rt_sigqueueinfo

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 *info);

       int rt_tgsigqueueinfo(pid_t tgid, pid_t tid, int sig,
                             siginfo_t *info);

       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 info 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 should be one of the SI_* codes in the Linux kernel source
              file include/asm-generic/siginfo.h.  If the signal is being sent
              to any process other than the caller itself, the following
              restrictions apply:

              *  The code can't be a value greater than or equal to zero.  In
                 particular, it can't be SI_USER, which is used by the kernel
                 to indicate a signal sent by kill(2), and nor can it be
                 SI_KERNEL, which is used to indicate a signal generated by
                 the kernel.

              *  The code can't (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
       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).

       EPERM  tgid specifies a process other than the caller and info->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
       specified process or thread exists.

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

COLOPHON
       This page is part of release 5.06 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                             2019-10-10                RT_SIGQUEUEINFO(2)