examples/PIPS/posixsignals/sigtermSignal/src/sigtermSignal.c

00001 // sigtermSignal.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: The source code file for sigtermSignal.
00016 //
00017 
00018 #include <stdio.h>
00019 #include <stdlib.h>
00020 #include <unistd.h>
00021 #include <sys/types.h>
00022 #include <signal.h>
00023 #include <e32def.h>
00024 #include <time.h>
00025 
00026 
00027 FILE *gfp = NULL;
00028 char *testfile = "C:\\testfile.txt";
00029 
00033 void PressKey()
00034     {
00035     int ch;
00036     printf("Press 'e'+Enter to exit\n");
00037     while((ch=getchar())!= 'e')
00038         {
00039         if(ch == '\n')
00040             continue;
00041         else
00042             printf("wrong option selected, please try again!!!\n");
00043         }
00044     }
00051 void SIGTERM_handler(int signum)
00052     {
00053     if(signum == SIGTERM)
00054         {
00055         if(gfp != NULL)
00056             {
00057             printf("Received the SIGTERM signal from the raiseSignal process\n");
00058             fclose(gfp);
00059             remove(testfile);
00060             gfp = NULL;
00061             printf("The open file descriptor was closed\n");
00062             PressKey();
00063             exit (0);
00064             }
00065         }
00066     }
00067 
00077 int main()
00078     {
00079     char input[11];   
00080     int count = 0,num;
00081     int ch,ret;
00082     pid_t usrProcsID;
00083     const int delay = 4;                                    //Time delay of 4 sec provided.
00084     const int size = 50;                                    //No.of characters allowed in the filename.
00085     const int index = 3;                                    //No.of elements in the array.
00086     
00087     char *usrProcess = "Z:\\sys\\bin\\raisesignal.exe";    //Filename of process used for raising SIGTERM signal.
00088     char **argv = (char**)malloc(index*sizeof(char*));      //Variable holding values to be passed on to the raiseSignal process. 
00089     argv[0] = (char*)malloc(size*sizeof(char));
00090     argv[1] = (char*)malloc(index*sizeof(char));
00091     argv[2] = NULL;
00092 
00093     
00094     strcpy(argv[0], "z:\\sys\\bin\\raisesignal.exe");       //argv[0] holding name of the child process.
00095     sprintf(argv[1],"%d",getpid());                         //argv[1] holding parent pid.
00096 
00097     printf("*****************************************************************************************\n");
00098     printf("* Welcome to the demonstration of a graceful process termination using a SIGTERM signal *\n");
00099     printf("*****************************************************************************************\n");
00100     
00101     printf("* This example shows how a SIGTERM signal can be used to gracefully terminate a process.\n");
00102     printf("* The example first creates a process called sigtermSignal, assigns a custom handler\nfor the SIGTERM signal, opens a file and gets names from the user to be written in to it.\n");
00103     printf("* It then simultaneously spawns a raiseSignal process and starts reading from the file.\n");
00104     printf("* The raiseSignal process sends a SIGTERM signal to the sigtermSignal process.\n");
00105     printf("* On receiving the SIGTERM signal, the sigtermSignal process closes all the \nopen file descriptors and prepares to exit.\n");
00106     
00107     printf("\nPress the Enter key to continue\n");
00108     getchar();
00109 
00110     signal(SIGTERM, SIGTERM_handler);
00111     printf("************ In the sigtermSignal process ************\n");
00112     printf("Enter the number of names you want to enter (e.g. 8) :\n");
00113     scanf("%d", &count);
00114     gfp=fopen(testfile, "w+");   //Opening the file for read and write.
00115     if(gfp != NULL)
00116         {
00117         printf("File open sucessful\n");
00118         }
00119     else
00120         {
00121         printf("File open failed\n");
00122         }
00123     for(num=1; num<=count; num++)
00124         {
00125         printf("Name (%d)=", num);
00126         scanf("%s", input);
00127         fprintf(gfp, "%s\n", input);
00128         }
00129     
00130     printf("Press the Enter key to spawn the raiseSignal process\n");
00131     getchar();
00132     getchar();
00133     //Spawning raiseSignal process to accept user input.
00134     ret = posix_spawn(&usrProcsID,usrProcess,NULL,NULL,argv,(char**)NULL);
00135     if(ret != 0)     
00136         {         
00137         printf("\n*** failure posix_spawn ***\n");        
00138         return EXIT_FAILURE;     
00139         }
00140      rewind(gfp);
00141      printf("Starting to read from the file\n");
00142      for(num=1; num<=count; num++)
00143          {
00144          sleep (delay);       
00145          printf("Name (%d)=", num);
00146          while((ch=(fgetc(gfp))) != '\n')
00147                   {
00148                   putchar(ch);
00149                   }
00150          printf("\n");
00151          
00152          }
00153     if(!fclose(gfp))
00154         {
00155         remove(testfile);
00156         gfp = NULL;
00157         printf("File closed successfully\n");
00158         }
00159     else
00160         {
00161         printf("File close failed\n");
00162         }
00163   
00164     PressKey();
00165     return EXIT_SUCCESS;
00166     }

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