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25 .TH RT_SIGQUEUEINFO 2 2021-03-22 "Linux" "Linux Programmer's Manual"
27 rt_sigqueueinfo, rt_tgsigqueueinfo \- queue a signal and data
30 .BR "#include <linux/signal.h>" " /* Definition of " SI_* " constants */"
31 .BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
32 .B #include <unistd.h>
34 .BI "int syscall(SYS_rt_sigqueueinfo, pid_t " tgid ,
35 .BI " int " sig ", siginfo_t *" info );
36 .BI "int syscall(SYS_rt_tgsigqueueinfo, pid_t " tgid ", pid_t " tid ,
37 .BI " int " sig ", siginfo_t *" info );
41 There are no glibc wrappers for these system calls; see NOTES.
44 .BR rt_sigqueueinfo ()
46 .BR rt_tgsigqueueinfo ()
47 system calls are the low-level interfaces used to send a signal plus data
48 to a process or thread.
49 The receiver of the signal can obtain the accompanying data
50 by establishing a signal handler with the
55 These system calls are not intended for direct application use;
56 they are provided to allow the implementation of
59 .BR pthread_sigqueue (3).
62 .BR rt_sigqueueinfo ()
63 system call sends the signal
65 to the thread group with the ID
67 (The term "thread group" is synonymous with "process", and
69 corresponds to the traditional UNIX process ID.)
70 The signal will be delivered to an arbitrary member of the thread group
71 (i.e., one of the threads that is not currently blocking the signal).
75 argument specifies the data to accompany the signal.
76 This argument is a pointer to a structure of type
80 (and defined by including
82 The caller should set the following fields in this structure:
85 This should be one of the
87 codes in the Linux kernel source file
88 .IR include/asm\-generic/siginfo.h .
89 If the signal is being sent to any process other than the caller itself,
90 the following restrictions apply:
93 The code can't be a value greater than or equal to zero.
94 In particular, it can't be
96 which is used by the kernel to indicate a signal sent by
100 which is used to indicate a signal generated by the kernel.
102 The code can't (since Linux 2.6.39) be
104 which is used by the kernel to indicate a signal sent using
110 This should be set to a process ID,
111 typically the process ID of the sender.
114 This should be set to a user ID,
115 typically the real user ID of the sender.
118 This field contains the user data to accompany the signal.
119 For more information, see the description of the last
120 .RI ( "union sigval" )
124 Internally, the kernel sets the
126 field to the value specified in
128 so that the receiver of the signal can also obtain
129 the signal number via that field.
132 .BR rt_tgsigqueueinfo ()
134 .BR rt_sigqueueinfo (),
135 but sends the signal and data to the single thread
136 specified by the combination of
141 a thread in that thread group.
143 On success, these system calls return 0.
144 On error, they return \-1 and
146 is set to indicate the error.
150 The limit of signals which may be queued has been reached.
153 for further information.)
163 The caller does not have permission to send the signal to the target.
164 For the required permissions, see
169 specifies a process other than the caller and
174 .BR rt_sigqueueinfo ():
175 No thread group matching
179 .BR rt_tgsigqueinfo ():
187 .BR rt_sigqueueinfo ()
188 system call was added to Linux in version 2.2.
190 .BR rt_tgsigqueueinfo ()
191 system call was added to Linux in version 2.6.31.
193 These system calls are Linux-specific.
195 Since these system calls are not intended for application use,
196 there are no glibc wrapper functions; use
198 in the unlikely case that you want to call them directly.
202 the null signal (0) can be used to check if the specified process
206 .BR pidfd_send_signal (2),
210 .BR pthread_sigqueue (3),