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]](../stylesheet/note.png) |
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 fileinclude/asm-generic/siginfo.h, with the restriction that the code must be negative (i.e., cannot beSI_USER, which is used by the kernel to indicate a signal sent by kill(2)) and cannot (since Linux 2.6.39) beSI_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, ortidwas 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_codeis invalid. - ESRCH
-
rt_sigqueueinfo(): No thread group matchingtgidwas 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.
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), sigaction(2), sigprocmask(2), tgkill(2), pthread_sigqueue(3), sigqueue(3), signal(7)
COLOPHON
This page is part of release 4.07 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/.
|
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