On Tue, Mar 17, 2020 at 01:08:01PM -0700, Andrii Nakryiko wrote:
> On Sun, Mar 15, 2020 at 5:57 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
> >
> > A char[] is currently printed as an integer array.
> > This patch will print it as a string when
> > 1) The array element type is an one byte int
> > 2) The array element type has a BTF_INT_CHAR encoding or
> > the array element type's name is "char"
> > 3) All characters is between (0x1f, 0x7f) and it is terminated
> > by a null character.
> >
> > Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
> > ---
> > tools/bpf/bpftool/btf_dumper.c | 41 ++++++++++++++++++++++++++++++++++
> > 1 file changed, 41 insertions(+)
> >
> > diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
> > index 57bd6c0fafc9..1d2d8d2cedea 100644
> > --- a/tools/bpf/bpftool/btf_dumper.c
> > +++ b/tools/bpf/bpftool/btf_dumper.c
> > @@ -77,6 +77,42 @@ static void btf_dumper_enum(const struct btf_dumper *d,
> > jsonw_int(d->jw, value);
> > }
> >
> > +static bool is_str_array(const struct btf *btf, const struct btf_array *arr,
> > + const char *s)
> > +{
> > + const struct btf_type *elem_type;
> > + const char *end_s;
> > +
> > + if (!arr->nelems)
> > + return false;
> > +
> > + elem_type = btf__type_by_id(btf, arr->type);
> > + /* Not skipping typedef. typedef to char does not count as
> > + * a string now.
> > + */
> > + while (elem_type && btf_is_mod(elem_type))
> > + elem_type = btf__type_by_id(btf, elem_type->type);
> > +
> > + if (!elem_type || !btf_is_int(elem_type) || elem_type->size != 1)
> > + return false;
> > +
> > + if (btf_int_encoding(elem_type) != BTF_INT_CHAR &&
> > + strcmp("char", btf__name_by_offset(btf, elem_type->name_off)))
> > + return false;
> > +
> > + end_s = s + arr->nelems;
> > + while (s < end_s) {
> > + if (!*s)
> > + return true;
> > + if (*s <= 0x1f || *s >= 0x7f)
> > + return false;
> > + s++;
> > + }
> > +
> > + /* '\0' is not found */
> > + return false;
> > +}
> > +
> > static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
> > const void *data)
> > {
> > @@ -86,6 +122,11 @@ static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
> > int ret = 0;
> > __u32 i;
> >
> > + if (is_str_array(d->btf, arr, data)) {
> > + jsonw_string(d->jw, data);
> > + return 0;
> > + }
> > +
>
> Looks good, but curious how the string that contains ' or " will be
> output in json? Will it be escaped properly or will result in
> malformed JSON?
They will be escaped.
