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cpp

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Drake University *

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Course

313

Subject

Philosophy

Date

Oct 30, 2023

Type

cpp

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Uploaded by MinisterBoulderLobster32

//multiples dont work #include <iostream> #include <vector> #include <string> #include <sys/types.h> #include <sys/wait.h> #include <unistd.h> #include <cstring> #include <fcntl.h> #include <sys/stat.h> #include <sys/param.h> #include <pwd.h> #include <ctime> #include "Tokenizer.h" using namespace std; // Function to handle single command execution with I/O redirection void executeSingleCommand(const vector<string>& command, bool is_background, string input_file = "", string output_file = "") { pid_t pid = fork(); if (pid < 0) { perror("fork"); exit(2); } if (pid == 0) { // Child process // Implement checks for I/O redirection and handle them using dup2 if (!input_file.empty()) { int in_fd = open(input_file.c_str(), O_RDONLY); if (in_fd == -1) { perror("open"); exit(2); } dup2(in_fd, 0); close(in_fd); } if (!output_file.empty()) { int out_fd = open(output_file.c_str(), O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR); if (out_fd == -1) { perror("open"); exit(2); } dup2(out_fd, 1); close(out_fd); } // Create an array of C-style strings from the vector vector<char*> args; for (const string& arg : command) { args.push_back(const_cast<char*>(arg.c_str())); } args.push_back(nullptr); // Execute the command in the child process execvp(args[0], args.data());

perror("execvp"); exit(2); } else { // Parent process if (!is_background) { int status = 0; waitpid(pid, &status, 0); if (status > 1) { exit(status); } } } } void executePipedCommands(const vector<vector<string>>& commands, bool is_background, string input_file = "", string output_file = "") { int prev_pipe_fd[2] = {-1, -1}; int next_pipe_fd[2] = {-1, -1}; for (size_t i = 0; i < commands.size(); ++i) { if (i < commands.size() - 1) { if (pipe(next_pipe_fd) == -1) { perror("pipe"); exit(2); } } pid_t pid = fork(); if (pid < 0) { perror("fork"); exit(2); } if (pid == 0) { // Child process if (i < commands.size() - 1) { close(next_pipe_fd[0]); dup2(next_pipe_fd[1], 1); close(next_pipe_fd[1]); } if (i > 0) { close(prev_pipe_fd[1]); dup2(prev_pipe_fd[0], 0); close(prev_pipe_fd[0]); } // Implement checks for I/O redirection if (i == 0) { if (!input_file.empty()) { int in_fd = open(input_file.c_str(), O_RDONLY); if (in_fd == -1) { perror("open"); exit(2); } dup2(in_fd, 0); close(in_fd); } } if (i == commands.size() - 1) {

if (!output_file.empty()) { int out_fd = open(output_file.c_str(), O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR); if (out_fd == -1) { perror("open"); exit(2); } dup2(out_fd, 1); close(out_fd); } } // Create an array of C-style strings from the vector vector<char*> args; for (const string& arg : commands[i]) { args.push_back(const_cast<char*>(arg.c_str())); } args.push_back(nullptr); // Execute the command in the child process execvp(args[0], args.data()); perror("execvp"); exit(2); } else { // Parent process if (!is_background) { // Close pipe file descriptors in the parent if (prev_pipe_fd[0] != -1) { close(prev_pipe_fd[0]); } if (prev_pipe_fd[1] != -1) { close(prev_pipe_fd[1]); } int status = 0; waitpid(pid, &status, 0); if (status > 1) { exit(status); } } // Update previous pipe file descriptors if (prev_pipe_fd[0] != -1) { close(prev_pipe_fd[0]); } if (prev_pipe_fd[1] != -1) { close(prev_pipe_fd[1]); } if (i < commands.size() - 1) { prev_pipe_fd[0] = next_pipe_fd[0]; prev_pipe_fd[1] = next_pipe_fd[1]; } } } } int main() {

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int original_stdin = dup(0); int original_stdout = dup(1); char prevWorkingDir[PATH_MAX]; vector<pid_t> background_pids; if (getcwd(prevWorkingDir, sizeof(prevWorkingDir)) == NULL) { perror("getcwd"); exit(EXIT_FAILURE); } for (;;) { time_t now = time(0); struct tm current_time; char timestamp[80]; current_time = *localtime(&now); strftime(timestamp, sizeof(timestamp), "%Y-%m-d %H:%M:%S", &current_time); struct passwd* pw = getpwuid(getuid()); const char* username = pw->pw_name; char current_dir[PATH_MAX]; if (getcwd(current_dir, sizeof(current_dir)) != NULL) { // Successfully obtained the current working directory } else { perror("getcwd"); exit(EXIT_FAILURE); } cout << "Shell " << timestamp << " " << username << ":" << current_dir << "$ "; string input; getline(cin, input); if (input == "exit") { cout << "Now exiting shell..." << endl << "Goodbye" << endl; break; } bool is_background = false; if (!input.empty() && input[input.length() - 1] == '&') { is_background = true; input.pop_back(); } // Debug: Print the input before tokenization cout << "Input: " << input << endl; if (input == "cd") { // Handle "cd" command without forking a new process if (chdir(getenv("HOME")) == -1) { perror("chdir"); } else { // Save the previous working directory strcpy(prevWorkingDir, current_dir); } } else if (input == "cd -") { // Handle "cd -" command without forking a new process if (prevWorkingDir[0] != '\0') {

if (chdir(prevWorkingDir) == -1) { perror("chdir"); } } else { cerr << "Previous working directory is not set.\n"; } } else if (input.compare(0, 3, "cd ") == 0) { char* newDir = &input[3]; if (chdir(newDir) == -1) { perror("chdir"); } else { // Save the previous working directory strcpy(prevWorkingDir, current_dir); } } else { // Tokenize the user input Tokenizer tknr(input); // Debug: Print parsed commands and associated input/output files for (size_t i = 0; i < tknr.commands.size(); ++i) { cout << "Command " << i << ": "; for (const string& arg : tknr.commands[i]->args) { cout << arg << " "; } cout << "Input file: " << tknr.commands[i]->in_file << " Output file: " << tknr.commands[i]->out_file << endl; } // Check if it's a single command or piped commands if (tknr.commands.size() == 1) { string input_file = tknr.commands[0]->in_file; string output_file = tknr.commands[0]->out_file; executeSingleCommand(tknr.commands[0]->args, is_background, input_file, output_file); } else { // Convert tknr.commands to a vector of vector of strings vector<vector<string>> commandStrings; for (size_t i = 0; i < tknr.commands.size(); ++i) { commandStrings.push_back(tknr.commands[i]->args); } string input_file = tknr.commands[0]->in_file; string output_file = tknr.commands[tknr.commands.size() - 1]- >out_file; executePipedCommands(commandStrings, is_background, input_file, output_file); } } } dup2(original_stdin, 0); dup2(original_stdout, 1); return 0; }