make sure 'length' is >=0 in afc_file_write

trying to write a negative amount of data doesn't make much sense, and bad
things will happen if we try to do that. Just treat negative length values
as an invalid argument. An alternative way of handling it would be to
silently return OK/0 bytes written.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/AFC.c b/src/AFC.c
index 54b3795..c97141c 100644
--- a/src/AFC.c
+++ b/src/AFC.c
@@ -819,7 +819,7 @@ afc_file_write(afc_client_t client, uint64_t handle,
 	char *out_buffer = NULL;
 	afc_error_t ret = AFC_E_SUCCESS;
 
-	if (!client || !client->afc_packet || !client->connection || !bytes || (handle == 0))
+	if (!client || !client->afc_packet || !client->connection || !bytes || (handle == 0) || (length < 0))
 		return AFC_E_INVALID_ARGUMENT;
 
 	afc_lock(client);