1# zx_eventpair_create 2 3## NAME 4 5eventpair_create - create an event pair 6 7## SYNOPSIS 8 9``` 10#include <zircon/syscalls.h> 11 12zx_status_t zx_eventpair_create(uint32_t options, zx_handle_t* out0, zx_handle_t* out1); 13``` 14 15 16## DESCRIPTION 17 18**eventpair_create**() creates an event pair, which is a pair of objects that 19are mutually signalable. 20 21The signals *ZX_EVENTPAIR_SIGNALED* and *ZX_USER_SIGNAL_n* (where *n* is 0 through 7) 22may be set or cleared using **object_signal**() (modifying the signals on the 23object itself), or **object_signal_peer**() (modifying the signals on its 24counterpart). 25 26When all the handles to one of the objects have been closed, the 27*ZX_EVENTPAIR_PEER_CLOSED* signal will be asserted on the opposing object. 28 29The newly-created handles will have the *ZX_RIGHT_TRANSFER*, 30*ZX_RIGHT_DUPLICATE*, *ZX_RIGHT_READ*, *ZX_RIGHT_WRITE*, *ZX_RIGHT_SIGNAL*, 31and *ZX_RIGHT_SIGNAL_PEER* rights. 32 33Currently, no options are supported, so *options* must be set to 0. 34 35 36## RIGHTS 37 38TODO(ZX-2399) 39 40## RETURN VALUE 41 42**eventpair_create**() returns **ZX_OK** on success. On failure, a (negative) 43error code is returned. 44 45 46## ERRORS 47 48**ZX_ERR_INVALID_ARGS** *out0* or *out1* is an invalid pointer or NULL. 49 50**ZX_ERR_NOT_SUPPORTED** *options* has an unsupported flag set (i.e., is not 0). 51 52**ZX_ERR_NO_MEMORY** Failure due to lack of memory. 53There is no good way for userspace to handle this (unlikely) error. 54In a future build this error will no longer occur. 55 56 57## SEE ALSO 58 59[event_create](event_create.md), 60[handle_close](handle_close.md), 61[handle_duplicate](handle_duplicate.md), 62[object_wait_one](object_wait_one.md), 63[object_wait_many](object_wait_many.md), 64[handle_replace](handle_replace.md), 65[object_signal](object_signal.md), 66[object_signal_peer](object_signal.md). 67