Function pwrite

pkg/sentry/syscalls/linux/sys_read_write.go:482–522

(t *kernel.Task, file *vfs.FileDescription, src usermem.IOSequence, offset int64, opts vfs.WriteOptions)

}

func pwrite(t *kernel.Task, file *vfs.FileDescription, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
	n, err := file.PWrite(t, src, offset, opts)
	if !linuxerr.Equals(linuxerr.ErrWouldBlock, err) {
		return n, err
	}

	allowBlock, deadline, hasDeadline := blockPolicy(t, file)
	if !allowBlock {
		return n, err
	}

	// Register for notifications.
	w, ch := waiter.NewChannelEntry(eventMaskWrite)
	if err := file.EventRegister(&w); err != nil {
		return n, err
	}

	total := n
	for {
		// Shorten src to reflect bytes previously written.
		src = src.DropFirst(int(n))

		// Issue the request and break out if it completes with anything other than
		// "would block".
		n, err = file.PWrite(t, src, offset+total, opts)
		total += n
		if !linuxerr.Equals(linuxerr.ErrWouldBlock, err) {
			break
		}

		// Wait for a notification that we should retry.
		if err = t.BlockWithDeadline(ch, hasDeadline, deadline); err != nil {
			if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
				err = linuxerr.ErrWouldBlock
			}
			break
		}
	}
	file.EventUnregister(&w)
	return total, err
}

func blockPolicy(t *kernel.Task, file *vfs.FileDescription) (allowBlock bool, deadline ktime.Time, hasDeadline bool) {
	if file.StatusFlags()&linux.O_NONBLOCK != 0 {