Copyright (c) 2005 David Xu <davidxu@FreeBSD.org> All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice(s), this list of conditions and the following disclaimer as the first lines of this file unmodified other than the possible addition of one or more copyright notices. 2. Redistributions in binary form...
NAMEsigtimedwait , sigwaitinfo - wait for queued signals (REALTIME)
SYNOPSISIn signal.h Ft int Fo sigtimedwait Fa const sigset_t *restrict set siginfo_t *restrict info Fa const struct timespec *restrict timeout Fc Ft int Fn sigwaitinfo const sigset_t * restrict set siginfo_t * restrict info
DESCRIPTIONThe Fn sigtimedwait system call is equivalent to Fn sigwaitinfo except that if none of the signals specified by Fa set are pending, Fn sigtimedwait waits for the time interval specified in the Vt timespec structure referenced by Fa timeout . If the Vt timespec structure pointed to by Fa timeout is zero-valued and if none of the signals specified by Fa set are pending, then Fn sigtimedwait returns immediately with an error. If Fa timeout is the NULL pointer, the behavior is unspecified. CLOCK_MONOTONIC clock is used to measure the time interval specified by the Fa timeout argument.
The Fn sigwaitinfo system call selects the pending signal from the set specified by Fa set . Should any of multiple pending signals in the range SIGRTMIN to SIGRTMAX be selected, it shall be the lowest numbered one. The selection order between realtime and non-realtime signals, or between multiple pending non-realtime signals, is unspecified. If no signal in Fa set is pending at the time of the call, the calling thread is suspended until one or more signals in Fa set become pending or until it is interrupted by an unblocked, caught signal.
The Fn sigwaitinfo system call is equivalent to the Fn sigwait system call if the Fa info argument is NULL If the Fa info argument is non- NULL the Fn sigwaitinfo function is equivalent to Fn sigwait , except that the selected signal number shall be stored in the si_signo member, and the cause of the signal shall be stored in the si_code member. Besides this, the Fn sigwaitinfo and Fn sigtimedwait system calls may return Er EINTR if interrupted by signal, which is not allowed for the Fn sigwait function.
If any value is queued to the selected signal, the first such queued value is dequeued and, if the info argument is non- NULL the value is stored in the si_value member of Fa info . The system resource used to queue the signal is released and returned to the system for other use. If no value is queued, the content of the si_value member is zero-valued. If no further signals are queued for the selected signal, the pending indication for that signal is reset.
RETURN VALUESUpon successful completion (that is, one of the signals specified by Fa set is pending or is generated) Fn sigwaitinfo and Fn sigtimedwait return the selected signal number. Otherwise, the functions return a value of -1 and set the global variable errno to indicate the error.
ERRORSThe Fn sigtimedwait system call will fail if:
- Bq Er EAGAIN
- No signal specified by set was generated within the specified timeout period.
The Fn sigtimedwait and Fn sigwaitinfo system calls fail if:
- Bq Er EINTR
- The wait was interrupted by an unblocked, caught signal.
The Fn sigtimedwait system call may also fail if:
- Bq Er EINVAL
- The Fa timeout argument specified a tv_nsec value less than zero or greater than or equal to 1000 million. Kernel only checks for this error if no signal is pending in set and it is necessary to wait.