doit.cpp

#include <iostream>
using namespace std;
#include <cstring>
#include <unistd.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <stdlib.h>

extern char **environ;

struct backgroundJob {
    pid_t pid;
    struct timeval startTime;
    struct timeval endTime;
    char command[128];
};

void printProcessStats(struct timeval start, struct timeval end) {
    struct rusage usage;
    getrusage(RUSAGE_CHILDREN, &usage);

    // Print CPU Time
    cout << "User CPU Time: " << usage.ru_utime.tv_sec << "s " << usage.ru_utime.tv_usec << "us" << endl;
    cout << "System CPU Time: " << usage.ru_stime.tv_sec << "s " << usage.ru_stime.tv_usec << "us" << endl;

    // Print Wall-Clock Time
    cout << "Wall-Clock Time: " << (end.tv_sec - start.tv_sec) << "s " << (end.tv_usec - start.tv_usec) << "us" << endl;

    // Print Preempted Involuntarily
    cout << "Preempted Involuntarily: " << usage.ru_nivcsw << endl;

    // Print Voluntary Context Switches
    cout << "Voluntary Context Switches: " << usage.ru_nvcsw << endl;

    // Print Page Faults
    cout << "Major Page Faults: " << usage.ru_majflt << endl;
    cout << "Minor Page Faults: " << usage.ru_minflt << endl;
}

int main(int argc, char *argv[]) {
    char *argvNew[32];
    //cout << "Hello, World!" << endl;

    /*for (int i = 0; i < argc; i++) {
        cout << "Argument " << i << ": " << argv[i] << endl;
    }*/
    if (argc == 1) {
        //Create Shell
        char prompt[32] = "==>";
        backgroundJob background[128];
        int bgCount = 1;
        while (true) {
            struct timeval start;
            struct timeval end;
            gettimeofday(&start, NULL);
            bool isBackground = false;
            char* line = new char[128];
            cout << prompt;
            cin.getline(line, 128);
            gettimeofday(&start, NULL);
            if (strcmp(line, "exit") == 0) {
                delete[] line;
                break;
            }
            // Tokenize the input line
            char* token = strtok(line, " ");
            int i = 0;
            while (token != NULL && i < 32) {
                argvNew[i++] = token;
                token = strtok(NULL, " ");
            }
            if (strcmp(argvNew[i - 1], "&") == 0) {
                argvNew[i - 1] = NULL;
                isBackground = true;
            }
            argvNew[i] = NULL;

            if (strcmp(argvNew[0], "cd") == 0) {
                if (chdir(argvNew[1]) != 0) {
                    cerr << "CD error\n";
                } else {
                    argvNew[1] = getcwd(NULL, 0);
                    cout << "Directory changed to: " << argvNew[1] << endl;
                }
                continue;
            } else if (strcmp(argvNew[0], "set") == 0 && strcmp(argvNew[1], "prompt") == 0 && strcmp(argvNew[2], "=") == 0) {
                if (argvNew[3] != NULL) {
                    strncpy(prompt, argvNew[3], sizeof(prompt) - 1);
                    prompt[sizeof(prompt) - 1] = '\0';  // Ensure null-termination
                    cout << "Prompt set to: " << prompt << endl;
                }
                continue;
            } else if (strcmp(argvNew[0], "jobs") == 0) {
                // List background jobs
                for (int i = 1; i < bgCount; i++) {
                    cout << "[" << i << "] " << background[i].pid << " " << background[i].command << endl;
                }
            }

            // Check if any background jobs have completed
            for (int i = 1; i <= bgCount; i++) {
                //cout << "Checking job [" << i << "]" << background[i].startTime.tv_sec << endl;
                if (waitpid(background[i].pid, NULL, WNOHANG) > 0) {
                    cout << "Background job [" << i << "] completed." << endl;
                    gettimeofday(&background[i].endTime, NULL);
                    //cout << background[i].startTime.tv_sec << " " << background[i].endTime.tv_sec << endl;
                    printProcessStats(background[i].startTime, background[i].endTime);
                    // Remove the completed job from the list
                    for (int j = i; j < bgCount - 1; j++) {
                        background[j] = background[j + 1];
                    }
                    bgCount--;
                    i--;
                }
            }

            // Fork and exec the command
            pid_t child_pid = fork();
            if (child_pid == 0) {
                execvp(argvNew[0], argvNew);
                cerr << "Exec error\n";
                exit(1);
            } else if (child_pid < 0) {
                cerr << "Fork error\n";
                exit(1);
            } else {
                if (isBackground) {
                    if (waitpid(child_pid, NULL, WNOHANG) == 0) {
                        struct timeval temp;
                        background[bgCount].pid = child_pid;
                        strncpy(background[bgCount].command, argvNew[0], sizeof(background[bgCount].command) - 1);
                        background[bgCount].command[sizeof(background[bgCount].command) - 1] = '\0';  // Ensure null-termination
                        temp.tv_sec = start.tv_sec;
                        temp.tv_usec = start.tv_usec;
                        background[bgCount].startTime = temp;
                        cout << bgCount << " " << background[bgCount].startTime.tv_sec << endl;
                        cout << "[" << bgCount++ << "] " << child_pid << endl;
                        continue;
                    } else if (waitpid(child_pid, NULL, 0) < 0) {
                        cerr << "Waitpid error\n";
                    } else {
                        cout << "\n" << background[bgCount].command << " command executed successfully\nCommand Statistics:" << endl;
                        gettimeofday(&background[bgCount].endTime, NULL);
                        printProcessStats(background[bgCount].startTime, background[bgCount].endTime);
                    }
                }
                waitpid(child_pid, NULL, 0);
                cout << "\n" << argvNew[0] << " command executed successfully\nCommand Statistics:" << endl;
                gettimeofday(&end, NULL);
                printProcessStats(start, end);
            }
            delete[] line;
        }
    } else {
        pid_t pid = fork();
        struct timeval start1, end1;
        gettimeofday(&start1, NULL);
        

        if (pid < 0) {
            cerr << "Fork error\n";
            exit(1);
        } else if (pid == 0) {
            //cout << "In child process" << endl;
            // Child process
            //string path = "wc";
            argvNew[0] = argv[1];
            argvNew[1] = argv[2];
            argvNew[2] = NULL;


            /*
            if (execvp(argvNew[0], argvNew) < 0) {
                cerr << "Exec error\n";
                exit(1);
            }*/
        execvp(argvNew[0], argvNew);
        cerr << "Exec error\n";
        exit(1);
        } else {
            int status;
            // Parent process
            waitpid(pid, &status, 0);
            if (argc > 1) {
                //cout << "\n" << argv[1] << " command executed successfully\nCommand Statistics:" << endl;
                gettimeofday(&end1, NULL);
                printProcessStats(start1, end1);
            }

            //cout << "Child exited with status " << status << endl;
        }

        //cout << "Done" << endl;
        return 0;
    }
}