ProcessManager.c

#include "ProcessManager.h"

void Execute(){

    char **args = GetInput();

    /*
    - `start <command>`: Starts a new process with the specified command.
    - `stop <pid>`: Stops the process with the specified process ID (PID).
    - `signal <pid> <signal>`: Sends a signal to the process with the specified PID.
    - `info <pid>`: Displays information about the process with the specified PID.
    - `list`: Displays a list of all running processes.
    - `help`: Displays a list of available commands.
    */

    char* command = args[0];
    args = RemoveSignalElement(args); // Removes command from args array

    if(strcmp(command, "start") == 0){
        if(Start(args) != 0)
            die("Start command error");
    }else if(strcmp(command, "stop") == 0){
        if(Stop(args) != 0)
            die("Stop command error");
    }else if(strcmp(command, "signal") == 0){
        // Signal(args);
    }else if(strcmp(command, "info") == 0){
        // Info(args);
    }else if(strcmp(command, "list") == 0){
        List();
    }else if(strcmp(command, "help") == 0){
        // Help();
    }else if(strcmp(command, "exit") == 0){
        die("Program Exit");
    }else{
        // InputError();
    }

}

/**
 * Start process with given command and arguments
 *
 * @param args Command name to execute and its arguments as string array
 * @return 0 for successful execution, -1 for any errors
 */
int Start(char **args){
    // Usage of this function could be changed later
    
    // Creating child process to execute command
    pid_t pid = fork();
    int status;

    if(pid < 0)
        // PID Error Case
        return -1;
    else if(pid == 0){
        // Child process
        if(execvp(args[0], args) == -1) return -1;
    }
    else
        // Parent process
        waitpid(pid, &status, 0);

    return 0;
}

/**
 * Stops the given pid with kill command
 *
 * @param args Process pid to kill
 * @return 0 for successfull execution, -1 for any errors
 */
int Stop(char **args){
    int pid = atoi(args[0]);
    return kill(pid, SIGKILL); 
}

/**
 * <Summary>
 *
 * @param args <Summary>
 * @return <Summary>
 */
char** RemoveSignalElement(char **args){
    int i = 0;
    // Remove signals: "start", "kill"
    if(args[i+1] != NULL){
        for(i = 0; args[i + 1] != NULL; i++)
            args[i] = args[i + 1];
        args[i] = NULL; 
    }

    // Remove any trailing whitespace
    for(i = 0; args[i] != NULL; i++){
        int len = strlen(args[i]);
        while(len > 0 && isspace(args[i][len - 1]))
            args[i][len-- - 1] = '\0';
    }
    return args;
}

void List(){
    FILE* fp;
    char path[1024];
    char cmdline[1024];

    printf("%-10s %s\n", "PID", "Command");

    fp = popen("ps -e -o pid,cmd --no-header", "r");
    if (fp == NULL)
        perror("popen failed");

    while (fgets(cmdline, sizeof(cmdline), fp) != NULL) {
        int pid;
        sscanf(cmdline, "%d %[^\n]", &pid, path);

        // Print the process ID and command line
        printf("%-10d %.*s\n", pid, 25, path);
    }

    pclose(fp);
}