From 7cddd3728e964164e99c59e5c9443508d9ee0161 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 20 Nov 2014 16:27:11 +0100 Subject: [PATCH] block: Read only one sector for format probing 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 Message-id: 1416497234-29880-7-git-send-email-kwolf@redhat.com Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- 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 aa7edf8911..809ec54587 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 a1c17b9578..cd94559a64 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;