Section: Linux Programmer's Manual (2)
sigpending, rt_sigpending - examine pending signals
int sigpending(sigset_t *set);
Feature Test Macro Requirements for glibc (see
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
returns 0 on success and -1 on error.
In the event of an error,
is set to indicate the cause.
points to memory which is not a valid part of the process address space.
for details on manipulating signal sets.
If a signal is both blocked and has a disposition of "ignored", it is
added to the mask of pending signals when generated.
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
A child created via
initially has an empty pending signal set;
the pending signal set is preserved across an
C library/kernel differences
The original Linux system call was named
However, with the addition of real-time signals in Linux 2.2,
the fixed-size, 32-bit
argument supported by that system call was no longer fit for purpose.
Consequently, a new system call,
was added to support an enlarged
The new system call takes a second argument,
which specifies the size in bytes of the signal set in
wrapper function hides these details from us, transparently calling
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
which means that information about pending real-time signals
is not correctly returned.
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