Commit a570f386 authored by Blake Jones's avatar Blake Jones Committed by Andrii Nakryiko
Browse files

Tests for the ".emit_strings" functionality in the BTF dumper. 



When this mode is turned on, "emit_zeroes" and "compact" have no effect,
and embedded NUL characters always terminate printing of an array.

Signed-off-by: default avatarBlake Jones <blakejones@google.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250603203701.520541-2-blakejones@google.com
parent 87c9c79a

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

+118 −0
Original line number Diff line number Diff line
@@ -879,6 +879,122 @@ static void test_btf_dump_var_data(struct btf *btf, struct btf_dump *d, 
			  "static int bpf_cgrp_storage_busy = (int)2", 2);

}



struct btf_dump_string_ctx {

	struct btf *btf;

	struct btf_dump *d;

	char *str;

	struct btf_dump_type_data_opts *opts;

	int array_id;

};



static int btf_dump_one_string(struct btf_dump_string_ctx *ctx,

			       char *ptr, size_t ptr_sz,

			       const char *expected_val)

{

	size_t type_sz;

	int ret;



	ctx->str[0] = '\0';

	type_sz = btf__resolve_size(ctx->btf, ctx->array_id);

	ret = btf_dump__dump_type_data(ctx->d, ctx->array_id, ptr, ptr_sz, ctx->opts);

	if (type_sz <= ptr_sz) {

		if (!ASSERT_EQ(ret, type_sz, "failed/unexpected type_sz"))

			return -EINVAL;

	}

	if (!ASSERT_STREQ(ctx->str, expected_val, "ensure expected/actual match"))

		return -EFAULT;

	return 0;

}



static void btf_dump_strings(struct btf_dump_string_ctx *ctx)

{

	struct btf_dump_type_data_opts *opts = ctx->opts;



	opts->emit_strings = true;



	opts->compact = true;

	opts->emit_zeroes = false;



	opts->skip_names = false;

	btf_dump_one_string(ctx, "foo", 4, "(char[4])\"foo\"");



	opts->skip_names = true;

	btf_dump_one_string(ctx, "foo", 4, "\"foo\"");



	/* This should have no effect. */

	opts->emit_zeroes = false;

	btf_dump_one_string(ctx, "foo", 4, "\"foo\"");



	/* This should have no effect. */

	opts->compact = false;

	btf_dump_one_string(ctx, "foo", 4, "\"foo\"");



	/* Non-printable characters come out as hex. */

	btf_dump_one_string(ctx, "fo\xff", 4, "\"fo\\xff\"");

	btf_dump_one_string(ctx, "fo\x7", 4, "\"fo\\x07\"");



	/*

	 * Strings that are too long for the specified type ("char[4]")

	 * should fall back to the current behavior.

	 */

	opts->compact = true;

	btf_dump_one_string(ctx, "abcde", 6, "['a','b','c','d',]");



	/*

	 * Strings that are too short for the specified type ("char[4]")

	 * should work normally.

	 */

	btf_dump_one_string(ctx, "ab", 3, "\"ab\"");



	/* Non-NUL-terminated arrays don't get printed as strings. */

	char food[4] = { 'f', 'o', 'o', 'd' };

	char bye[3] = { 'b', 'y', 'e' };



	btf_dump_one_string(ctx, food, 4, "['f','o','o','d',]");

	btf_dump_one_string(ctx, bye, 3, "['b','y','e',]");



	/* The embedded NUL should terminate the string. */

	char embed[4] = { 'f', 'o', '\0', 'd' };



	btf_dump_one_string(ctx, embed, 4, "\"fo\"");

}



static void test_btf_dump_string_data(void)

{

	struct test_ctx t = {};

	char str[STRSIZE];

	struct btf_dump *d;

	DECLARE_LIBBPF_OPTS(btf_dump_type_data_opts, opts);

	struct btf_dump_string_ctx ctx;

	int char_id, int_id, array_id;



	if (test_ctx__init(&t))

		return;



	d = btf_dump__new(t.btf, btf_dump_snprintf, str, NULL);

	if (!ASSERT_OK_PTR(d, "could not create BTF dump"))

		return;



	/* Generate BTF for a four-element char array. */

	char_id = btf__add_int(t.btf, "char", 1, BTF_INT_CHAR);

	ASSERT_EQ(char_id, 1, "char_id");

	int_id = btf__add_int(t.btf, "int", 4, BTF_INT_SIGNED);

	ASSERT_EQ(int_id, 2, "int_id");

	array_id = btf__add_array(t.btf, int_id, char_id, 4);

	ASSERT_EQ(array_id, 3, "array_id");



	ctx.btf = t.btf;

	ctx.d = d;

	ctx.str = str;

	ctx.opts = &opts;

	ctx.array_id = array_id;



	btf_dump_strings(&ctx);



	btf_dump__free(d);

	test_ctx__free(&t);

}



static void test_btf_datasec(struct btf *btf, struct btf_dump *d, char *str,

			     const char *name, const char *expected_val,

			     void *data, size_t data_sz)
@@ -970,6 +1086,8 @@ void test_btf_dump() { 
		test_btf_dump_struct_data(btf, d, str);

	if (test__start_subtest("btf_dump: var_data"))

		test_btf_dump_var_data(btf, d, str);

	if (test__start_subtest("btf_dump: string_data"))

		test_btf_dump_string_data();

	btf_dump__free(d);

	btf__free(btf);