Re: [Libguestfs] [libnbd PATCH v3 05/22] states: Prepare to receive 64-bit replies

[Richard W.M. Jones]

On Thu, Jun 01, 2023 at 11:04:05AM +0200, Laszlo Ersek wrote:
> On 5/25/23 15:00, Eric Blake wrote:
> > @@ -69,11 +75,18 @@  REPLY.STRUCTURED_REPLY.RECV_REMAINING:
> >   REPLY.STRUCTURED_REPLY.CHECK:
> >    struct command *cmd = h->reply_cmd;
> >    uint16_t flags, type;
> > -  uint32_t length;
> > +  uint64_t length;
> > +  uint64_t offset = -1;
> 
> (6) I disagree with initializing the local variable "offset" here.
> 
> Below (in the rest of REPLY.STRUCTURED_REPLY.CHECK), we only read
> "offset" back if "extended_headers" is set. But if "extended_headers" is
> set, we also store a value to "offset", before the read.
> 
> Initializing "offset" to -1 suggests that the code might otherwise read
> an indeterminate value from "offset" -- but that's not the case.

You may find that the compiler will give a warning.  It's usually not
good about dealing with the case where a variable being initialized +
used depends on another variable being true.

Rich.

-- 
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