[PATCH v2] erofs-utils: tests: add test for negative GNU tar mtimes

[Gao Xiang <hsiangkao@linux.alibaba.com>]

From: Vansh Choudhary <ch@vnsh.in>

Add a regression test for negative GNU tar mtimes.

It creates a tarball with a file whose mtime is -1, checks that the
mtime field is encoded in GNU base-256 format, and verifies that the
timestamp is preserved after building and extracting the image.

Signed-off-by: Vansh Choudhary <ch@vnsh.in>
Signed-off-by: Gao Xiang <xiang@kernel.org>
---
v2:
 - use dump.erofs instead of fsck.erofs;
 - switch to MIT license.

 tests/Makefile.am   |  3 +++
 tests/erofs/030     | 55 +++++++++++++++++++++++++++++++++++++++++++++
 tests/erofs/030.out |  2 ++
 3 files changed, 60 insertions(+)
 create mode 100755 tests/erofs/030
 create mode 100644 tests/erofs/030.out

diff --git a/tests/Makefile.am b/tests/Makefile.am
index d8ac067805e8..28edc0d744d1 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -126,6 +126,9 @@ TESTS += erofs/028
 # 029 - test FUSE daemon and kernel error handling on corrupted inodes
 TESTS += erofs/029
 
+# 030 - regression test for negative GNU tar mtimes
+TESTS += erofs/030
+
 # NEW TEST CASE HERE
 # TESTS += erofs/999
 
diff --git a/tests/erofs/030 b/tests/erofs/030
new file mode 100755
index 000000000000..72765cb19aee
--- /dev/null
+++ b/tests/erofs/030
@@ -0,0 +1,55 @@
+#!/bin/sh
+# SPDX-License-Identifier: MIT
+#
+# 030 - regression test for negative GNU tar mtimes
+#
+seq=`basename $0`
+seqres=$RESULT_DIR/$(echo $0 | awk '{print $((NF-1))"/"$NF}' FS="/")
+
+# get standard environment, filters and checks
+. "${srcdir}/common/rc"
+
+cleanup()
+{
+	cd /
+	rm -rf $tmp.*
+}
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+echo "QA output created by $seq"
+
+if [ -z "$SCRATCH_DEV" ]; then
+	SCRATCH_DEV=$tmp/erofs_$seq.img
+	rm -f $SCRATCH_DEV
+fi
+
+localdir="$tmp/$seq"
+rm -rf $localdir
+mkdir -p $localdir/src
+
+touch -d @-1 $localdir/src/testfile >> $seqres.full 2>&1 || \
+	_notrun "touch -d @-1 is not supported"
+tar --format=gnu -C $localdir/src -cf $localdir/foo.tar testfile >> $seqres.full 2>&1 || \
+	_fail "failed to create tarball"
+
+mtime=$(od -An -t x1 -j 136 -N 12 $localdir/foo.tar | tr -d '[:space:]')
+[ "$mtime" = "ffffffffffffffffffffffff" ] || \
+	_notrun "tar did not encode a negative GNU mtime"
+
+$MKFS_EROFS_PROG --tar=f $SCRATCH_DEV $localdir/foo.tar \
+	>> $seqres.full 2>&1 || _fail "failed to mkfs tarball"
+
+output=$($DUMP_EROFS_PROG --path=/testfile $SCRATCH_DEV 2>&1)
+[ $? -eq 0 ] || _fail "failed to dump testfile"
+echo "$output" >> $seqres.full
+
+mtime=$(grep '^Timestamp:' <<< $output | sed 's/^.*: //')
+[ "x$mtime" = "x1970-01-01 07:59:59.000000000" ] || \
+	_fail "negative GNU mtime was not preserved"
+
+echo Silence is golden
+status=0
+exit 0
diff --git a/tests/erofs/030.out b/tests/erofs/030.out
new file mode 100644
index 000000000000..06a1c8fe02bb
--- /dev/null
+++ b/tests/erofs/030.out
@@ -0,0 +1,2 @@
+QA output created by 030
+Silence is golden
-- 
2.43.5