Thread: Problem with read().(from K&R)

I am in the learning phase of c. I am reading K & R and trying to execute one of the program "listing directories".

Code:

#include "cDirent.h"
#include<sys/stat.h>
#include<string.h>
#include<sys/types.h>
#include "syscall.h"
#include<fcntl.h>
#include<sys/dir.h>
#include<stdlib.h>
#ifndef DIRSIZ
#define DIRSIZ 14
#endif

Dir *copendir(char *dirname){
  int fd;
  struct stat stbuf;
  Dir *dp;
  if((fd=open(dirname,O_RDONLY,0)) == -1 || fstat(fd,&stbuf) == -1 || (stbuf.st_mode & S_IFMT) != S_IFDIR || (dp = (Dir *) malloc (sizeof(Dir))) == NULL)
    return NULL;
  dp->fd=fd;
  return dp;
}

void cclosedir(Dir *d){
  if(d){
    close(d->fd);
    free(d);
  }
}

Dirent *creaddir(Dir *dp){
  struct direct dirbuf;
  static Dirent d;
  int c;
  while((c=read(dp->fd,(char *) &dirbuf,sizeof(dirbuf))) == sizeof(dirbuf)){
    if(dirbuf.d_ino == 0)
      continue;
    d.inod = dirbuf.d_ino;
    strncpy(d.name,dirbuf.d_name,DIRSIZ);
    d.name[DIRSIZ]='\0';
    return &d;
  }
  return NULL;
}

.
I am calling these function from other program. First I opened the directory and it went fine. But when i use the creaddir function,its giving me NULL, because the system call read is giving -1. I have debugged the program using gdb, and found that fd passed is 6, which i got from the copendir function.
Can someone please help regarding this?
Thank you.

When a system call returns error, you should check errno; in this case I suspect that read() is setting errno to EISDIR. That is, your read() probably refuses to read from a directory. POSIX provides opendir() and readdir() for reading directories. I suppose that using those functions to implement your own versions would be rather, boring, though!