list.c

gnu tar 源码包。 tar 软件是 Unix 系统下的一个打包软件

	      recent_long_link_blocks = next_long_link_blocks;
	    }
	  else
	    {
	      memcpy (namebuf, h->linkname, sizeof h->linkname);
	      namebuf[sizeof h->linkname] = '\0';
	      name = namebuf;
	      recent_long_link = 0;
	      recent_long_link_blocks = 0;
	    }
	  assign_string (&info->link_name, name);

	  return HEADER_SUCCESS;
	}
    }
}

enum read_header
read_header (bool raw_extended_headers)
{
  return read_header_primitive (raw_extended_headers, &current_stat_info);
}

static char *
decode_xform (char *file_name, void *data)
{
  xform_type type = *(xform_type*)data;

  switch (type)
    {
    case xform_symlink:
      /* FIXME: It is not quite clear how and to which extent are the symbolic
	 links subject to filename transformation.  In the absence of another
	 solution, symbolic links are exempt from component stripping and
	 name suffix normalization, but subject to filename transformation
	 proper. */ 
      return file_name;
      
    case xform_link:
      file_name = safer_name_suffix (file_name, true, absolute_names_option);
      break;
      
    case xform_regfile:
      file_name = safer_name_suffix (file_name, false, absolute_names_option);
      break;
    }
  
  if (strip_name_components)
    {
      size_t prefix_len = stripped_prefix_len (file_name,
					       strip_name_components);
      if (prefix_len == (size_t) -1)
	prefix_len = strlen (file_name);
      file_name += prefix_len;
    }
  return file_name;
}

bool
transform_member_name (char **pinput, xform_type type)
{
  return transform_name_fp (pinput, decode_xform, &type);
}

#define ISOCTAL(c) ((c)>='0'&&(c)<='7')

/* Decode things from a file HEADER block into STAT_INFO, also setting
   *FORMAT_POINTER depending on the header block format.  If
   DO_USER_GROUP, decode the user/group information (this is useful
   for extraction, but waste time when merely listing).

   read_header() has already decoded the checksum and length, so we don't.

   This routine should *not* be called twice for the same block, since
   the two calls might use different DO_USER_GROUP values and thus
   might end up with different uid/gid for the two calls.  If anybody
   wants the uid/gid they should decode it first, and other callers
   should decode it without uid/gid before calling a routine,
   e.g. print_header, that assumes decoded data.  */
void
decode_header (union block *header, struct tar_stat_info *stat_info,
	       enum archive_format *format_pointer, int do_user_group)
{
  enum archive_format format;

  if (strcmp (header->header.magic, TMAGIC) == 0)
    {
      if (header->star_header.prefix[130] == 0
	  && ISOCTAL (header->star_header.atime[0])
	  && header->star_header.atime[11] == ' '
	  && ISOCTAL (header->star_header.ctime[0])
	  && header->star_header.ctime[11] == ' ')
	format = STAR_FORMAT;
      else if (stat_info->xhdr.size)
	format = POSIX_FORMAT;
      else
	format = USTAR_FORMAT;
    }
  else if (strcmp (header->header.magic, OLDGNU_MAGIC) == 0)
    format = OLDGNU_FORMAT;
  else
    format = V7_FORMAT;
  *format_pointer = format;

  stat_info->stat.st_mode = MODE_FROM_HEADER (header->header.mode);
  stat_info->mtime.tv_sec = TIME_FROM_HEADER (header->header.mtime);
  stat_info->mtime.tv_nsec = 0;
  assign_string (&stat_info->uname,
		 header->header.uname[0] ? header->header.uname : NULL);
  assign_string (&stat_info->gname,
		 header->header.gname[0] ? header->header.gname : NULL);

  if (format == OLDGNU_FORMAT && incremental_option)
    {
      stat_info->atime.tv_sec = TIME_FROM_HEADER (header->oldgnu_header.atime);
      stat_info->ctime.tv_sec = TIME_FROM_HEADER (header->oldgnu_header.ctime);
      stat_info->atime.tv_nsec = stat_info->ctime.tv_nsec = 0;
    }
  else if (format == STAR_FORMAT)
    {
      stat_info->atime.tv_sec = TIME_FROM_HEADER (header->star_header.atime);
      stat_info->ctime.tv_sec = TIME_FROM_HEADER (header->star_header.ctime);
      stat_info->atime.tv_nsec = stat_info->ctime.tv_nsec = 0;
    }
  else
    stat_info->atime = stat_info->ctime = start_time;

  if (format == V7_FORMAT)
    {
      stat_info->stat.st_uid = UID_FROM_HEADER (header->header.uid);
      stat_info->stat.st_gid = GID_FROM_HEADER (header->header.gid);
      stat_info->stat.st_rdev = 0;
    }
  else
    {
      if (do_user_group)
	{
	  /* FIXME: Decide if this should somewhat depend on -p.  */

	  if (numeric_owner_option
	      || !*header->header.uname
	      || !uname_to_uid (header->header.uname, &stat_info->stat.st_uid))
	    stat_info->stat.st_uid = UID_FROM_HEADER (header->header.uid);

	  if (numeric_owner_option
	      || !*header->header.gname
	      || !gname_to_gid (header->header.gname, &stat_info->stat.st_gid))
	    stat_info->stat.st_gid = GID_FROM_HEADER (header->header.gid);
	}

      switch (header->header.typeflag)
	{
	case BLKTYPE:
	case CHRTYPE:
	  stat_info->stat.st_rdev =
	    makedev (MAJOR_FROM_HEADER (header->header.devmajor),
		     MINOR_FROM_HEADER (header->header.devminor));
	  break;

	default:
	  stat_info->stat.st_rdev = 0;
	}
    }

  stat_info->archive_file_size = stat_info->stat.st_size;
  xheader_decode (stat_info);

  if (sparse_member_p (stat_info))
    {
      sparse_fixup_header (stat_info);
      stat_info->is_sparse = true;
    }
  else
    {
      stat_info->is_sparse = false;
      if (((current_format == GNU_FORMAT
	    || current_format == OLDGNU_FORMAT)
	   && current_header->header.typeflag == GNUTYPE_DUMPDIR)
          || stat_info->dumpdir)
	stat_info->is_dumpdir = true;
    }

  transform_member_name (&stat_info->file_name, xform_regfile);
}

/* Convert buffer at WHERE0 of size DIGS from external format to
   uintmax_t.  DIGS must be positive.  If TYPE is nonnull, the data
   are of type TYPE.  The buffer must represent a value in the range
   -MINUS_MINVAL through MAXVAL.  If OCTAL_ONLY, allow only octal
   numbers instead of the other GNU extensions.  Return -1 on error,
   diagnosing the error if TYPE is nonnull and if !SILENT.  */
static uintmax_t
from_header (char const *where0, size_t digs, char const *type,
	     uintmax_t minus_minval, uintmax_t maxval,
	     bool octal_only, bool silent)
{
  uintmax_t value;
  char const *where = where0;
  char const *lim = where + digs;
  int negative = 0;

  /* Accommodate buggy tar of unknown vintage, which outputs leading
     NUL if the previous field overflows.  */
  where += !*where;

  /* Accommodate older tars, which output leading spaces.  */
  for (;;)
    {
      if (where == lim)
	{
	  if (type && !silent)
	    ERROR ((0, 0,
		    /* TRANSLATORS: %s is type of the value (gid_t, uid_t, etc.) */
		    _("Blanks in header where numeric %s value expected"),
		    type));
	  return -1;
	}
      if (!ISSPACE ((unsigned char) *where))
	break;
      where++;
    }

  value = 0;
  if (ISODIGIT (*where))
    {
      char const *where1 = where;
      uintmax_t overflow = 0;

      for (;;)
	{
	  value += *where++ - '0';
	  if (where == lim || ! ISODIGIT (*where))
	    break;
	  overflow |= value ^ (value << LG_8 >> LG_8);
	  value <<= LG_8;
	}

      /* Parse the output of older, unportable tars, which generate
         negative values in two's complement octal.  If the leading
         nonzero digit is 1, we can't recover the original value
         reliably; so do this only if the digit is 2 or more.  This
         catches the common case of 32-bit negative time stamps.  */
      if ((overflow || maxval < value) && '2' <= *where1 && type)
	{
	  /* Compute the negative of the input value, assuming two's
	     complement.  */
	  int digit = (*where1 - '0') | 4;
	  overflow = 0;
	  value = 0;
	  where = where1;
	  for (;;)
	    {
	      value += 7 - digit;
	      where++;
	      if (where == lim || ! ISODIGIT (*where))
		break;
	      digit = *where - '0';
	      overflow |= value ^ (value << LG_8 >> LG_8);
	      value <<= LG_8;
	    }
	  value++;
	  overflow |= !value;

	  if (!overflow && value <= minus_minval)
	    {
	      if (!silent)
		WARN ((0, 0,
		       /* TRANSLATORS: Second %s is a type name (gid_t,uid_t,etc.) */
		       _("Archive octal value %.*s is out of %s range; assuming two's complement"),
		       (int) (where - where1), where1, type));
	      negative = 1;
	    }
	}

      if (overflow)
	{
	  if (type && !silent)
	    ERROR ((0, 0,
		    /* TRANSLATORS: Second %s is a type name (gid_t,uid_t,etc.) */
		    _("Archive octal value %.*s is out of %s range"),
		    (int) (where - where1), where1, type));
	  return -1;
	}
    }
  else if (octal_only)
    {
      /* Suppress the following extensions.  */
    }
  else if (*where == '-' || *where == '+')
    {
      /* Parse base-64 output produced only by tar test versions
	 1.13.6 (1999-08-11) through 1.13.11 (1999-08-23).
	 Support for this will be withdrawn in future releases.  */
      int dig;
      if (!silent)
	{
	  static bool warned_once;
	  if (! warned_once)
	    {
	      warned_once = true;
	      WARN ((0, 0, _("Archive contains obsolescent base-64 headers")));
	    }
	}
      negative = *where++ == '-';
      while (where != lim
	     && (dig = base64_map[(unsigned char) *where]) < 64)
	{
	  if (value << LG_64 >> LG_64 != value)
	    {
	      char *string = alloca (digs + 1);
	      memcpy (string, where0, digs);
	      string[digs] = '\0';
	      if (type && !silent)
		ERROR ((0, 0,
			_("Archive signed base-64 string %s is out of %s range"),
			quote (string), type));
	      return -1;
	    }
	  value = (value << LG_64) | dig;
	  where++;
	}
    }
  else if (*where == '\200' /* positive base-256 */
	   || *where == '\377' /* negative base-256 */)
    {
      /* Parse base-256 output.  A nonnegative number N is
	 represented as (256**DIGS)/2 + N; a negative number -N is
	 represented as (256**DIGS) - N, i.e. as two's complement.
	 The representation guarantees that the leading bit is
	 always on, so that we don't confuse this format with the
	 others (assuming ASCII bytes of 8 bits or more).  */
      int signbit = *where & (1 << (LG_256 - 2));
      uintmax_t topbits = (((uintmax_t) - signbit)
			   << (CHAR_BIT * sizeof (uintmax_t)
			       - LG_256 - (LG_256 - 2)));
      value = (*where++ & ((1 << (LG_256 - 2)) - 1)) - signbit;
      for (;;)
	{
	  value = (value << LG_256) + (unsigned char) *where++;
	  if (where == lim)
	    break;
	  if (((value << LG_256 >> LG_256) | topbits) != value)
	    {
	      if (type && !silent)
		ERROR ((0, 0,
			_("Archive base-256 value is out of %s range"),
			type));
	      return -1;
	    }
	}
      negative = signbit;
      if (negative)
	value = -value;
    }

  if (where != lim && *where && !ISSPACE ((unsigned char) *where))
    {
      if (type)
	{
	  char buf[1000]; /* Big enough to represent any header.  */
	  static struct quoting_options *o;

	  if (!o)
	    {
	      o = clone_quoting_options (0);
	      set_quoting_style (o, locale_quoting_style);
	    }

	  while (where0 != lim && ! lim[-1])
	    lim--;
	  quotearg_buffer (buf, sizeof buf, where0, lim - where, o);
	  if (!silent)
	    ERROR ((0, 0,
		    /* TRANSLATORS: Second %s is a type name (gid_t,uid_t,etc.) */
		    _("Archive contains %.*s where numeric %s value expected"),
		    (int) sizeof buf, buf, type));
	}

      return -1;
    }

  if (value <= (negative ? minus_minval : maxval))
    return negative ? -value : value;

  if (type && !silent)
    {
      char minval_buf[UINTMAX_STRSIZE_BOUND + 1];
      char maxval_buf[UINTMAX_STRSIZE_BOUND];
      char value_buf[UINTMAX_STRSIZE_BOUND + 1];
      char *minval_string = STRINGIFY_BIGINT (minus_minval, minval_buf + 1);
      char *value_string = STRINGIFY_BIGINT (value, value_buf + 1);
      if (negative)
	*--value_string = '-';
      if (minus_minval)
	*--minval_string = '-';
      /* TRANSLATORS: Second %s is type name (gid_t,uid_t,etc.) */
      ERROR ((0, 0, _("Archive value %s is out of %s range %s..%s"),
	      value_string, type,
	      minval_string, STRINGIFY_BIGINT (maxval, maxval_buf)));
    }

  return -1;
}

gid_t
gid_from_header (const char *p, size_t s)
{
  return from_header (p, s, "gid_t",
		      - (uintmax_t) TYPE_MINIMUM (gid_t),
		      (uintmax_t) TYPE_MAXIMUM (gid_t),
		      false, false);
}

major_t
major_from_header (const char *p, size_t s)
{
  return from_header (p, s, "major_t",
		      - (uintmax_t) TYPE_MINIMUM (major_t),
		      (uintmax_t) TYPE_MAXIMUM (major_t), false, false);
}

minor_t
minor_from_header (const char *p, size_t s)
{
  return from_header (p, s, "minor_t",
		      - (uintmax_t) TYPE_MINIMUM (minor_t),
		      (uintmax_t) TYPE_MAXIMUM (minor_t), false, false);
}

mode_t
mode_from_header (const char *p, size_t s)
{
  /* Do not complain about unrecognized mode bits.  */
  unsigned u = from_header (p, s, "mode_t",
			    - (uintmax_t) TYPE_MINIMUM (mode_t),
			    TYPE_MAXIMUM (uintmax_t), false, false);
  return ((u & TSUID ? S_ISUID : 0)
	  | (u & TSGID ? S_ISGID : 0)
	  | (u & TSVTX ? S_ISVTX : 0)
	  | (u & TUREAD ? S_IRUSR : 0)
	  | (u & TUWRITE ? S_IWUSR : 0)
	  | (u & TUEXEC ? S_IXUSR : 0)
	  | (u & TGREAD ? S_IRGRP : 0)
	  | (u & TGWRITE ? S_IWGRP : 0)
	  | (u & TGEXEC ? S_IXGRP : 0)
	  | (u & TOREAD ? S_IROTH : 0)
	  | (u & TOWRITE ? S_IWOTH : 0)
	  | (u & TOEXEC ? S_IXOTH : 0));