RT_SIGQUEUEINFO
Section: Linux Programmer's Manual (2)
Updated: 2017-09-15
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NAME
rt_sigqueueinfo, rt_tgsigqueueinfo - queue a signal and data
SYNOPSIS
int rt_sigqueueinfo(pid_t tgid, int sig, siginfo_t *uinfo);
int rt_tgsigqueueinfo(pid_t tgid, pid_t tid, int sig,
siginfo_t *uinfo);
Note:
There are no glibc wrappers for these system calls; see NOTES.
DESCRIPTION
The
rt_sigqueueinfo()
and
rt_tgsigqueueinfo()
system calls are the low-level interfaces used to send a signal plus data
to a process or thread.
The receiver of the signal can obtain the accompanying data
by establishing a signal handler with the
sigaction(2)
SA_SIGINFO
flag.
These system calls are not intended for direct application use;
they are provided to allow the implementation of
sigqueue(3)
and
pthread_sigqueue(3).
The
rt_sigqueueinfo()
system call sends the signal
sig
to the thread group with the ID
tgid.
(The term "thread group" is synonymous with "process", and
tid
corresponds to the traditional UNIX process ID.)
The signal will be delivered to an arbitrary member of the thread group
(i.e., one of the threads that is not currently blocking the signal).
The
uinfo
argument specifies the data to accompany the signal.
This argument is a pointer to a structure of type
siginfo_t,
described in
sigaction(2)
(and defined by including
<sigaction.h>).
The caller should set the following fields in this structure:
- si_code
-
This must be one of the
SI_*
codes in the Linux kernel source file
include/asm-generic/siginfo.h,
with the restriction that the code must be negative
(i.e., cannot be
SI_USER,
which is used by the kernel to indicate a signal sent by
kill(2))
and cannot (since Linux 2.6.39) be
SI_TKILL
(which is used by the kernel to indicate a signal sent using
tgkill(2)).
- si_pid
-
This should be set to a process ID,
typically the process ID of the sender.
- si_uid
-
This should be set to a user ID,
typically the real user ID of the sender.
- si_value
-
This field contains the user data to accompany the signal.
For more information, see the description of the last
(union sigval)
argument of
sigqueue(3).
Internally, the kernel sets the
si_signo
field to the value specified in
sig,
so that the receiver of the signal can also obtain
the signal number via that field.
The
rt_tgsigqueueinfo()
system call is like
rt_sigqueueinfo(),
but sends the signal and data to the single thread
specified by the combination of
tgid,
a thread group ID,
and
tid,
a thread in that thread group.
RETURN VALUE
On success, these system calls return 0.
On error, they return -1 and
errno
is set to indicate the error.
ERRORS
- EAGAIN
-
The limit of signals which may be queued has been reached.
(See
signal(7)
for further information.)
- EINVAL
-
sig,
tgid,
or
tid
was invalid.
- EPERM
-
The caller does not have permission to send the signal to the target.
For the required permissions, see
kill(2).
Or:
uinfo->si_code
is invalid.
- ESRCH
-
rt_sigqueueinfo():
No thread group matching
tgid
was found.
rt_tgsigqueinfo():
No thread matching
tgid
and
tid
was found.
VERSIONS
The
rt_sigqueueinfo()
system call was added to Linux in version 2.2.
The
rt_tgsigqueueinfo()
system call was added to Linux in version 2.6.31.
CONFORMING TO
These system calls are Linux-specific.
NOTES
Since these system calls are not intended for application use,
there are no glibc wrapper functions; use
syscall(2)
in the unlikely case that you want to call them directly.
As with
kill(2),
the null signal (0) can be used to check if the specified process
or thread exists.
SEE ALSO
kill(2),
sigaction(2),
sigprocmask(2),
tgkill(2),
pthread_sigqueue(3),
sigqueue(3),
signal(7)
COLOPHON
This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- VERSIONS
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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