On Sat, Jul 1, 2017 at 11:49 AM, Kirspel, Kevin <kevin-kirs...@idexx.com> wrote: > This is how I fixed it. I did similar things for EXTRACT_32BITS and > EXTRACT_64BITS. > > > > static inline u_int16_t > > EXTRACT_16BITS(const void *p) > > { > > #if defined(__arm__) && defined(__rtems__) > > if(((uint32_t)p % 2) != 0) { > > u_int16_t value; > > u_int8_t *ptr = (u_int8_t *)&value; > > ptr[0] = ((const u_int8_t *)p)[0]; > > ptr[1] = ((const u_int8_t *)p)[1]; > > p = &value; >
Is it correct to assign a pointer to a block-scoped variable here? It looks suspect to me. I'd at least put the declaration of 'value' before the block here. > } > > #endif /* __rtems__ */ > > return ((u_int16_t)ntohs(*(const u_int16_t *)(p))); > > } > > > > Kevin Kirspel > > Electrical Engineer - Sr. Staff > > Idexx Roswell > > 235 Hembree Park Drive > > Roswell GA 30076 > > Tel: (770)-510-4444 ext. 81642 > > Direct: (770)-688-1642 > > Fax: (770)-510-4445 > > > > From: Joel Sherrill [mailto:j...@rtems.org] > Sent: Saturday, July 01, 2017 11:39 AM > To: Gedare Bloom <ged...@rtems.org> > Cc: rtems-de...@rtems.org <devel@rtems.org>; Kirspel, Kevin > <kevin-kirs...@idexx.com> > Subject: Re: LIBBSD TCPDUMP > > > > > > > > On Jul 1, 2017 10:34 AM, "Gedare Bloom" <ged...@rtems.org> wrote: > > On Sat, Jul 1, 2017 at 10:01 AM, Kirspel, Kevin <kevin-kirs...@idexx.com> > wrote: >> I get a crash when running the tcpdump command in LIBBSD. It is due to >> the >> following structure >> >> >> >> struct stp_bpdu_ { >> >> u_int8_t protocol_id[2]; >> >> u_int8_t protocol_version; >> >> u_int8_t bpdu_type; >> >> u_int8_t flags; >> >> u_int8_t root_id[8]; >> >> u_int8_t root_path_cost[4]; >> >> u_int8_t bridge_id[8]; >> >> u_int8_t port_id[2]; >> >> u_int8_t message_age[2]; >> >> u_int8_t max_age[2]; >> >> u_int8_t hello_time[2]; >> >> u_int8_t forward_delay[2]; >> >> u_int8_t v1_length; >> >> }; >> >> >> >> In the code, there is an access to the port_id field as follows: >> EXTRACT_16BITS(&stp_bpdu->port_id). EXTRACT_16BITS calls ntohs() . Since >> the address of “&stp_bpdu->port_id” is at an odd word (16 bit) boundary, >> an >> exception is generated. What is the correct way to fix this? I was going >> to update EXTRACT_16BITS to check for an odd boundary and fix it up before >> calling ntohs(). >> > > That would probably be a more portable fix than allowing unaligned > accesses. I think the alignment should be made to the CPU_ALIGNMENT > macro. > > > > Can't you also just pull it out a byte at a time, form the net version and > then ntohs()? > > > > That's what I coded recently in some marahalling code. > > > > > >> >> >> Kevin Kirspel >> >> Electrical Engineer - Sr. Staff >> >> Idexx Roswell >> >> 235 Hembree Park Drive >> >> Roswell GA 30076 >> >> Tel: (770)-510-4444 ext. 81642 >> >> Direct: (770)-688-1642 >> >> Fax: (770)-510-4445 >> >> >> >> > >> _______________________________________________ >> devel mailing list >> devel@rtems.org >> http://lists.rtems.org/mailman/listinfo/devel > _______________________________________________ > devel mailing list > devel@rtems.org > http://lists.rtems.org/mailman/listinfo/devel > > _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel