magenta/docs/syscalls/fifo_read.md

mx_fifo_read

NAME

fifo_read - read data from a fifo

SYNOPSIS

#include <magenta/syscalls.h>

mx_status_t mx_fifo_read(mx_handle_t handle,
                         void* buffer, size_t size,
                         uint32_t* num_entries_read) {

DESCRIPTION

fifo_read() attempts to read some number of elements out of the fifo specified by handle. size will be rounded down to a multiple of the fifo's element-size.

It is not legal to read zero elements.

Fewer elements may be read than requested if there are insufficient elements in the fifo to fulfill the entire request.

RETURN VALUE

fifo_read() returns MX_OK on success, and returns the number of elements read (at least one) via num_entries_read.

ERRORS

MX_ERR_BAD_HANDLE handle is not a valid handle.

MX_ERR_WRONG_TYPE handle is not a fifo handle.

MX_ERR_INVALID_ARGS buffer is an invalid pointer or num_entries_read is an invalid pointer.

MX_ERR_OUT_OF_RANGE size was smaller than the size of a single element.

MX_ERR_ACCESS_DENIED handle does not have MX_RIGHT_READ.

MX_ERR_PEER_CLOSED The other side of the fifo is closed.

MX_ERR_SHOULD_WAIT The fifo is empty.

SEE ALSO

fifo_create, fifo_write.