Messages in this thread | | | Date | Mon, 24 Apr 2023 09:44:18 -0700 | Subject | Re: [PATCH bpf-next v2] bpftool: Dump map id instead of value for map_of_maps types | From | Kui-Feng Lee <> |
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On 4/24/23 02:09, Xueming Feng wrote: > When using `bpftool map dump` in plain format, it is usually > more convenient to show the inner map id instead of raw value. > Changing this behavior would help with quick debugging with > `bpftool`, without disrupting scripted behavior. Since user > could dump the inner map with id, and need to convert value. > > Signed-off-by: Xueming Feng <kuro@kuroa.me> > --- > Changes in v2: > - Fix commit message grammar. > - Change `print_uint` to only print to stdout, make `arg` const, and rename > `n` to `arg_size`. > - Make `print_uint` able to take any size of argument up to `unsigned long`, > and print it as unsigned decimal. > > Thanks for the review and suggestions! I have changed my patch accordingly. > There is a possibility that `arg_size` is larger than `unsigned long`, > but previous review suggested that it should be up to the caller function to > set `arg_size` correctly. So I didn't add check for that, should I? > > tools/bpf/bpftool/main.c | 15 +++++++++++++++ > tools/bpf/bpftool/main.h | 1 + > tools/bpf/bpftool/map.c | 9 +++++++-- > 3 files changed, 23 insertions(+), 2 deletions(-) > > diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c > index 08d0ac543c67..810c0dc10ecb 100644 > --- a/tools/bpf/bpftool/main.c > +++ b/tools/bpf/bpftool/main.c > @@ -251,6 +251,21 @@ int detect_common_prefix(const char *arg, ...) > return 0; > } > > +void print_uint(const void *arg, unsigned int arg_size) > +{ > + const unsigned char *data = arg; > + unsigned long val = 0ul; > + > + #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ > + memcpy(&val, data, arg_size); > + #else > + memcpy((unsigned char *)&val + sizeof(val) - arg_size, > + data, arg_size); > + #endif
Is it possible that arg_size is bigger than sizeof(val)?
> + > + fprintf(stdout, "%lu", val); > +} > + > void fprint_hex(FILE *f, void *arg, unsigned int n, const char *sep) > { > unsigned char *data = arg; > diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h > index 0ef373cef4c7..0de671423431 100644 > --- a/tools/bpf/bpftool/main.h > +++ b/tools/bpf/bpftool/main.h > @@ -90,6 +90,7 @@ void __printf(1, 2) p_info(const char *fmt, ...); > > bool is_prefix(const char *pfx, const char *str); > int detect_common_prefix(const char *arg, ...); > +void print_uint(const void *arg, unsigned int arg_size); > void fprint_hex(FILE *f, void *arg, unsigned int n, const char *sep); > void usage(void) __noreturn; > > diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c > index aaeb8939e137..f5be4c0564cf 100644 > --- a/tools/bpf/bpftool/map.c > +++ b/tools/bpf/bpftool/map.c > @@ -259,8 +259,13 @@ static void print_entry_plain(struct bpf_map_info *info, unsigned char *key, > } > > if (info->value_size) { > - printf("value:%c", break_names ? '\n' : ' '); > - fprint_hex(stdout, value, info->value_size, " "); > + if (map_is_map_of_maps(info->type)) { > + printf("id:%c", break_names ? '\n' : ' '); > + print_uint(value, info->value_size); > + } else { > + printf("value:%c", break_names ? '\n' : ' '); > + fprint_hex(stdout, value, info->value_size, " "); > + } > } > > printf("\n");
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