c programming project

#include <stdlib.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <readline/readline.h> #include "builtin.h" #include "parse.h" /******************************************* * Set to 1 to view the command line parse * *******************************************/ #define DEBUG_PARSE 0 void print_banner () { printf (" ________ \n"); printf ("_________________________ /_ \n"); printf ("___ __ \\_ ___/_ ___/_ __ \\ \n"); printf ("__ /_/ /(__ )_(__ )_ / / / \n"); printf ("_ .___//____/ /____/ /_/ /_/ \n"); printf ("/_/ Type 'exit' or ctrl+c to quit\n\n"); } /* returns a string for building the prompt * * Note: * If you modify this function to return a string on the heap, * be sure to free() it later when appropirate! */ static char* build_prompt () { return "$ "; } /* return true if command is found, either: * - a valid fully qualified path was supplied to an existing file * - the executable file was found in the system's PATH * false is returned otherwise */ static int command_found (const char* cmd) { char* dir; char* tmp; char* PATH; char* state; char probe[PATH_MAX]; int ret = 0; if (access (cmd, X_OK) == 0) return 1; PATH = strdup (getenv("PATH")); for (tmp=PATH; ; tmp=NULL) { dir = strtok_r (tmp, ":", &state); if (!dir) break; strncpy (probe, dir, PATH_MAX-1); strncat (probe, "/", PATH_MAX-1); strncat (probe, cmd, PATH_MAX-1); if (access (probe, X_OK) == 0) { ret = 1; break; } } free (PATH); return ret; } /* Called upon receiving a successful parse. * This function is responsible for cycling through the * tasks, and forking, executing, etc as necessary to get * the job done! */ void execute_tasks (Parse* P) { unsigned int t; for (t = 0; t < P->ntasks; t++) { if (is_builtin (P->tasks[t].cmd)) { builtin_execute (P->tasks[t]); } else if (command_found (P->tasks[t].cmd)) { printf ("pssh: found but can't exec: %s\n", P->tasks[t].cmd); } else { printf ("pssh: command not found: %s\n", P->tasks[t].cmd); break; } } } int main (int argc, char** argv) { char* cmdline; Parse* P; print_banner (); while (1) { cmdline = readline (build_prompt()); if (!cmdline) /* EOF (ex: ctrl-d) */ exit (EXIT_SUCCESS); P = parse_cmdline (cmdline); if (!P) goto next; if (P->invalid_syntax) { printf ("pssh: invalid syntax\n"); goto next; } #if DEBUG_PARSE parse_debug (P); #endif execute_tasks (P); next: parse_destroy (&P); free(cmdline); } }