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RT_SIGQUEUEINFO(2)	   Linux Programmer's Manual	    RT_SIGQUEUEINFO(2)

       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);

       Note: There are no glibc wrappers for these system calls; see NOTES.

       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 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.

	      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

       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_sigqueueinfo(): No thread group matching tgid was found.
	      rt_tgsigqueinfo(): 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 speci-
       fied process or thread exists.

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

       This  page  is  part of release 4.10 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

Linux				  2012-07-13		    RT_SIGQUEUEINFO(2)