fg_bg.c

#include "def.h"

int zFlag1 = 0, savePid = 0;

void handleZ1(int signal)
{
    zFlag1 = 1;

    return;
}

void fg_bg(char curCommand[], int flag, int **proc_size, process proc[])
{
    // printf("%s curCommand\n", curCommand);
    char **store = (char**) malloc(sizeof(char*) * MAX_SIZE);

    char saveName[MAX_SIZE];
    strcpy(saveName, curCommand);

    if(flag)
    {
        strcpy(proc[**proc_size].name, curCommand);
    }

    char *token = strtok(curCommand, " \t\n");   

    int cnt = 0;

    while(token != NULL)
    {
        store[cnt] = token;
        // printf("%s *\n", store[cnt]);
        // printf("%s *** %d\n", token, cnt);
        // store[cnt][strlen(token)] = '\0';
        cnt++;

        token = strtok(NULL, " \t");
        // printf("%s token\n", token);
    }
    store[cnt++] = NULL;

    // If '&' was present, then run in background
    if(flag)
    {
        int pid = fork();

        if(pid < 0)
        {
            perror(store[0]);
        }

        if(pid == 0)
        {
            // printf("*\n");
            setpgid(0, 0);
            // close(STDERR_FILENO); // So that processes like firefox does not print error after closing
            if(execvp(store[0], store) == -1)
            {
                printf("%s: Command Not Found\n", store[0]);
                // exit(0);
            }
        }
        
        if(pid > 0)
        {
            setpgid(pid, pid);
            
            proc[**proc_size].pid = pid;
            strcpy(proc[**proc_size].name, saveName);
            (**proc_size)++;
        }
    }

    // Run in foreground
    else
    {
        // printf("* %s\n", store[0]);

        // int pid = 7;
        int pid = fork();

        if(pid < 0)
        {
            perror(store[0]);
        }

        else if(pid == 0)
        {
            setpgid(0, 0);

            // printf("hello ***\n");

            // fflush(stdout);
            if(execvp(store[0], store) == -1)
            {
                // printf("******\n");
                printf("%s: Command Not Found\n", store[0]);
                exit(0);
            }
        }

        else
        {
            savePid = pid;
            // signal(SIGTSTP, handleZ1);
         
            // int status;
            // waitpid(pid, &status, WUNTRACED);
            
            // if(zFlag1 == 1)
            // {
            //     kill(savePid, SIGSTOP);
                
            //     proc[**proc_size].pid = savePid;
            //     strcpy(proc[**proc_size].name, saveName);
            //     (**proc_size)++;

            //     zFlag1 = 0;
            // }   

            int shellPid = getpid();
            int status;
            signal(SIGTTOU, SIG_IGN);
            signal(SIGTTIN, SIG_IGN);
            tcsetpgrp(0, pid);
            tcsetpgrp(1, pid);
            // printf("**\n"); 
            waitpid(savePid, &status, WUNTRACED);
            // printf("**\n");
            tcsetpgrp(0, getpgid(shellPid));
            tcsetpgrp(1, getpgid(shellPid));
            
            signal(SIGTTOU, SIG_DFL);
            signal(SIGTTIN, SIG_DFL);

            if(WIFSTOPPED(status))
            {
                kill(savePid, SIGSTOP);
                
                proc[**proc_size].pid = savePid;
                strcpy(proc[**proc_size].name, saveName);
                (**proc_size)++;
            }

        }
    }
}