man2/rt_sigqueueinfo.2

   1 .\" Copyright (c) 2002, 2011 Michael Kerrisk <mtk.manpages@gmail.com>
   2 .\"
   3 .\" Permission is granted to make and distribute verbatim copies of this
   4 .\" manual provided the copyright notice and this permission notice are
   5 .\" preserved on all copies.
   6 .\"
   7 .\" Permission is granted to copy and distribute modified versions of this
   8 .\" manual under the conditions for verbatim copying, provided that the
   9 .\" entire resulting derived work is distributed under the terms of a
  10 .\" permission notice identical to this one.
  11 .\"
  12 .\" Since the Linux kernel and libraries are constantly changing, this
  13 .\" manual page may be incorrect or out-of-date.  The author(s) assume no
  14 .\" responsibility for errors or omissions, or for damages resulting from
  15 .\" the use of the information contained herein.  The author(s) may not
  16 .\" have taken the same level of care in the production of this manual,
  17 .\" which is licensed free of charge, as they might when working
  18 .\" professionally.
  19 .\"
  20 .\" Formatted or processed versions of this manual, if unaccompanied by
  21 .\" the source, must acknowledge the copyright and authors of this work.
  22 .\"
  23 .TH RT_SIGQUEUEINFO 2 2012-07-13 "Linux" "Linux Programmer's Manual"
  24 .SH NAME
  25 rt_sigqueueinfo, rt_tgsigqueueinfo \- queue a signal and data
  26 .SH SYNOPSIS
  27 .nf
  28 .BI "int rt_sigqueueinfo(pid_t " tgid ", int " sig ", siginfo_t *" uinfo );
  29 .sp
  30 .BI "int rt_tgsigqueueinfo(pid_t " tgid ", pid_t " tid ", int " sig ,
  31 .BI "                      siginfo_t *" uinfo );
  32 .fi
  33
  34 .IR Note :
  35 There are no glibc wrappers for these system calls; see NOTES.
  36 .SH DESCRIPTION
  37 The
  38 .BR rt_sigqueueinfo ()
  39 and
  40 .BR rt_tgsigqueueinfo ()
  41 system calls are the low-level interfaces used to send a signal plus data
  42 to a process or thread.
  43 The receiver of the signal can obtain the accompanying data
  44 by establishing a signal handler with the
  45 .BR sigaction (2)
  46 .B SA_SIGINFO
  47 flag.
  48
  49 These system calls are not intended for direct application use;
  50 they are provided to allow the implementation of
  51 .BR sigqueue (3)
  52 and
  53 .BR pthread_sigqueue (3).
  54
  55 The
  56 .BR rt_sigqueueinfo ()
  57 system call sends the signal
  58 .I sig
  59 to the thread group with the ID
  60 .IR tgid .
  61 (The term "thread group" is synonymous with "process", and
  62 .I tid
  63 corresponds to the traditional UNIX process ID.)
  64 The signal will be delivered to an arbitrary member of the thread group
  65 (i.e., one of the threads that is not currently blocking the signal).
  66
  67 The
  68 .I uinfo
  69 argument specifies the data to accompany the signal.
  70 This argument is a pointer to a structure of type
  71 .IR siginfo_t ,
  72 described in
  73 .BR sigaction (2)
  74 (and defined by including
  75 .IR <sigaction.h> ).
  76 The caller should set the following fields in this structure:
  77 .TP
  78 .I si_code
  79 This must be one of the
  80 .B SI_*
  81 codes in the kernel source file
  82 .IR include/asm-generic/siginfo.h ,
  83 with the restriction that the code must be negative
  84 (i.e., cannot be
  85 .BR SI_USER ,
  86 which is used by the kernel to indicate a signal sent by
  87 .BR kill (2))
  88 and cannot (since Linux 2.6.39) be
  89 .BR SI_TKILL
  90 (which is used by the kernel to indicate a signal sent using
  91 .\" tkill(2) or
  92 .BR tgkill (2)).
  93 .TP
  94 .I si_pid
  95 This should be set to a process ID,
  96 typically the process ID of the sender.
  97 .TP
  98 .I si_uid
  99 This should be set to a user ID,
 100 typically the real user ID of the sender.
 101 .TP
 102 .I si_value
 103 This field contains the user data to accompany the signal.
 104 For more information, see the description of the last
 105 .RI ( "union sigval" )
 106 argument of
 107 .BR sigqueue (3).
 108 .PP
 109 Internally, the kernel sets the
 110 .I si_signo
 111 field to the value specified in
 112 .IR sig ,
 113 so that the receiver of the signal can also obtain
 114 the signal number via that field.
 115
 116 The
 117 .BR rt_tgsigqueueinfo ()
 118 system call is like
 119 .BR rt_sigqueueinfo (),
 120 but sends the signal and data to the single thread
 121 specified by the combination of
 122 .IR tgid ,
 123 a thread group ID,
 124 and
 125 .IR tid ,
 126 a thread in that thread group.
 127 .SH "RETURN VALUE"
 128 On success, these system calls return 0.
 129 On error, they return \-1 and
 130 .I errno
 131 is set to indicate the error.
 132 .SH ERRORS
 133 .TP
 134 .B EAGAIN
 135 The limit of signals which may be queued has been reached.
 136 (See
 137 .BR signal (7)
 138 for further information.)
 139 .TP
 140 .B EINVAL
 141 .IR sig ,
 142 .IR tgid ,
 143 or
 144 .IR tid
 145 was invalid.
 146 .TP
 147 .B EPERM
 148 The caller does not have permission to send the signal to the target.
 149 For the required permissions, see
 150 .BR kill (2).
 151 Or:
 152 .I uinfo->si_code
 153 is invalid.
 154 .TP
 155 .B ESRCH
 156 .BR rt_sigqueueinfo ():
 157 No thread group matching
 158 .I tgid
 159 was found.
 160 .br
 161 .BR rt_tgsigqueinfo ():
 162 No thread matching
 163 .I tgid
 164 and
 165 .I tid
 166 was found.
 167 .SH VERSIONS
 168 The
 169 .BR rt_sigqueueinfo ()
 170 system call was added to Linux in version 2.2.
 171 The
 172 .BR rt_tgsigqueueinfo ()
 173 system call was added to Linux in version 2.6.31.
 174 .SH "CONFORMING TO"
 175 These system calls are Linux-specific.
 176 .SH NOTES
 177 Since these system calls are not intended for application use,
 178 there are no glibc wrapper functions; use
 179 .BR syscall (2)
 180 in the unlikely case that you want to call them directly.
 181
 182 As with
 183 .BR kill (2),
 184 the null signal (0) can be used to check if the specified process
 185 or thread exists.
 186 .SH "SEE ALSO"
 187 .BR kill (2),
 188 .BR sigaction (2),
 189 .BR sigprocmask (2),
 190 .BR tgkill (2),
 191 .BR pthread_sigqueue (3),
 192 .BR sigqueue (3),
 193 .BR signal (7)