sigpending, rt_sigpending - examine pending signals
int sigpending(sigset_t *set);
sigpending() returns the set of signals that are pending for delivery to
the calling thread (i.e., the signals which have been raised while blocked).
The mask of pending signals is returned in set.
sigpending() returns 0 on success and -1 on error. In the event of an
error, errno is set to indicate the cause.
See sigsetops(3) for details on manipulating signal sets.
- set points to memory which is not a valid part of the process
If a signal is both blocked and has a disposition of
"ignored", it is not added to the mask of pending signals
The set of signals that is pending for a thread is the union of
the set of signals that is pending for that thread and the set of signals
that is pending for the process as a whole; see signal(7).
A child created via fork(2) initially has an empty pending
signal set; the pending signal set is preserved across an
The original Linux system call was named sigpending(). However, with the
addition of real-time signals in Linux 2.2, the fixed-size, 32-bit
sigset_t argument supported by that system call was no longer fit for
purpose. Consequently, a new system call, rt_sigpending(), was added to
support an enlarged sigset_t type. The new system call takes a second
argument, size_t sigsetsize, which specifies the size in bytes of the
signal set in set. The glibc sigpending() wrapper function hides
these details from us, transparently calling rt_sigpending() when the
kernel provides it.
In versions of glibc up to and including 2.2.1, there is a bug in the wrapper
function for sigpending() which means that information about pending
real-time signals is not correctly returned.
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