[PATCH] archive-tar: split long paths more carefully
- From
René Scharfe <rene.scharfe@lsrfire.ath.cx>
- Date
- Jan 5, 2013, 22:49 UTC
- Message-ID
- <50E8AE12.8040102@lsrfire.ath.cx>
- In-Reply-To
- <7vwqw7mb09.fsf@alter.siamese.dyndns.org>
The name field of a tar header has a size of 100 characters. This limit was extended long ago in a backward compatible way by providing the additional prefix field, which can hold 155 additional characters. The actual path is constructed at extraction time by concatenating the prefix field, a slash and the name field.
get_path_prefix() is used to determine which slash in the path is used as the cutting point and thus which part of it is placed into the field prefix and which into the field name. It tries to cram as much into the prefix field as possible. (And only if we can't fit a path into the provided 255 characters we use a pax extended header to store it.)
If a path is longer than 100 but shorter than 156 characters and ends with a slash (i.e. is for a directory) then get_path_prefix() puts the whole path in the prefix field and leaves the name field empty. GNU tar reconstructs the path without complaint, but the tar included with NetBSD 6 does not: It reports the header to be invalid.
For compatibility with this version of tar, make sure to never leave the name field empty. In order to do that, trim the trailing slash from the part considered as possible prefix, if it exists -- that way the last path component (or more, but not less) will end up in the name field.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> --- archive-tar.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/archive-tar.c b/archive-tar.c index 0ba3f25..923daf5 100644 --- a/archive-tar.c +++ b/archive-tar.c @@ -153,6 +153,8 @@ static unsigned int ustar_header_chksum(const struct ustar_header *header) static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen) { size_t i = pathlen; + if (i > 1 && path[i - 1] == '/') + i--; if (i > maxlen) i = maxlen; do {
-- 1.7.12