# HG changeset patch
# User Andre Przywara <andre.przywara@amd.com>
# Date 1243981771 -7200
# Node ID aef9bba654f1d2ce5c7b451da7a5f5c92408c42b
# Parent  3c62e9afafc6a70cb897ea77a99d5da1f6b9652e
allow empty QCOW images in blktap

diff -r 3c62e9afafc6 -r aef9bba654f1 tools/blktap/drivers/block-qcow.c
--- a/tools/blktap/drivers/block-qcow.c	Wed Jun 03 00:25:25 2009 +0200
+++ b/tools/blktap/drivers/block-qcow.c	Wed Jun 03 00:29:31 2009 +0200
@@ -824,7 +824,7 @@
 	l1_table_block = ROUNDUP(l1_table_block, 512);
 	ret = posix_memalign((void **)&buf2, 4096, l1_table_block);
 	if (ret != 0) goto fail;
-	if (read(fd, buf2, l1_table_block) != l1_table_block)
+	if (read(fd, buf2, l1_table_block) < l1_table_size + s->l1_table_offset)
 		goto fail;
 	memcpy(s->l1_table, buf2 + s->l1_table_offset, l1_table_size);
 
@@ -878,7 +878,8 @@
 
 			memcpy(buf2 + s->l1_table_offset, s->l1_table, l1_table_size);
 			lseek(fd, 0, SEEK_SET);
-			if (write(fd, buf2, l1_table_block) != l1_table_block) {
+			if (write(fd, buf2, l1_table_block) < 
+				l1_table_size + s->l1_table_offset) {
 				DPRINTF("qcow: Failed to write new L1 table\n");
 				goto fail;
 			}