Commit f4d385e4 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

selftests/bpf: Test "incremental" btf_dump in C format 



Add test validating that btf_dump works fine with BTFs that are modified and
incrementally generated.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200929232843.1249318-5-andriin@fb.com
parent 9c6c5c48

tools/testing/selftests/bpf/prog_tests/btf_dump.c

+105 −0
Original line number Diff line number Diff line
@@ -129,6 +129,109 @@ static int test_btf_dump_case(int n, struct btf_dump_test_case *t) 
	return err;

}



static char *dump_buf;

static size_t dump_buf_sz;

static FILE *dump_buf_file;



void test_btf_dump_incremental(void)

{

	struct btf *btf = NULL;

	struct btf_dump *d = NULL;

	struct btf_dump_opts opts;

	int id, err, i;



	dump_buf_file = open_memstream(&dump_buf, &dump_buf_sz);

	if (!ASSERT_OK_PTR(dump_buf_file, "dump_memstream"))

		return;

	btf = btf__new_empty();

	if (!ASSERT_OK_PTR(btf, "new_empty"))

		goto err_out;

	opts.ctx = dump_buf_file;

	d = btf_dump__new(btf, NULL, &opts, btf_dump_printf);

	if (!ASSERT_OK(libbpf_get_error(d), "btf_dump__new"))

		goto err_out;



	/* First, generate BTF corresponding to the following C code:

	 *

	 * enum { VAL = 1 };

	 *

	 * struct s { int x; };

	 *

	 */

	id = btf__add_enum(btf, NULL, 4);

	ASSERT_EQ(id, 1, "enum_id");

	err = btf__add_enum_value(btf, "VAL", 1);

	ASSERT_OK(err, "enum_val_ok");



	id = btf__add_int(btf, "int", 4, BTF_INT_SIGNED);

	ASSERT_EQ(id, 2, "int_id");



	id = btf__add_struct(btf, "s", 4);

	ASSERT_EQ(id, 3, "struct_id");

	err = btf__add_field(btf, "x", 2, 0, 0);

	ASSERT_OK(err, "field_ok");



	for (i = 1; i <= btf__get_nr_types(btf); i++) {

		err = btf_dump__dump_type(d, i);

		ASSERT_OK(err, "dump_type_ok");

	}



	fflush(dump_buf_file);

	dump_buf[dump_buf_sz] = 0; /* some libc implementations don't do this */

	ASSERT_STREQ(dump_buf,

"enum {\n"

"	VAL = 1,\n"

"};\n"

"\n"

"struct s {\n"

"	int x;\n"

"};\n\n", "c_dump1");



	/* Now, after dumping original BTF, append another struct that embeds

	 * anonymous enum. It also has a name conflict with the first struct:

	 *

	 * struct s___2 {

	 *     enum { VAL___2 = 1 } x;

	 *     struct s s;

	 * };

	 *

	 * This will test that btf_dump'er maintains internal state properly.

	 * Note that VAL___2 enum value. It's because we've already emitted

	 * that enum as a global anonymous enum, so btf_dump will ensure that

	 * enum values don't conflict;

	 *

	 */

	fseek(dump_buf_file, 0, SEEK_SET);



	id = btf__add_struct(btf, "s", 4);

	ASSERT_EQ(id, 4, "struct_id");

	err = btf__add_field(btf, "x", 1, 0, 0);

	ASSERT_OK(err, "field_ok");

	err = btf__add_field(btf, "s", 3, 32, 0);

	ASSERT_OK(err, "field_ok");



	for (i = 1; i <= btf__get_nr_types(btf); i++) {

		err = btf_dump__dump_type(d, i);

		ASSERT_OK(err, "dump_type_ok");

	}



	fflush(dump_buf_file);

	dump_buf[dump_buf_sz] = 0; /* some libc implementations don't do this */

	ASSERT_STREQ(dump_buf,

"struct s___2 {\n"

"	enum {\n"

"		VAL___2 = 1,\n"

"	} x;\n"

"	struct s s;\n"

"};\n\n" , "c_dump1");



err_out:

	fclose(dump_buf_file);

	free(dump_buf);

	btf_dump__free(d);

	btf__free(btf);

}



void test_btf_dump() {

	int i;
@@ -140,4 +243,6 @@ void test_btf_dump() { 


		test_btf_dump_case(i, &btf_dump_test_cases[i]);

	}

	if (test__start_subtest("btf_dump: incremental"))

		test_btf_dump_incremental();

}