[RFC PATCH bpf-next 12/17] libbpf: Add btf__find_by_glob_kind function

Jiri Olsa
2022-08-08T14:08:52Z

Adding btf__find_by_glob_kind function that returns array of
BTF ids that match given kind and allow/deny patterns.

int btf__find_by_glob_kind(const struct btf *btf, __u32 kind,
const char *allow_pattern,
const char *deny_pattern,
__u32 **__ids);

The __ids array is allocated and needs to be manually freed.

The pattern check is done by glob_match function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/lib/bpf/btf.c | 41 +++++++++++++++++++++++++++++++++
tools/lib/bpf/btf.h | 3 +++
tools/lib/bpf/libbpf.c | 2 +-
tools/lib/bpf/libbpf_internal.h | 1 +
4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 2d14f1a52d7a..ffe08acb2f9b 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -770,6 +770,47 @@ __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
return btf_find_by_name_kind(btf, 1, type_name, kind);
}

+int btf__find_by_glob_kind(const struct btf *btf, __u32 kind,
+ const char *allow_pattern, const char *deny_pattern,
+ __u32 **__ids)
+{
+ __u32 i, nr_types = btf__type_cnt(btf);
+ int cnt = 0, alloc = 0;
+ __u32 *ids = NULL;
+
+ for (i = 1; i < nr_types; i++) {
+ const struct btf_type *t = btf__type_by_id(btf, i);
+ const char *name;
+ __u32 *p;
+
+ if (btf_kind(t) != kind)
+ continue;
+ name = btf__name_by_offset(btf, t->name_off);
+ if (!name)
+ continue;
+
+ if (deny_pattern && glob_match(name, deny_pattern))
+ continue;
+ if (allow_pattern && !glob_match(name, allow_pattern))
+ continue;
+
+ if (cnt == alloc) {
+ alloc = max(16, alloc * 3 / 2);
+ p = libbpf_reallocarray(ids, alloc, sizeof(__u32));
+ if (!p) {
+ free(ids);
+ return -ENOMEM;
+ }
+ ids = p;
+ }
+ ids[cnt] = i;
+ cnt++;
+ }
+
+ *__ids = ids;
+ return cnt;
+}
+
static bool btf_is_modifiable(const struct btf *btf)
{
return (void *)btf->hdr != btf->raw_data;
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 583760df83b4..4c05d2e77771 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -546,6 +546,9 @@ static inline struct btf_decl_tag *btf_decl_tag(const struct btf_type *t)
return (struct btf_decl_tag *)(t + 1);
}

+int btf__find_by_glob_kind(const struct btf *btf, __u32 kind,
+ const char *allow_pattern, const char *deny_pattern,
+ __u32 **__ids);
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 77e3797cf75a..0952eac92eab 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10153,7 +10153,7 @@ struct bpf_link *bpf_program__attach_ksyscall(const struct bpf_program *prog,
}

/* Adapted from perf/util/string.c */
-static bool glob_match(const char *str, const char *pat)
+bool glob_match(const char *str, const char *pat)
{
while (*str && *pat && *pat != '*') {
if (*pat == '?') { /* Matches any single character */
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 4135ae0a2bc3..9dfc11f26364 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -573,4 +573,5 @@ static inline bool is_pow_of_2(size_t x)
return x && (x & (x - 1)) == 0;
}

+bool glob_match(const char *str, const char *pat);
#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
--
2.37.1