rename archival/libunarchive -> archival/libarchive; move bz/ into it

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

archival/libarchive/get_header_tar_gz.c

@@ -0,0 +1,36 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+
+#include "libbb.h"
+#include "archive.h"
+
+char FAST_FUNC get_header_tar_gz(archive_handle_t *archive_handle)
+{
+#if BB_MMU
+	unsigned char magic[2];
+#endif
+
+	/* Can't lseek over pipes */
+	archive_handle->seek = seek_by_read;
+
+	/* Check gzip magic only if open_transformer will invoke unpack_gz_stream (MMU case).
+	 * Otherwise, it will invoke an external helper "gunzip -cf" (NOMMU case) which will
+	 * need the header. */
+#if BB_MMU
+	xread(archive_handle->src_fd, &magic, 2);
+	/* Can skip this check, but error message will be less clear */
+	if ((magic[0] != 0x1f) || (magic[1] != 0x8b)) {
+		bb_error_msg_and_die("invalid gzip magic");
+	}
+#endif
+
+	open_transformer(archive_handle->src_fd, unpack_gz_stream, "gunzip");
+	archive_handle->offset = 0;
+	while (get_header_tar(archive_handle) == EXIT_SUCCESS)
+		continue;
+
+	/* Can only do one file at a time */
+	return EXIT_FAILURE;
+}