Zig 0.17.0-dev (Split by item)

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read

Queues (but does not submit) an SQE to perform a read(2) or preadv(2) depending on the buffer type.

Reading into a ReadBuffer.buffer uses read(2)
Reading into a ReadBuffer.iovecs uses preadv(2) If you want to do a preadv2(2) then set rw_flags on the returned SQE. See https://man7.org/linux/man-pages/man2/preadv2.2.html

Returns a pointer to the SQE.

IoUring.read

pub fn read(
    self: *IoUring,
    user_data: u64,
    fd: linux.fd_t,
    buffer: ReadBuffer,
    offset: u64,
) !*linux.io_uring_sqe

File

lib/std/os/linux/IoUring.zig:393

Code

pub fn read(
    self: *IoUring,
    user_data: u64,
    fd: linux.fd_t,
    buffer: ReadBuffer,
    offset: u64,
) !*linux.io_uring_sqe {
    const sqe = try self.get_sqe();
    switch (buffer) {
        .buffer => |slice| sqe.prep_read(fd, slice, offset),
        .iovecs => |vecs| sqe.prep_readv(fd, vecs, offset),
        .buffer_selection => |selection| {
            sqe.prep_rw(.READ, fd, 0, selection.len, offset);
            sqe.flags |= linux.IOSQE_BUFFER_SELECT;
            sqe.buf_index = selection.group_id;
        },
    }
    sqe.user_data = user_data;
    return sqe;
}