[SeaBIOS] [PATCH v2 04/16] usb-msc: support commands without payload

[Paolo Bonzini]

This lets the usb-msc driver send TEST UNIT READY commands.

Signed-off-by: Paolo Bonzini 
---
    The new hunk was present in the previous submission but
    was in patch 06/16.  It didn't break bisectability, but
    was not nice.

src/usb-msc.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/usb-msc.c b/src/usb-msc.c
index 13ef93e..357e638 100644
--- a/src/usb-msc.c
+++ b/src/usb-msc.c
@@ -79,9 +79,11 @@ usb_cmd_data(struct disk_op_s *op, void *cdbcmd, u16 blocksize)
         goto fail;

// Transfer data from device.
-    ret = usb_send_bulk(bulkin, USB_DIR_IN, op->buf_fl, bytes);
-    if (ret)
-        goto fail;
+    if (bytes) {
+        ret = usb_send_bulk(bulkin, USB_DIR_IN, op->buf_fl, bytes);
+        if (ret)
+            goto fail;
+    }

// Transfer csw info.
     struct csw_s csw;
@@ -95,7 +97,8 @@ usb_cmd_data(struct disk_op_s *op, void *cdbcmd, u16 blocksize)
     if (csw.bCSWStatus == 2)
         goto fail;

-    op->count -= csw.dCSWDataResidue / blocksize;
+    if (csw.dCSWDataResidue)
+        op->count -= csw.dCSWDataResidue / blocksize;
     return DISK_RET_EBADTRACK;

fail: