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., can‐
              not 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 indi‐
              cate 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 fur‐
              ther 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_tgsigqueue‐
       info() 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),  sig‐
       nal(7)

COLOPHON
       This  page  is  part of release 3.74 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)