Thread: having trouble with my chdir() function

for some reason its only allowing me to change my cwd once i was just needing some insight if i was using the chdir() correctly or not. Thanks

Code:

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>




#define MAX_COMMAND_SIZE 80
#define MAX_ARGS 9
#define HIS_SIZE 100




typedef struct
{
  int argument;                                   // userCom arguments
  char *arg[MAX_ARGS + 1];                  // userCom arguments array  
  //char *history[HIS_SIZE];                    //history array 
  char *input;                          // hold input file
  char *output;                        // hold output file
} Command;






    


int main()
{
    Command userCom = {0};                         //holds userCom struct
    const char *whitespace = " \n\r\t\v\f";      // userCom delimiting chars
    char* username = getenv("USER");              //Get user name 
    char* curDirect = getenv("HOME");             //get cwd
    char* token[MAX_ARGS];    
    char* history[HIS_SIZE];
    char* cwd;
    char* buf;
    char* cmd;
    char buffer[MAX_COMMAND_SIZE + 1];         //hold userCom line
    //char history[HIS_SIZE][MAX_ARGS +1];    //2D array for history 
    int tok = 0;
    int new;
    int i;
    int limit;
    int last = 0; 
    int hist = 0;                            //initialize history size to 0 
    long size;
    struct stat buff;                        //holds file information
     
     
    //gets current working directory and also changes buffer if necessary 
    size = pathconf(".", _PC_PATH_MAX);
    if ((buf = (char *)malloc((size_t)size)) != NULL)
    cwd = getcwd(buf, (size_t)size);
    
    while(1){
    userCom.argument = 0; 
    userCom.input = NULL;
    userCom.output = NULL; 
    
      
    //prints users prompt 
    printf("\n%s@myshell:%s>", username,cwd); 
    
    //gets string from userCom line
    fgets(buffer, MAX_COMMAND_SIZE + 1, stdin);
    
    buffer[strlen(buffer)-1] = 0 ;//set null
    
    //set-up history function 
     history[last% HIS_SIZE] = cmd;
     last++;
    
    //parses tokens and looks for delimiters 
    token[tok] = strtok(buffer,whitespace);
    while(token[tok])
    {
        ++tok;
        if(tok == MAX_ARGS){
        printf("Reached MAX userCom arguments");
        break;
        }
        token[tok] = strtok(NULL, whitespace);
    }
    
    i =0;
    //sort tokens based on special characters
    for (;i<tok;++i)


    {
        if(!strcmp(token[i], "<"))
            {
             userCom.output = token[++i];
            }
        else if(!strcmp(token[i], ">"))
        {
            userCom.input = token[++i];
        }
        else if (token[i][0] == '$')
        {
          char* toktok = getenv((const char*)&token[i][1]);


          if (!toktok)
            {
              printf("%s: ERROR: variable.\n", token[i]);
              return 0;
            }
          else
            {
              userCom.arg[userCom.argument] = toktok;
              ++(userCom.argument);
            }
        }


      else
        {
          userCom.arg[userCom.argument] = token[i];
          ++(userCom.argument);
    
        }
    }
        tok = 0;
        userCom.arg[userCom.argument] = 0;    
        
    //handles the "cd" command
        if((strcmp(userCom.arg[0],"cd") == 0))
        {    
            if (userCom.argument > 2){
          printf("cd: Too many arguments\n");
          }
          // change directories if valid target and update cwd


          else if (userCom.argument == 2)
                {
                 new = chdir(cwd);
                  if (new != 0)
                      printf("%s: No such file or directory\n",cwd);
                      else{
                      size = pathconf(".", _PC_PATH_MAX);
                        if ((buf = (char *)malloc((size_t)size)) != NULL)
                        cwd = getcwd(buf, (size_t)size);
                      }
                }
                // if no argument is given, new directory should be $HOME
                  else{
                    new = chdir(curDirect);
            
                    size = pathconf(".", _PC_PATH_MAX);
                    if ((buf = (char *)malloc((size_t)size)) != NULL)
                    cwd = getcwd(buf, (size_t)size);
                }
        }//end "cd" function

A more thorough description of your problem would be good, with sample input and any output/error messages you see. Note, if your program is failing, but you get no error message, then you are probably not checking for all the errors you should be. Also, code that compiles: you're missing a few closing braces at least, and possibly other code that between line 166 above and the end of your program; who knows what else.

Lastly, make sure you give all your variables (e.g. cmd) a value before you use them. Using uninitialized variables results in undefined behavior.