1 | @c |
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2 | @c COPYRIGHT (c) 1988-1998. |
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3 | @c On-Line Applications Research Corporation (OAR). |
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4 | @c All rights reserved. |
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5 | @c |
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6 | @c $Id$ |
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7 | @c |
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8 | |
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9 | @chapter Signal Manager |
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10 | |
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11 | @section Introduction |
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12 | |
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13 | The signal manager ... |
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14 | |
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15 | The directives provided by the signal manager are: |
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16 | |
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17 | @itemize @bullet |
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18 | @item @code{sigaddset} - Add a Signal to a Signal Set |
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19 | @item @code{sigdelset} - Delete a Signal from a Signal Set |
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20 | @item @code{sigfillset} - Fill a Signal Set |
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21 | @item @code{sigismember} - Is Signal a Member of a Signal Set |
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22 | @item @code{sigemptyset} - Empty a Signal Set |
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23 | @item @code{sigaction} - Examine and Change Signal Action |
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24 | @item @code{pthread_kill} - Send a Signal to a Thread |
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25 | @item @code{sigprocmask} - Examine and Change Process Blocked Signals |
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26 | @item @code{pthread_sigmask} - Examine and Change Thread Blocked Signals |
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27 | @item @code{kill} - Send a Signal to a Process |
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28 | @item @code{sigpending} - Examine Pending Signals |
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29 | @item @code{sigsuspend} - Wait for a Signal |
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30 | @item @code{pause} - Suspend Process Execution |
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31 | @item @code{sigwait} - Synchronously Accept a Signal |
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32 | @item @code{sigwaitinfo} - Synchronously Accept a Signal |
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33 | @item @code{sigtimedwait} - Synchronously Accept a Signal with Timeout |
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34 | @item @code{sigqueue} - Queue a Signal to a Process |
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35 | @item @code{alarm} - Schedule Alarm |
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36 | @end itemize |
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37 | |
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38 | @section Background |
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39 | |
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40 | @subsection Signal Delivery |
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41 | |
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42 | Signals directed at a thread are delivered to the specified thread. |
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43 | |
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44 | Signals directed at a process are delivered to a thread which is selected |
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45 | based on the following algorithm: |
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46 | |
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47 | @enumerate |
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48 | @item If the action for this signal is currently @code{SIG_IGN}, |
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49 | then the signal is simply ignored. |
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50 | |
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51 | @item If the currently executing thread has the signal unblocked, then |
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52 | the signal is delivered to it. |
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53 | |
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54 | @item If any threads are currently blocked waiting for this signal |
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55 | (@code{sigwait()}), then the signal is delivered to the highest priority |
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56 | thread waiting for this signal. |
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57 | |
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58 | @item If any other threads are willing to accept delivery of the signal, then |
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59 | the signal is delivered to the highest priority thread of this set. In the |
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60 | event, multiple threads of the same priority are willing to accept this |
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61 | signal, then priority is given first to ready threads, then to threads |
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62 | blocked on calls which may be interrupted, and finally to threads blocked |
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63 | on non-interruptible calls. |
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64 | |
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65 | @item In the event the signal still can not be delivered, then it is left |
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66 | pending. The first thread to unblock the signal (@code{sigprocmask()} or |
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67 | @code{pthread_sigprocmask()}) or to wait for this signal |
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68 | (@code{sigwait()}) will be the recipient of the signal. |
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69 | |
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70 | @end enumerate |
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71 | |
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72 | @section Operations |
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73 | |
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74 | There is currently no text in this section. |
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75 | |
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76 | @section Directives |
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77 | |
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78 | This section details the signal manager's directives. |
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79 | A subsection is dedicated to each of this manager's directives |
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80 | and describes the calling sequence, related constants, usage, |
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81 | and status codes. |
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82 | |
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83 | @page |
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84 | @subsection sigaddset - Add a Signal to a Signal Set |
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85 | |
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86 | @subheading CALLING SEQUENCE: |
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87 | |
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88 | @example |
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89 | #include <signal.h> |
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90 | |
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91 | int sigaddset( |
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92 | sigset_t *set, |
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93 | int signo |
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94 | ); |
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95 | @end example |
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96 | |
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97 | @subheading STATUS CODES: |
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98 | |
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99 | @table @b |
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100 | @item EINVAL |
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101 | Invalid argument passed. |
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102 | |
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103 | @end table |
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104 | |
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105 | @subheading DESCRIPTION: |
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106 | |
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107 | This function adds the @code{signo} to the specified signal @code{set}. |
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108 | |
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109 | @subheading NOTES: |
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110 | |
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111 | NONE |
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112 | |
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113 | @page |
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114 | @subsection sigdelset - Delete a Signal from a Signal Set |
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115 | |
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116 | @subheading CALLING SEQUENCE: |
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117 | |
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118 | @example |
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119 | #include <signal.h> |
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120 | |
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121 | int sigdelset( |
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122 | sigset_t *set, |
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123 | int signo |
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124 | ); |
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125 | @end example |
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126 | |
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127 | @subheading STATUS CODES: |
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128 | |
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129 | @table @b |
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130 | @item EINVAL |
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131 | Invalid argument passed. |
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132 | |
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133 | @end table |
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134 | |
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135 | @subheading DESCRIPTION: |
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136 | |
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137 | This function deletes the @code{signo} to the specified signal @code{set}. |
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138 | |
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139 | @subheading NOTES: |
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140 | |
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141 | NONE |
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142 | |
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143 | @page |
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144 | @subsection sigfillset - Fill a Signal Set |
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145 | |
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146 | @subheading CALLING SEQUENCE: |
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147 | |
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148 | @example |
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149 | #include <signal.h> |
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150 | |
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151 | int sigfillset( |
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152 | sigset_t *set |
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153 | ); |
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154 | @end example |
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155 | |
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156 | @subheading STATUS CODES: |
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157 | |
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158 | @table @b |
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159 | |
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160 | @item EINVAL |
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161 | Invalid argument passed. |
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162 | |
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163 | @end table |
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164 | |
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165 | @subheading DESCRIPTION: |
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166 | |
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167 | This function fills the specified signal @code{set} such that all |
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168 | signals are set. |
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169 | |
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170 | @subheading NOTES: |
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171 | |
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172 | NONE |
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173 | |
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174 | @page |
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175 | @subsection sigismember - Is Signal a Member of a Signal Set |
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176 | |
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177 | @subheading CALLING SEQUENCE: |
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178 | |
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179 | @example |
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180 | #include <signal.h> |
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181 | |
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182 | int sigismember( |
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183 | const sigset_t *set, |
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184 | int signo |
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185 | ); |
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186 | @end example |
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187 | |
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188 | @subheading STATUS CODES: |
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189 | |
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190 | @table @b |
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191 | |
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192 | @item EINVAL |
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193 | Invalid argument passed. |
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194 | |
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195 | @end table |
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196 | |
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197 | @subheading DESCRIPTION: |
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198 | |
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199 | This function returns returns 1 if @code{signo} is a member of @code{set} |
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200 | and 0 otherwise. |
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201 | |
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202 | @subheading NOTES: |
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203 | |
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204 | NONE |
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205 | |
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206 | @page |
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207 | @subsection sigemptyset - Empty a Signal Set |
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208 | |
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209 | @subheading CALLING SEQUENCE: |
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210 | |
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211 | @example |
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212 | #include <signal.h> |
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213 | |
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214 | int sigemptyset( |
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215 | sigset_t *set |
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216 | ); |
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217 | @end example |
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218 | |
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219 | @subheading STATUS CODES: |
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220 | |
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221 | @table @b |
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222 | |
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223 | @item EINVAL |
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224 | Invalid argument passed. |
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225 | |
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226 | @end table |
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227 | |
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228 | @subheading DESCRIPTION: |
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229 | |
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230 | This function fills the specified signal @code{set} such that all |
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231 | signals are cleared. |
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232 | |
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233 | @subheading NOTES: |
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234 | |
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235 | NONE |
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236 | |
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237 | @page |
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238 | @subsection sigaction - Examine and Change Signal Action |
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239 | |
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240 | @subheading CALLING SEQUENCE: |
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241 | |
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242 | @example |
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243 | #include <signal.h> |
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244 | |
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245 | int sigaction( |
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246 | int sig, |
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247 | const struct sigaction *act, |
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248 | struct sigaction *oact |
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249 | ); |
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250 | @end example |
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251 | |
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252 | @subheading STATUS CODES: |
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253 | |
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254 | @table @b |
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255 | @item EINVAL |
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256 | Invalid argument passed. |
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257 | |
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258 | @item ENOTSUP |
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259 | Realtime Signals Extension option not supported. |
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260 | |
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261 | @end table |
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262 | |
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263 | @subheading DESCRIPTION: |
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264 | |
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265 | This function is used to change the action taken by a process on |
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266 | receipt of the specfic signal @code{sig}. The new action is |
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267 | specified by @code{act} and the previous action is returned |
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268 | via @code{oact}. |
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269 | |
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270 | @subheading NOTES: |
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271 | |
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272 | The signal number cannot be SIGKILL. |
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273 | |
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274 | @page |
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275 | @subsection pthread_kill - Send a Signal to a Thread |
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276 | |
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277 | @subheading CALLING SEQUENCE: |
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278 | |
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279 | @example |
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280 | #include <signal.h> |
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281 | |
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282 | int pthread_kill( |
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283 | pthread_t thread, |
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284 | int sig |
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285 | ); |
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286 | @end example |
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287 | |
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288 | @subheading STATUS CODES: |
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289 | |
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290 | @table @b |
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291 | |
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292 | @item ESRCH |
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293 | The thread indicated by the parameter thread is invalid. |
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294 | |
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295 | @item EINVAL |
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296 | Invalid argument passed. |
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297 | |
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298 | @end table |
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299 | |
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300 | @subheading DESCRIPTION: |
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301 | |
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302 | This functions sends the specified signal @code{sig} to @code{thread}. |
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303 | |
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304 | @subheading NOTES: |
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305 | |
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306 | NONE |
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307 | |
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308 | @page |
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309 | @subsection sigprocmask - Examine and Change Process Blocked Signals |
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310 | |
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311 | @subheading CALLING SEQUENCE: |
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312 | |
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313 | @example |
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314 | #include <signal.h> |
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315 | |
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316 | int sigprocmask( |
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317 | int how, |
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318 | const sigset_t *set, |
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319 | sigset_t *oset |
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320 | ); |
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321 | @end example |
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322 | |
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323 | @subheading STATUS CODES: |
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324 | |
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325 | @table @b |
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326 | |
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327 | @item EINVAL |
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328 | Invalid argument passed. |
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329 | |
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330 | @end table |
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331 | |
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332 | @subheading DESCRIPTION: |
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333 | |
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334 | This function is used to alter the set of currently blocked signals |
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335 | on a process wide basis. A blocked signal will not be received by the |
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336 | process. The behavior of this function is dependent on the value of |
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337 | @code{how} which may be one of the following: |
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338 | |
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339 | @table @code |
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340 | |
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341 | @item SIG_BLOCK |
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342 | The set of blocked signals is set to the union of @code{set} and |
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343 | those signals currently blocked. |
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344 | |
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345 | @item SIG_UNBLOCK |
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346 | The signals specific in @code{set} are removed from the currently |
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347 | blocked set. |
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348 | |
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349 | @item SIG_SETMASK |
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350 | The set of currently blocked signals is set to @code{set}. |
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351 | |
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352 | @end table |
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353 | |
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354 | If @code{oset} is not @code{NULL}, then the set of blocked signals |
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355 | prior to this call is returned in @code{oset}. |
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356 | |
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357 | @subheading NOTES: |
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358 | |
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359 | It is not an error to unblock a signal which is not blocked. |
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360 | |
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361 | @page |
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362 | @subsection pthread_sigmask - Examine and Change Thread Blocked Signals |
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363 | |
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364 | @subheading CALLING SEQUENCE: |
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365 | |
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366 | @example |
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367 | #include <signal.h> |
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368 | |
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369 | int pthread_sigmask( |
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370 | int how, |
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371 | const sigset_t *set, |
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372 | sigset_t *oset |
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373 | ); |
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374 | @end example |
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375 | |
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376 | @subheading STATUS CODES: |
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377 | @table @b |
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378 | @item EINVAL |
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379 | Invalid argument passed. |
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380 | |
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381 | @end table |
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382 | |
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383 | @subheading DESCRIPTION: |
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384 | |
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385 | This function is used to alter the set of currently blocked signals |
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386 | for the calling thread. A blocked signal will not be received by the |
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387 | process. The behavior of this function is dependent on the value of |
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388 | @code{how} which may be one of the following: |
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389 | |
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390 | @table @code |
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391 | @item SIG_BLOCK |
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392 | The set of blocked signals is set to the union of @code{set} and |
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393 | those signals currently blocked. |
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394 | |
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395 | @item SIG_UNBLOCK |
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396 | The signals specific in @code{set} are removed from the currently |
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397 | blocked set. |
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398 | |
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399 | @item SIG_SETMASK |
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400 | The set of currently blocked signals is set to @code{set}. |
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401 | |
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402 | @end table |
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403 | |
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404 | If @code{oset} is not @code{NULL}, then the set of blocked signals |
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405 | prior to this call is returned in @code{oset}. |
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406 | |
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407 | @subheading NOTES: |
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408 | |
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409 | It is not an error to unblock a signal which is not blocked. |
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410 | |
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411 | |
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412 | @page |
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413 | @subsection kill - Send a Signal to a Process |
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414 | |
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415 | @subheading CALLING SEQUENCE: |
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416 | |
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417 | @example |
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418 | #include <sys/types.h> |
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419 | #include <signal.h> |
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420 | |
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421 | int kill( |
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422 | pid_t pid, |
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423 | int sig |
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424 | ); |
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425 | @end example |
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426 | |
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427 | @subheading STATUS CODES: |
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428 | @table @b |
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429 | @item EINVAL |
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430 | Invalid argument passed. |
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431 | |
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432 | @item EPERM |
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433 | Process does not have permission to send the signal to any receiving process. |
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434 | |
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435 | @item ESRCH |
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436 | The process indicated by the parameter pid is invalid. |
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437 | |
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438 | @end table |
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439 | |
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440 | @subheading DESCRIPTION: |
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441 | |
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442 | This function sends the signal @code{sig} to the process @code{pid}. |
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443 | |
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444 | @subheading NOTES: |
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445 | |
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446 | NONE |
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447 | |
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448 | @page |
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449 | @subsection sigpending - Examine Pending Signals |
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450 | |
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451 | @subheading CALLING SEQUENCE: |
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452 | |
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453 | @example |
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454 | #include <signal.h> |
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455 | |
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456 | int sigpending( |
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457 | const sigset_t *set |
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458 | ); |
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459 | @end example |
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460 | |
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461 | @subheading STATUS CODES: |
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462 | |
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463 | On error, this routine returns -1 and sets @code{errno} to one of |
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464 | the following: |
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465 | |
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466 | @table @b |
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467 | |
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468 | @item EFAULT |
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469 | Invalid address for set. |
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470 | |
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471 | @end table |
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472 | |
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473 | @subheading DESCRIPTION: |
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474 | |
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475 | This function allows the caller to examine the set of currently pending |
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476 | signals. A pending signal is one which has been raised but is currently |
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477 | blocked. The set of pending signals is returned in @code{set}. |
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478 | |
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479 | @subheading NOTES: |
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480 | |
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481 | NONE |
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482 | |
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483 | @page |
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484 | @subsection sigsuspend - Wait for a Signal |
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485 | |
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486 | @subheading CALLING SEQUENCE: |
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487 | |
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488 | @example |
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489 | #include <signal.h> |
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490 | |
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491 | int sigsuspend( |
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492 | const sigset_t *sigmask |
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493 | ); |
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494 | @end example |
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495 | |
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496 | @subheading STATUS CODES: |
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497 | |
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498 | On error, this routine returns -1 and sets @code{errno} to one of |
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499 | the following: |
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500 | |
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501 | @table @b |
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502 | |
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503 | @item EINTR |
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504 | Signal interrupted this function. |
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505 | |
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506 | @end table |
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507 | |
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508 | @subheading DESCRIPTION: |
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509 | |
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510 | This function temporarily replaces the signal mask for the process |
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511 | with that specified by @code{sigmask} and blocks the calling thread |
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512 | until the signal is raised. |
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513 | |
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514 | @subheading NOTES: |
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515 | |
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516 | NONE |
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517 | |
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518 | @page |
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519 | @subsection pause - Suspend Process Execution |
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520 | |
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521 | @subheading CALLING SEQUENCE: |
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522 | |
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523 | @example |
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524 | #include <signal.h> |
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525 | |
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526 | int pause( void ); |
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527 | @end example |
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528 | |
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529 | @subheading STATUS CODES: |
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530 | |
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531 | On error, this routine returns -1 and sets @code{errno} to one of |
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532 | the following: |
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533 | |
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534 | @table @b |
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535 | |
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536 | @item EINTR |
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537 | Signal interrupted this function. |
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538 | |
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539 | @end table |
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540 | |
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541 | @subheading DESCRIPTION: |
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542 | |
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543 | This function causes the calling thread to be blocked until the signal |
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544 | is received. |
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545 | |
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546 | @subheading NOTES: |
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547 | |
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548 | NONE |
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549 | |
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550 | @page |
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551 | @subsection sigwait - Synchronously Accept a Signal |
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552 | |
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553 | @subheading CALLING SEQUENCE: |
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554 | |
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555 | @example |
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556 | #include <signal.h> |
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557 | |
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558 | int sigwait( |
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559 | const sigset_t *set, |
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560 | int *sig |
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561 | ); |
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562 | @end example |
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563 | |
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564 | @subheading STATUS CODES: |
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565 | @table @b |
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566 | @item EINVAL |
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567 | Invalid argument passed. |
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568 | |
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569 | @item EINTR |
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570 | Signal interrupted this function. |
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571 | |
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572 | @end table |
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573 | |
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574 | @subheading DESCRIPTION: |
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575 | |
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576 | This function selects a pending signal based on the set specified in |
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577 | @code{set}, atomically clears it from the set of pending signals, and |
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578 | returns the signal number for that signal in @code{sig}. |
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579 | |
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580 | |
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581 | @subheading NOTES: |
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582 | |
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583 | NONE |
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584 | |
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585 | @page |
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586 | @subsection sigwaitinfo - Synchronously Accept a Signal |
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587 | |
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588 | @subheading CALLING SEQUENCE: |
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589 | |
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590 | @example |
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591 | #include <signal.h> |
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592 | |
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593 | int sigwaitinfo( |
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594 | const sigset_t *set, |
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595 | siginfo_t *info |
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596 | ); |
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597 | @end example |
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598 | |
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599 | @subheading STATUS CODES: |
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600 | @table @b |
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601 | @item EINTR |
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602 | Signal interrupted this function. |
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603 | |
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604 | @end table |
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605 | |
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606 | @subheading DESCRIPTION: |
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607 | |
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608 | This function selects a pending signal based on the set specified in |
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609 | @code{set}, atomically clears it from the set of pending signals, and |
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610 | returns information about that signal in @code{info}. |
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611 | |
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612 | @subheading NOTES: |
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613 | |
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614 | NONE |
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615 | |
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616 | @page |
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617 | @subsection sigtimedwait - Synchronously Accept a Signal with Timeout |
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618 | |
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619 | @subheading CALLING SEQUENCE: |
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620 | |
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621 | @example |
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622 | #include <signal.h> |
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623 | |
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624 | int sigtimedwait( |
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625 | const sigset_t *set, |
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626 | siginfo_t *info, |
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627 | const struct timespec *timeout |
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628 | ); |
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629 | @end example |
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630 | |
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631 | @subheading STATUS CODES: |
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632 | @table @b |
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633 | @item EAGAIN |
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634 | Timed out while waiting for the specified signal set. |
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635 | |
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636 | @item EINVAL |
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637 | Nanoseconds field of the timeout argument is invalid. |
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638 | |
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639 | @item EINTR |
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640 | Signal interrupted this function. |
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641 | |
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642 | @end table |
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643 | |
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644 | @subheading DESCRIPTION: |
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645 | |
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646 | This function selects a pending signal based on the set specified in |
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647 | @code{set}, atomically clears it from the set of pending signals, and |
---|
648 | returns information about that signal in @code{info}. The calling thread |
---|
649 | will block up to @code{timeout} waiting for the signal to arrive. |
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650 | |
---|
651 | @subheading NOTES: |
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652 | |
---|
653 | If @code{timeout} is NULL, then the calling thread will wait forever for |
---|
654 | the specified signal set. |
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655 | |
---|
656 | @page |
---|
657 | @subsection sigqueue - Queue a Signal to a Process |
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658 | |
---|
659 | @subheading CALLING SEQUENCE: |
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660 | |
---|
661 | @example |
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662 | #include <signal.h> |
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663 | |
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664 | int sigqueue( |
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665 | pid_t pid, |
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666 | int signo, |
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667 | const union sigval value |
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668 | ); |
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669 | @end example |
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670 | |
---|
671 | @subheading STATUS CODES: |
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672 | |
---|
673 | @table @b |
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674 | |
---|
675 | @item EAGAIN |
---|
676 | No resources available to queue the signal. The process has already |
---|
677 | queued SIGQUEUE_MAX signals that are still pending at the receiver |
---|
678 | or the systemwide resource limit has been exceeded. |
---|
679 | |
---|
680 | @item EINVAL |
---|
681 | The value of the signo argument is an invalid or unsupported signal |
---|
682 | number. |
---|
683 | |
---|
684 | @item EPERM |
---|
685 | The process does not have the appropriate privilege to send the signal |
---|
686 | to the receiving process. |
---|
687 | |
---|
688 | @item ESRCH |
---|
689 | The process pid does not exist. |
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690 | |
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691 | @end table |
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692 | |
---|
693 | @subheading DESCRIPTION: |
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694 | |
---|
695 | This function sends the signal specified by @code{signo} to the |
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696 | process @code{pid} |
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697 | |
---|
698 | @subheading NOTES: |
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699 | |
---|
700 | NONE |
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701 | |
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702 | @page |
---|
703 | @subsection alarm - Schedule Alarm |
---|
704 | |
---|
705 | @subheading CALLING SEQUENCE: |
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706 | |
---|
707 | @example |
---|
708 | #include <signal.h> |
---|
709 | |
---|
710 | unsigned int alarm( |
---|
711 | unsigned int seconds |
---|
712 | ); |
---|
713 | @end example |
---|
714 | |
---|
715 | @subheading STATUS CODES: |
---|
716 | |
---|
717 | This call always succeeds. |
---|
718 | |
---|
719 | @subheading DESCRIPTION: |
---|
720 | |
---|
721 | If there was a previous @code{alarm()} request with time remaining, |
---|
722 | then this routine returns the number of seconds until that outstanding |
---|
723 | alarm would have fired. If no previous @code{alarm()} request was |
---|
724 | outstanding, then zero is returned. |
---|
725 | |
---|
726 | @subheading NOTES: |
---|
727 | |
---|
728 | NONE |
---|