Symbian3/Examples/guid-6013a680-57f9-415b-8851-c4fa63356636/basic_signals_8c_source.html
Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
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<h1>examples/PIPS/posixsignals/basicSignals/basicSignals.c</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// basicSignals.c</span>
<a name="l00002"></a>00002 <span class="comment">//</span>
<a name="l00003"></a>00003 <span class="comment">// Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).</span>
<a name="l00004"></a>00004 <span class="comment">// All rights reserved.</span>
<a name="l00005"></a>00005 <span class="comment">// This component and the accompanying materials are made available</span>
<a name="l00006"></a>00006 <span class="comment">// under the terms of "Eclipse Public License v1.0"</span>
<a name="l00007"></a>00007 <span class="comment">// which accompanies this distribution, and is available</span>
<a name="l00008"></a>00008 <span class="comment">// at the URL "http://www.eclipse.org/legal/epl-v10.html".</span>
<a name="l00009"></a>00009 <span class="comment">//</span>
<a name="l00010"></a>00010 <span class="comment">// Initial Contributors:</span>
<a name="l00011"></a>00011 <span class="comment">// Nokia Corporation - initial contribution.</span>
<a name="l00012"></a>00012 <span class="comment">//</span>
<a name="l00013"></a>00013 <span class="comment">// Contributors:</span>
<a name="l00014"></a>00014 <span class="comment">//</span>
<a name="l00015"></a>00015 <span class="comment">// Description:This example demonstrates the basic signal functionality .</span>
<a name="l00016"></a>00016 <span class="comment">//</span>
<a name="l00017"></a>00017
<a name="l00018"></a>00018 <span class="preprocessor">#include <stdio.h></span>
<a name="l00019"></a>00019 <span class="preprocessor">#include <stdlib.h></span>
<a name="l00020"></a>00020 <span class="preprocessor">#include <unistd.h></span>
<a name="l00021"></a>00021 <span class="preprocessor">#include <sys/types.h></span>
<a name="l00022"></a>00022 <span class="preprocessor">#include <signal.h></span> <span class="comment">//The header for signal functionality.</span>
<a name="l00023"></a>00023 <span class="preprocessor">#include <time.h></span> <span class="comment">//The header for timer functionality.</span>
<a name="l00024"></a>00024 <span class="preprocessor">#include <e32def.h></span>
<a name="l00025"></a>00025
<a name="l00026"></a>00026 <span class="keywordtype">char</span> <span class="keyword">const</span> *gstr = <span class="stringliteral">"\nPress '7'+Enter to return to the options menu or 'e'+ENTER to exit the example\n"</span>;
<a name="l00027"></a>00027 <span class="keywordtype">char</span> <span class="keyword">const</span> *gnote = <span class="stringliteral">"\nPress the Enter key to proceed with the use case\n"</span>;
<a name="l00028"></a>00028
<a name="l00032"></a>00032 <span class="keywordtype">void</span> PressKey()
<a name="l00033"></a>00033 {
<a name="l00034"></a>00034 fflush(stdout);
<a name="l00035"></a>00035 getchar();
<a name="l00036"></a>00036 }
<a name="l00037"></a>00037
<a name="l00042"></a>00042 <span class="keywordtype">void</span> timestamp(<span class="keywordtype">char</span> *str)
<a name="l00043"></a>00043 {
<a name="l00044"></a>00044 time_t t;
<a name="l00045"></a>00045 time(&t);
<a name="l00046"></a>00046 printf(<span class="stringliteral">"The time %s is %s\n"</span>, str, ctime(&t));
<a name="l00047"></a>00047 }
<a name="l00048"></a>00048
<a name="l00053"></a>00053 <span class="keywordtype">void</span> SIGCHLD_handler(<span class="keywordtype">int</span> signum)
<a name="l00054"></a>00054 {
<a name="l00055"></a>00055 <span class="keywordflow">if</span>(signum == SIGCHLD)
<a name="l00056"></a>00056 printf(<span class="stringliteral">"Now in SIGCHLD handler function\n"</span>);
<a name="l00057"></a>00057 }
<a name="l00058"></a>00058
<a name="l00063"></a>00063 <span class="keywordtype">void</span> SIGALRM_handler(<span class="keywordtype">int</span> signum)
<a name="l00064"></a>00064 {
<a name="l00065"></a>00065 <span class="keywordflow">if</span>(signum == SIGALRM)
<a name="l00066"></a>00066 printf(<span class="stringliteral">"Now in SIGALRM handler function\n"</span>);
<a name="l00067"></a>00067 }
<a name="l00068"></a>00068
<a name="l00073"></a>00073 <span class="keywordtype">void</span> SIGUSR1_handler(<span class="keywordtype">int</span> signum)
<a name="l00074"></a>00074 {
<a name="l00075"></a>00075 <span class="keywordflow">if</span>(signum == SIGUSR1)
<a name="l00076"></a>00076 printf(<span class="stringliteral">"Now in SIGUSR1 handler function\n"</span>);
<a name="l00077"></a>00077 }
<a name="l00078"></a>00078
<a name="l00083"></a>00083 <span class="keywordtype">void</span> SIGUSR2_handler(<span class="keywordtype">int</span> signum)
<a name="l00084"></a>00084 {
<a name="l00085"></a>00085 <span class="keywordflow">if</span>(signum == SIGUSR2)
<a name="l00086"></a>00086 printf(<span class="stringliteral">"Now in SIGUSR2 handler function\n"</span>);
<a name="l00087"></a>00087
<a name="l00088"></a>00088 sigrelse(SIGUSR1);
<a name="l00089"></a>00089 printf(<span class="stringliteral">"SIGUSR1 got released and hence its handler function will get called\n"</span>);
<a name="l00090"></a>00090 }
<a name="l00091"></a>00091
<a name="l00096"></a>00096 <span class="keywordtype">void</span> SIGPIPE_handler(<span class="keywordtype">int</span> signum)
<a name="l00097"></a>00097 {
<a name="l00098"></a>00098 <span class="keywordflow">if</span>(signum == SIGPIPE)
<a name="l00099"></a>00099 printf(<span class="stringliteral">"In SIGPIPE handler function\n"</span>);
<a name="l00100"></a>00100 }
<a name="l00101"></a>00101
<a name="l00105"></a>00105 <span class="keywordtype">void</span> DisplaySignalOptions()
<a name="l00106"></a>00106 {
<a name="l00107"></a>00107 printf(<span class="stringliteral">"\nSignal options:\n"</span>);
<a name="l00108"></a>00108 printf(<span class="stringliteral">"1) Sending and handling a signal using the default handler\n"</span>);
<a name="l00109"></a>00109 printf(<span class="stringliteral">"2) Sending and handling a signal using a customized signal handler\n"</span>);
<a name="l00110"></a>00110 printf(<span class="stringliteral">"3) Ignoring an incoming signal\n"</span>);
<a name="l00111"></a>00111 printf(<span class="stringliteral">"4) Blocking and releasing a signal\n"</span>);
<a name="l00112"></a>00112 printf(<span class="stringliteral">"5) Waiting for a signal\n"</span>);
<a name="l00113"></a>00113 printf(<span class="stringliteral">"6) Generating and handling a SIGPIPE signal\n"</span>);
<a name="l00114"></a>00114 printf(<span class="stringliteral">"Type the number of the option you wish to run followed by an enter,\n"</span>);
<a name="l00115"></a>00115 printf(<span class="stringliteral">"or type 'e'+Enter to exit the example.\n"</span>);
<a name="l00116"></a>00116 }
<a name="l00117"></a>00117
<a name="l00121"></a>00121 <span class="keywordtype">void</span> CallDefaultHandler()
<a name="l00122"></a>00122 {
<a name="l00123"></a>00123 pid_t my_pid;
<a name="l00124"></a>00124 my_pid = getpid();
<a name="l00125"></a>00125 printf(<span class="stringliteral">"Raising a SIGCHLD signal\n"</span>);
<a name="l00126"></a>00126
<a name="l00127"></a>00127 signal(SIGCHLD, SIG_DFL);
<a name="l00128"></a>00128
<a name="l00129"></a>00129 <span class="comment">//Raising SIGCHLD signal using kill command.</span>
<a name="l00130"></a>00130 kill(my_pid, SIGCHLD);
<a name="l00131"></a>00131
<a name="l00132"></a>00132 printf(<span class="stringliteral">"Default handler causes SIGCHLD to get ignored\n"</span>);
<a name="l00133"></a>00133 PressKey();
<a name="l00134"></a>00134
<a name="l00135"></a>00135 printf(<span class="stringliteral">"\nRaising a SIGALRM signal\nDefault handler of SIGALRM will terminate the existing process.\n"</span>);
<a name="l00136"></a>00136 printf(<span class="stringliteral">"\nRestart the example to view the other use cases.\n"</span>);
<a name="l00137"></a>00137 printf(<span class="stringliteral">"Press the enter key to terminate the example.\n"</span>);
<a name="l00138"></a>00138 PressKey();
<a name="l00139"></a>00139
<a name="l00140"></a>00140 signal(SIGALRM, SIG_DFL);
<a name="l00141"></a>00141
<a name="l00142"></a>00142 <span class="comment">//Raising SIGALRM signal.</span>
<a name="l00143"></a>00143 kill(my_pid, SIGALRM);
<a name="l00144"></a>00144 printf(<span class="stringliteral">"After SIGALRM being raised\n"</span>);
<a name="l00145"></a>00145
<a name="l00146"></a>00146 printf(gstr);
<a name="l00147"></a>00147 }
<a name="l00148"></a>00148
<a name="l00152"></a>00152 <span class="keywordtype">void</span> CallSignalHandler()
<a name="l00153"></a>00153 {
<a name="l00154"></a>00154 <span class="keyword">struct </span>sigaction sa1,sa2;
<a name="l00155"></a>00155 sa1.sa_handler = SIGCHLD_handler;
<a name="l00156"></a>00156 sigemptyset(&sa1.sa_mask);
<a name="l00157"></a>00157 sa1.sa_flags = 0;
<a name="l00158"></a>00158
<a name="l00159"></a>00159 sa2.sa_handler = SIGALRM_handler;
<a name="l00160"></a>00160 sigemptyset(&sa2.sa_mask);
<a name="l00161"></a>00161 sa2.sa_flags = 0;
<a name="l00162"></a>00162
<a name="l00163"></a>00163 <span class="keywordflow">if</span> (sigaction(SIGCHLD, &sa1, NULL) == -1)
<a name="l00164"></a>00164 {
<a name="l00165"></a>00165 printf(<span class="stringliteral">"error in setting the handler for SIGCHLD\n"</span>);
<a name="l00166"></a>00166 }
<a name="l00167"></a>00167
<a name="l00168"></a>00168 <span class="keywordflow">if</span> (sigaction(SIGALRM, &sa2, NULL) == -1)
<a name="l00169"></a>00169 {
<a name="l00170"></a>00170 printf(<span class="stringliteral">"error in setting the handler for SIGALRM\n"</span>);
<a name="l00171"></a>00171 }
<a name="l00172"></a>00172
<a name="l00173"></a>00173 printf(<span class="stringliteral">"\nRaising a SIGCHLD signal\n"</span>);
<a name="l00174"></a>00174 kill(getpid(), SIGCHLD); <span class="comment">//Raising SIGCHLD signal using kill command.</span>
<a name="l00175"></a>00175 printf(<span class="stringliteral">"SIGCHLD has been handled\n"</span>);
<a name="l00176"></a>00176
<a name="l00177"></a>00177 printf(<span class="stringliteral">"\nRaising a SIGALRM signal\n"</span>);
<a name="l00178"></a>00178 kill(getpid(), SIGALRM); <span class="comment">//Raising SIGALRM signal using kill command.</span>
<a name="l00179"></a>00179 printf(<span class="stringliteral">"SIGALRM has been handled\n"</span>);
<a name="l00180"></a>00180
<a name="l00181"></a>00181 printf(gstr);
<a name="l00182"></a>00182 }
<a name="l00183"></a>00183
<a name="l00187"></a>00187 <span class="keywordtype">void</span> IgnoreSignal()
<a name="l00188"></a>00188 {
<a name="l00189"></a>00189 <span class="keyword">struct </span>sigaction sa1,sa2; <span class="comment">//The variables for holding signal specific settings, used in sigaction function call. </span>
<a name="l00190"></a>00190 sa1.sa_handler = SIG_IGN;
<a name="l00191"></a>00191 sigemptyset(&sa1.sa_mask);
<a name="l00192"></a>00192 sa1.sa_flags = 0;
<a name="l00193"></a>00193
<a name="l00194"></a>00194 sa2.sa_handler = SIG_IGN;
<a name="l00195"></a>00195 sigemptyset(&sa2.sa_mask);
<a name="l00196"></a>00196 sa2.sa_flags = 0;
<a name="l00197"></a>00197
<a name="l00198"></a>00198 <span class="comment">// Set the signal handler for SIGCHLD.</span>
<a name="l00199"></a>00199 <span class="keywordflow">if</span> (sigaction(SIGCHLD, &sa1, NULL) == -1)
<a name="l00200"></a>00200 printf(<span class="stringliteral">"sigaction for SIGCHLD failed\n"</span>);
<a name="l00201"></a>00201
<a name="l00202"></a>00202 <span class="comment">// Set the signal handler for SIGALRM.</span>
<a name="l00203"></a>00203 <span class="keywordflow">if</span> (sigaction(SIGALRM, &sa2, NULL) == -1)
<a name="l00204"></a>00204 printf(<span class="stringliteral">"sigaction for SIGALRM failed\n"</span>);
<a name="l00205"></a>00205
<a name="l00206"></a>00206 printf(<span class="stringliteral">"\nRaising a SIGCHLD signal\n"</span>);
<a name="l00207"></a>00207 kill(getpid(), SIGCHLD); <span class="comment">//Raisisng SIGCHLD signal using kill command.</span>
<a name="l00208"></a>00208 printf(<span class="stringliteral">"SIGCHLD was ignored\n"</span>);
<a name="l00209"></a>00209
<a name="l00210"></a>00210 printf(<span class="stringliteral">"\nRaising a SIGALRM signal\n"</span>);
<a name="l00211"></a>00211 kill(getpid(), SIGALRM); <span class="comment">//Raisisng SIGALRM signal using kill command.</span>
<a name="l00212"></a>00212 printf(<span class="stringliteral">"SIGALRM was ignored\n"</span>);
<a name="l00213"></a>00213
<a name="l00214"></a>00214 printf(gstr);
<a name="l00215"></a>00215 }
<a name="l00216"></a>00216
<a name="l00220"></a>00220 <span class="keywordtype">void</span> MaskSignal()
<a name="l00221"></a>00221 {
<a name="l00222"></a>00222 <span class="comment">// Define a new mask set.</span>
<a name="l00223"></a>00223 sigset_t mask_set;
<a name="l00224"></a>00224
<a name="l00225"></a>00225 printf(<span class="stringliteral">"* This use case uses SIGUSR1 and SIGUSR2 signals to demonstrate the mask and the release of a signal\n"</span>);
<a name="l00226"></a>00226 printf(<span class="stringliteral">"* We mask the SIGUSR1 signal so that when it is raised it gets blocked and keeps pending until it is\nreleased.\n"</span>);
<a name="l00227"></a>00227 printf(<span class="stringliteral">"* We then raise the SIGUSR2 signal to release the blocked SIGUSR1 signal.\n"</span>);
<a name="l00228"></a>00228 printf(<span class="stringliteral">"* The custom handler of the SIGUSR2 signal releases SIGUSR1, and SIGUSR1's\ncustom handler gets called to handle it.\n"</span>);
<a name="l00229"></a>00229
<a name="l00230"></a>00230 printf(gnote);
<a name="l00231"></a>00231 PressKey();
<a name="l00232"></a>00232 PressKey();
<a name="l00233"></a>00233
<a name="l00234"></a>00234 <span class="comment">// Set the signal handler for SIGUSR1 and SIGUSR2 signals.</span>
<a name="l00235"></a>00235 signal(SIGUSR1, SIGUSR1_handler);
<a name="l00236"></a>00236 signal(SIGUSR2, SIGUSR2_handler);
<a name="l00237"></a>00237
<a name="l00238"></a>00238 <span class="comment">// Clearing the mask set so that it doesn't contain any signal numbers.</span>
<a name="l00239"></a>00239 sigemptyset(&mask_set);
<a name="l00240"></a>00240 <span class="comment">// Adding SIGUSR1 to the mask set.</span>
<a name="l00241"></a>00241 sigaddset(&mask_set, SIGUSR1);
<a name="l00242"></a>00242 <span class="comment">// Masking the signal.</span>
<a name="l00243"></a>00243 printf(<span class="stringliteral">"Masking the SIGUSR1 signal\n"</span>);
<a name="l00244"></a>00244 sigprocmask(SIG_SETMASK, &mask_set, NULL);
<a name="l00245"></a>00245
<a name="l00246"></a>00246 printf(<span class="stringliteral">"\nRaising the SIGUSR1 signal"</span>);
<a name="l00247"></a>00247 printf(gnote);
<a name="l00248"></a>00248 PressKey();
<a name="l00249"></a>00249
<a name="l00250"></a>00250 <span class="keyword">raise</span>(SIGUSR1);
<a name="l00251"></a>00251 printf(<span class="stringliteral">"SIGUSR1 was ignored as it was masked\n"</span>);
<a name="l00252"></a>00252
<a name="l00253"></a>00253 printf(<span class="stringliteral">"\nRaising the SIGUSR2 signal"</span>);
<a name="l00254"></a>00254 printf(gnote);
<a name="l00255"></a>00255 PressKey();
<a name="l00256"></a>00256
<a name="l00257"></a>00257 <span class="keyword">raise</span>(SIGUSR2);
<a name="l00258"></a>00258 printf(<span class="stringliteral">"SIGUSR2 has been handled\n"</span>);
<a name="l00259"></a>00259
<a name="l00260"></a>00260 printf(gstr);
<a name="l00261"></a>00261 }
<a name="l00262"></a>00262
<a name="l00266"></a>00266 <span class="keywordtype">void</span> WaitForSignal()
<a name="l00267"></a>00267 {
<a name="l00268"></a>00268 <span class="keywordtype">int</span> count,result;
<a name="l00269"></a>00269 <span class="keyword">const</span> <span class="keywordtype">int</span> delay = 2; <span class="comment">//Time delay of 2 seconds.</span>
<a name="l00270"></a>00270 sigset_t waitset,outset; <span class="comment">// Define new mask sets.</span>
<a name="l00271"></a>00271 <span class="keyword">struct </span>timespec timeout; <span class="comment">// A variable for holding timeout values.</span>
<a name="l00272"></a>00272 siginfo_t info; <span class="comment">// A variable for holding signal info.</span>
<a name="l00273"></a>00273
<a name="l00274"></a>00274 signal(SIGALRM, SIGALRM_handler); <span class="comment">// Set the signal handler for SIGALRM.</span>
<a name="l00275"></a>00275 sigemptyset(&waitset);
<a name="l00276"></a>00276 sigaddset(&waitset, SIGALRM); <span class="comment">// Adding SIGALRM to mask set.</span>
<a name="l00277"></a>00277 sigprocmask(SIG_BLOCK, &waitset, NULL);
<a name="l00278"></a>00278
<a name="l00279"></a>00279 printf(<span class="stringliteral">"* This use case demonstrates how a process waits for a SIGALRM signal.\n"</span>);
<a name="l00280"></a>00280 printf(<span class="stringliteral">"* A fixed timeout period of 5 seconds is set.\n"</span>);
<a name="l00281"></a>00281 printf(<span class="stringliteral">"* The SIGALRM signal is first blocked and then we wait on it until it is raised.\n"</span>);
<a name="l00282"></a>00282 printf(<span class="stringliteral">"* The SIGALRM signal is raised twice, once after 6 seconds and another after 4 seconds.\n"</span>);
<a name="l00283"></a>00283 printf(<span class="stringliteral">"* When SIGALRM is raised after 6 seconds an error is generated as timeout has occurred.\nBut when SIGALRM is raised after 4 seconds the signal is received.\n"</span>);
<a name="l00284"></a>00284 printf(<span class="stringliteral">"* Even though the SIGALRM signal is received it cannot be handled as it is blocked.\nHence we finally unblock it and handle it.\n"</span>);
<a name="l00285"></a>00285
<a name="l00286"></a>00286 printf(gnote);
<a name="l00287"></a>00287 PressKey();
<a name="l00288"></a>00288 PressKey();
<a name="l00289"></a>00289
<a name="l00290"></a>00290 <span class="comment">//Setting the timeout for 5 seconds.</span>
<a name="l00291"></a>00291 timeout.tv_sec = 5;
<a name="l00292"></a>00292 timeout.tv_nsec = 500;
<a name="l00293"></a>00293
<a name="l00294"></a>00294 <span class="keywordflow">for</span>(count=0;count<2;count++)
<a name="l00295"></a>00295 {
<a name="l00296"></a>00296 <span class="keywordflow">if</span>(count)
<a name="l00297"></a>00297 {
<a name="l00298"></a>00298 printf(<span class="stringliteral">"Raising SIGALRM after 6 sec\n"</span>);
<a name="l00299"></a>00299 printf(gnote);
<a name="l00300"></a>00300 PressKey();
<a name="l00301"></a>00301 alarm(6);
<a name="l00302"></a>00302 }
<a name="l00303"></a>00303 <span class="keywordflow">else</span>
<a name="l00304"></a>00304 {
<a name="l00305"></a>00305 printf(<span class="stringliteral">"Raising SIGALRM after 4 sec\n"</span>);
<a name="l00306"></a>00306 printf(gnote);
<a name="l00307"></a>00307 PressKey();
<a name="l00308"></a>00308 alarm(4);
<a name="l00309"></a>00309 }
<a name="l00310"></a>00310 timestamp(<span class="stringliteral">"before sigwait()"</span>);
<a name="l00311"></a>00311 result = sigtimedwait(&waitset, &info, &timeout);
<a name="l00312"></a>00312
<a name="l00313"></a>00313 <span class="keywordflow">if</span>( result == SIGALRM )
<a name="l00314"></a>00314 printf(<span class="stringliteral">"sigwait() returned successful for signal %d\n"</span>, info.si_signo);
<a name="l00315"></a>00315 <span class="keywordflow">else</span>
<a name="l00316"></a>00316 {
<a name="l00317"></a>00317 printf(<span class="stringliteral">"sigwait() returned an error, since the alarm was generated after the specified time period.error number = %d\n"</span>, errno);
<a name="l00318"></a>00318 }
<a name="l00319"></a>00319 timestamp(<span class="stringliteral">"after sigwait()"</span>);
<a name="l00320"></a>00320 sleep(delay);
<a name="l00321"></a>00321 }
<a name="l00322"></a>00322
<a name="l00323"></a>00323 printf(<span class="stringliteral">"Press Enter to unblock the SIGALRM signal and handle it\n"</span>);
<a name="l00324"></a>00324 PressKey();
<a name="l00325"></a>00325 sigemptyset(&outset);
<a name="l00326"></a>00326 sigprocmask(SIG_UNBLOCK, &waitset, &outset);
<a name="l00327"></a>00327
<a name="l00328"></a>00328 printf(gstr);
<a name="l00329"></a>00329 }
<a name="l00330"></a>00330
<a name="l00334"></a>00334 <span class="keywordtype">void</span> HandleSigpipe()
<a name="l00335"></a>00335 {
<a name="l00336"></a>00336 <span class="keywordtype">int</span> ret,fds[2]; <span class="comment">// fds, used for holding the read and write descriptors for pipe</span>
<a name="l00337"></a>00337 printf(<span class="stringliteral">"* This use case demonstrates how writing to a broken pipe generates a SIGPIPE signal.\n"</span>);
<a name="l00338"></a>00338 printf(<span class="stringliteral">"* We first create a pipe and obtain the read and write descriptors.\n"</span>);
<a name="l00339"></a>00339 printf(<span class="stringliteral">"* To obtain a broken pipe we close the read end of the pipe.\n"</span>);
<a name="l00340"></a>00340 printf(<span class="stringliteral">"* Once a write is performed to the broken pipe, an EPIPE error is returned\nand hence the SIGPIPE signal is generated.\n"</span>);
<a name="l00341"></a>00341
<a name="l00342"></a>00342 printf(gnote);
<a name="l00343"></a>00343 getchar();
<a name="l00344"></a>00344 PressKey();
<a name="l00345"></a>00345
<a name="l00346"></a>00346 <span class="comment">//Set the signal handler for the SIGPIPE signal.</span>
<a name="l00347"></a>00347 signal(SIGPIPE, SIGPIPE_handler);
<a name="l00348"></a>00348
<a name="l00349"></a>00349 <span class="comment">//Create a pipe.</span>
<a name="l00350"></a>00350 ret = pipe(fds);
<a name="l00351"></a>00351 <span class="keywordflow">if</span>(ret != 0)
<a name="l00352"></a>00352 {
<a name="l00353"></a>00353 printf(<span class="stringliteral">"Failed to create a pipe and the errno is %d\n"</span>,errno);
<a name="l00354"></a>00354 }
<a name="l00355"></a>00355 <span class="keywordflow">else</span>
<a name="l00356"></a>00356 {
<a name="l00357"></a>00357 printf(<span class="stringliteral">"The pipe was created successfully\n"</span>);
<a name="l00358"></a>00358 }
<a name="l00359"></a>00359 <span class="comment">//Close the read end of a pipe.</span>
<a name="l00360"></a>00360 close(fds[0]);
<a name="l00361"></a>00361
<a name="l00362"></a>00362 <span class="comment">//Write to a pipe whose read end is closed (a broken pipe).</span>
<a name="l00363"></a>00363 printf(<span class="stringliteral">"Writing to a broken pipe\n"</span>);
<a name="l00364"></a>00364 ret = write(fds[1], <span class="stringliteral">"sigpipe"</span>, 10);
<a name="l00365"></a>00365 <span class="keywordflow">if</span>((ret != -1) && (errno != EPIPE))
<a name="l00366"></a>00366 {
<a name="l00367"></a>00367 printf(<span class="stringliteral">"Failed to generate the SIGPIPE signal on pipe\n"</span>);
<a name="l00368"></a>00368 }
<a name="l00369"></a>00369 <span class="keywordflow">else</span>
<a name="l00370"></a>00370 {
<a name="l00371"></a>00371 printf(<span class="stringliteral">"Writing to a pipe with the read end closed, has returned EPIPE and hence generated the SIGPIPE signal\n"</span>);
<a name="l00372"></a>00372 }
<a name="l00373"></a>00373
<a name="l00374"></a>00374 printf(gstr);
<a name="l00375"></a>00375 }
<a name="l00376"></a>00376
<a name="l00381"></a>00381 <span class="keywordtype">int</span> <a class="code" href="redirectprintf_8c.html#a840291bc02cba5474a4cb46a9b9566fe">main</a>()
<a name="l00382"></a>00382 {
<a name="l00383"></a>00383 <span class="keywordtype">int</span> character;
<a name="l00384"></a>00384 <span class="keywordtype">int</span> val = TRUE;
<a name="l00385"></a>00385 <span class="comment">//Welcome Note.</span>
<a name="l00386"></a>00386 printf(<span class="stringliteral">"************************************************************************\n"</span>);
<a name="l00387"></a>00387 printf(<span class="stringliteral">"* Welcome to the Signal Example *\n"</span>);
<a name="l00388"></a>00388 printf(<span class="stringliteral">"* This example demonstrates some basic signal use cases *\n"</span>);
<a name="l00389"></a>00389 printf(<span class="stringliteral">"************************************************************************\n"</span>);
<a name="l00390"></a>00390 printf(<span class="stringliteral">"Please refer to the overview for a better understanding of this example.\n"</span>);
<a name="l00391"></a>00391
<a name="l00392"></a>00392 <span class="comment">//Generating menu for various signal functions.</span>
<a name="l00393"></a>00393 DisplaySignalOptions();
<a name="l00394"></a>00394 <span class="keywordflow">while</span>(val)
<a name="l00395"></a>00395 {
<a name="l00396"></a>00396 <span class="keywordflow">while</span>((character = getchar())!= <span class="charliteral">'\n'</span>)
<a name="l00397"></a>00397 {
<a name="l00398"></a>00398 <span class="keywordflow">switch</span>(character)
<a name="l00399"></a>00399 {
<a name="l00400"></a>00400 <span class="keywordflow">case</span> <span class="charliteral">'1'</span>:
<a name="l00401"></a>00401 printf(<span class="stringliteral">"\nDemonstrating sending and handling of 2 signals by the default handler\n"</span>);
<a name="l00402"></a>00402 printf(<span class="stringliteral">"**********************************************************************\n"</span>);
<a name="l00403"></a>00403 CallDefaultHandler();
<a name="l00404"></a>00404 <span class="keywordflow">break</span>;
<a name="l00405"></a>00405 <span class="keywordflow">case</span> <span class="charliteral">'2'</span>:
<a name="l00406"></a>00406 printf(<span class="stringliteral">"\nDemonstrating sending and handling of 2 signals using a custom signal handler\n"</span>);
<a name="l00407"></a>00407 printf(<span class="stringliteral">"*****************************************************************************\n"</span>);
<a name="l00408"></a>00408 CallSignalHandler();
<a name="l00409"></a>00409 <span class="keywordflow">break</span>;
<a name="l00410"></a>00410 <span class="keywordflow">case</span> <span class="charliteral">'3'</span>:
<a name="l00411"></a>00411 printf(<span class="stringliteral">"\nDemonstrating ignoring an incoming signal\n"</span>);
<a name="l00412"></a>00412 printf(<span class="stringliteral">"*****************************************\n"</span>);
<a name="l00413"></a>00413 IgnoreSignal();
<a name="l00414"></a>00414 <span class="keywordflow">break</span>;
<a name="l00415"></a>00415 <span class="keywordflow">case</span> <span class="charliteral">'4'</span>:
<a name="l00416"></a>00416 printf(<span class="stringliteral">"\nDemonstrating masking and releasing of a signal\n"</span>);
<a name="l00417"></a>00417 printf(<span class="stringliteral">"***********************************************\n"</span>);
<a name="l00418"></a>00418 MaskSignal();
<a name="l00419"></a>00419 <span class="keywordflow">break</span>;
<a name="l00420"></a>00420 <span class="keywordflow">case</span> <span class="charliteral">'5'</span>:
<a name="l00421"></a>00421 printf(<span class="stringliteral">"\nDemonstrating waiting for a signal\n"</span>);
<a name="l00422"></a>00422 printf(<span class="stringliteral">"**********************************\n"</span>);
<a name="l00423"></a>00423 WaitForSignal();
<a name="l00424"></a>00424 <span class="keywordflow">break</span>;
<a name="l00425"></a>00425 <span class="keywordflow">case</span> <span class="charliteral">'6'</span>:
<a name="l00426"></a>00426 printf(<span class="stringliteral">"\nDemonstrating generating and handling a SIGPIPE signal\n"</span>);
<a name="l00427"></a>00427 printf(<span class="stringliteral">"******************************************************\n"</span>);
<a name="l00428"></a>00428 HandleSigpipe();
<a name="l00429"></a>00429 <span class="keywordflow">break</span>;
<a name="l00430"></a>00430 <span class="keywordflow">case</span> <span class="charliteral">'7'</span>:
<a name="l00431"></a>00431 DisplaySignalOptions();
<a name="l00432"></a>00432 <span class="keywordflow">break</span>;
<a name="l00433"></a>00433 <span class="keywordflow">case</span> <span class="charliteral">'e'</span>:
<a name="l00434"></a>00434 printf(<span class="stringliteral">"Exiting from the main menu\n"</span>);
<a name="l00435"></a>00435 val = FALSE;
<a name="l00436"></a>00436 <span class="keywordflow">break</span>;
<a name="l00437"></a>00437 <span class="keywordflow">default</span>:
<a name="l00438"></a>00438 printf(<span class="stringliteral">"You chose a wrong option!!! Select again.\n"</span>);
<a name="l00439"></a>00439 <span class="keywordflow">break</span>;
<a name="l00440"></a>00440 }
<a name="l00441"></a>00441 }
<a name="l00442"></a>00442 }
<a name="l00443"></a>00443 printf(<span class="stringliteral">"Ok [Press the Enter key to exit]\n"</span>);
<a name="l00444"></a>00444 PressKey();
<a name="l00445"></a>00445 <span class="keywordflow">return</span> EXIT_SUCCESS; <span class="comment">//Returns the success code.</span>
<a name="l00446"></a>00446 }
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