Unix_Shell/main.c at main · sanjitakr/Unix_Shell · GitHub

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#include "commands.h"

char** parse_input(char *input){
    size_t buffer_size=MAX_INPUT;
    char **tokens = malloc(buffer_size*sizeof(char*));
    char* token=NULL;
    size_t position=0;
    size_t token_length=0;
    if(!tokens){
        perror("Malloc");
        exit(1);
    }
    for(size_t i=0; input[i]; i++){
        token=&input[i];
        while(input[i] == ' ' || input[i] == '\n' || input[i] == '\t' || input[i] == '\r' || input[i] == '\a'){
            i++;
        }

        if(input[i] == '\0') break;
        token = &input[i];
        while (input[i] != '\0' && input[i] != ' ' && input[i] != '\n' && input[i] != '\t' && input[i] != '\r' && input[i] != '\a'){
            token_length++;
            i++;
        }

        tokens[position]=malloc((token_length+1)*sizeof(char));
        if(!tokens[position]){
            perror("Malloc");
            exit(1);
        }
        for (size_t j=0; j<token_length; j++){
            tokens[position][j]=token[j];
        }
        tokens[position][token_length]='\0';
        position++;
        token_length=0;
    }

    tokens[position] = NULL;
    return tokens;
}

void free_objects(char** tokens){
    if (tokens)
        return;
    for (size_t i = 0; tokens[i]; i++){
        free(tokens[i]);
    }
    free(tokens);
}

void display_all_commands(){
    printf("cd <directory>      - Change the current directory.\n");
    printf("pwd                 - Print the current working directory.\n");
    printf("echo <text>         - Print the given data.\n");
    printf("env                 - Display all env variables.\n");
    printf("setenv VAR=value    - Set an env var.\n");
    printf("unsetenv <variable> - Remove an env var.\n");
    printf("which <command>     - Locate an exec in the system's PATH.\n");
    printf("help                - Display this help message.\n");
    printf("exit or quit        - Exit shell.\n");
}

int shell_built_in(char **args, char **env, char *initial_dir){
    (void) env;
    (void) initial_dir;
    if (strcmp(args[0], "cd") == 0) {
        return command_cd(args, initial_dir);
    } else if (strcmp(args[0], "pwd") == 0) {
        command_pwd();
    } else if (strcmp(args[0], "echo") == 0) {
        command_echo(args, env);
    } else if (strcmp(args[0], "env") == 0) {
        command_env(env);
    } else if (strcmp(args[0], "which") == 0) {
        command_which(args, env);
    } else if (strcmp(args[0], "exit") == 0 || strcmp(args[0], "quit") == 0) {
        exit(EXIT_SUCCESS);
    }
    else if(strcmp(args[0],"help")==0){
        display_all_commands();
    }
    else {
        return execute(args,env);
    }
    return 0;
}

void call_shell_commands(char ** env){
    char* input=NULL;
    size_t input_size=0;

    char * initial_dir=getcwd(NULL,0);
    char **args;
    while(1){
        printf("$");
        if(getline(&input, &input_size, stdin)==-1){
            perror("getline");
            break;
        }

        args=parse_input(input);
        if(args[0]!=NULL && strcmp(args[0], "setenv") == 0){
            env = command_setenv(args, env);
        }
        else if(args[0]!=NULL && strcmp(args[0], "unsetenv") == 0){
            env = command_unsetenv(args, env);
        }
        else if(args[0]!=NULL){
            shell_built_in(args,env,initial_dir);
        }
        else{
            return;
        }

    }


    free_objects(args);
}

int main(int argc, char** argv, char **ev){
    (void)argc;
    (void)argv;

    call_shell_commands(ev);
}