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,
: There are no glibc wrappers for these system calls; see NOTES.
() 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
These system calls are not intended for direct application use; they are
provided to allow the implementation of sigqueue(3)
() system call sends the signal sig
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).
argument specifies the data to accompany the signal. This
argument is a pointer to a structure of type siginfo_t
, described in
(and defined by including <sigaction.h>
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)).
- This should be set to a process ID, typically the process ID of the
- This should be set to a user ID, typically the real user ID of the
- 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
, so that the receiver of the signal can also obtain the signal
number via that field.
() system call is like rt_sigqueueinfo
sends the signal and data to the single thread specified by the combination of
, a thread group ID, and tid
, a thread in that thread group.
On success, these system calls return 0. On error, they return -1 and
is set to indicate the error.
- The limit of signals which may be queued has been reached. (See
signal(7) for further information.)
- sig, tgid, or tid was invalid.
- The caller does not have permission to send the signal to the target. For
the required permissions, see kill(2). Or: uinfo->si_code
- rt_sigqueueinfo(): No thread group matching tgid was found.
rt_tgsigqueinfo(): No thread matching tgid and tid was
() system call was added to Linux in version 2.2. The
() system call was added to Linux in version 2.6.31.
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
specified process or thread exists.
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