74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
//
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// Wrote for Computer Networks and Systems lab classes
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// AUTHOR : Sergiusz Warga
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <time.h>
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const char * time_from_main_exec() {
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struct timeval now;
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gettimeofday(&now, NULL);
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char buff[127];
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sprintf(&buff, "us : %d", now.tv_usec);
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return buff;
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}
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void parent_before_child() {
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pid_t pid;
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printf("\nparent_before_child()\n");
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pid = fork();
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if (pid == -1) { // If something went wrong.
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perror("Fork: ");
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exit(EXIT_FAILURE);
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}
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if (pid != 0) { // If this is a parent process.
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printf("===\n%s\nI am a parent.\nMy PID is: %d\n===", time_from_main_exec(), getpid());
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kill(getpid(), SIGTERM);
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} else {
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sleep(1);
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printf("===\n%s\nI am a child.\nMy PID is: %d\n===", time_from_main_exec(), getpid()); // This line will not be printed, as (usually) parent process will finish
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// its execution in less than 1 second
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}
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}
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void child_before_parent() {
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pid_t pid;
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printf("\nchild_before_parent()\n");
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printf("PID before fork: %d\n", getpid());
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pid = fork();
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if (pid == -1) { // If something went wrong.
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perror("Fork: ");
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exit(EXIT_FAILURE);
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}
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if (pid == 0) { // If this is a parent process.
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printf("===\n%s\nI am a child.\nMy PID is: %d\n===", time_from_main_exec(), getpid());
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kill(getpid(), SIGTERM);
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} else {
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sleep(1);
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printf("===\n%s\nI am a parent.\nMy PID is: %d\n===", time_from_main_exec(), getpid());
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}
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}
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int main() {
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pid_t pid;
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printf("%s: Grandparent process has PID: %d\n", time_from_main_exec(), getpid());
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pid = fork();
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if (pid == 0) { // If child process
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printf("%s: Process with PID %d will execute funs.\n", time_from_main_exec(), getpid());
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child_before_parent();
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sleep(1);
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parent_before_child();
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sleep(1);
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} else { // If parent process
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printf("%s: Grandparent's child process has PID: %d\n", time_from_main_exec(), pid);
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sleep(5);
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}
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return 0;
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} |