goodixmoc: Fix template struct for required length calculation

The length is only a single byte in the transfer. However, the struct
had a uint32_t in that place, breaking the sizeof() calculation and
seemingly creating issues for certain lengths of user id strings (which
depend on the username).

Fix this by changing the type to uint8_t. Also add the initial 0x43
prefix byte and a byte of apparent padding that the struct contains.
Leave the two reserved bytes at the end, as they seem to actually have a
meaning (i.e. they are seemingly send in listings).

This effectively makes the struct one byte smaller, bringing it down to
127 bytes from 128 bytes.

Closes: #428, #404

1 files changed, 4 insertions, 2 deletions

diff --git a/libfprint/drivers/goodixmoc/goodix_proto.h b/libfprint/drivers/goodixmoc/goodix_proto.h
index bcd1cdd..000be2f 100644
--- a/libfprint/drivers/goodixmoc/goodix_proto.h
+++ b/libfprint/drivers/goodixmoc/goodix_proto.h
@@ -113,14 +113,16 @@ typedef struct _gxfp_enroll_init
 #pragma pack(push, 1)
 typedef struct _template_format
 {
+  uint8_t _0x43_byte;
   uint8_t type;
   uint8_t finger_index;
+  uint8_t pad0;
   uint8_t accountid[32];
   uint8_t tid[32];
   struct
   {
-    uint32_t size;
-    uint8_t  data[56];
+    uint8_t size;
+    uint8_t data[56];
   } payload;
   uint8_t reserve[2];
 } template_format_t, *ptemplate_format_t;