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Diffstat (limited to 'man7/sigevent.7')
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diff --git a/man7/sigevent.7 b/man7/sigevent.7 new file mode 100644 index 0000000..1ae860f --- /dev/null +++ b/man7/sigevent.7 @@ -0,0 +1,120 @@ +.\" Copyright (C) 2006, 2010 Michael Kerrisk <mtk.manpages@gmail.com> +.\" Copyright (C) 2009 Petr Baudis <pasky@suse.cz> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH sigevent 7 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +sigevent \- structure for notification from asynchronous routines +.SH SYNOPSIS +.nf +#include <signal.h> +.PP +union sigval { /* Data passed with notification */ + int sival_int; /* Integer value */ + void *sival_ptr; /* Pointer value */ +}; +.PP +struct sigevent { + int sigev_notify; /* Notification method */ + int sigev_signo; /* Notification signal */ + union sigval sigev_value; + /* Data passed with notification */ + void (*sigev_notify_function)(union sigval); + /* Function used for thread + notification (SIGEV_THREAD) */ + void *sigev_notify_attributes; + /* Attributes for notification thread + (SIGEV_THREAD) */ + pid_t sigev_notify_thread_id; + /* ID of thread to signal + (SIGEV_THREAD_ID); Linux-specific */ +}; +.fi +.SH DESCRIPTION +The +.I sigevent +structure is used by various APIs +to describe the way a process is to be notified about an event +(e.g., completion of an asynchronous request, expiration of a timer, +or the arrival of a message). +.PP +The definition shown in the SYNOPSIS is approximate: +some of the fields in the +.I sigevent +structure may be defined as part of a union. +Programs should employ only those fields relevant +to the value specified in +.IR sigev_notify . +.PP +The +.I sigev_notify +field specifies how notification is to be performed. +This field can have one of the following values: +.TP +.B SIGEV_NONE +A "null" notification: don't do anything when the event occurs. +.TP +.B SIGEV_SIGNAL +Notify the process by sending the signal specified in +.IR sigev_signo . +.IP +If the signal is caught with a signal handler that was registered using the +.BR sigaction (2) +.B SA_SIGINFO +flag, then the following fields are set in the +.I siginfo_t +structure that is passed as the second argument of the handler: +.RS +.TP 10 +.I si_code +This field is set to a value that depends on the API +delivering the notification. +.TP +.I si_signo +This field is set to the signal number (i.e., the same value as in +.IR sigev_signo ). +.TP +.I si_value +This field is set to the value specified in +.IR sigev_value . +.RE +.IP +Depending on the API, other fields may also be set in the +.I siginfo_t +structure. +.IP +The same information is also available if the signal is accepted using +.BR sigwaitinfo (2). +.TP +.B SIGEV_THREAD +Notify the process by invoking +.I sigev_notify_function +"as if" it were the start function of a new thread. +(Among the implementation possibilities here are that +each timer notification could result in the creation of a new thread, +or that a single thread is created to receive all notifications.) +The function is invoked with +.I sigev_value +as its sole argument. +If +.I sigev_notify_attributes +is not NULL, it should point to a +.I pthread_attr_t +structure that defines attributes for the new thread (see +.BR pthread_attr_init (3)). +.TP +.BR SIGEV_THREAD_ID " (Linux-specific)" +.\" | SIGEV_SIGNAL vs not? +Currently used only by POSIX timers; see +.BR timer_create (2). +.SH SEE ALSO +.BR timer_create (2), +.BR aio_fsync (3), +.BR aio_read (3), +.BR aio_write (3), +.BR getaddrinfo_a (3), +.BR lio_listio (3), +.BR mq_notify (3), +.BR aio (7), +.BR pthreads (7) |