-.so man2/sigqueue.2
+.\" Copyright (c) 2002, 2011 Michael Kerrisk <mtk.manpages@gmail.com>
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+.TH RT_SIGQUEUEINFO 2 2011-09-18 "Linux" "Linux Programmer's Manual"
+.SH NAME
+rt_sigqueueinfo, rt_tgsigqueueinfo \- queue a signal and data
+.SH SYNOPSIS
+.nf
+.BI "int rt_sigqueueinfo(pid_t " tgid ", int " sig ", siginfo_t *" uinfo );
+.sp
+.BI "int rt_tgsigqueueinfo(pid_t " tgid ", pid_t " tid ", int " sig ,
+.BI " siginfo_t *" uinfo );
+.fi
+.SH DESCRIPTION
+The
+.BR rt_sigqueueinfo ()
+and
+.BR 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
+.BR sigaction (2)
+.B SA_SIGINFO
+flag.
+
+These system calls are not intended for direct application use;
+they are provided to allow the implementation of
+.BR sigqueue (3)
+and
+.BR pthread_sigqueue (3).
+
+The
+.BR rt_sigqueueinfo ()
+system call sends the signal
+.I sig
+to the thread group with the ID
+.IR tgid .
+(The term "thread group" is synonomous with "process", and
+.I 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
+.I uinfo
+argument specifies the data to accompany the signal.
+This argument is a pointer to a structure of type
+.IR siginfo_t ,
+described in
+.BR sigaction (2)
+(and defined by including
+.IR <sigaction.h> ).
+The caller should set the following fields in this structure:
+.TP
+.I si_code
+This must be one of the
+.B SI_*
+codes in the kernel source file
+.IR include/asm-generic/siginfo.h ,
+with the restriction that the code must be negative
+(i.e., cannot be
+.BR SI_USER ,
+which is used by the kernel to indicate a signal sent by
+.BR kill (2))
+and cannot (since Linux 2.6.39) be
+.BR SI_TKILL
+(which is used by the kernel to indicate a signal sent using
+.\" tkill(2) or
+.BR tgkill (2)).
+.TP
+.I si_pid
+This should be set to a process ID,
+typically the process ID of the sender.
+.TP
+.I si_uid
+This should be set to a user ID,
+typically the real user ID of the sender.
+.TP
+.I si_value
+This field contains the user data to accompany the signal.
+For more information, see the description of the last
+.RI ( "union sigval" )
+argument of
+.BR sigqueue (3).
+.PP
+Internally, the kernel sets the
+.I si_signo
+field to the value specified in
+.IR sig ,
+so that the receiver of the signal can also obtain
+the signal number via that field.
+
+The
+.BR rt_tgsigueueinfo ()
+system call is like
+.BR rt_sigueueinfo (),
+but sends the signal and data to the single thread
+specified by the combination of
+.IR tgid ,
+a thread group ID,
+and
+.IR tid ,
+a thread in that thread group.
+.SH "RETURN VALUE"
+On success, these system calls return 0.
+On error, they return \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The limit of signals which may be queued has been reached.
+(See
+.BR signal (7)
+for further information.)
+.TP
+.B EINVAL
+.IR sig ,
+.IR tgid ,
+or
+.IR tid
+was invalid.
+.TP
+.B EPERM
+The caller does not have permission to send the signal to the target.
+For the required permissions, see
+.BR kill (2).
+Or:
+.I uinfo->si_code
+is invalid.
+.TP
+.B ESRCH
+.BR rt_sigqueinfo ():
+No thread group matching
+.I tgid
+was found.
+.br
+.BR rt_rtsigqueinfo ():
+No thread matching
+.I tgid
+and
+.I tid
+was found.
+.SH VERSIONS
+The
+.BR rt_sigqueueinfo ()
+system call was added to Linux in version 2.2.
+The
+.BR rt_tgsigqueueinfo ()
+system call was added to Linux in version 2.6.31.
+.SH "CONFORMING TO"
+These system calls are Linux-specific.
+.SH NOTES
+Since these system calls are not intended for application use,
+there are no glibc wrapper functions; use
+.BR syscall (2)
+in the unlikely case that you want to call them directly.
+
+As with
+.BR kill (2),
+the null signal (0) can be used to check if the specified process
+or thread exists.
+.SH "SEE ALSO"
+.BR kill (2),
+.BR sigaction (2),
+.BR sigprocmask (2),
+.BR tgkill (2),
+.BR pthread_sigqueue (3),
+.BR sigqueue (3),
+.BR signal (7)
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