static int finalize_btf_ext()

in compile/remote-compile/lbc/libbpf/src/linker.c [2755:2903]

• 120 lines of code
• 28 McCabe index (conditional complexity)

static int finalize_btf_ext(struct bpf_linker *linker)
{
	size_t funcs_sz = 0, lines_sz = 0, core_relos_sz = 0, total_sz = 0;
	size_t func_rec_sz = 0, line_rec_sz = 0, core_relo_rec_sz = 0;
	struct btf_ext_header *hdr;
	void *data, *cur;
	int i, err, sz;

	/* validate that all sections have the same .BTF.ext record sizes
	 * and calculate total data size for each type of data (func info,
	 * line info, core relos)
	 */
	for (i = 1; i < linker->sec_cnt; i++) {
		struct dst_sec *sec = &linker->secs[i];

		if (sec->func_info.rec_cnt) {
			if (func_rec_sz == 0)
				func_rec_sz = sec->func_info.rec_sz;
			if (func_rec_sz != sec->func_info.rec_sz) {
				pr_warn("mismatch in func_info record size %zu != %u\n",
					func_rec_sz, sec->func_info.rec_sz);
				return -EINVAL;
			}

			funcs_sz += sizeof(struct btf_ext_info_sec) + func_rec_sz * sec->func_info.rec_cnt;
		}
		if (sec->line_info.rec_cnt) {
			if (line_rec_sz == 0)
				line_rec_sz = sec->line_info.rec_sz;
			if (line_rec_sz != sec->line_info.rec_sz) {
				pr_warn("mismatch in line_info record size %zu != %u\n",
					line_rec_sz, sec->line_info.rec_sz);
				return -EINVAL;
			}

			lines_sz += sizeof(struct btf_ext_info_sec) + line_rec_sz * sec->line_info.rec_cnt;
		}
		if (sec->core_relo_info.rec_cnt) {
			if (core_relo_rec_sz == 0)
				core_relo_rec_sz = sec->core_relo_info.rec_sz;
			if (core_relo_rec_sz != sec->core_relo_info.rec_sz) {
				pr_warn("mismatch in core_relo_info record size %zu != %u\n",
					core_relo_rec_sz, sec->core_relo_info.rec_sz);
				return -EINVAL;
			}

			core_relos_sz += sizeof(struct btf_ext_info_sec) + core_relo_rec_sz * sec->core_relo_info.rec_cnt;
		}
	}

	if (!funcs_sz && !lines_sz && !core_relos_sz)
		return 0;

	total_sz += sizeof(struct btf_ext_header);
	if (funcs_sz) {
		funcs_sz += sizeof(__u32); /* record size prefix */
		total_sz += funcs_sz;
	}
	if (lines_sz) {
		lines_sz += sizeof(__u32); /* record size prefix */
		total_sz += lines_sz;
	}
	if (core_relos_sz) {
		core_relos_sz += sizeof(__u32); /* record size prefix */
		total_sz += core_relos_sz;
	}

	cur = data = calloc(1, total_sz);
	if (!data)
		return -ENOMEM;

	hdr = cur;
	hdr->magic = BTF_MAGIC;
	hdr->version = BTF_VERSION;
	hdr->flags = 0;
	hdr->hdr_len = sizeof(struct btf_ext_header);
	cur += sizeof(struct btf_ext_header);

	/* All offsets are in bytes relative to the end of this header */
	hdr->func_info_off = 0;
	hdr->func_info_len = funcs_sz;
	hdr->line_info_off = funcs_sz;
	hdr->line_info_len = lines_sz;
	hdr->core_relo_off = funcs_sz + lines_sz;
	hdr->core_relo_len = core_relos_sz;

	if (funcs_sz) {
		*(__u32 *)cur = func_rec_sz;
		cur += sizeof(__u32);

		for (i = 1; i < linker->sec_cnt; i++) {
			struct dst_sec *sec = &linker->secs[i];

			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->func_info);
			if (sz < 0) {
				err = sz;
				goto out;
			}

			cur += sz;
		}
	}

	if (lines_sz) {
		*(__u32 *)cur = line_rec_sz;
		cur += sizeof(__u32);

		for (i = 1; i < linker->sec_cnt; i++) {
			struct dst_sec *sec = &linker->secs[i];

			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->line_info);
			if (sz < 0) {
				err = sz;
				goto out;
			}

			cur += sz;
		}
	}

	if (core_relos_sz) {
		*(__u32 *)cur = core_relo_rec_sz;
		cur += sizeof(__u32);

		for (i = 1; i < linker->sec_cnt; i++) {
			struct dst_sec *sec = &linker->secs[i];

			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->core_relo_info);
			if (sz < 0) {
				err = sz;
				goto out;
			}

			cur += sz;
		}
	}

	linker->btf_ext = btf_ext__new(data, total_sz);
	err = libbpf_get_error(linker->btf_ext);
	if (err) {
		linker->btf_ext = NULL;
		pr_warn("failed to parse final .BTF.ext data: %d\n", err);
		goto out;
	}

out:
	free(data);
	return err;
}