134 lines
3.4 KiB
C
134 lines
3.4 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#define MAX_SIZE 1024
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// int LogCommandHistory(char* buf, char** command_log, int n) {
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// command_log[n] = buf;
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// }
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void PrintCurrentDir() { // pwd
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char cwd[MAX_SIZE];
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if (getcwd(cwd, sizeof(cwd)) != NULL) {
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printf("[%s] $ ", cwd);
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} else {
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perror("getcwd() error");
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}
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}
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int ChangeDirectory(char** args) { // cd
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args++; // Moving pointer to the next element (cd requires local or global path, the first argument is command name, so it's skipped)
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char* path = args[0];
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if (path == NULL || strcmp(path, "~") == 0) {
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path = getenv("HOME");
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}
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if (chdir(path) != 0) {
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perror("cd");
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return -1;
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}
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return 0;
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}
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void PrintHelp() { // help
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printf("C Microshell implementation by Maciej Życzyński\n");
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}
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int HandleBuiltInCommands(char* command, char** args) { // Manual implementation of commands unsupported by execvp()
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if (strcmp(command, "cd") == 0) {
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ChangeDirectory(args);
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return 1;
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}
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else if (strcmp(command, "help") == 0) {
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PrintHelp();
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return 1;
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}
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else if (strcmp(command, "exit") == 0) {
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return 2;
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}
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return 0;
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}
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int HandleCommand(char* command, char** args) { // Execute commands supported by execvp()
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if (execvp(command, args) == -1) {
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perror("Error executing command");
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return -1;
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}
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return 0;
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}
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int ParseCommand(char* buf, char** command, char** args) {
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char buf_cp[MAX_SIZE];
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strcpy(buf_cp, buf); // Leave the original buffer (important for command history implementation)
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buf_cp[strlen(buf_cp) - 1] = '\0'; // Remove newline from input string
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char* token = strtok(buf_cp, " ");
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int tok_count = 0;
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if (token == NULL) { // Retrieve command and arguments
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return -1;
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}
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*command = token;
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while (token != NULL) {
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args[tok_count] = token;
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tok_count++;
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token = strtok(NULL, " ");
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}
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args[tok_count] = NULL; // Manually add NULL at the end (execvp() requires the argument array to be null-terminated)
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return 0;
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}
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int main() {
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char buf[MAX_SIZE];
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char* command_log[MAX_SIZE];
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int n = 0;
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while (1) {
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PrintCurrentDir();
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char* command;
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char* args[MAX_SIZE];
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fgets(buf, sizeof(buf), stdin);
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if (ParseCommand(buf, &command, args) < 0) {
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printf("Invalid command\n");
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continue;
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}
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// LogCommandHistory(buf, &command_log, n);
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// n++;
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int handler_value = HandleBuiltInCommands(command, args);
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if (handler_value == 2) { // Exit command
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break;
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}
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else if (handler_value == 0) { // Not a built-in command
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// Forking logic
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pid_t pid = fork();
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if (pid < 0) {
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perror("Error while forking\n");
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}
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else if (pid == 0) { // Child process
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if (HandleCommand(command, args) == -1) {
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exit(EXIT_FAILURE);
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}
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exit(EXIT_SUCCESS);
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}
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else { // Parent process
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int status;
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if (waitpid(pid, &status, 0) == -1) {
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perror("Error with parent process\n");
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}
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}
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}
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}
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return 0;
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} |