FileDescriptor

struct FileDescriptor

Owning file descriptor that is closed explicitly with close().

Movable but not copyable, so exactly one value owns the descriptor. -1 is the niche, so Optional[FileDescriptor] is the size of a descriptor.

Examples:

from std.io import FileDescriptor

def release(var fd: FileDescriptor) raises:
    fd^.close()

Implemented traits

AnyType, Movable, UnsafeNicheable, _FieldNicheable

Methods

__init__

def __init__(out self, *, unsafe_raw_fd: RawFileDescriptor)

Takes ownership of a raw file descriptor.

Args:

• ​unsafe_raw_fd (RawFileDescriptor): The descriptor to own. Nothing else may close it, so never pass stdin, stdout, stderr or the descriptor behind a FileHandle.

def __init__(out self, *, copy_borrowed: BorrowedFileDescriptor)

Constructs a new owner by duplicating a borrowed descriptor.

The new FileDescriptor owns a fresh descriptor that refers to the same open file description as copy_borrowed, so the two share the file offset and status flags but are closed independently. The copy is close-on-exec, so child processes don't inherit it.

Args:

• ​copy_borrowed (BorrowedFileDescriptor): The descriptor to duplicate.

Raises:

If the duplication fails.

close

def close(deinit self)

Closes the owned file descriptor.

Raises:

If the close fails. A failed close can mean buffered writes never reached the file.

unsafe_into_raw

def unsafe_into_raw(deinit self) -> RawFileDescriptor

Releases ownership of the descriptor without closing it.

Use this to hand the descriptor to an API that takes ownership of it, such as fdopen, which closes it on fclose.

Safety: The caller becomes responsible for closing the descriptor exactly once.

Returns:

RawFileDescriptor: The raw descriptor.