ftw.c

Newlib 嵌入式 C库 标准实现代码

			{
			  /* Please note that we overwrite a slash.  */
			  data->dirbuf[data->ftw.base - 1] = '\0';

			  if (chdir (data->dirbuf) < 0)
			    result = -1;

			  data->dirbuf[data->ftw.base - 1] = '/';
			}
		    }
		}
	    }
	}
      else
	result = (*data->func) (data->dirbuf, &st, data->cvt_arr[flag],
				&data->ftw);
    }

  return result;
}


static int
ftw_dir (struct ftw_data *data, struct STAT *st)
{
  struct dir_data dir;
  struct dirent64 *d;
  int previous_base = data->ftw.base;
  int result;
  char *startp;

  /* Open the stream for this directory.  This might require that
     another stream has to be closed.  */
  result = open_dir_stream (data, &dir);
  if (result != 0)
    {
      if (errno == EACCES)
	/* We cannot read the directory.  Signal this with a special flag.  */
	result = (*data->func) (data->dirbuf, st, FTW_DNR, &data->ftw);

      return result;
    }

  /* First, report the directory (if not depth-first).  */
  if (!(data->flags & FTW_DEPTH))
    {
      result = (*data->func) (data->dirbuf, st, FTW_D, &data->ftw);
      if (result != 0)
	return result;
    }

  /* If necessary, change to this directory.  */
  if (data->flags & FTW_CHDIR)
    {
      if (fchdir (dirfd (dir.stream)) < 0)
	{
	  if (errno == ENOSYS)
	    {
	      if (chdir (data->dirbuf) < 0)
		result = -1;
	    }
	  else
	    result = -1;
	}

      if (result != 0)
	{
	  int save_err = errno;
	  closedir (dir.stream);
	  __set_errno (save_err);

	  if (data->actdir-- == 0)
	    data->actdir = data->maxdir - 1;
	  data->dirstreams[data->actdir] = NULL;

	  return result;
	}
    }

  /* Next, update the `struct FTW' information.  */
  ++data->ftw.level;
  startp = strchr (data->dirbuf, '\0');
  /* There always must be a directory name.  */
  assert (startp != data->dirbuf);
  if (startp[-1] != '/')
    *startp++ = '/';
  data->ftw.base = startp - data->dirbuf;

  while (dir.stream != NULL && (d = __readdir64 (dir.stream)) != NULL)
    {
      result = process_entry (data, &dir, d->d_name, strlen (d->d_name));
      if (result != 0)
	break;
    }

  if (dir.stream != NULL)
    {
      /* The stream is still open.  I.e., we did not need more
	 descriptors.  Simply close the stream now.  */
      int save_err = errno;

      assert (dir.content == NULL);

      closedir (dir.stream);
      __set_errno (save_err);

      if (data->actdir-- == 0)
	data->actdir = data->maxdir - 1;
      data->dirstreams[data->actdir] = NULL;
    }
  else
    {
      int save_err;
      char *runp = dir.content;

      while (result == 0 && *runp != '\0')
	{
	  char *endp = strchr (runp, '\0');

	  result = process_entry (data, &dir, runp, endp - runp);

	  runp = endp + 1;
	}

      save_err = errno;
      free (dir.content);
      __set_errno (save_err);
    }

  /* Prepare the return, revert the `struct FTW' information.  */
  data->dirbuf[data->ftw.base - 1] = '\0';
  --data->ftw.level;
  data->ftw.base = previous_base;

  /* Finally, if we process depth-first report the directory.  */
  if (result == 0 && (data->flags & FTW_DEPTH))
    result = (*data->func) (data->dirbuf, st, FTW_DP, &data->ftw);

  return result;
}


static int
ftw_startup (const char *dir, int is_nftw, void *func, int descriptors,
	     int flags)
{
  struct ftw_data data;
  struct STAT st;
  int result = 0;
  int save_err;
  int len;
  char *cwd = NULL;
  char *cp;

  /* First make sure the parameters are reasonable.  */
  if (dir[0] == '\0')
    {
      __set_errno (ENOENT);
      return -1;
    }

  if (access (dir, R_OK) != 0)
    return -1;

  data.maxdir = descriptors < 1 ? 1 : descriptors;
  data.actdir = 0;
  data.dirstreams = (struct dir_data **) alloca (data.maxdir
						 * sizeof (struct dir_data *));
  memset (data.dirstreams, '\0', data.maxdir * sizeof (struct dir_data *));

#ifdef PATH_MAX
  data.dirbufsize = MAX (2 * strlen (dir), PATH_MAX);
#else
  data.dirbufsize = 2 * strlen (dir);
#endif
  data.dirbuf = (char *) malloc (data.dirbufsize);
  if (data.dirbuf == NULL)
    return -1;
  len = strlen (dir);
  cp = mempcpy (data.dirbuf, dir, len);
  /* Strip trailing slashes.  */
  while (cp > data.dirbuf + 1 && cp[-1] == '/')
    --cp;
  *cp = '\0';

  data.ftw.level = 0;

  /* Find basename.  */
  while (cp > data.dirbuf && cp[-1] != '/')
    --cp;
  data.ftw.base = cp - data.dirbuf;

  data.flags = flags;

  /* This assignment might seem to be strange but it is what we want.
     The trick is that the first three arguments to the `ftw' and
     `nftw' callback functions are equal.  Therefore we can call in
     every case the callback using the format of the `nftw' version
     and get the correct result since the stack layout for a function
     call in C allows this.  */
  data.func = (NFTW_FUNC_T) func;

  /* Since we internally use the complete set of FTW_* values we need
     to reduce the value range before calling a `ftw' callback.  */
  data.cvt_arr = is_nftw ? nftw_arr : ftw_arr;

  /* No object known so far.  */
  data.known_objects = NULL;

  /* Now go to the directory containing the initial file/directory.  */
  if ((flags & FTW_CHDIR) && data.ftw.base > 0)
    {
      /* GNU extension ahead.  */
      cwd =  getcwd (NULL, 0);
      if (cwd == NULL)
	result = -1;
      else
	{
	  /* Change to the directory the file is in.  In data.dirbuf
	     we have a writable copy of the file name.  Just NUL
	     terminate it for now and change the directory.  */
	  if (data.ftw.base == 1)
	    /* I.e., the file is in the root directory.  */
	    result = chdir ("/");
	  else
	    {
	      char ch = data.dirbuf[data.ftw.base - 1];
	      data.dirbuf[data.ftw.base - 1] = '\0';
	      result = chdir (data.dirbuf);
	      data.dirbuf[data.ftw.base - 1] = ch;
	    }
	}
    }

  /* Get stat info for start directory.  */
  if (result == 0)
    {
      if (((flags & FTW_PHYS)
	   ? LXSTAT (data.dirbuf, &st)
	   : XSTAT (data.dirbuf, &st)) < 0)
	{
	  if (errno == EACCES)
	    result = (*data.func) (data.dirbuf, &st, FTW_NS, &data.ftw);
	  else if (!(flags & FTW_PHYS)
		   && errno == ENOENT
		   && LXSTAT (dir, &st) == 0
		   && S_ISLNK (st.st_mode))
	    result = (*data.func) (data.dirbuf, &st, data.cvt_arr[FTW_SLN],
				   &data.ftw);
	  else
	    /* No need to call the callback since we cannot say anything
	       about the object.  */
	    result = -1;
	}
      else
	{
	  if (S_ISDIR (st.st_mode))
	    {
	      /* Remember the device of the initial directory in case
		 FTW_MOUNT is given.  */
	      data.dev = st.st_dev;

	      /* We know this directory now.  */
	      if (!(flags & FTW_PHYS))
		result = add_object (&data, &st);

	      if (result == 0)
		result = ftw_dir (&data, &st);
	    }
	  else
	    {
	      int flag = S_ISLNK (st.st_mode) ? FTW_SL : FTW_F;

	      result = (*data.func) (data.dirbuf, &st, data.cvt_arr[flag],
				     &data.ftw);
	    }
	}
    }

  /* Return to the start directory (if necessary).  */
  if (cwd != NULL)
    {
      int save_err = errno;
      chdir (cwd);
      free (cwd);
      __set_errno (save_err);
    }

  /* Free all memory.  */
  save_err = errno;
  tdestroy (data.known_objects, free);
  free (data.dirbuf);
  __set_errno (save_err);

  return result;
}



/* Entry points.  */

int
FTW_NAME (path, func, descriptors)
     const char *path;
     FTW_FUNC_T func;
     int descriptors;
{
  return ftw_startup (path, 0, func, descriptors, 0);
}

int
NFTW_NAME (path, func, descriptors, flags)
     const char *path;
     NFTW_FUNC_T func;
     int descriptors;
     int flags;
{
  return ftw_startup (path, 1, func, descriptors, flags);
}