Since the tar bidder can never get called more than once, it

doesn't need to compensate for this situation.

While here, fix a minor longstanding bug that empty tar archives
(which begin with at least 512 zero bytes) never properly reported
their format.  In particular, this fixes the output of:
   bsdtar tvvf /dev/zero

And, of course, a new test to verify that libarchive correctly
recognizes the format of such files.

1 files changed, 47 insertions, 0 deletions

diff --git a/lib/libarchive/test/test_read_format_tar.c b/lib/libarchive/test/test_read_format_tar.c
index 8f8b83b..bfe0b13 100644
--- a/lib/libarchive/test/test_read_format_tar.c
+++ b/lib/libarchive/test/test_read_format_tar.c
@@ -36,6 +36,52 @@ __FBSDID("$FreeBSD$");
  * '2' is a symlink, '5' is a dir, etc.
  */
 
+/* Empty archive. */
+static unsigned char archiveEmpty[] = {
+	/* 512 zero bytes */
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
+	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0
+};
+
+static void verifyEmpty(void)
+{
+	struct archive_entry *ae;
+	struct archive *a;
+
+	assert((a = archive_read_new()) != NULL);
+	assertA(0 == archive_read_support_compression_all(a));
+	assertA(0 == archive_read_support_format_all(a));
+	assertA(0 == archive_read_open_memory(a, archiveEmpty, 512));
+	assertEqualIntA(a, ARCHIVE_EOF, archive_read_next_header(a, &ae));
+	assertEqualInt(archive_compression(a), ARCHIVE_COMPRESSION_NONE);
+	failure("512 zero bytes should be recognized as a tar archive.");
+	assertEqualInt(archive_format(a), ARCHIVE_FORMAT_TAR);
+
+	assert(0 == archive_read_close(a));
+#if ARCHIVE_API_VERSION > 1
+	assert(0 == archive_read_finish(a));
+#else
+	archive_read_finish(a);
+#endif
+}
+
 /* Single entry with a hardlink. */
 static unsigned char archive1[] = {
 'h','a','r','d','l','i','n','k',0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
@@ -411,6 +457,7 @@ static void verify(unsigned char *d, size_t s,
 
 DEFINE_TEST(test_read_format_tar)
 {
+	verifyEmpty();
 	verify(archive1, sizeof(archive1), verify1,
 	    ARCHIVE_COMPRESSION_NONE, ARCHIVE_FORMAT_TAR_USTAR);
 	verify(archive2, sizeof(archive2), verify2,