text: /*
   * opendir.c --
   *
   *	This file provides dirent-style directory-reading procedures for V7
   *	Unix systems that don't have such procedures. The origin of this code
   *	is unclear, but it seems to have come originally from Larry Wall.
   */
  
  #include "tclInt.h"
  
  #undef DIRSIZ
  #define DIRSIZ(dp) \
      ((sizeof(struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
  
  /*
   * open a directory.
   */
  
  DIR *
  opendir(
      char *name)
  {
      register DIR *dirp;
      register int fd;
      char *myname;
  
      myname = ((*name == '\0') ? "." : name);
      if ((fd = open(myname, 0, 0)) == -1) {
  	return NULL;
      }
      dirp = (DIR *) Tcl_Alloc(sizeof(DIR));
      if (dirp == NULL) {
  	/* unreachable? */
  	close(fd);
  	return NULL;
      }
      dirp->dd_fd = fd;
      dirp->dd_loc = 0;
      return dirp;
  }
  
  /*
   * read an old style directory entry and present it as a new one
   */
  #ifndef pyr
  #define	ODIRSIZ	14
  
  struct olddirect {
      ino_t od_ino;
      char od_name[ODIRSIZ];
  };
  #else	/* a Pyramid in the ATT universe */
  #define	ODIRSIZ	248
  
  struct olddirect {
      long od_ino;
      short od_fill1, od_fill2;
      char od_name[ODIRSIZ];
  };
  #endif
  
  /*
   * get next entry in a directory.
   */
  
  struct dirent *
  readdir(
      register DIR *dirp)
  {
      register struct olddirect *dp;
      static struct dirent dir;
  
      for (;;) {
  	if (dirp->dd_loc == 0) {
  	    dirp->dd_size = read(dirp->dd_fd, dirp->dd_buf, DIRBLKSIZ);
  	    if (dirp->dd_size <= 0) {
  		return NULL;
  	    }
  	}
  	if (dirp->dd_loc >= dirp->dd_size) {
  	    dirp->dd_loc = 0;
  	    continue;
  	}
  	dp = (struct olddirect *)(dirp->dd_buf + dirp->dd_loc);
  	dirp->dd_loc += sizeof(struct olddirect);
  	if (dp->od_ino == 0) {
  	    continue;
  	}
  	dir.d_ino = dp->od_ino;
  	strncpy(dir.d_name, dp->od_name, ODIRSIZ);
  	dir.d_name[ODIRSIZ] = '\0'; /* insure null termination */
  	dir.d_namlen = strlen(dir.d_name);
  	dir.d_reclen = DIRSIZ(&dir);
  	return &dir;
      }
  }
  
  /*
   * close a directory.
   */
  
  void
  closedir(
      register DIR *dirp)
  {
      close(dirp->dd_fd);
      dirp->dd_fd = -1;
      dirp->dd_loc = 0;
      Tcl_Free(dirp);
  }
  