1SIGEVENT(7) Linux Programmer's Manual SIGEVENT(7)
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6 sigevent - structure for notification from asynchronous routines
7
9 #include <signal.h>
10 union sigval { /* Data passed with notification */
12 int sival_int; /* Integer value */
13 void *sival_ptr; /* Pointer value */
14 };
15 struct sigevent {
17 int sigev_notify; /* Notification method */
18 int sigev_signo; /* Notification signal */
19 union sigval sigev_value;
20 /* Data passed with notification */
21 void (*sigev_notify_function)(union sigval);
22 /* Function used for thread
23 notification (SIGEV_THREAD) */
24 void *sigev_notify_attributes;
25 /* Attributes for notification thread
26 (SIGEV_THREAD) */
27 pid_t sigev_notify_thread_id;
28 /* ID of thread to signal
29 (SIGEV_THREAD_ID); Linux-specific */
30 };
31
33 The sigevent structure is used by various APIs to describe the way a
34 process is to be notified about an event (e.g., completion of an asyn‐
35 chronous request, expiration of a timer, or the arrival of a message).
36 The definition shown in the SYNOPSIS is approximate: some of the fields
38 in the sigevent structure may be defined as part of a union. Programs
39 should employ only those fields relevant to the value specified in
40 sigev_notify.
41 The sigev_notify field specifies how notification is to be performed.
43 This field can have one of the following values:
44 SIGEV_NONE
46 A "null" notification: don't do anything when the event occurs.
47 SIGEV_SIGNAL
49 Notify the process by sending the signal specified in
50 sigev_signo.
51 If the signal is caught with a signal handler that was regis‐
53 tered using the sigaction(2) SA_SIGINFO flag, then the following
54 fields are set in the siginfo_t structure that is passed as the
55 second argument of the handler:
56 si_code This field is set to a value that depends on the API
58 delivering the notification.
59 si_signo This field is set to the signal number (i.e., the same
61 value as in sigev_signo).
62 si_value This field is set to the value specified in
64 sigev_value.
65 Depending on the API, other fields may also be set in the sig‐
67 info_t structure.
68 The same information is also available if the signal is accepted
70 using sigwaitinfo(2).
71 SIGEV_THREAD
73 Notify the process by invoking sigev_notify_function "as if" it
74 were the start function of a new thread. (Among the implementa‐
75 tion possibilities here are that each timer notification could
76 result in the creation of a new thread, or that a single thread
77 is created to receive all notifications.) The function is in‐
78 voked with sigev_value as its sole argument. If sigev_no‐
79 tify_attributes is not NULL, it should point to a pthread_attr_t
80 structure that defines attributes for the new thread (see
81 pthread_attr_init(3)).
82 SIGEV_THREAD_ID (Linux-specific)
84 Currently used only by POSIX timers; see timer_create(2).
85
87 timer_create(2), aio_fsync(3), aio_read(3), aio_write(3), getad‐
88 drinfo_a(3), lio_listio(3), mq_notify(3), aio(7), pthreads(7)
89
91 This page is part of release 5.12 of the Linux man-pages project. A
92 description of the project, information about reporting bugs, and the
93 latest version of this page, can be found at
94 https://www.kernel.org/doc/man-pages/.
95GNU 2021-03-22 SIGEVENT(7)