that did not take the f_pos_lock mutex, then that call is on the current thread.

pub unsafe fn assume_no_fdget_pos(me: ARef<LocalFile>) -> ARef<File>

Assume that there are no active fdget_pos calls that prevent us from sharing this file.

This makes it safe to transfer this file to other threads. No checks are performed, and using it incorrectly may lead to a data race on the file position if the file is shared with another thread.

This method is intended to be used together with LocalFile::fget when the caller knows statically that there are no fdget_pos calls on the current thread. For example, you might use it when calling fget from an ioctl, since ioctls usually do not touch the file position.

Safety

There must not be any active fdget_pos calls on the current thread.

pub fn as_ptr(&self) -> *mut file

Returns a raw pointer to the inner C struct.

pub fn cred(&self) -> &Credential

Returns the credentials of the task that originally opened the file.

pub fn flags(&self) -> u32

Returns the flags associated with the file.

The flags are a combination of the constants in flags.

Trait Implementations

impl AlwaysRefCounted for LocalFile

fn inc_ref(&self)

Increments the reference count on the object.

unsafe fn dec_ref(obj: NonNull<LocalFile>)

Decrements the reference count on the object.