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       rt_sigqueueinfo, rt_tgsigqueueinfo - queue a signal and data


       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);


       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

       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:

              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.

              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.


       On success, these system calls return 0.  On error, they return -1  and
       errno is set to indicate the error.


       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.


       The rt_sigqueueinfo() system call was added to Linux  in  version  2.2.
       The  rt_tgsigqueueinfo()  system  call  was  added  to Linux in version


       These system calls are Linux-specific.


       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.


       kill(2),  sigaction(2), sigprocmask(2), tgkill(2), pthread_sigqueue(3),
       sigqueue(3), signal(7)


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