From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35988) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XrTdz-0002Dj-IJ for qemu-devel@nongnu.org; Thu, 20 Nov 2014 10:27:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XrTdr-0003p7-W7 for qemu-devel@nongnu.org; Thu, 20 Nov 2014 10:27:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45459) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XrTdr-0003ox-OK for qemu-devel@nongnu.org; Thu, 20 Nov 2014 10:27:31 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sAKFRVl0008540 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Thu, 20 Nov 2014 10:27:31 -0500 From: Kevin Wolf Date: Thu, 20 Nov 2014 16:27:11 +0100 Message-Id: <1416497234-29880-7-git-send-email-kwolf@redhat.com> In-Reply-To: <1416497234-29880-1-git-send-email-kwolf@redhat.com> References: <1416497234-29880-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH v3 6/9] block: Read only one sector for format probing List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, jcody@redhat.com, armbru@redhat.com, mreitz@redhat.com, stefanha@redhat.com The only image format driver that even potentially accesses anything after 512 bytes in its bdrv_probe() implementation is VMDK, which reads a plain-text descriptor file. In practice, the field it's looking for seems to come first and will be well within the first 512 bytes, too. Signed-off-by: Kevin Wolf Reviewed-by: Stefan Hajnoczi Reviewed-by: Max Reitz --- block.c | 6 +++--- include/block/block_int.h | 2 ++ 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/block.c b/block.c index a0051cb..9114cfa 100644 --- a/block.c +++ b/block.c @@ -654,8 +654,8 @@ BlockDriver *bdrv_find_protocol(const char *filename, * we do it anyway for backward compatibility. * * @buf contains the image's first @buf_size bytes. - * @buf_size is the buffer size in bytes (generally 2048, but can be smaller - * if the image file is smaller) + * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE, + * but can be smaller if the image file is smaller) * @filename is its filename. * * For all block drivers, call the bdrv_probe() method to get its @@ -685,7 +685,7 @@ static int find_image_format(BlockDriverState *bs, const char *filename, BlockDriver **pdrv, Error **errp) { BlockDriver *drv; - uint8_t buf[2048]; + uint8_t buf[BLOCK_PROBE_BUF_SIZE]; int ret = 0; /* Return the raw BlockDriver * to scsi-generic devices or empty drives */ diff --git a/include/block/block_int.h b/include/block/block_int.h index a1c17b9..cd94559 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -57,6 +57,8 @@ #define BLOCK_OPT_REDUNDANCY "redundancy" #define BLOCK_OPT_NOCOW "nocow" +#define BLOCK_PROBE_BUF_SIZE 512 + typedef struct BdrvTrackedRequest { BlockDriverState *bs; int64_t offset; -- 1.8.3.1