Re: [libvirt] [PATCH 02/10] Provide a simple object for encoding/decoding RPC messages

On 06/22/2011 09:33 AM, Daniel P. Berrange wrote: > This provides a new struct that contains a buffer for the RPC > message header+payload, as well as a decoded copy of the message > header. There is an API for applying a XDR encoding & decoding > of the message headers and payloads. There are also APIs for > maintaining a simple FIFO queue of message instances. > > Expected usage scenarios are: > > To send a message > > msg = virNetMessageNew() > > ...fill in msg->header fields.. > virNetMessageEncodeHeader(msg) > ...loook at msg->header fields to determine payload filter > virNetMessageEncodePayload(msg, xdrfilter, data) > ...send msg->bufferLength worth of data from buffer > > To receive a message > > msg = virNetMessageNew() > ...read VIR_NET_MESSAGE_LEN_MAX of data into buffer > virNetMessageDecodeLength(msg) > ...read msg->bufferLength-msg->bufferOffset of data into buffer > virNetMessageDecodeHeader(msg) > ...look at msg->header fields to determine payload filter > virNetMessageDecodePayload(msg, xdrfilter, data) > ...run payload processor 'make check' fails: virnetmessagetest-virnetmessagetest.o: In function `testMessageHeaderEncode': /home/remote/eblake/libvirt/tests/virnetmessagetest.c:57: undefined reference to `virNetMessageEncodeHeader' But that was easy enough to fix.

> +++ b/src/rpc/virnetmessage.h > @@ -0,0 +1,82 @@ > +/* > + > +#ifndef __VIR_NET_MESSAGE_H__ > +# define __VIR_NET_MESSAGE_H__ > + > +# include <stdbool.h> Is this include still necessary?

> +int virtTestDifferenceBin(FILE *stream, > + const char *expect, > + const char *actual, > + size_t length) > +{ > + size_t start = 0, end = length; > + ssize_t i; > + > + if (!virTestGetDebug()) > + return 0; > + > + if (virTestGetDebug() < 2) { > + /* Skip to first character where they differ */ > + for (i = 0 ; i < length ; i++) { > + if (expect[i] != actual[i]) { > + start = i; > + break; > + } > + } > + > + /* Work backwards to last character where they differ */ > + for (i = (length -1) ; i >= 0 ; i--) { > + if (expect[i] != actual[i]) { > + end = i; > + break; > + } > + } > + } > + /* Round to nearest boundary of 4 */ > + start -= (start % 4); > + end += 4 - (end % 4); This could make end go beyond length, if the difference was in the last byte or two on an unaligned length. And if expect or actual are also unaligned, then this means that reading beyond bounds could segfault (at any rate, valgrind will certainly call you on it).