提交 d80507d1 编写于 作者: S Stanislav Fomichev 提交者: Daniel Borkmann

selftests/bpf: test_progs: fix verbose mode garbage

fseeko(.., 0, SEEK_SET) on a memstream just puts the buffer pointer
to the beginning so when we call fflush on it we get some garbage
log data from the previous test. Let's manually set terminating
byte to zero at the reported buffer size.

To show the issue consider the following snippet:

	stream = open_memstream (&buf, &len);

	fprintf(stream, "aaa");
	fflush(stream);
	printf("buf=%s, len=%zu\n", buf, len);
	fseeko(stream, 0, SEEK_SET);

	fprintf(stream, "b");
	fflush(stream);
	printf("buf=%s, len=%zu\n", buf, len);

Output:

	buf=aaa, len=3
	buf=baa, len=1

Fixes: 946152b3 ("selftests/bpf: test_progs: switch to open_memstream")
Signed-off-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
上级 bdb15a29
......@@ -45,6 +45,7 @@ static void dump_test_log(const struct prog_test_def *test, bool failed)
if (env.verbose || test->force_log || failed) {
if (env.log_cnt) {
env.log_buf[env.log_cnt] = '\0';
fprintf(env.stdout, "%s", env.log_buf);
if (env.log_buf[env.log_cnt - 1] != '\n')
fprintf(env.stdout, "\n");
......
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