+ if (!drv) {
+ ret = -ENOENT;
+ }
+ *pdrv = drv;
+ return ret;
+}
+
+/**
+ * Set the current 'total_sectors' value
+ */
+static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
+{
+ BlockDriver *drv = bs->drv;
+
+ /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
+ if (bs->sg)
+ return 0;
+
+ /* query actual device if possible, otherwise just trust the hint */
+ if (drv->bdrv_getlength) {
+ int64_t length = drv->bdrv_getlength(bs);
+ if (length < 0) {
+ return length;
+ }
+ hint = length >> BDRV_SECTOR_BITS;
+ }
+
+ bs->total_sectors = hint;
+ return 0;
+}
+
+/*
+ * Common part for opening disk images and files
+ */
+static int bdrv_open_common(BlockDriverState *bs, const char *filename,
+ int flags, BlockDriver *drv)
+{
+ int ret, open_flags;
+
+ assert(drv != NULL);
+
+ bs->file = NULL;
+ bs->total_sectors = 0;
+ bs->encrypted = 0;
+ bs->valid_key = 0;
+ bs->open_flags = flags;
+ /* buffer_alignment defaulted to 512, drivers can change this value */
+ bs->buffer_alignment = 512;
+
+ pstrcpy(bs->filename, sizeof(bs->filename), filename);
+
+ if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
+ return -ENOTSUP;
+ }
+
+ bs->drv = drv;
+ bs->opaque = qemu_mallocz(drv->instance_size);
+
+ /*
+ * Yes, BDRV_O_NOCACHE aka O_DIRECT means we have to present a
+ * write cache to the guest. We do need the fdatasync to flush
+ * out transactions for block allocations, and we maybe have a
+ * volatile write cache in our backing device to deal with.
+ */
+ if (flags & (BDRV_O_CACHE_WB|BDRV_O_NOCACHE))
+ bs->enable_write_cache = 1;
+
+ /*
+ * Clear flags that are internal to the block layer before opening the
+ * image.
+ */
+ open_flags = flags & ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
+
+ /*
+ * Snapshots should be writeable.
+ */
+ if (bs->is_temporary) {
+ open_flags |= BDRV_O_RDWR;
+ }
+
+ /* Open the image, either directly or using a protocol */
+ if (drv->bdrv_file_open) {
+ ret = drv->bdrv_file_open(bs, filename, open_flags);
+ } else {
+ ret = bdrv_file_open(&bs->file, filename, open_flags);
+ if (ret >= 0) {
+ ret = drv->bdrv_open(bs, open_flags);
+ }
+ }
+
+ if (ret < 0) {
+ goto free_and_fail;
+ }
+
+ bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR);
+
+ ret = refresh_total_sectors(bs, bs->total_sectors);
+ if (ret < 0) {
+ goto free_and_fail;
+ }
+
+#ifndef _WIN32
+ if (bs->is_temporary) {
+ unlink(filename);
+ }
+#endif
+ return 0;
+
+free_and_fail:
+ if (bs->file) {
+ bdrv_delete(bs->file);
+ bs->file = NULL;
+ }
+ qemu_free(bs->opaque);
+ bs->opaque = NULL;
+ bs->drv = NULL;
+ return ret;