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

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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: Blake Jones <blakejones@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250603203701.520541-2-blakejones@google.com
This commit is contained in:
Blake Jones 2025-06-03 13:37:01 -07:00 committed by Andrii Nakryiko
parent 87c9c79a02
commit a570f386f3
1 changed files with 118 additions and 0 deletions
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118
tools/testing/selftests/bpf/prog_tests/btf_dump.c
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@ -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);