tar: fix mishandling of repeated hardlink in tarball; expand tests

function                                             old     new   delta
data_extract_all                                     727     767     +40
get_header_tar                                      1576    1572      -4

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 73 insertions, 16 deletions

diff --git a/archival/libunarchive/data_extract_all.c b/archival/libunarchive/data_extract_all.c
index cc4894229..de2367ac2 100644
--- a/archival/libunarchive/data_extract_all.c
+++ b/archival/libunarchive/data_extract_all.c
@@ -34,12 +34,30 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
 
         if (archive_handle->ah_flags & ARCHIVE_UNLINK_OLD) {
                 /* Remove the entry if it exists */
-                if ((!S_ISDIR(file_header->mode))
-                 && (unlink(file_header->name) == -1)
-                 && (errno != ENOENT)
-                ) {
-                        bb_perror_msg_and_die("can't remove old file %s",
-                                        file_header->name);
+                if (!S_ISDIR(file_header->mode)) {
+                        /* Is it hardlink?
+                         * We encode hard links as regular files of size 0 with a symlink */
+                        if (S_ISREG(file_header->mode)
+                         && file_header->link_target
+                         && file_header->size == 0
+                        ) {
+                                /* Ugly special case:
+                                 * tar cf t.tar hardlink1 hardlink2 hardlink1
+                                 * results in this tarball structure:
+                                 * hardlink1
+                                 * hardlink2 -> hardlink1
+                                 * hardlink1 -> hardlink1 <== !!!
+                                 */
+                                if (strcmp(file_header->link_target, file_header->name) == 0)
+                                        goto ret;
+                        }
+                        /* Proceed with deleting */
+                        if (unlink(file_header->name) == -1
+                         && errno != ENOENT
+                        ) {
+                                bb_perror_msg_and_die("can't remove old file %s",
+                                                file_header->name);
+                        }
                 }
         }
         else if (archive_handle->ah_flags & ARCHIVE_EXTRACT_NEWER) {
@@ -65,7 +83,7 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
         }
 
         /* Handle hard links separately
-         * We identified hard links as regular files of size 0 with a symlink */
+         * We encode hard links as regular files of size 0 with a symlink */
         if (S_ISREG(file_header->mode)
          && file_header->link_target
          && file_header->size == 0
diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c
index cf0b9ab02..adb4c157b 100644
--- a/archival/libunarchive/get_header_tar.c
+++ b/archival/libunarchive/get_header_tar.c
@@ -507,8 +507,9 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
                 archive_handle->action_header(/*archive_handle->*/ file_header);
                 /* Note that we kill the '/' only after action_header() */
                 /* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */
-                if (cp) *cp = '\0';
-                archive_handle->ah_flags |= ARCHIVE_EXTRACT_QUIET;
+                if (cp)
+                        *cp = '\0';
+                //archive_handle->ah_flags |= ARCHIVE_EXTRACT_QUIET; // why??
                 archive_handle->action_data(archive_handle);
                 llist_add_to(&(archive_handle->passed), file_header->name);
         } else {
diff --git a/testsuite/tar.tests b/testsuite/tar.tests
index 71095cb20..dd8f11062 100755
--- a/testsuite/tar.tests
+++ b/testsuite/tar.tests
@@ -4,20 +4,25 @@
 
 . ./testing.sh
 
-mkdir tempdir && cd tempdir || exit 1
+rm -rf tar.tempdir 2>/dev/null
+mkdir tar.tempdir && cd tar.tempdir || exit 1
 
 # testing "test name" "script" "expected result" "file input" "stdin"
 
-testing "tar hardlinks and repeated files" "\
+testing "tar hardlinks and repeated files" '\
 rm -rf input_* test.tar 2>/dev/null
 >input_hard1
 ln input_hard1 input_hard2
 mkdir input_dir
 >input_dir/file
+chmod -R 644 *
+chmod    755 input_dir
 tar cf test.tar input input_dir/ input_hard1 input_hard2 input_hard1 input_dir/ input
-tar tvf test.tar | sed 's/.*[0-9] input/input/'
-tar xf test.tar 2>&1 && echo Ok
-" "\
+tar tvf test.tar | sed "s/.*[0-9] input/input/"
+tar xf test.tar 2>&1
+echo Ok: $?
+ls -l . input_dir/* | grep input_ | sed "s/\\(^[^ ]*\\) .* input/\\1 input/"
+' "\
 input
 input_dir/
 input_dir/file
@@ -27,7 +32,40 @@ input_hard1 -> input_hard1
 input_dir/
 input_dir/file
 input
-Ok
+Ok: 0
+-rw-r--r-- input_dir/file
+drwxr-xr-x input_dir
+-rw-r--r-- input_hard1
+-rw-r--r-- input_hard2
+" \
+"" ""
+
+testing "tar hardlinks mode" '\
+rm -rf input_* test.tar 2>/dev/null
+>input_hard1
+chmod 741 input_hard1
+ln input_hard1 input_hard2
+mkdir input_dir
+chmod 550 input_dir
+ln input_hard1 input_dir
+ln input_hard2 input_dir
+tar cf test.tar input_*
+tar tvf test.tar | sed "s/.*[0-9] input/input/"
+tar xf test.tar 2>&1
+echo Ok: $?
+ls -l . input_dir/* | grep input_ | sed "s/\\(^[^ ]*\\) .* input/\\1 input/"
+' "\
+input_dir/
+input_dir/input_hard1
+input_dir/input_hard2 -> input_dir/input_hard1
+input_hard1 -> input_dir/input_hard1
+input_hard2 -> input_dir/input_hard1
+Ok: 0
+-rwxr----x input_dir/input_hard1
+-rwxr----x input_dir/input_hard2
+dr-xr-x--- input_dir
+-rwxr----x input_hard1
+-rwxr----x input_hard2
 " \
 "" ""
 
@@ -46,6 +84,6 @@ Ok
 "Ok\n" ""
 SKIP=
 
-cd .. && rm -rf tempdir || exit 1
+cd .. && rm -rf tar.tempdir || exit 1
 
 exit $FAILCOUNT