bpftool: Fix bpftool build by switching to bpf_object__open_file()

As part of libbpf in 5e61f270 ("libbpf: stop enforcing kern_version,
populate it for users") non-LIBBPF_API __bpf_object__open_xattr() API
was removed from libbpf.h header. This broke bpftool, which relied on
that function. This patch fixes the build by switching to newly added
bpf_object__open_file() which provides the same capabilities, but is
official and future-proof API.

v1->v2:
- fix prog_type shadowing (Stanislav).

Fixes: 5e61f270 ("libbpf: stop enforcing kern_version, populate it for users")
Reported-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20191007225604.2006146-1-andriin@fb.com

tools/bpf/bpftool/main.c

@@ -27,7 +27,7 @@ bool json_output;
 bool show_pinned;
 bool block_mount;
 bool verifier_logs;
-int bpf_flags;
+bool relaxed_maps;
 struct pinned_obj_table prog_table;
 struct pinned_obj_table map_table;
 
@@ -396,7 +396,7 @@ int main(int argc, char **argv)
 			show_pinned = true;
 			break;
 		case 'm':
-			bpf_flags = MAPS_RELAX_COMPAT;
+			relaxed_maps = true;
 			break;
 		case 'n':
 			block_mount = true;

tools/bpf/bpftool/main.h

@@ -94,7 +94,7 @@ extern bool json_output;
 extern bool show_pinned;
 extern bool block_mount;
 extern bool verifier_logs;
-extern int bpf_flags;
+extern bool relaxed_maps;
 extern struct pinned_obj_table prog_table;
 extern struct pinned_obj_table map_table;
 

tools/bpf/bpftool/prog.c

@@ -1092,9 +1092,7 @@ static int do_run(int argc, char **argv)
 static int load_with_options(int argc, char **argv, bool first_prog_only)
 {
 	struct bpf_object_load_attr load_attr = { 0 };
-	struct bpf_object_open_attr open_attr = {
-		.prog_type = BPF_PROG_TYPE_UNSPEC,
-	};
+	enum bpf_prog_type common_prog_type = BPF_PROG_TYPE_UNSPEC;
 	enum bpf_attach_type expected_attach_type;
 	struct map_replace *map_replace = NULL;
 	struct bpf_program *prog = NULL, *pos;
@@ -1105,11 +1103,16 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 	const char *pinfile;
 	unsigned int i, j;
 	__u32 ifindex = 0;
+	const char *file;
 	int idx, err;
 
+	LIBBPF_OPTS(bpf_object_open_opts, open_opts,
+		.relaxed_maps = relaxed_maps,
+	);
+
 	if (!REQ_ARGS(2))
 		return -1;
-	open_attr.file = GET_ARG();
+	file = GET_ARG();
 	pinfile = GET_ARG();
 
 	while (argc) {
@@ -1118,7 +1121,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 
 			NEXT_ARG();
 
-			if (open_attr.prog_type != BPF_PROG_TYPE_UNSPEC) {
+			if (common_prog_type != BPF_PROG_TYPE_UNSPEC) {
 				p_err("program type already specified");
 				goto err_free_reuse_maps;
 			}
@@ -1135,8 +1138,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 			strcat(type, *argv);
 			strcat(type, "/");
 
-			err = libbpf_prog_type_by_name(type,
-						       &open_attr.prog_type,
+			err = libbpf_prog_type_by_name(type, &common_prog_type,
 						       &expected_attach_type);
 			free(type);
 			if (err < 0)
@@ -1224,16 +1226,16 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 
 	set_max_rlimit();
 
-	obj = __bpf_object__open_xattr(&open_attr, bpf_flags);
+	obj = bpf_object__open_file(file, &open_opts);
 	if (IS_ERR_OR_NULL(obj)) {
 		p_err("failed to open object file");
 		goto err_free_reuse_maps;
 	}
 
 	bpf_object__for_each_program(pos, obj) {
-		enum bpf_prog_type prog_type = open_attr.prog_type;
+		enum bpf_prog_type prog_type = common_prog_type;
 
-		if (open_attr.prog_type == BPF_PROG_TYPE_UNSPEC) {
+		if (prog_type == BPF_PROG_TYPE_UNSPEC) {
 			const char *sec_name = bpf_program__title(pos, false);
 
 			err = libbpf_prog_type_by_name(sec_name, &prog_type,