This extension allows GNU tar to process file names in excess of the 100
characters defined by the original tar standard. It does this by faking a
file, named '././@LongLink' containing the true file name, and then adding
the file with a truncated name. The idea is that tar without this
extension will write out a file with the long file name, and write the
contents into a file with truncated name.
Unfortunately, GNU tar does a lousy job at times. When truncating results
in a _directory_ name, it will happily use _that_ as a truncated name for
the file.
An example where this actually happens is gcc-4.1.2, where the full path
of the file WeThrowThisExceptionHelper.java truncates _exactly_ before the
basename. So, we have to support that ad-hoc extension.
This bug was noticed by Chris Riddoch on IRC.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
Does anybody know why they decided to limit the LongLink to 256
characters, when 512 bytes are wasted _anyway_?
BTW I am a little too tired to find out why import-tars failed so
badly without this patch. It _should_ have behaved like tar
without that extension. Instead, it tripped completely, losing the
correct block boundary.
contrib/fast-import/import-tars.perl | 19 +++++++++++++++++++
1 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/contrib/fast-import/import-tars.perl b/contrib/fast-import/import-tars.perl
index d2363a4..a43b2c5 100755
--- a/contrib/fast-import/import-tars.perl
+++ b/contrib/fast-import/import-tars.perl
@@ -52,6 +52,25 @@ foreach my $tar_file (@ARGV)
Z8 Z1 Z100 Z6
Z2 Z32 Z32 Z8 Z8 Z*', $_;
last unless $name;
+ if ($name eq '././@LongLink') {
+ # GNU tar extension
+ if (read(I, $_, 512) != 512) {
+ die ('Short archive');
+ }
+ $name = unpack 'Z257', $_;
+ next unless $name;
+
+ my $dummy;
+ if (read(I, $_, 512) != 512) {
+ die ('Short archive');
+ }
+ ($dummy, $mode, $uid, $gid, $size, $mtime,
+ $chksum, $typeflag, $linkname, $magic,
+ $version, $uname, $gname, $devmajor, $devminor,
+ $prefix) = unpack 'Z100 Z8 Z8 Z8 Z12 Z12
+ Z8 Z1 Z100 Z6
+ Z2 Z32 Z32 Z8 Z8 Z*', $_;
+ }
next if $name =~ m{/\z};
$mode = oct $mode;
$size = oct $size;
--
1.5.2.rc1.2428.g1b62-dirty
-
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