mshell/src/shell.c

#include "../include/shell.h"
#include "../include/input.h"
#include "../include/output.h"
#include "../include/utils.h"

/* Global definitions */
char *builtin[] = {
    "cd",
    "exit",
    "exec"};

int (*builtin_func[])(char **) = {
    &sh_cd,
    &sh_exit,
    &sh_exec};

/**
 * @brief Function for main loop. It prints prompt, reads user's input and executes it
 */
void process_command()
{
    cmds_p *coms = NULL;

    char *prompt = compose_prompt();
    print_str(prompt, strlen(prompt));

    char *line = read_line();

    char *tmp = trim_string(line, false);
    free(line);
    line = tmp;

    process_line(line, &coms);

    cmds_p *curr = coms;
    int status = 0;
    while (curr != NULL)
    {
        status = execute(curr);

        if (curr->stat.invert)
            if (status == 0)
                status = 1;
            else
                status = 0;

        curr->stat.s = status;
        term.last_status = curr->stat.s;

        if (curr->sep_next == AND_SEP)
        {
            if (term.last_status != 0)
                break;
        }
        else if (curr->sep_next == OR_SEP)
        {
            if (term.last_status == 0)
                break;
        }

        curr = curr->next;
    }

    free(line);
    free(prompt);
}

/**
 * @brief Extracts command and its arguments from line
 * 
 * @param line 
 * @param args 
 */
int process_line(char *line, cmds_p **coms)
{
    char *tmp = strdup(line), *free_tmp = tmp;
    int line_size = strlen(line), args_am = 0;

    *coms = new_cmd();

    cmds_p *curr_cmd = *coms;

    for (int i = 0; i < line_size; i++)
    {
        if (line[i] == '"')
        {
            tmp++;
            i++;
            int j = i;
            for (; j < line_size; j++)
                if (line[j] == '"')
                {
                    free_tmp[j] = '\0';

                    append_to_str_arr(&(curr_cmd->args), &args_am, trim_string(tmp, false));

                    tmp += strlen(curr_cmd->args[args_am - 1]) + 1;

                    break;
                }

            if (j >= line_size)
            {
                char *ap_line = read_line();

                line = realloc(line, strlen(line) + strlen(ap_line) + 1);
                line = strcat(line, ap_line);

                line_size = strlen(line);

                free(ap_line);
                i--;
                continue;
            }

            i = j;
            
            if (tmp[0] == ' ')
            {
                tmp++;
                i++;
            }
        }
        else if (line[i] == ';' || (line[i] == '&' && line[i + 1] == '&') || (line[i] == '|' && line[i + 1] == '|'))
        {
            free_tmp[i] = '\0';
            if (line[i - 1] != ' ')
            {
                append_to_str_arr(&(curr_cmd->args), &args_am, trim_string(tmp, false));
                tmp += strlen(curr_cmd->args[args_am - 1]) + 1;
            }
            else
                tmp++;

            curr_cmd->args = realloc(curr_cmd->args, sizeof(char *) * (args_am + 1));
            curr_cmd->args[args_am] = NULL;

            switch (line[i])
            {
            case ';':
                curr_cmd->sep_next = SEMICOLON_SEP;
                break;

            case '&':
                curr_cmd->sep_next = AND_SEP;
                i++;
                tmp++;
                break;

            case '|':
                curr_cmd->sep_next = OR_SEP;
                i++;
                tmp++;
                break;
            }

            if (tmp[0] == ' ')
            {
                tmp++;
                i++;
            }

            cmds_p *next = new_cmd();

            curr_cmd->next = next;
            curr_cmd = curr_cmd->next;
            args_am = 0;
        }
        else if (line[i] == ' ')
        {
            free_tmp[i] = '\0';

            append_to_str_arr(&(curr_cmd->args), &args_am, trim_string(tmp, false));

            tmp += strlen(curr_cmd->args[args_am - 1]) + 1;
        }
        else if (line[i] == '#')
        {
            break;
        }
    }

    if (tmp[0] != '\0' && tmp[0] != '#')
    {
        append_to_str_arr(&(curr_cmd->args), &args_am, trim_string(tmp, false));
    }

    if (curr_cmd->args[0] != NULL)
    {
        if (strcmp(curr_cmd->args[0], "!") == 0)
        {
            curr_cmd->stat.invert = true;
        }
    }

    free(free_tmp);

    curr_cmd->args = realloc(curr_cmd->args, sizeof(char *) * (args_am + 1));
    curr_cmd->args[args_am] = NULL;
    return args_am;
}

/**
 * @brief Executes either builtin or system command
 * 
 * @param args 
 * @return int 
 */
int execute(cmds_p *command)
{
    if (command->args[0] == NULL)
        return 1;

    char **args = command->args;

    if (strcmp(command->args[0], "!") == 0)
        args = slice_array(args, 1, -1, true);

    for (int i = 0; i < BUILTIN_NUM; i++)
        if (strcmp(args[0], builtin[i]) == 0)
            return (*builtin_func[i])(args);

    return launch(args);
}

/**
 * @brief Launches separate process and executes specified command
 * 
 * @param args 
 * @return int 
 */
int launch(char **args)
{
    pid_t pid, wpid;
    int status;

    pid = fork();

    if (pid == 0)
    {
        sh_exec(args);
    }
    else if (pid < 0)
    {
        perror("myshell1");
    }
    else
        do
            wpid = waitpid(pid, &status, WUNTRACED);
        while (!WIFEXITED(status) && !WIFSIGNALED(status));

    change_mode(1);

    return status;
}

/**
 * @brief Shell builtin command. Changes current working directory
 * 
 * @param args 
 * @return int 
 */
int sh_cd(char **args)
{
    if (args[1] == NULL)
        chdir(getenv("HOME"));
    else if (chdir(args[1]) < 0)
        perror("myshell2");

    return 0;
}

/**
 * @brief Shell builtin command. Exits shell
 * 
 * @param args 
 * @return int 
 */
int sh_exit(char **args)
{
    exit(0);
}

/**
 * @brief Shell builtin command. Executes command replacing shell with it
 * 
 * @param args 
 * @return int 
 */
int sh_exec(char **args)
{
    change_mode(0);
    signal(SIGINT, SIG_DFL);

    if (strcmp(args[0], "exec") == 0)
        args = slice_array(args, 1, -1, 1);

    if (execvp(args[0], args) < 0)
    {
        perror("myshell3");
    }

    exit(EXIT_FAILURE);
}

char *get_ip_addr()
{
    struct ifaddrs *host, *tmp;
    getifaddrs(&host);
    tmp = host;
    char *ip = NULL;

    while (tmp)
    {
        if (tmp->ifa_addr && tmp->ifa_addr->sa_family == AF_INET)
        {
            struct sockaddr_in *pAddr = (struct sockaddr_in *)tmp->ifa_addr;
            ip = inet_ntoa(pAddr->sin_addr);
            if (strncmp(ip, "127", 3) != 0)
                break;
        }

        tmp = tmp->ifa_next;
    }

    freeifaddrs(host);

    return ip;
}

/**
 * @brief Creates prompt string
 * 
 * @return char* 
 */
char *compose_prompt()
{
    // New line
    char *prompt = strdup("");

    // Username
    char *username = getenv("USER");
    if (username == NULL)
        username = "none";
    prompt = realloc(prompt, strlen(prompt) + strlen("\033[97;44m") + strlen(username) + 2);
    prompt = strcat(prompt, "\033[97;44m");
    prompt = strcat(prompt, username);

    // Current host ip
    char *ip = get_ip_addr();
    if (ip == NULL)
        ip = "none";
    prompt = realloc(prompt, strlen(prompt) + 1 + strlen(ip) + strlen("\033[39m") + strlen("\033[48;2;28;32;35m") + 2);
    prompt = strcat(prompt, "@");
    prompt = strcat(prompt, ip);
    prompt = strcat(prompt, "\033[39m");
    prompt = strcat(prompt, "\033[48;2;28;32;35m");
    prompt = strcat(prompt, ":");

    // Current path
    char *full_path = get_current_dir_name();
    prompt = realloc(prompt, strlen(prompt) + strlen("\033[92;1m") + strlen("\033[39;0m") + strlen(full_path) + 2);
    prompt = strcat(prompt, "\033[92;1m");
    prompt = strcat(prompt, full_path);
    prompt = strcat(prompt, "\033[39;0m");
    free(full_path);

    // Previous status
    if (term.last_status != 0)
    {
        char *status = malloc(snprintf(NULL, 0, " \033[91m%d\033[39m", term.last_status));
        sprintf(status, " \033[91m%d\033[39m", term.last_status);
        prompt = realloc(prompt, strlen(prompt) + strlen(status) + 1);
        prompt = strcat(prompt, status);
        free(status);
    }

    // Permissions specific character before user input
    prompt = realloc(prompt, strlen(prompt) + 4);
    if (getuid() == 0)
    {
        prompt = strcat(prompt, "\n# ");
    }
    else
        prompt = strcat(prompt, "\n% ");

    return prompt;
}

cmds_p *new_cmd()
{
    cmds_p *new = malloc(sizeof(cmds_p));
    new->args = calloc(0, sizeof(char *));
    new->stat.s = 0;
    new->stat.invert = false;
    new->next = NULL;
}