sgx_tstd/src/sys/ext/fs.rs

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use io;
/// Unix-specific extensions to `File`
pub trait FileExt {
    /// Reads a number of bytes starting from a given offset.
    ///
    /// Returns the number of bytes read.
    ///
    /// The offset is relative to the start of the file and thus independent
    /// from the current cursor.
    ///
    /// The current file cursor is not affected by this function.
    ///
    /// Note that similar to `File::read`, it is not an error to return with a
    /// short read.
    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize>;

    /// Writes a number of bytes starting from a given offset.
    ///
    /// Returns the number of bytes written.
    ///
    /// The offset is relative to the start of the file and thus independent
    /// from the current cursor.
    ///
    /// The current file cursor is not affected by this function.
    ///
    /// When writing beyond the end of the file, the file is appropriately
    /// extended and the intermediate bytes are initialized with the value 0.
    ///
    /// Note that similar to `File::write`, it is not an error to return a
    /// short write.
    fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize>;
}