create.c

gnu tar 源码包。 tar 软件是 Unix 系统下的一个打包软件

{
  uid_t r;
#ifdef UID_NOBODY
  r = UID_NOBODY;
#else
  static uid_t uid_nobody;
  if (!uid_nobody && !uname_to_uid ("nobody", &uid_nobody))
    uid_nobody = -2;
  r = uid_nobody;
#endif
  *negative = r < 0;
  return r;
}

bool
uid_to_chars (uid_t v, char *p, size_t s)
{
  return to_chars (v < 0, (uintmax_t) v, sizeof v, uid_substitute, p, s, "uid_t");
}

bool
uintmax_to_chars (uintmax_t v, char *p, size_t s)
{
  return to_chars (0, v, sizeof v, 0, p, s, "uintmax_t");
}

void
string_to_chars (char const *str, char *p, size_t s)
{
  tar_copy_str (p, str, s);
  p[s - 1] = '\0';
}


/* A file is considered dumpable if it is sparse and both --sparse and --totals
   are specified.
   Otherwise, it is dumpable unless any of the following conditions occur:

   a) it is empty *and* world-readable, or
   b) current archive is /dev/null */

bool
file_dumpable_p (struct tar_stat_info *st)
{
  if (dev_null_output)
    return totals_option && sparse_option && ST_IS_SPARSE (st->stat);
  return !(st->archive_file_size == 0
	   && (st->stat.st_mode & MODE_R) == MODE_R);
}


/* Writing routines.  */

/* Write the EOT block(s).  Zero at least two blocks, through the end
   of the record.  Old tar, as previous versions of GNU tar, writes
   garbage after two zeroed blocks.  */
void
write_eot (void)
{
  union block *pointer = find_next_block ();
  memset (pointer->buffer, 0, BLOCKSIZE);
  set_next_block_after (pointer);
  pointer = find_next_block ();
  memset (pointer->buffer, 0, available_space_after (pointer));
  set_next_block_after (pointer);
}

/* Write a "private" header */
union block *
start_private_header (const char *name, size_t size)
{
  time_t t;
  union block *header = find_next_block ();

  memset (header->buffer, 0, sizeof (union block));

  tar_name_copy_str (header->header.name, name, NAME_FIELD_SIZE);
  OFF_TO_CHARS (size, header->header.size);

  time (&t);
  TIME_TO_CHARS (t, header->header.mtime);
  MODE_TO_CHARS (S_IFREG|S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH, header->header.mode);
  UID_TO_CHARS (getuid (), header->header.uid);
  GID_TO_CHARS (getgid (), header->header.gid);
  MAJOR_TO_CHARS (0, header->header.devmajor);
  MINOR_TO_CHARS (0, header->header.devminor);
  strncpy (header->header.magic, TMAGIC, TMAGLEN);
  strncpy (header->header.version, TVERSION, TVERSLEN);
  return header;
}

/* Create a new header and store there at most NAME_FIELD_SIZE bytes of
   the file name */

static union block *
write_short_name (struct tar_stat_info *st)
{
  union block *header = find_next_block ();
  memset (header->buffer, 0, sizeof (union block));
  tar_name_copy_str (header->header.name, st->file_name, NAME_FIELD_SIZE);
  return header;
}

#define FILL(field,byte) do {            \
  memset(field, byte, sizeof(field)-1);  \
  (field)[sizeof(field)-1] = 0;          \
} while (0)

/* Write a GNUTYPE_LONGLINK or GNUTYPE_LONGNAME block.  */
static void
write_gnu_long_link (struct tar_stat_info *st, const char *p, char type)
{
  size_t size = strlen (p) + 1;
  size_t bufsize;
  union block *header;
  char *tmpname;

  header = start_private_header ("././@LongLink", size);
  FILL(header->header.mtime, '0');
  FILL(header->header.mode, '0');
  FILL(header->header.uid, '0');
  FILL(header->header.gid, '0');
  FILL(header->header.devmajor, 0);
  FILL(header->header.devminor, 0);
  uid_to_uname (0, &tmpname);
  UNAME_TO_CHARS (tmpname, header->header.uname);
  free (tmpname);
  gid_to_gname (0, &tmpname);
  GNAME_TO_CHARS (tmpname, header->header.gname);
  free (tmpname);

  strcpy (header->header.magic, OLDGNU_MAGIC);
  header->header.typeflag = type;
  finish_header (st, header, -1);

  header = find_next_block ();

  bufsize = available_space_after (header);

  while (bufsize < size)
    {
      memcpy (header->buffer, p, bufsize);
      p += bufsize;
      size -= bufsize;
      set_next_block_after (header + (bufsize - 1) / BLOCKSIZE);
      header = find_next_block ();
      bufsize = available_space_after (header);
    }
  memcpy (header->buffer, p, size);
  memset (header->buffer + size, 0, bufsize - size);
  set_next_block_after (header + (size - 1) / BLOCKSIZE);
}

static size_t
split_long_name (const char *name, size_t length)
{
  size_t i;

  if (length > PREFIX_FIELD_SIZE)
    length = PREFIX_FIELD_SIZE + 1;
  for (i = length - 1; i > 0; i--)
    if (ISSLASH (name[i]))
      break;
  return i;
}

static union block *
write_ustar_long_name (const char *name)
{
  size_t length = strlen (name);
  size_t i;
  union block *header;

  if (length > PREFIX_FIELD_SIZE + NAME_FIELD_SIZE + 1)
    {
      ERROR ((0, 0, _("%s: file name is too long (max %d); not dumped"),
	      quotearg_colon (name),
	      PREFIX_FIELD_SIZE + NAME_FIELD_SIZE + 1));
      return NULL;
    }

  i = split_long_name (name, length);
  if (i == 0 || length - i - 1 > NAME_FIELD_SIZE)
    {
      ERROR ((0, 0,
	      _("%s: file name is too long (cannot be split); not dumped"),
	      quotearg_colon (name)));
      return NULL;
    }

  header = find_next_block ();
  memset (header->buffer, 0, sizeof (header->buffer));
  memcpy (header->header.prefix, name, i);
  memcpy (header->header.name, name + i + 1, length - i - 1);

  return header;
}

/* Write a long link name, depending on the current archive format */
static void
write_long_link (struct tar_stat_info *st)
{
  switch (archive_format)
    {
    case POSIX_FORMAT:
      xheader_store ("linkpath", st, NULL);
      break;

    case V7_FORMAT:			/* old V7 tar format */
    case USTAR_FORMAT:
    case STAR_FORMAT:
      ERROR ((0, 0,
	      _("%s: link name is too long; not dumped"),
	      quotearg_colon (st->link_name)));
      break;

    case OLDGNU_FORMAT:
    case GNU_FORMAT:
      write_gnu_long_link (st, st->link_name, GNUTYPE_LONGLINK);
      break;

    default:
      abort(); /*FIXME*/
    }
}

static union block *
write_long_name (struct tar_stat_info *st)
{
  switch (archive_format)
    {
    case POSIX_FORMAT:
      xheader_store ("path", st, NULL);
      break;

    case V7_FORMAT:
      if (strlen (st->file_name) > NAME_FIELD_SIZE-1)
	{
	  ERROR ((0, 0, _("%s: file name is too long (max %d); not dumped"),
		  quotearg_colon (st->file_name),
		  NAME_FIELD_SIZE - 1));
	  return NULL;
	}
      break;

    case USTAR_FORMAT:
    case STAR_FORMAT:
      return write_ustar_long_name (st->file_name);

    case OLDGNU_FORMAT:
    case GNU_FORMAT:
      write_gnu_long_link (st, st->file_name, GNUTYPE_LONGNAME);
      break;

    default:
      abort(); /*FIXME*/
    }
  return write_short_name (st);
}

union block *
write_extended (bool global, struct tar_stat_info *st, union block *old_header)
{
  union block *header, hp;
  char *p;
  int type;

  if (st->xhdr.buffer || st->xhdr.stk == NULL)
    return old_header;

  xheader_finish (&st->xhdr);
  memcpy (hp.buffer, old_header, sizeof (hp));
  if (global)
    {
      type = XGLTYPE;
      p = xheader_ghdr_name ();
    }
  else
    {
      type = XHDTYPE;
      p = xheader_xhdr_name (st);
    }
  xheader_write (type, p, &st->xhdr);
  free (p);
  header = find_next_block ();
  memcpy (header, &hp.buffer, sizeof (hp.buffer));
  return header;
}

static union block *
write_header_name (struct tar_stat_info *st)
{
  if (archive_format == POSIX_FORMAT && !string_ascii_p (st->file_name))
    {
      xheader_store ("path", st, NULL);
      return write_short_name (st);
    }
  else if (NAME_FIELD_SIZE - (archive_format == OLDGNU_FORMAT)
	   < strlen (st->file_name))
    return write_long_name (st);
  else
    return write_short_name (st);
}


/* Header handling.  */

/* Make a header block for the file whose stat info is st,
   and return its address.  */

union block *
start_header (struct tar_stat_info *st)
{
  union block *header;

  header = write_header_name (st);
  if (!header)
    return NULL;

  /* Override some stat fields, if requested to do so.  */

  if (owner_option != (uid_t) -1)
    st->stat.st_uid = owner_option;
  if (group_option != (gid_t) -1)
    st->stat.st_gid = group_option;
  if (mode_option)
    st->stat.st_mode =
      ((st->stat.st_mode & ~MODE_ALL)
       | mode_adjust (st->stat.st_mode, S_ISDIR (st->stat.st_mode) != 0,
		      initial_umask, mode_option, NULL));

  /* Paul Eggert tried the trivial test ($WRITER cf a b; $READER tvf a)
     for a few tars and came up with the following interoperability
     matrix:

	      WRITER
	1 2 3 4 5 6 7 8 9   READER
	. . . . . . . . .   1 = SunOS 4.2 tar
	# . . # # . . # #   2 = NEC SVR4.0.2 tar
	. . . # # . . # .   3 = Solaris 2.1 tar
	. . . . . . . . .   4 = GNU tar 1.11.1
	. . . . . . . . .   5 = HP-UX 8.07 tar
	. . . . . . . . .   6 = Ultrix 4.1
	. . . . . . . . .   7 = AIX 3.2
	. . . . . . . . .   8 = Hitachi HI-UX 1.03
	. . . . . . . . .   9 = Omron UNIOS-B 4.3BSD 1.60Beta

	     . = works
	     # = ``impossible file type''

     The following mask for old archive removes the `#'s in column 4
     above, thus making GNU tar both a universal donor and a universal
     acceptor for Paul's test.  */

  if (archive_format == V7_FORMAT || archive_format == USTAR_FORMAT)
    MODE_TO_CHARS (st->stat.st_mode & MODE_ALL, header->header.mode);
  else
    MODE_TO_CHARS (st->stat.st_mode, header->header.mode);

  {
    uid_t uid = st->stat.st_uid;
    if (archive_format == POSIX_FORMAT
	&& MAX_OCTAL_VAL (header->header.uid) < uid)
      {
	xheader_store ("uid", st, NULL);
	uid = 0;
      }
    if (!UID_TO_CHARS (uid, header->header.uid))
      return NULL;
  }

  {
    gid_t gid = st->stat.st_gid;
    if (archive_format == POSIX_FORMAT
	&& MAX_OCTAL_VAL (header->header.gid) < gid)
      {
	xheader_store ("gid", st, NULL);
	gid = 0;
      }
    if (!GID_TO_CHARS (gid, header->header.gid))
      return NULL;
  }

  {
    off_t size = st->stat.st_size;
    if (archive_format == POSIX_FORMAT
	&& MAX_OCTAL_VAL (header->header.size) < size)
      {
	xheader_store ("size", st, NULL);
	size = 0;
      }
    if (!OFF_TO_CHARS (size, header->header.size))
      return NULL;
  }

  {
    struct timespec mtime = set_mtime_option ? mtime_option : st->mtime;
    if (archive_format == POSIX_FORMAT)
      {
	if (MAX_OCTAL_VAL (header->header.mtime) < mtime.tv_sec
	    || mtime.tv_nsec != 0)
	  xheader_store ("mtime", st, &mtime);
	if (MAX_OCTAL_VAL (header->header.mtime) < mtime.tv_sec)
	  mtime.tv_sec = 0;
      }
    if (!TIME_TO_CHARS (mtime.tv_sec, header->header.mtime))
      return NULL;
  }

  /* FIXME */
  if (S_ISCHR (st->stat.st_mode)
      || S_ISBLK (st->stat.st_mode))
    {
      major_t devmajor = major (st->stat.st_rdev);
      minor_t devminor = minor (st->stat.st_rdev);

      if (archive_format == POSIX_FORMAT
	  && MAX_OCTAL_VAL (header->header.devmajor) < devmajor)
	{
	  xheader_store ("devmajor", st, NULL);
	  devmajor = 0;
	}
      if (!MAJOR_TO_CHARS (devmajor, header->header.devmajor))
	return NULL;

      if (archive_format == POSIX_FORMAT
	  && MAX_OCTAL_VAL (header->header.devminor) < devminor)
	{
	  xheader_store ("devminor", st, NULL);
	  devminor = 0;
	}
      if (!MINOR_TO_CHARS (devminor, header->header.devminor))
	return NULL;
    }
  else if (archive_format != GNU_FORMAT && archive_format != OLDGNU_FORMAT)
    {
      if (!(MAJOR_TO_CHARS (0, header->header.devmajor)
	    && MINOR_TO_CHARS (0, header->header.devminor)))
	return NULL;
    }

  if (archive_format == POSIX_FORMAT)
    {
      xheader_store ("atime", st, NULL);
      xheader_store ("ctime", st, NULL);
    }
  else if (incremental_option)
    if (archive_format == OLDGNU_FORMAT || archive_format == GNU_FORMAT)