On Sat, Jun 17, 2017 at 03:27:30PM +0300, Dmitry V. Levin wrote:
> On Sat, Jun 17, 2017 at 07:18:29PM +0800, JingPiao Chen wrote:
> > On Sat, Jun 17, 2017 at 12:35:15AM +0300, Dmitry V. Levin wrote:
> > > On Sat, May 20, 2017 at 07:42:19PM +0800, JingPiao Chen wrote:
> > [...]
> > > > diff --git a/netlink.c b/netlink.c
> > > > index 52f3806..cadfccb 100644
> > > > --- a/netlink.c
> > > > +++ b/netlink.c
> > > > @@ -78,9 +78,138 @@ print_nlattr(const struct nlattr *const nla,
> > > > }
> > > >
> > > > static void
> > > > -decode_nlattr_with_data(struct tcb *tcp, kernel_ulong_t addr,
> > > > - kernel_ulong_t len, const struct xlat *table,
> > > > - const char *dflt)
> > > > +decode_nlattr_data(struct tcb *tcp,
> > > > + kernel_ulong_t addr,
> > > > + kernel_ulong_t len,
> > > > + unsigned int nla_type,
> > > > + unsigned int policy_size,
> > > > + const struct nla_policy *policy,
> > > > + bool(*fallback_parser)(struct tcb *,
> > > > + kernel_ulong_t addr,
> > > > + kernel_ulong_t len,
> > > > + int nla_type,
> > > > + void *opaque_data),
> > > > + void *const opaque_data)
> > > > +{
> > > > + if (!policy || nla_type >= policy_size) {
> > > > + printstrn(tcp, addr, len);
> > > > + return;
> > > > + }
> > > > +
> > > > + switch (policy[nla_type].type) {
> > > > + case NLA_U8: {
> > > > + uint8_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRIu8, num);
> > > > + break;
> > > > + }
> > > > + case NLA_U16: {
> > > > + uint16_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRIu16, num);
> > > > + break;
> > > > + }
> > > > + case NLA_U32: {
> > > > + uint32_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRIu32, num);
> > > > + break;
> > > > + }
> > > > + case NLA_MSECS:
> > > > + case NLA_U64: {
> > > > + uint64_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRIu64, num);
> > > > + break;
> > > > + }
> > > > + case NLA_STRING: {
> > > > + uint16_t str_len = len;
> > > > +
> > > > + if (policy[nla_type].len && policy[nla_type].len < len)
> > > > + str_len = policy[nla_type].len;
> > > > + printstrn(tcp, addr, str_len);
> > > > + break;
> > > > + }
> > > > + case NLA_NUL_STRING:
> > > > + printstr(tcp, addr);
> > > > + break;
> > > > + case NLA_S8: {
> > > > + int8_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRId8, num);
> > > > + break;
> > > > + }
> > > > + case NLA_S16: {
> > > > + int16_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRId16, num);
> > > > + break;
> > > > + }
> > > > + case NLA_S32: {
> > > > + int32_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRId32, num);
> > > > + break;
> > > > + }
> > > > + case NLA_S64: {
> > > > + int64_t num;
> > > > +
> > > > + if (len < sizeof(num))
> > > > + printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
> > > > + else if (!umove_or_printaddr(tcp, addr, &num))
> > > > + tprintf("%" PRId64, num);
> > > > + break;
> > > > + }
> > >
> > > All these numeric cases look very similar, could you think of something
> > > that would save us from these cut-n-paste lines?
> > >
> >
> > Use macro, Is this ok?
> >
> > switch (policy[nla_type].type) {
> > #define CASE_DECODE_INTEGER(type, data_type, fmt) \
> > case type: { \
> > data_type num; \
> > \
> > if (len < sizeof(num)) \
> > printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX); \
> > else if (!umove_or_printaddr(tcp, addr, &num)) \
> > tprintf(fmt, num); \
> > break; \
> > }
> >
> > CASE_DECODE_INTEGER(NLA_U8, uint8_t, "%" PRIu8)
> > CASE_DECODE_INTEGER(NLA_U16, uint16_t, "%" PRIu16)
> > CASE_DECODE_INTEGER(NLA_U32, uint32_t, "%" PRIu32)
> > CASE_DECODE_INTEGER(NLA_U64, uint64_t, "%" PRIu64)
> > CASE_DECODE_INTEGER(NLA_S8, int8_t, "%" PRId8)
> > CASE_DECODE_INTEGER(NLA_S16, int16_t, "%" PRId16)
> > CASE_DECODE_INTEGER(NLA_S32, int32_t, "%" PRId32)
> > CASE_DECODE_INTEGER(NLA_S64, int64_t, "%" PRId64)
> > CASE_DECODE_INTEGER(NLA_MSECS, uint64_t, "%" PRIu64)
>
> This is better, but yet you'd create two different parsers
> for NLA_U64 and NLA_MSECS which are identical.
>
> Would it be better if we introduced functions for parsing each nla type?
I prefer to introduced functions for parsing each nla type,
Like this:
typedef (*nla_decoder_t)(struct tcb *,
kernel_ulong_t addr,
kernel_ulong_t len,
void *opaque_data);
static const nla_decoder_t unix_nla_decoders[] = {
[UNIX_DIAG_PEER] = decode_nla_u32,
[UNIX_DIAG_ICONS] = decode_unix_diag_icons
};
> Are we ever going to need struct nla_policy.len?
Only when is NLA_STRING use nla_policy.len, but seem useless.
> Would it be enough and more convenient to have function pointer tables
> instead of struct nla_policy tables and accompanying switch statements?
I think it convenient than:
struct {
uint16_t type;
uint16_t len;
nla_decoder_t parser;
};
--
JingPiao Chen
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