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] 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 4.07 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/.


  Copyright (c) 2002, 2011 Michael Kerrisk <mtk.manpagesgmail.com>

%%%LICENSE_START(VERBATIM)
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
%%%LICENSE_END