read(fd, buf, count) correspond (in order) to the fields aio_fildes, aio_buf, and aio_nbytes of the structure pointed to by aiocbp. (See aio(7) for a description of the aiocb structure.) The data is read starting at the absolute position aiocbp->aio_offset, regardless of the file offset. After the call, the value of the file offset is unspecified. The "asynchronous" means that this call returns as soon as the request has been enqueued; the read may or may not have completed when the call returns. One tests for completion using aio_error(3). The return status of a completed I/O operation can be obtained by aio_return(3). Asynchronous notification of I/O completion can be obtained by setting aiocbp->aio_sigevent appropriately; see sigevent(7) for details. If _POSIX_PRIORITIZED_IO is defined, and this file supports it, then the asynchronous operation is submitted at a priority equal to that of the calling process minus aiocbp->aio_reqprio. The field aiocbp->aio_lio_opcode is ignored. No data is read from a regular file beyond its maximum offset.
- Out of resources.
- aio_fildes is not a valid file descriptor open for reading.
- One or more of aio_offset, aio_reqprio, or aio_nbytes are invalid.
- aio_read() is not implemented.
- The file is a regular file, we start reading before end-of-file and want at least one byte, but the starting position is past the maximum offset for this file.
|aio_read ()||Thread safety||MT-Safe|