Struct base::sys::unix::shm::SharedMemory

pub struct SharedMemory {
    fd: File,
    size: u64,
}

A shared memory file descriptor and its size.

Fields

fd: File

size: u64

Implementations

impl SharedMemory

pub fn new(debug_name: &CStr, size: u64) -> Result<SharedMemory>

Creates a new shared memory file descriptor with the specified size in bytes.

name will appear in /proc/self/fd/<shm fd> for the purposes of debugging. The name does not need to be unique.

The file descriptor is opened with the close on exec flag and allows memfd sealing.

If the MFD_NOEXEC_SEAL flag is supported, the resulting file will also be created with a non-executable file mode (in other words, it cannot be passed to the exec family of system calls).

pub fn from_safe_descriptor(
    descriptor: SafeDescriptor,
    size: u64
) -> Result<SharedMemory>

Creates a SharedMemory instance from a SafeDescriptor owning a reference to a shared memory descriptor. Ownership of the underlying descriptor is transferred to the new SharedMemory object.

pub fn from_file(file: File) -> Result<SharedMemory>

Constructs a SharedMemory instance from a File that represents shared memory.

The size of the resulting shared memory will be determined using File::seek. If the given file’s size can not be determined this way, this will return an error.

pub fn get_seals(&self) -> Result<MemfdSeals>

Gets the memfd seals that have already been added to this.

This may fail if this instance was not constructed from a memfd.

pub fn add_seals(&mut self, seals: MemfdSeals) -> Result<()>

Adds the given set of memfd seals.

This may fail if this instance was not constructed from a memfd with sealing allowed or if the seal seal (F_SEAL_SEAL) bit was already added.

pub fn size(&self) -> u64

Gets the size in bytes of the shared memory.

The size returned here does not reflect changes by other interfaces or users of the shared memory file descriptor..

pub fn set_size(&mut self, size: u64) -> Result<()>

Sets the size in bytes of the shared memory.

Note that if some process has already mapped this shared memory and the new size is smaller, that process may get signaled with SIGBUS if they access any page past the new size.

pub fn read_name(&self) -> Result<String>

Reads the name from the underlying file as a String.

If the underlying file was not created with SharedMemory::new or with memfd_create, the results are undefined. Because this returns a String, the name’s bytes are interpreted as utf-8.

Trait Implementations

impl AsRawDescriptor for SharedMemory

fn as_raw_descriptor(&self) -> RawDescriptor

Returns the underlying raw descriptor.

impl Debug for SharedMemory

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for SharedMemory

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>where
    __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<SharedMemory> for File

fn from(s: SharedMemory) -> File

Converts to this type from the input type.

impl IntoRawDescriptor for SharedMemory

fn into_raw_descriptor(self) -> RawDescriptor

impl Read for &SharedMemory

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

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

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8, Global>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

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

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

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

Read the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>where
    Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R>where
    R: Read,
    Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>where
    Self: Sized,

Creates an adapter which will read at most limit bytes from it.

impl Read for SharedMemory

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

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

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8, Global>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

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

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

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

Read the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>where
    Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R>where
    R: Read,
    Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>where
    Self: Sized,

Creates an adapter which will read at most limit bytes from it.

impl Seek for &SharedMemory

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream.

fn stream_len(&mut self) -> Result<u64, Error>

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

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream.

impl Seek for SharedMemory

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream.

fn stream_len(&mut self) -> Result<u64, Error>

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

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream.

impl Serialize for SharedMemory

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>where
    __S: Serializer,

Serialize this value into the given Serde serializer.

impl Write for &SharedMemory

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

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

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

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

Attempts to write multiple buffers into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl Write for SharedMemory

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

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

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

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

Attempts to write multiple buffers into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,

Creates a “by reference” adapter for this instance of Write.