storage: Pass drive name to hyperstart with the newcontainer command

For hyperstart to use the drive passed on qemu command line,
we pass the drive name and the file system type of the block
device. The drive name needs to be passed as image field
in the newcontainer json.
The drive name is deduced based on the index at which the drive is
passed to qemu.

Signed-off-by: Archana Shinde <archana.m.shinde@intel.com>

src/proxy.c

@@ -1330,6 +1330,7 @@ cc_proxy_run_hyper_new_container (struct cc_oci_config *config,
 	JsonArray *additional_gids = NULL;
 	gchar     *uid_str = NULL;
 	gchar     *gid_str = NULL;
+	gchar     *drive_name = NULL;
 
 	/* json stanza for NEWCONTAINER*/
 	/*
@@ -1378,9 +1379,20 @@ cc_proxy_run_hyper_new_container (struct cc_oci_config *config,
 
 	json_object_set_array_member (newcontainer_payload, "fsmap", cc_get_hyper_fsmap(config));
 
-	json_object_set_string_member (newcontainer_payload, "rootfs", rootfs);
+	if (config->state.block_fstype) {
+		drive_name = cc_get_virtio_drive_name(config->state.block_index);
+		if (! drive_name) {
+			return false;
+		}
+
+		json_object_set_string_member (newcontainer_payload, "image", drive_name);
+		json_object_set_string_member (newcontainer_payload, "fstype", config->state.block_fstype);
+		json_object_set_string_member (newcontainer_payload, "rootfs", "rootfs");
+	} else {
+		json_object_set_string_member (newcontainer_payload, "rootfs", rootfs);
+		json_object_set_string_member (newcontainer_payload, "image", image);
+	}
 
-	json_object_set_string_member (newcontainer_payload, "image", image);
 	/*json_object_set_string_member (newcontainer_payload, "image",
 	  config->optarg_container_id);
 	  */
@@ -1479,6 +1491,7 @@ cc_proxy_run_hyper_new_container (struct cc_oci_config *config,
 		return false;
 	}
 
+	g_free_if_set(drive_name);
 	return true;
 }
 

src/util.c

@@ -33,6 +33,11 @@
 #include "util.h"
 #include "config.h"
 
+/* Length for virtio disk name
+ * Ref: https://github.com/torvalds/linux/blob/08c521a2011ff492490aa9ed6cc574be4235ce2b/include/linux/genhd.h#L61
+ */
+#define DISK_NAME_LEN 32
+
 /** Full path to \c rm(1) command. */
 #define CC_OCI_RM_CMD "/bin/rm"
 
@@ -741,6 +746,65 @@ get_random_bytes(uint num) {
 	return buf;
 }
 
+// Legacy naming scheme for virtio block devices
+// Reference : https://github.com/torvalds/linux/blob/master/drivers/block/virtio_blk.c @c0aa3e0916d7e531e69b02e426f7162dfb1c6c0f
+static int
+virtblk_name_format(char *prefix, int index, char *buf, int buflen)
+{
+	char *p;
+	int unit;
+
+	if (! (prefix && buf)) {
+		return -1;
+	}
+
+	const int base = 'z' - 'a' + 1;
+	char *begin = buf + strlen(prefix);
+	char *end = buf + buflen;
+
+	p = end - 1;
+	*p = '\0';
+	unit = base;
+
+	do {
+		if (p == begin) {
+			return -EINVAL;
+		}
+
+		*--p = (char)('a' + (index % unit));
+		index = (index / unit) - 1;
+	} while (index >= 0);
+
+	memmove(begin, p, (size_t)(end - p));
+	memcpy(buf, prefix, strlen(prefix));
+
+	return 0;
+}
+
+/*!
+ * Get the name of a virtio-block drive
+ *
+ * \param buf Buffer storing the big endian value
+ *
+ * \return \c guint32 in big endian order.
+ */
+
+gchar *
+cc_get_virtio_drive_name(int index)
+{
+	char disk_name[DISK_NAME_LEN];
+
+	if (index < 0) {
+		return NULL;
+	}
+
+	if (virtblk_name_format("vd", index, disk_name, DISK_NAME_LEN) != 0) {
+		return NULL;
+	}
+
+	return strdup(disk_name);
+}
+
 #ifdef DEBUG
 static gboolean
 cc_oci_node_dump_aux(GNode* node, gpointer data) {

src/util.h

@@ -95,6 +95,7 @@ gboolean cc_oci_enable_networking (void);
 guint32 cc_oci_get_big_endian_32(const guint8 *buf);
 gboolean cc_oci_handle_signals (void);
 gboolean dup_over_stdio(int *fdp);
+gchar *cc_get_virtio_drive_name(int index);
 uint8_t *get_random_bytes(uint size);
 
 #endif /* _CC_OCI_UTIL_H */