Re: [PATCH bpf-next 1/2] libbpf: Implement btf__save_to_file()
From: Andrii Nakryiko <hidden>
Date: 2021-10-28 18:36:41
Also in:
bpf
On Wed, Oct 27, 2021 at 1:37 PM Mauricio Vásquez [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Implement helper function to save the contents of a BTF object to a file. Signed-off-by: Mauricio Vásquez <redacted> Signed-off-by: Rafael David Tinoco <redacted> Signed-off-by: Lorenzo Fontana <redacted> --- tools/lib/bpf/btf.c | 22 ++++++++++++++++++++++ tools/lib/bpf/btf.h | 2 ++ tools/lib/bpf/libbpf.map | 1 + 3 files changed, 25 insertions(+)diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 0c628c33e23b..087035574dba 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c@@ -4773,3 +4773,25 @@ int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void return 0; } + +int btf__save_to_file(struct btf *btf, const char *path)
given we have its loading counterpart as btf__parse_raw(), let's call this one btf__save_raw()?
+{
+ const void *data;
+ __u32 data_sz;
+ FILE *file;
+
+ data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);use btf__raw_data() instead? no need to think about btf->swapped_endian here
+ if (!data) + return -ENOMEM;
please use libbpf_err() helper for returning errors, see other use cases
+
+ file = fopen(path, "wb");
+ if (!file)
+ return -errno;
+
+ if (fwrite(data, 1, data_sz, file) != data_sz) {
+ fclose(file);
+ return -EIO;why not propagating original errno? make sure you save it before fclose(), though
+ } + + return fclose(file);
hm... I'd just do fclose(file) separately and return 0 (because success). If file closing fails, there isn't anything that can be done (but it also shouldn't fail in any normal situation).
quoted hunk ↗ jump to hunk
+}diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index bc005ba3ceec..300ad498c615 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h@@ -114,6 +114,8 @@ LIBBPF_API struct btf *btf__parse_elf_split(const char *path, struct btf *base_b LIBBPF_API struct btf *btf__parse_raw(const char *path); LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf); +LIBBPF_API int btf__save_to_file(struct btf *btf, const char *path);
const struct btf? btf__raw_data() (even though it internally modifies btf) accepts `const struct btf*`, because this is conceptually read-only operation
quoted hunk ↗ jump to hunk
+ LIBBPF_API struct btf *btf__load_vmlinux_btf(void); LIBBPF_API struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf); LIBBPF_API struct btf *libbpf_find_kernel_btf(void);diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 15239c05659c..0e9bed7c9b9e 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map@@ -399,4 +399,5 @@ LIBBPF_0.6.0 { btf__add_decl_tag; btf__raw_data; btf__type_cnt; + btf__save_to_file; } LIBBPF_0.5.0; --2.25.1