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Date: Fri, 2 Aug 2019 19:57:40 +0000
From: Andrii Nakryiko <andriin@...com>
To: Stanislav Fomichev <sdf@...gle.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"bpf@...r.kernel.org" <bpf@...r.kernel.org>
CC: "davem@...emloft.net" <davem@...emloft.net>,
"ast@...nel.org" <ast@...nel.org>,
"daniel@...earbox.net" <daniel@...earbox.net>,
"andrii.nakryiko@...il.com" <andrii.nakryiko@...il.com>
Subject: Re: [PATCH bpf-next 1/3] selftests/bpf: test_progs: switch to
open_memstream
On 8/2/19 10:17 AM, Stanislav Fomichev wrote:
> Use open_memstream to override stdout during test execution.
> The copy of the original stdout is held in env.stdout and used
> to print subtest info and dump failed log.
I really like the idea. I didn't know about open_memstream, it's awesome. Thanks!
>
> test_{v,}printf are now simple wrappers around stdout and will be
> removed in the next patch.
>
> Cc: Andrii Nakryiko <andriin@...com>
> Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
> ---
> tools/testing/selftests/bpf/test_progs.c | 100 ++++++++++-------------
> tools/testing/selftests/bpf/test_progs.h | 2 +-
> 2 files changed, 46 insertions(+), 56 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
> index db00196c8315..00d1565d01a3 100644
> --- a/tools/testing/selftests/bpf/test_progs.c
> +++ b/tools/testing/selftests/bpf/test_progs.c
> @@ -40,14 +40,22 @@ static bool should_run(struct test_selector *sel, int num, const char *name)
>
> static void dump_test_log(const struct prog_test_def *test, bool failed)
> {
> - if (env.verbose || test->force_log || failed) {
> - if (env.log_cnt) {
> - fprintf(stdout, "%s", env.log_buf);
> - if (env.log_buf[env.log_cnt - 1] != '\n')
> - fprintf(stdout, "\n");
> + if (stdout == env.stdout)
> + return;
> +
> + fflush(stdout); /* exports env.log_buf & env.log_cap */
> +
> + if (env.log_cap && (env.verbose || test->force_log || failed)) {
> + int len = strlen(env.log_buf);
env.log_cap is not really a capacity, it's actual number of bytes (without terminating zero), so there is no need to do strlen and it's probably better to rename env.log_cap into env.log_cnt.
> +
> + if (len) {
> + fprintf(env.stdout, "%s", env.log_buf);
> + if (env.log_buf[len - 1] != '\n')
> + fprintf(env.stdout, "\n");
> +
> + fseeko(stdout, 0, SEEK_SET);
Same bug as I already fixed with env.log_cnt = 0 being inside this if. You want to do seek always, not just when you print output log.
> /* rewind */
> }
> }
> - env.log_cnt = 0;
> }
>
> void test__end_subtest()
> @@ -62,7 +70,7 @@ void test__end_subtest()
>
> dump_test_log(test, sub_error_cnt);
>
> - printf("#%d/%d %s:%s\n",
> + fprintf(env.stdout, "#%d/%d %s:%s\n",
> test->test_num, test->subtest_num,
> test->subtest_name, sub_error_cnt ? "FAIL" : "OK");
> }
> @@ -100,53 +108,7 @@ void test__force_log() {
>
> void test__vprintf(const char *fmt, va_list args)
> {
> - size_t rem_sz;
> - int ret = 0;
> -
> - if (env.verbose || (env.test && env.test->force_log)) {
> - vfprintf(stderr, fmt, args);
> - return;
> - }
> -
> -try_again:
> - rem_sz = env.log_cap - env.log_cnt;
> - if (rem_sz) {
> - va_list ap;
> -
> - va_copy(ap, args);
> - /* we reserved extra byte for \0 at the end */
> - ret = vsnprintf(env.log_buf + env.log_cnt, rem_sz + 1, fmt, ap);
> - va_end(ap);
> -
> - if (ret < 0) {
> - env.log_buf[env.log_cnt] = '\0';
> - fprintf(stderr, "failed to log w/ fmt '%s'\n", fmt);
> - return;
> - }
> - }
> -
> - if (!rem_sz || ret > rem_sz) {
> - size_t new_sz = env.log_cap * 3 / 2;
> - char *new_buf;
> -
> - if (new_sz < 4096)
> - new_sz = 4096;
> - if (new_sz < ret + env.log_cnt)
> - new_sz = ret + env.log_cnt;
> -
> - /* +1 for guaranteed space for terminating \0 */
> - new_buf = realloc(env.log_buf, new_sz + 1);
> - if (!new_buf) {
> - fprintf(stderr, "failed to realloc log buffer: %d\n",
> - errno);
> - return;
> - }
> - env.log_buf = new_buf;
> - env.log_cap = new_sz;
> - goto try_again;
> - }
> -
> - env.log_cnt += ret;
> + vprintf(fmt, args);
> }
>
> void test__printf(const char *fmt, ...)
> @@ -477,6 +439,32 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
> return 0;
> }
>
> +static void stdout_hijack(void)
> +{
> + if (env.verbose || (env.test && env.test->force_log)) {
> + /* nothing to do, output to stdout by default */
> + return;
> + }
> +
> + /* stdout -> buffer */
> + fflush(stdout);
> + stdout = open_memstream(&env.log_buf, &env.log_cap);
Check errors and restore original stdout if something went wrong? (And emit some warning to stderr).
> +}
> +
> +static void stdout_restore(void)
> +{
> + if (stdout == env.stdout)
> + return;
> +
> + fclose(stdout);
> + free(env.log_buf);
> +
> + env.log_buf = NULL;
> + env.log_cap = 0;
> +
> + stdout = env.stdout;
> +}
> +
> int main(int argc, char **argv)
> {
> static const struct argp argp = {
> @@ -495,6 +483,7 @@ int main(int argc, char **argv)
> srand(time(NULL));
>
> env.jit_enabled = is_jit_enabled();
> + env.stdout = stdout;
>
> for (i = 0; i < prog_test_cnt; i++) {
> struct prog_test_def *test = &prog_test_defs[i];
> @@ -508,6 +497,7 @@ int main(int argc, char **argv)
> test->test_num, test->test_name))
> continue;
>
> + stdout_hijack();
Why do you do this for every test? Just do once before all the tests and restore after?
> test->run_test();
> /* ensure last sub-test is finalized properly */
> if (test->subtest_name)
> @@ -522,6 +512,7 @@ int main(int argc, char **argv)
> env.succ_cnt++;
>
> dump_test_log(test, test->error_cnt);
> + stdout_restore();
>
> printf("#%d %s:%s\n", test->test_num, test->test_name,
> test->error_cnt ? "FAIL" : "OK");
> @@ -529,7 +520,6 @@ int main(int argc, char **argv)
> printf("Summary: %d/%d PASSED, %d FAILED\n",
> env.succ_cnt, env.sub_succ_cnt, env.fail_cnt);
>
> - free(env.log_buf);
> free(env.test_selector.num_set);
> free(env.subtest_selector.num_set);
>
> diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
> index afd14962456f..9fd89078494f 100644
> --- a/tools/testing/selftests/bpf/test_progs.h
> +++ b/tools/testing/selftests/bpf/test_progs.h
> @@ -56,8 +56,8 @@ struct test_env {
> bool jit_enabled;
>
> struct prog_test_def *test;
> + FILE *stdout;
> char *log_buf;
> - size_t log_cnt;
> size_t log_cap;
So it's actually log_cnt that's assigned on fflush for memstream, according to man page, so probably keep log_cnt, delete log_cap.
>
> int succ_cnt; /* successful tests */
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