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RT_SIGQUEUEINFO(2) Linux Programmer's Manual RT_SIGQUEUEINFO(2)
NAME
rt_sigqueueinfo - queue a signal and data to a process
SYNOPSIS
long sys_rt_sigqueueinfo(int pid, int sig, siginfo_t * uinfo);
DESCRIPTION
sys_rt_sigqueueinfo() sends the signal specified in sig to the process
whose PID is given in pid. The null signal (0) can be used to check if
a process with a given PID exists.
The uinfo argument is used to specify an accompanying item of data
(either an integer or a pointer value) in the sigval part of the sig-
info_t structure to be sent with the signal.
If the receiving process has installed a handler for this signal using
the SA_SIGINFO flag to sigaction(2), then it can obtain this data via
the si_value field of the siginfo_t structure passed as the second
argument to the handler. Furthermore, the si_code field of that struc-
ture will be set to SI_QUEUE.
RETURN VALUE
On success, sys_rt_sigqueueinfo() returns 0, indicating that the signal
was successfully queued to the receiving proces. Otherwise, one of the
following errors is returned.
ERRORS
-EAGAIN
The limit of signals which may be queued has been reached.
-EINVAL
sig was invalid.
-ESRCH No process has a PID matching pid.
-EPERM The process does not have permission to send the signal to the
receiving process.
-EFAULT
memory error.
NOTES
If this function results in the sending of a signal to the process that
invoked it, and that signal was not blocked by the calling thread, and
no other threads were willing to handle this signal (either by having
it unblocked, or by waiting for it using sigwait(3)), then at least
some signal must be delivered to this thread before this function
returns.
CONFORMING TO
POSIX 1003.1-2001
SEE ALSO
kill(2), sigaction(2), signal(2), sigwait(3), signal(7), sigqueue(2)
RT_SIGQUEUEINFO(2) Linux Programmer's Manual RT_SIGQUEUEINFO(2)
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 combi-
nation 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 speci-
fied 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 3.69 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
http://www.kernel.org/doc/man-pages/.
Linux 2012-07-13 RT_SIGQUEUEINFO(2)
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