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Be smarter about hardlink sizes: some tar programs write

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a non-zero size but no body, some write a non-zero size and include
a body.  To distinguish these cases, look for a valid tar header immediately
following a hardlink header with non-zero size.
This commit is contained in:
kientzle 2004-05-18 18:16:30 +00:00
parent 1704e84aba
commit a7d0d63b7f
1 changed files with 18 additions and 2 deletions
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20
lib/libarchive/archive_read_support_format_tar.c
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@ -209,12 +209,12 @@ archive_read_format_tar_bid(struct archive *a)
header = h;
/* This distinguishes POSIX formats from GNU tar formats. */
/* Recognize POSIX formats. */
if ((memcmp(header->magic, "ustar\0", 6) == 0)
&&(memcmp(header->version, "00", 2)==0))
bid += 56;
/* Recognize GNU tar format as well. */
/* Recognize GNU tar format. */
if ((memcmp(header->magic, "ustar ", 6) == 0)
&&(memcmp(header->version, " \0", 2)==0))
bid += 56;
@ -593,6 +593,22 @@ header_common(struct archive *a, struct tar *tar, struct archive_entry *entry,
*/
if (st->st_size > 0)
st->st_mode |= S_IFREG;
/*
* A tricky point: Traditionally, tar programs have
* ignored the size field when reading hardlink
* entries. As a result, some programs write non-zero
* sizes, even though the body is empty and expect the
* reader to ignore that. POSIX.1-2001 broke this by
* permitting hardlink entries to store valid bodies
* in pax interchange 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.
*/
if (st->st_size > 0 && archive_read_format_tar_bid(a) > 50)
st->st_size = 0;
break;
case '2': /* Symlink */
st->st_mode |= S_IFLNK;