io_setup - create an asynchronous I/O context

Note: this page describes the raw Linux system call interface. The wrapper function provided by libaio uses a different type for the ctx_idp argument. See VERSIONS. The io_setup() system call creates an asynchronous I/O context suitable for concurrently processing nr_events operations. The ctx_idp argument must not point to an AIO context that already exists, and must be initialized to 0 prior to the call. On successful creation of the AIO context, *ctx_idp is filled in with the resulting handle.

EAGAIN The specified nr_events exceeds the limit of available events, as defined in /proc/sys/fs/aio-max-nr (see proc(5)). EFAULT An invalid pointer is passed for ctx_idp. EINVALctx_idp is not initialized, or the specified nr_events exceeds internal limits. nr_events should be greater than 0. ENOMEM Insufficient kernel resources are available. ENOSYSio_setup() is not implemented on this architecture.

Linux 2.5.

Standard C library (libc, -lc) Alternatively, Asynchronous I/O library (libaio, -laio); see VERSIONS.

io_setup - create an asynchronous I/O context

On success, io_setup() returns 0. For the failure return, see VERSIONS.

io_cancel(2), io_destroy(2), io_getevents(2), io_submit(2), aio(7) Linux man-pages 6.9.1 2024-05-02 io_setup(2)

Linux.

#include<linux/aio_abi.h> /* Defines needed types */ longio_setup(unsignedintnr_events,aio_context_t*ctx_idp);Note: There is no glibc wrapper for this system call; see VERSIONS.

glibc does not provide a wrapper for this system call. You could invoke it using syscall(2). But instead, you probably want to use the io_setup() wrapper function provided by libaio. Note that the libaio wrapper function uses a different type (io_context_t*) for the ctx_idp argument. Note also that the libaio wrapper does not follow the usual C library conventions for indicating errors: on error it returns a negated error number (the negative of one of the values listed in ERRORS). If the system call is invoked via syscall(2), then the return value follows the usual conventions for indicating an error: -1, with errno set to a (positive) value that indicates the error.