>From c8ff44a85c9ef537a757bf6c4faf8fc11df044bf Mon Sep 17 00:00:00 2001
From: Pavel Raiskup <address@hidden>
Date: Sun, 15 Nov 2015 12:54:19 +0100
Subject: [PATCH 3/3] incremen: don't indefinitely recurse into symlink loop

This complements previous commit.

* src/common.h (nl_dir_loop_point): New prototype.
* src/incremen.c (nl_dir_loop_point): New function.
* src/names.c (add_hierarchy_to_namelist): Don't recurse down to
the directory if the directory is already in namelist.  Use
nl_dir_loop_point for detection.
* tests/deref02.at: New testcase.
* tests/testsuite.at: Mention new testcase.
* tests/Makefile.am (TESTSUITE_AT): Likewise.
---
 src/common.h       |  1 +
 src/incremen.c     | 19 +++++++++++++++++++
 src/names.c        |  8 ++++++++
 tests/Makefile.am  |  1 +
 tests/deref02.at   | 40 ++++++++++++++++++++++++++++++++++++++++
 tests/testsuite.at |  1 +
 6 files changed, 70 insertions(+)
 create mode 100644 tests/deref02.at

diff --git a/src/common.h b/src/common.h
index 8c69f29..d320d57 100644
--- a/src/common.h
+++ b/src/common.h
@@ -551,6 +551,7 @@ void update_parent_directory (struct tar_stat_info *st);
 size_t dumpdir_size (const char *p);
 bool is_dumpdir (struct tar_stat_info *stat_info);
 void clear_directory_table (void);
+bool nl_dir_loop_point (struct name *name);
 
 /* Module list.c.  */
 
diff --git a/src/incremen.c b/src/incremen.c
index d73a7bb..d514841 100644
--- a/src/incremen.c
+++ b/src/incremen.c
@@ -1758,6 +1758,25 @@ try_purge_directory (char const *directory_name)
   return true;
 }
 
+bool
+nl_dir_loop_point (struct name *name)
+{
+  const struct name *ptr = name;
+
+  if (!dereference_option)
+    return false;
+
+  while (ptr->parent)
+    {
+      ptr = ptr->parent;
+      if (ptr->directory->device_number == name->directory->device_number
+          && ptr->directory->inode_number == name->directory->inode_number)
+        return true;
+    }
+
+  return false;
+}
+
 void
 purge_directory (char const *directory_name)
 {
diff --git a/src/names.c b/src/names.c
index 6e4616d..b31c747 100644
--- a/src/names.c
+++ b/src/names.c
@@ -1044,6 +1044,14 @@ add_hierarchy_to_namelist (struct tar_stat_info *st, struct name *name)
   const char *buffer;
 
   name->directory = scan_directory (st);
+
+  if (nl_dir_loop_point (name))
+    {
+      WARN ((0, 0, _("%s: stopping recursion due to directory loop"),
+             name->name));
+      return;
+    }
+
   buffer = directory_contents (name->directory);
   if (buffer)
     {
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 9a783e5..4fa08f2 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -68,6 +68,7 @@ TESTSUITE_AT = \
  delete04.at\
  delete05.at\
  deref01.at\
+ deref02.at\
  exclude.at\
  exclude01.at\
  exclude02.at\
diff --git a/tests/deref02.at b/tests/deref02.at
new file mode 100644
index 0000000..0c20c08
--- /dev/null
+++ b/tests/deref02.at
@@ -0,0 +1,40 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+#
+# Test suite for GNU tar.
+# Copyright 2015 Free Software Foundation, Inc.
+
+# This file is part of GNU tar.
+
+# GNU tar 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 of the License, or
+# (at your option) any later version.
+
+# GNU tar 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, see <http://www.gnu.org/licenses/>.
+#
+# Test description:
+# Symlink loop on directory with --dereference and --incremental.
+
+AT_SETUP([dereference: symlink loop and --incremental])
+AT_KEYWORDS([create dereference deref02 incremental])
+
+AT_TAR_CHECK([
+mkdir dir
+ln -s ../dir dir/dir || AT_SKIP_TEST
+tar --incremental -chf test.tar dir && tar -tf test.tar
+],
+[0],
+[dir/
+dir/dir/
+],
+[tar: dir/dir: stopping recursion due to directory loop
+],
+[],[],[gnu, oldgnu, posix])
+
+AT_CLEANUP
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 0b0a778..a9e0cf2 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -218,6 +218,7 @@ m4_include([recurs02.at])
 m4_include([shortrec.at])
 m4_include([iotty.at])
 m4_include([deref01.at])
+m4_include([deref02.at])
 
 AT_BANNER([The --same-order option])
 m4_include([same-order01.at])
-- 
2.5.0