Fix string may be truncated issue with using snprintf

New compiler options introduced by commit
519c428 will cause DM compile failure
which caused by warnings from some snprintf usage might be truncated.

Expanding the string buffer to make compiler happy.

v3: change format string
v2: Address comment from Hao, shrink bident string size to satify
tname length in blockif_open.

Signed-off-by: Rusty Lynch <rusty.lynch@intel.com>
Signed-off-by: Liu Shuo <shuo.a.liu@intel.com>

Author: Liu Shuo

devicemodel/hw/pci/ahci.c

@@ -2312,10 +2312,11 @@ pci_ahci_read(struct vmctx *ctx, int vcpu, struct pci_vdev *dev, int baridx,
 static int
 pci_ahci_init(struct vmctx *ctx, struct pci_vdev *dev, char *opts, int atapi)
 {
-	char bident[sizeof("XX:XX:XX")];
+	char bident[16];
 	struct blockif_ctxt *bctxt;
 	struct pci_ahci_vdev *ahci_dev;
-	int ret, slots, p;
+	int ret, slots;
+	uint8_t p;
 	MD5_CTX mdctx;
 	u_char digest[16];
 	char *next, *next2;
@@ -2365,7 +2366,7 @@ pci_ahci_init(struct vmctx *ctx, struct pci_vdev *dev, char *opts, int atapi)
 		 * Attempt to open the backing image. Use the PCI slot/func
 		 * and the port number for the identifier string.
 		 */
-		snprintf(bident, sizeof(bident), "%d:%d:%d", dev->slot,
+		snprintf(bident, sizeof(bident), "%02x:%02x:%02x", dev->slot,
 		    dev->func, p);
 		bctxt = blockif_open(opts, bident);
 		if (bctxt == NULL) {

devicemodel/hw/pci/virtio/virtio_block.c

@@ -285,7 +285,7 @@ virtio_blk_notify(void *vdev, struct virtio_vq_info *vq)
 static int
 virtio_blk_init(struct vmctx *ctx, struct pci_vdev *dev, char *opts)
 {
-	char bident[sizeof("XX:X:X")];
+	char bident[16];
 	struct blockif_ctxt *bctxt;
 	MD5_CTX mdctx;
 	u_char digest[16];