filesys.c

gcc-2.95.3 Linux下最常用的C编译器

/* Add a filename and its expansion to our list. */
static void
remember_info_filename (filename, expansion)
     char *filename, *expansion;
{
  FILENAME_LIST *new;

  if (names_and_files_index + 2 > names_and_files_slots)
    {
      int alloc_size;
      names_and_files_slots += 10;

      alloc_size = names_and_files_slots * sizeof (FILENAME_LIST *);

      names_and_files =
        (FILENAME_LIST **) xrealloc (names_and_files, alloc_size);
    }

  new = (FILENAME_LIST *)xmalloc (sizeof (FILENAME_LIST));
  new->filename = xstrdup (filename);
  new->expansion = expansion ? xstrdup (expansion) : (char *)NULL;

  names_and_files[names_and_files_index++] = new;
  names_and_files[names_and_files_index] = (FILENAME_LIST *)NULL;
}

static void
maybe_initialize_infopath ()
{
  if (!infopath_size)
    {
      infopath = (char *)
        xmalloc (infopath_size = (1 + strlen (DEFAULT_INFOPATH)));

      strcpy (infopath, DEFAULT_INFOPATH);
    }
}

/* Add PATH to the list of paths found in INFOPATH.  2nd argument says
   whether to put PATH at the front or end of INFOPATH. */
void
info_add_path (path, where)
     char *path;
     int where;
{
  int len;

  if (!infopath)
    {
      infopath = (char *)xmalloc (infopath_size = 200 + strlen (path));
      infopath[0] = '\0';
    }

  len = strlen (path) + strlen (infopath);

  if (len + 2 >= infopath_size)
    infopath = (char *)xrealloc (infopath, (infopath_size += (2 * len) + 2));

  if (!*infopath)
    strcpy (infopath, path);
  else if (where == INFOPATH_APPEND)
    {
      strcat (infopath, ":");
      strcat (infopath, path);
    }
  else if (where == INFOPATH_PREPEND)
    {
      char *temp = xstrdup (infopath);
      strcpy (infopath, path);
      strcat (infopath, ":");
      strcat (infopath, temp);
      free (temp);
    }
}

/* Make INFOPATH have absolutely nothing in it. */
void
zap_infopath ()
{
  if (infopath)
    free (infopath);

  infopath = (char *)NULL;
  infopath_size = 0;
}

/* Read the contents of PATHNAME, returning a buffer with the contents of
   that file in it, and returning the size of that buffer in FILESIZE.
   FINFO is a stat struct which has already been filled in by the caller.
   If the file cannot be read, return a NULL pointer. */
char *
filesys_read_info_file (pathname, filesize, finfo)
     char *pathname;
     long *filesize;
     struct stat *finfo;
{
  long st_size;

  *filesize = filesys_error_number = 0;

  if (compressed_filename_p (pathname))
    return (filesys_read_compressed (pathname, filesize, finfo));
  else
    {
      int descriptor;
      char *contents;

      descriptor = open (pathname, O_RDONLY, 0666);

      /* If the file couldn't be opened, give up. */
      if (descriptor < 0)
        {
          filesys_error_number = errno;
          return ((char *)NULL);
        }

      /* Try to read the contents of this file. */
      st_size = (long) finfo->st_size;
      contents = (char *)xmalloc (1 + st_size);
      if ((read (descriptor, contents, st_size)) != st_size)
        {
          filesys_error_number = errno;
          close (descriptor);
          free (contents);
          return ((char *)NULL);
        }

      close (descriptor);

      *filesize = st_size;
      return (contents);
    }
}

/* Typically, pipe buffers are 4k. */
#define BASIC_PIPE_BUFFER (4 * 1024)

/* We use some large multiple of that. */
#define FILESYS_PIPE_BUFFER_SIZE (16 * BASIC_PIPE_BUFFER)

char *
filesys_read_compressed (pathname, filesize, finfo)
     char *pathname;
     long *filesize;
     struct stat *finfo;
{
  FILE *stream;
  char *command, *decompressor;
  char *contents = (char *)NULL;

  *filesize = filesys_error_number = 0;

  decompressor = filesys_decompressor_for_file (pathname);

  if (!decompressor)
    return ((char *)NULL);

  command = (char *)xmalloc (10 + strlen (pathname) + strlen (decompressor));
  sprintf (command, "%s < %s", decompressor, pathname);

#if !defined (BUILDING_LIBRARY)
  if (info_windows_initialized_p)
    {
      char *temp;

      temp = (char *)xmalloc (5 + strlen (command));
      sprintf (temp, "%s...", command);
      message_in_echo_area ("%s", temp);
      free (temp);
    }
#endif /* !BUILDING_LIBRARY */

  stream = popen (command, "r");
  free (command);

  /* Read chunks from this file until there are none left to read. */
  if (stream)
    {
      int offset, size;
      char *chunk;
    
      offset = size = 0;
      chunk = (char *)xmalloc (FILESYS_PIPE_BUFFER_SIZE);

      while (1)
        {
          int bytes_read;

          bytes_read = fread (chunk, 1, FILESYS_PIPE_BUFFER_SIZE, stream);

          if (bytes_read + offset >= size)
            contents = (char *)xrealloc
              (contents, size += (2 * FILESYS_PIPE_BUFFER_SIZE));

          memcpy (contents + offset, chunk, bytes_read);
          offset += bytes_read;
          if (bytes_read != FILESYS_PIPE_BUFFER_SIZE)
            break;
        }

      free (chunk);
      pclose (stream);
      contents = (char *)xrealloc (contents, offset + 1);
      *filesize = offset;
    }
  else
    {
      filesys_error_number = errno;
    }

#if !defined (BUILDING_LIBARARY)
  if (info_windows_initialized_p)
    unmessage_in_echo_area ();
#endif /* !BUILDING_LIBRARY */
  return (contents);
}

/* Return non-zero if FILENAME belongs to a compressed file. */
int
compressed_filename_p (filename)
     char *filename;
{
  char *decompressor;

  /* Find the final extension of this filename, and see if it matches one
     of our known ones. */
  decompressor = filesys_decompressor_for_file (filename);

  if (decompressor)
    return (1);
  else
    return (0);
}

/* Return the command string that would be used to decompress FILENAME. */
char *
filesys_decompressor_for_file (filename)
     char *filename;
{
  register int i;
  char *extension = (char *)NULL;

  /* Find the final extension of FILENAME, and see if it appears in our
     list of known compression extensions. */
  for (i = strlen (filename) - 1; i > 0; i--)
    if (filename[i] == '.')
      {
        extension = filename + i;
        break;
      }

  if (!extension)
    return ((char *)NULL);

  for (i = 0; compress_suffixes[i].suffix; i++)
    if (strcmp (extension, compress_suffixes[i].suffix) == 0)
      return (compress_suffixes[i].decompressor);

  return ((char *)NULL);
}

/* The number of the most recent file system error. */
int filesys_error_number = 0;

/* A function which returns a pointer to a static buffer containing
   an error message for FILENAME and ERROR_NUM. */
static char *errmsg_buf = (char *)NULL;
static int errmsg_buf_size = 0;

char *
filesys_error_string (filename, error_num)
     char *filename;
     int error_num;
{
  int len;
  char *result;

  if (error_num == 0)
    return ((char *)NULL);

  result = strerror (error_num);

  len = 4 + strlen (filename) + strlen (result);
  if (len >= errmsg_buf_size)
    errmsg_buf = (char *)xrealloc (errmsg_buf, (errmsg_buf_size = 2 + len));

  sprintf (errmsg_buf, "%s: %s", filename, result);
  return (errmsg_buf);
}