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Tighten up the heuristic that decides whether or not we should

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obey or ignore the size field on a hardlink entry.  In particular,
if we're reading a non-POSIX archive, we should always ignore
the size field.

This should fix both the audio/xmcd port and the math/unixstat port.

Thanks to: Pav Lucistnik for pointing these two ports out to me.
MFC after: 7 days
This commit is contained in:
Tim Kientzle 2008-01-31 07:41:45 +00:00
parent 104954fe06
commit 6f6dfc16c2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=175842
1 changed files with 36 additions and 20 deletions
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56
lib/libarchive/archive_read_support_format_tar.c
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@ -943,30 +943,46 @@ header_common(struct archive_read *a, struct tar *tar,
* A tricky point: Traditionally, tar readers have
* ignored the size field when reading hardlink
* entries, and some writers put non-zero sizes even
* though the body is empty. POSIX.1-2001 broke with
* this tradition by permitting hardlink entries to
* store valid bodies in pax interchange format, but
* not in ustar format. Since there is no hard and
* fast way to distinguish pax interchange from
* earlier archives (the 'x' and 'g' entries are
* optional, after all), we need a heuristic. Here, I
* use the bid function to test whether or not there's
* a valid header following. Of course, if we know
* this is pax interchange format, then we must obey
* the size.
*
* This heuristic will only fail for a pax interchange
* archive that is storing hardlink bodies, no pax
* extended attribute entries have yet occurred, and
* we encounter a hardlink entry for a file that is
* itself an uncompressed tar archive.
* though the body is empty. POSIX blessed this
* convention in the 1988 standard, but broke with
* this tradition in 2001 by permitting hardlink
* entries to store valid bodies in pax interchange
* format, but not in ustar format. Since there is no
* hard and fast way to distinguish pax interchange
* from earlier archives (the 'x' and 'g' entries are
* optional, after all), we need a heuristic.
*/
if (archive_entry_size(entry) > 0 &&
a->archive.archive_format != ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE &&
archive_read_format_tar_bid(a) > 50) {
if (archive_entry_size(entry) == 0) {
/* If the size is already zero, we're done. */
} else if (a->archive.archive_format
== ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE) {
/* Definitely pax extended; must obey hardlink size. */
} else if (a->archive.archive_format == ARCHIVE_FORMAT_TAR
|| a->archive.archive_format == ARCHIVE_FORMAT_TAR_GNUTAR)
{
/* Old-style or GNU tar: we must ignore the size. */
archive_entry_set_size(entry, 0);
tar->entry_bytes_remaining = 0;
} else if (archive_read_format_tar_bid(a) > 50) {
/*
* We don't know if it's pax: If the bid
* function sees a valid ustar header
* immediately following, then let's ignore
* the hardlink size.
*/
archive_entry_set_size(entry, 0);
tar->entry_bytes_remaining = 0;
}
/*
* TODO: There are still two cases I'd like to handle:
* = a ustar non-pax archive with a hardlink entry at
* end-of-archive. (Look for block of nulls following?)
* = a pax archive that has not seen any pax headers
* and has an entry which is a hardlink entry storing
* a body containing an uncompressed tar archive.
* The first is worth addressing; I don't see any reliable
* way to deal with the second possibility.
*/
break;
case '2': /* Symlink */
archive_entry_set_filetype(entry, AE_IFLNK);