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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);

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  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_tgsigueueinfo() system call is like rt_sigueueinfo(), 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_sigqueinfo(): No thread group matching tgid was found.
              rt_rtsigqueinfo(): 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 3.35 of the Linux man-pages project.  A description of the
       project, and information about reporting bugs, can be found at  http://man7.org/linux/man-
       pages/.