From 584e1c355ae3c994331005b7196cc87a714e5317 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@FreeBSD.org>
Date: Wed, 3 Apr 2024 11:55:06 +0200
Subject: [PATCH] tarfs: Ignore global extended headers.

Previously, we would error out if we encountered a global extended
header, because we don't know what it means.  This doesn't really
matter though, and traditionally, tar implementations have either
ignored them or treated them as plain files, so just ignore them.
This allows tarfs to mount tar files created by `git archive`.

MFC after:	3 days
Sponsored by:	Juniper Networks, Inc.
Sponsored by:	Klara, Inc.
Reviewed by:	kevans
Differential Revision:	https://reviews.freebsd.org/D44600
---
 sys/fs/tarfs/tarfs_vfsops.c      | 13 +++++++------
 tests/sys/fs/tarfs/tarfs_test.sh | 24 ++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/sys/fs/tarfs/tarfs_vfsops.c b/sys/fs/tarfs/tarfs_vfsops.c
index df657fb1341..cbc3d88eaad 100644
--- a/sys/fs/tarfs/tarfs_vfsops.c
+++ b/sys/fs/tarfs/tarfs_vfsops.c
@@ -553,13 +553,14 @@ again:
 	TARFS_DPF(ALLOC, "%s: [%c] %zu @%jd %o %d:%d\n", __func__,
 	    hdrp->typeflag[0], sz, (intmax_t)mtime, mode, uid, gid);
 
-	/* extended header? */
+	/* global extended header? */
 	if (hdrp->typeflag[0] == TAR_TYPE_GLOBAL_EXTHDR) {
-		printf("%s: unsupported global extended header at %zu\n",
-		    __func__, (size_t)(TARFS_BLOCKSIZE * (blknum - 1)));
-		error = EFTYPE;
-		goto bad;
+		TARFS_DPF(ALLOC, "%s: %zu-byte global extended header at %zu\n",
+		    __func__, sz, TARFS_BLOCKSIZE * (blknum - 1));
+		goto skip;
 	}
+
+	/* extended header? */
 	if (hdrp->typeflag[0] == TAR_TYPE_EXTHDR) {
 		if (exthdr != NULL) {
 			TARFS_DPF(IO, "%s: multiple extended headers at %zu\n",
@@ -568,7 +569,7 @@ again:
 			goto bad;
 		}
 		/* read the contents of the exthdr */
-		TARFS_DPF(ALLOC, "%s: %zu-byte extended header at %zd\n",
+		TARFS_DPF(ALLOC, "%s: %zu-byte extended header at %zu\n",
 		    __func__, sz, TARFS_BLOCKSIZE * (blknum - 1));
 		exthdr = malloc(sz, M_TEMP, M_WAITOK);
 		res = tarfs_io_read_buf(tmp, false, exthdr,
diff --git a/tests/sys/fs/tarfs/tarfs_test.sh b/tests/sys/fs/tarfs/tarfs_test.sh
index 5d3fbca2f4e..f1322033fba 100644
--- a/tests/sys/fs/tarfs/tarfs_test.sh
+++ b/tests/sys/fs/tarfs/tarfs_test.sh
@@ -357,6 +357,29 @@ tarfs_long_paths_cleanup() {
 	tarfs_cleanup
 }
 
+atf_test_case tarfs_git_archive cleanup
+tarfs_git_archive_head() {
+	atf_set "descr" "Verify that tarfs supports archives created by git"
+	atf_set "require.user" "root"
+	atf_set "require.progs" "git"
+}
+tarfs_git_archive_body() {
+	tarfs_setup
+	mkdir foo
+	echo "Hello, world!" >foo/bar
+	git -C foo init --initial-branch=tarfs
+	git -C foo config user.name "File System"
+	git -C foo config user.email fs@freebsd.org
+	git -C foo add bar
+	git -C foo commit -m bar
+	git -C foo archive --output=../tarfs_git_archive.tar HEAD
+	atf_check mount -rt tarfs tarfs_git_archive.tar "${mnt}"
+	atf_check -o file:foo/bar cat "${mnt}"/bar
+}
+tarfs_git_archive_cleanup() {
+	tarfs_cleanup
+}
+
 atf_init_test_cases() {
 	atf_add_test_case tarfs_basic
 	atf_add_test_case tarfs_basic_gnu
@@ -374,4 +397,5 @@ atf_init_test_cases() {
 	atf_add_test_case tarfs_checksum
 	atf_add_test_case tarfs_long_names
 	atf_add_test_case tarfs_long_paths
+	atf_add_test_case tarfs_git_archive
 }