cmd.c

/* mshell - a job manager */

#include <stdio.h>
#include <signal.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "jobs.h"

#define BOLD "\033[00;01m"
#define NORM "\033[00;00m"

void do_help() {
    printf("available commands are:\n");
    printf(" exit - cause the shell to exit\n");
    printf(BOLD "\t exit\n" NORM);
    printf(" jobs - display status of jobs in the current session\n");
    printf(BOLD "\t jobs\n" NORM);
    printf(" fg   - run a job identified by its pid or job id in the foreground\n");
    printf(BOLD "\t fg " NORM "pid" BOLD "|" NORM "jobid \n");
    printf(" bg   - run a job identified by its pid or job id in the background\n");
    printf(BOLD "\t bg " NORM "pid" BOLD "|" NORM "jobid \n");
    printf(" stop - stop a job identified by its pid or job id\n");
    printf(BOLD "\t stop " NORM "pid" BOLD "|" NORM "jobid \n");
    printf(" kill - kill a job identified by its pid or job id\n");
    printf(BOLD "\t kill " NORM "pid" BOLD "|" NORM "jobid \n");
    printf(" help - print this message\n");
    printf(BOLD "\t help\n" NORM);
    printf("\n");
    printf("ctrl-z and ctrl-c can be used to send a SIGTSTP and a SIGINT, respectively\n\n");
}

/* treat_argv - Determine pid or jobid and return the associated job structure */
struct job_t *treat_argv(char **argv) {
    struct job_t *jobp = NULL;

    /* Ignore command if no argument */
    if (argv[1] == NULL) {
        printf("%s command requires PID or %%jobid argument\n", argv[0]);
        return NULL;
    }

    /* Parse the required PID or %JID arg */
    if (isdigit((int) argv[1][0])) {
        pid_t pid = atoi(argv[1]);
        if (!(jobp = jobs_getjobpid(pid))) {
            printf("(%d): No such process\n", (int) pid);
            return NULL;
        }
    } else if (argv[1][0] == '%') {
        int jid = atoi(&argv[1][1]);
        if (!(jobp = jobs_getjobjid(jid))) {
            printf("%s: No such job\n", argv[1]);
            return NULL;
        }
    } else {
        printf("%s: argument must be a PID or %%jobid\n", argv[0]);
        return NULL;
    }

    return jobp;
}


/* do_bg - Execute the builtin bg command */
void do_bg(char **argv) {
    
    struct job_t *job;
    int k;

    if (verbose) {
        printf("Entering BG\n");
    }

    job = treat_argv(argv);

    if (job == NULL) {
        if (verbose) {
            printf("Non existing job : exiting waitfg\n");
        }
        return;
    }

    job->jb_state = BG;
     k = kill(job->jb_pid,SIGCONT);

     if (k <0) {
        unix_error("kill error");
     }

    if (verbose) {
        printf("Exiting BG\n");
    }

    return;
}

/* waitfg - Block until process pid is no longer the foreground process */
void waitfg(pid_t pid) {
    
    struct job_t *job;
    
    if (verbose) {
        printf("Entering wait FG\n");
    } 

    job=jobs_getjobpid(pid);

    if (job == NULL) {
        if (verbose) {
            printf("Non existing job : exiting wait FG\n");
        }
        return;
    }

    while (job->jb_pid == pid && job->jb_state == FG) {
        sleep(1);
        if (verbose) {
            fprintf(stderr, "Waiting\n");
        }
        
    }

    if (verbose) {
        printf("Exiting wait FG\n");
    }


    return;
}

/* do_fg - Execute the builtin fg command */
void do_fg(char **argv) {
    
    struct job_t *job;
    int k;

    if (verbose) {
        printf("Entering FG\n");
    }

    job = treat_argv(argv);

    if (job == NULL) {
        if (verbose) {
            printf("Non existing job : exiting do_fg\n");
        }
        return;
    }

    job->jb_state = FG;
    k = kill(job->jb_pid,SIGCONT);

    if (k <0) {
        unix_error("kill error");
    }

    if (verbose) {
        printf("Exiting do_fg\n");
    }
    
    return;
}

/* do_stop - Execute the builtin stop command */
void do_stop(char **argv) {
    
    struct job_t *job;
    int k;

    if (verbose) {
        printf("Entering stop\n");
    }

    job = treat_argv(argv);

    if (job == NULL) {
        if(verbose) {
            printf("Non existing job : exiting stop\n");
            return;
        }
    }

    job->jb_state = ST;
    k = kill(job->jb_pid,SIGSTOP);

    if (k <0) {
        unix_error("kill error");
    }

    if (verbose) {
        printf("Exiting stop \n");
    }

    return;
}

/* do_kill - Execute the builtin kill command */
void do_kill(char **argv) {
    
   struct job_t *job;
   int k;
   

   if (verbose) {
    printf("Entering kill\n");
   }

   job = treat_argv(argv);

   if (job == NULL) {
    if (verbose) {
        printf("Non existing job : exiting kill\n");
    }
    return;
   }

   k= kill(job->jb_pid,SIGKILL);

   if (k <0) {
    unix_error("kill error");
   }
   
   if (verbose) {
    printf("Exiting kill\n");
   }

    return;
}

/* do_exit - Execute the builtin exit command */
void do_exit() {
    if (verbose) {
        printf("Exiting \n");
    }
    exit(EXIT_SUCCESS);
}

/* do_jobs - Execute the builtin fg command */
void do_jobs() {
    if (verbose) {
        printf("Current jobs in the foreground process\n");
    }
    jobs_listjobs();
}