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bpftool: Print as a string for char array 

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@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200318171643.129021-1-kafai@fb.com
alistair/sensors
Martin KaFai Lau 2020-03-18 10:16:43 -07:00 committed by Daniel Borkmann
parent ca7e6e45d1
commit 30255d3175
1 changed files with 41 additions and 0 deletions
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41
tools/bpf/bpftool/btf_dumper.c
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@ -81,6 +81,42 @@ static int btf_dumper_enum(const struct btf_dumper *d,
return 0;
}
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)
{
@ -90,6 +126,11 @@ 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;
}
elem_size = btf__resolve_size(d->btf, arr->type);
if (elem_size < 0)
return elem_size;