# rt_sigqueueinfo

## NAME



           rt_sigqueueinfo, rt_tgsigqueueinfo - queue a signal and data
    


## LIBRARY



           Standard C library (_libc_ , _-lc_)
    


## SYNOPSIS



           **#include <linux/signal.h>     **/* Definition of **SI_*** constants */
           **#include <sys/syscall.h>      **/* Definition of **SYS_*** constants */
           **#include <unistd.h>**
    
           **int syscall(SYS_rt_sigqueueinfo, pid_t** _tgid_**,**
                       **int** _sig_**, siginfo_t ***_info_**);**
           **int syscall(SYS_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 _tgid_ 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.
    


## STANDARDS



           Linux.
    


## 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.
    


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