libbpf: Constify few bpf_program getters

mainline inclusion
from mainline-5.13-rc1
commit a46410d5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a46410d5e4975d701d526397156fa0815747dc2f

-------------------------------------------------

bpf_program__get_type() and bpf_program__get_expected_attach_type() shouldn't
modify given bpf_program, so mark input parameter as const struct bpf_program.
This eliminates unnecessary compilation warnings or explicit casts in user
programs.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210324172941.2609884-1-andrii@kernel.org
(cherry picked from commit a46410d5)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/libbpf.c

@@ -8515,7 +8515,7 @@ int bpf_program__nth_fd(const struct bpf_program *prog, int n)
 	return fd;
 }
 
-enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog)
+enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog)
 {
 	return prog->type;
 }
@@ -8561,7 +8561,7 @@ BPF_PROG_TYPE_FNS(sk_lookup, BPF_PROG_TYPE_SK_LOOKUP);
 BPF_PROG_TYPE_FNS(sched, BPF_PROG_TYPE_SCHED);
 
 enum bpf_attach_type
-bpf_program__get_expected_attach_type(struct bpf_program *prog)
+bpf_program__get_expected_attach_type(const struct bpf_program *prog)
 {
 	return prog->expected_attach_type;
 }

tools/lib/bpf/libbpf.h

@@ -364,12 +364,12 @@ LIBBPF_API int bpf_program__set_extension(struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_sk_lookup(struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_sched(struct bpf_program *prog);
 
-LIBBPF_API enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog);
+LIBBPF_API enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
 LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,
 				      enum bpf_prog_type type);
 
 LIBBPF_API enum bpf_attach_type
-bpf_program__get_expected_attach_type(struct bpf_program *prog);
+bpf_program__get_expected_attach_type(const struct bpf_program *prog);
 LIBBPF_API void
 bpf_program__set_expected_attach_type(struct bpf_program *prog,
 				      enum bpf_attach_type type);