[PATCH] Add initial support for pax extended attributes
- From
- Pedro Alvarez <pedro.alvarez@codethink.co.uk>
- Date
- May 22, 2018, 10:05 UTC
- Message-ID
- <20180522100548.29881-1-pedro.alvarez@codethink.co.uk>
From: Pedro Alvarez Piedehierro <palvarez89@gmail.com>
Sometimes the tar files will contain pax extended attributes to deal with cases where the information needed doesn't fit in a standard ustar entry.
One of these cases is when the path is larger than 100 characters. A pax entry will appear containing two standard ustart entries. The first entry will have an 'x' typeflag, and contain the the extended attributes.
The pax extended attributes contain one or multiple records constructed as follows:
"%d %s=%s\n", <length>, <keyword>, <value>
This commit makes sure that we always read the extended attibutes from pax entries, and in the case of finding one, we parse its records looking for 'path' information. If this information is found, it's stored to be used in the next ustar entry.
Information about the Pax Interchange Format can be found at:
https://www.freebsd.org/cgi/man.cgi?manpath=FreeBSD+8-current&query=tar&sektion=5.
Before this change, importing gcc tarballs[1] would fail with the following error:
fast-import crash report:
fast-import process: 82899
parent process : 82897
at 2018-05-21 12:35:27 +0000fatal: Unsupported command: 29 atime=1516870168.93527949
Most Recent Commands Before Crash
---------------------------------
M 644 :22495 gcc-7.3.0/libstdc++-v3/testsuite/20_util/duration/PaxHeaders.4467/comparison_operators
M 644 :140367 gcc-7.3.0/gcc/ada/s-gloloc-mingw.adb
M 644 :75143 gcc-7.3.0/gcc/testsuite/gcc.c-torture/execute/builtins/PaxHeaders.4467/strncat-chk-lib.c<snip>
M 644 :135585 gcc-7.3.0/gcc/testsuite/c-c++-common/attr-warn-unused-result.c
M 644 :54956 gcc-7.3.0/gcc/testsuite/go.test/test/fixedbugs/PaxHeaders.4467/bug335.dir
M 644 :20632 27 mtime=1483272463.905435
* 29 atime=1516870168.93527949[1]: http://ftp.gnu.org/gnu/gcc/gcc-7.3.0/gcc-7.3.0.tar.xz
Signed-off-by: Pedro Alvarez <palvarez89@gmail.com> --- contrib/fast-import/import-tars.perl | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/contrib/fast-import/import-tars.perl b/contrib/fast-import/import-tars.perl index d60b4315ed..c2e54ec7a3 100755 --- a/contrib/fast-import/import-tars.perl +++ b/contrib/fast-import/import-tars.perl @@ -63,6 +63,8 @@ foreach my $tar_file (@ARGV) my $have_top_dir = 1; my ($top_dir, %files); + my $next_path = ''; + while (read(I, $_, 512) == 512) { my ($name, $mode, $uid, $gid, $size, $mtime, $chksum, $typeflag, $linkname, $magic, @@ -70,6 +72,13 @@ foreach my $tar_file (@ARGV) $prefix) = unpack 'Z100 Z8 Z8 Z8 Z12 Z12 Z8 Z1 Z100 Z6 Z2 Z32 Z32 Z8 Z8 Z*', $_; + + unless ($next_path eq '') { + # Recover name from previous extended header + $name = $next_path; + $next_path = ''; + } + last unless length($name); if ($name eq '././@LongLink') { # GNU tar extension @@ -90,13 +99,32 @@ foreach my $tar_file (@ARGV) Z8 Z1 Z100 Z6 Z2 Z32 Z32 Z8 Z8 Z*', $_; } - next if $name =~ m{/\z}; $mode = oct $mode; $size = oct $size; $mtime = oct $mtime; next if $typeflag == 5; # directory - if ($typeflag != 1) { # handle hard links later + if ($typeflag eq 'x') { # extended header + # If extended header, check for path + my $pax_header = ''; + while ($size > 0 && read(I, $_, 512) == 512) { + $pax_header = $pax_header . substr($_, 0, $size); + $size -= 512; + } + + my @lines = split /\n/, $pax_header; + foreach my $line (@lines) { + my ($len, $entry) = split / /, $line; + my ($key, $value) = split /=/, $entry; + if ($key eq 'path') { + $next_path = $value; + } + } + next; + } elsif ($name =~ m{/\z}) { + # If it's a folder, ignore + next; + } elsif ($typeflag != 1) { # handle hard links later print FI "blob\n", "mark :$next_mark\n"; if ($typeflag == 2) { # symbolic link print FI "data ", length($linkname), "\n",
-- 2.11.0