Hello,

attached are a regression test and sort of initial version of a fix
for https://bugzilla.redhat.com/656834 -- the problem is that during 
xheader_decode(), the file name obtained from "GNU.sparse.name" is later 
overriden by the dummy name stored in "path", which leads to a nonsense
file name stored on disk.  A minimal example may look like:

$ NAME=`seq 60 | tr -d '\n'`
$ truncate -s 10M $NAME
$ tar -c --sparse --posix $NAME | tar t

Attached is also a gdb trace that shows what happens.  Just two concerns
about the fix:

1) It expects that "GNU.sparse.major" comes before "path", what is IMO not 
guaranteed.

2) It inserts a sparse-related quirk into the common part of code.

I guess we should rather go through keyword_override_list or something like 
that, but I don't understand much the code.

Kamil
From 6dd0f205b1b9753e3ad4b11e31c93b119f3e9923 Mon Sep 17 00:00:00 2001
From: Kamil Dudka <[email protected]>
Date: Thu, 25 Nov 2010 00:01:52 +0100
Subject: [PATCH 1/2] tests: new test sparse04 for --sparse --posix and long names

* tests/Makefile.am (TESTSUITE_AT): Add sparse04.at.
* tests/sparse04.at: New file.
* tests/testsuite.at: Include it.
---
 tests/Makefile.am  |    1 +
 tests/sparse04.at  |   42 ++++++++++++++++++++++++++++++++++++++++++
 tests/testsuite.at |    1 +
 3 files changed, 44 insertions(+), 0 deletions(-)
 create mode 100644 tests/sparse04.at

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 7b1e226..ab7d104 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -146,6 +146,7 @@ TESTSUITE_AT = \
  sparse01.at\
  sparse02.at\
  sparse03.at\
+ sparse04.at\
  sparsemv.at\
  sparsemvp.at\
  spmvp00.at\
diff --git a/tests/sparse04.at b/tests/sparse04.at
new file mode 100644
index 0000000..b4513bc
--- /dev/null
+++ b/tests/sparse04.at
@@ -0,0 +1,42 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+
+# Test suite for GNU tar.
+# Copyright (C) 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301, USA.
+
+AT_SETUP([restoring long names of sparse files])
+AT_KEYWORDS([sparse sparse04])
+
+# Tar 1.25 incorrectly restored long names of sparse files from PAX header
+# Reference: https://bugzilla.redhat.com/656834
+
+m4_define([NAME_111],
+	  [123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960])
+
+AT_TAR_CHECK([
+genfile --sparse --file NAME_111 --block-size 512 8M A || AT_SKIP_TEST
+tar -c --sparse --posix NAME_111 | tar t
+],
+[0],
+[NAME_111
+],
+[],
+[],
+[],
+[pax])
+
+AT_CLEANUP
diff --git a/tests/testsuite.at b/tests/testsuite.at
index e8df868..40e1ea3 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -224,6 +224,7 @@ m4_include([shortrec.at])
 m4_include([sparse01.at])
 m4_include([sparse02.at])
 m4_include([sparse03.at])
+m4_include([sparse04.at])
 m4_include([sparsemv.at])
 m4_include([spmvp00.at])
 m4_include([spmvp01.at])
-- 
1.7.3.2

From 68e17f7bf15fee3b1473d5f4d4b92c77b2722769 Mon Sep 17 00:00:00 2001
From: Kamil Dudka <[email protected]>
Date: Thu, 25 Nov 2010 00:04:06 +0100
Subject: [PATCH 2/2] tar --sparse now properly restore long file names from PAX header

Problem reported by Bernd Schubert in
<https://bugzilla.redhat.com/656834>.
* xheader.c (decx): Do not override "GNU.sparse.name" by "path".
---
 src/xheader.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/src/xheader.c b/src/xheader.c
index 2284e97..8178aef 100644
--- a/src/xheader.c
+++ b/src/xheader.c
@@ -608,6 +608,8 @@ decx (void *data, char const *keyword, char const *value, size_t size)
 {
   struct xhdr_tab const *t;
   struct tar_stat_info *st = data;
+  if (0 < st->sparse_major && !strcmp ("path", keyword))
+    return;
 
   if (xheader_keyword_deleted_p (keyword)
       || xheader_keyword_override_p (keyword))
-- 
1.7.3.2

(gdb) break decx
Breakpoint 1 at 0x4125bf: file xheader.c, line 610.
(gdb) break path_decoder
Breakpoint 2 at 0x413a41: file xheader.c, line 1173.
(gdb) run

Breakpoint 1, decx (data=0x65aca0, keyword=0x660b43 "GNU.sparse.major", 
value=0x660b54 "1", size=1) at xheader.c:610
610       struct tar_stat_info *st = data;
(gdb) cont

Breakpoint 1, decx (data=0x65aca0, keyword=0x660b59 "GNU.sparse.minor", 
value=0x660b6a "0", size=1) at xheader.c:610
610       struct tar_stat_info *st = data;
(gdb)

Breakpoint 1, decx (data=0x65aca0, keyword=0x660b70 "GNU.sparse.name", 
value=0x660b80 
"123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960",
 size=111) at xheader.c:610
610       struct tar_stat_info *st = data;
(gdb)

Breakpoint 2, path_decoder (st=0x65aca0, keyword=0x660b70 "GNU.sparse.name", 
arg=0x660b80 
"123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960",
 size=111) at xheader.c:1173
1173      decode_string (&st->orig_file_name, arg);
(gdb) finish
0x0000000000412623 in decx (data=0x65aca0, keyword=0x660b70 "GNU.sparse.name", 
value=0x660b80 
"123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960",
 size=111) at xheader.c:618
618         t->decoder (st, keyword, value, size);
(gdb) print st->file_name
$1 = 0x66ad40 
"123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960"
(gdb) cont

Breakpoint 1, decx (data=0x65aca0, keyword=0x660bf3 "GNU.sparse.realsize", 
value=0x660c07 "10485760", size=8) at xheader.c:610
610       struct tar_stat_info *st = data;
(gdb)

Breakpoint 1, decx (data=0x65aca0, keyword=0x660c14 "path", value=0x660c19 
"./GNUSparseFile.18026/123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960",
 size=133) at xheader.c:610
610       struct tar_stat_info *st = data;
(gdb)

Breakpoint 2, path_decoder (st=0x65aca0, keyword=0x660c14 "path", arg=0x660c19 
"./GNUSparseFile.18026/123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960",
 size=133) at xheader.c:1173
1173      decode_string (&st->orig_file_name, arg);
(gdb) finish
0x0000000000412623 in decx (data=0x65aca0, keyword=0x660c14 "path", 
value=0x660c19 
"./GNUSparseFile.18026/123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960",
 size=133) at xheader.c:618
618         t->decoder (st, keyword, value, size);
(gdb) print st->file_name
$2 = 0x66a630 
"./GNUSparseFile.18026/123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960"

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