huschi.net

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., 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 combi-
       nation 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 speci-
       fied 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 4.15 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/.
Linux                             2017-09-15                RT_SIGQUEUEINFO(2)