TB10.1 Example Applications: examples/PIPS/posixsignals/asyncSignal/src/sigusr1.c Source File

00001 // sigusr1.c
-00002 //
-00003 // Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).
-00004 // All rights reserved.
-00005 // This component and the accompanying materials are made available
-00006 // under the terms of "Eclipse Public License v1.0"
-00007 // which accompanies this distribution, and is available
-00008 // at the URL "http://www.eclipse.org/legal/epl-v10.html".
-00009 //
-00010 // Initial Contributors:
-00011 // Nokia Corporation - initial contribution.
-00012 //
-00013 // Contributors:
-00014 //
-00015 // Description:This example demonstrates asynchronous signal handling.
-00016 //
-00017 
-00018 
-00019 #include <stdio.h>
-00020 #include <stdlib.h>
-00021 #include <signal.h> //The header for signal functionality.
-00022 #include <unistd.h> //The header used for getpid().
-00023 #include <e32def.h>
-00024 #include <spawn.h>
-00025 
-00026 int gch;            // The variable holding a character value, input by the user.
-00027 FILE *gfp = NULL;   // The file descriptor variable holding pointer to asyncFile.txt.
-00028 pid_t chldProcsID;  // The variable for holding the sigusr2 PID.
-00029 int gVal = TRUE;    // Variable used as a boolean value.
-00033 void SIGUSR1_handler(int signum)
-00034     {
-00035     int ret;
-00036     const int delay1 = 1;  //Time delay of 1 sec.
-00037     if (signum == SIGUSR1)
-00038         {
-00039         gVal = FALSE;
-00040         printf("\nReceived the SIGUSR1 signal from the sigusr2 process\n");
-00041         printf("Starting to read from the file\n");
-00042         while((gch = fgetc(gfp))!='\n')
-00043             {
-00044             putchar(gch);  //Writing to stdout.
-00045             }
-00046         printf("\n");  
-00047         sleep (delay1);     
-00048         
-00049         //Sending SIGUSR2 signal to sigusr2 process once the file content is written to the console.
-00050         printf("Reading from the file now completed, sending SIGUSR2 to the sigusr2 process\n");
-00051         
-00052         //Raising SIGUSR2 signal using kill command.
-00053         ret = kill(chldProcsID,SIGUSR2);
-00054         if(ret)
-00055             {
-00056             printf("kill() failed to send signal, errno=%d\n",errno);
-00057             }
-00058         }
-00059     }
-00060 
-00074 int main()
-00075     {
-00076     int ret;
-00077     const int delay = 1;                                        //Delay of 1 sec provided to wait for signal.
-00078     const int size = 50;                                        //No.of characters allowed in the filename.
-00079     const int index = 3;                                        //No.of elements in the array.
-00080     
-00081     char *filename = "C:\\asyncFile.txt" ;                      //Filename of the file that holds names input by the user.
-00082     char *childProcess = "Z:\\sys\\bin\\sigusr2.exe";           //Filename of sigusr2 process.
-00083     char **argv = (char**)malloc(index*sizeof(char*));          //Variable holding values to be passed to the sigusr2 process.
-00084     argv[0] = (char*)malloc(size*sizeof(char));
-00085     argv[1] = (char*)malloc(index*sizeof(char));
-00086     argv[2] = NULL;
-00087 
-00088     
-00089     strcpy(argv[0], "z:\\sys\\bin\\sigusr2.exe");               //argv[0] holding name of the sigusr2 process.
-00090     sprintf(argv[1],"%d",getpid());                             //argv[1] holding PID of sigusr1 process.
-00091     
-00092     //Setup the custom handler for SIGUSR1.
-00093     signal(SIGUSR1,SIGUSR1_handler);
-00094     
-00095     printf("*****************************************************************\n");
-00096     printf("*   Welcome to the asynchronous signal handling demonstration   *\n");
-00097     printf("*****************************************************************\n");
-00098     
-00099     printf("* This example demonstrates asynchronous signal handling using SIGUSR1 and SIGUSR2 signals.\n");
-00100     printf("* The example consists of two processes, the sigusr1 process and the sigusr2 process.\n");
-00101     printf("* The sigusr1 process handles the SIGUSR1 signal and sends a SIGUSR2 signal to the sigusr2 process.\n");
-00102     printf("* The sigusr2 process handles the SIGUSR2 signal and sends a SIGUSR1 signal to the sigusr1 process.\n");
-00103     printf("* The sigusr1 process opens a file and writes some text in it.\n");
-00104     printf("* The sigusr1 process then spawns the sigusr2 process and waits until SIGUSR1 is received from it.\n");
-00105     printf("* Once the sigusr1 process obtains a SIGUSR1 signal, it starts reading from the file and displays its\ncontent on the console.\n");
-00106     printf("* When all the file content is written, the sigusr1 process sends a SIGUSR2 signal to the sigusr2 process and prepares to exit.\n");
-00107     printf("* On other side the sigusr2 process keeps waiting for the SIGUSR2 signal from the sigusr1 process.\n");
-00108     printf("* On reception of the SIGUSR2 signal, the sigusr2 process prepares to exit.\n");
-00109     
-00110     printf("\nPress the Enter key to continue\n");
-00111     getchar();
-00112     
-00113     printf("****************** In the sigusr1 process ********************\n"); 
-00114   
-00115          
-00116     printf("\nOpening a file for read and write\n");
-00117     if((gfp = fopen(filename,"w+"))!=NULL)
-00118         {
-00119         printf("Successfully opened the file\n");
-00120         fprintf(gfp, "%s", "An asynchronous signal handling example using the SIGUSR1 and SIGUSR2 signals\n");
-00121         rewind(gfp);
-00122         printf("Writing to the file completed, preparing to start reading from the file\n");
-00123         
-00124         printf("Press the Enter key to spawn the sigusr2 process\n");
-00125         getchar();
-00126         
-00127         //Spawning sigusr2 process.
-00128         ret = posix_spawn(&chldProcsID,childProcess,NULL,NULL,argv,(char**)NULL);
-00129         if(ret != 0)     
-00130             {         
-00131             printf("\n*** failure posix_spawn ***\n");        
-00132             return EXIT_FAILURE;     
-00133             }
-00134         }
-00135     
-00136     printf("Waiting until SIGUSR1 is obtained from the sigusr2 process");
-00137     while(gVal)
-00138         {
-00139         printf(".");
-00140         sleep(delay);
-00141         }
-00142     
-00143     if(!fclose(gfp))
-00144         {
-00145         remove(filename);
-00146         gfp=NULL;
-00147         printf("The file was closed successfully.\n");
-00148         }
-00149     else
-00150         {
-00151         printf("File close failed.\n");
-00152         }
-00153     
-00154     printf("Press 'e'+Enter to exit from the sigusr1 process\n");
-00155     
-00156     while((gch=getchar())!= 'e')
-00157         {
-00158         if(gch == '\n')
-00159             continue;
-00160         else
-00161             printf("The wrong option was selected, please try again!!!\n");
-00162         }
-00163     return EXIT_SUCCESS;
-00164     }
-