* [PATCH] misc: Fix tst-select timeout handling (BZ#27648)
@ 2021-03-25 20:00 Adhemerval Zanella
2021-03-25 21:06 ` H.J. Lu
2021-03-26 9:43 ` Lukasz Majewski
0 siblings, 2 replies; 4+ messages in thread
From: Adhemerval Zanella @ 2021-03-25 20:00 UTC (permalink / raw)
To: libc-alpha
Instead of polling the stderr, create two pipes and fork to check
if child timeout as expected similar to tst-pselect.c. Also lower
the timeout value.
Checked on x86_64-linux-gnu.
---
misc/tst-select.c | 85 ++++++++++++++++++++++++++++++-----------------
1 file changed, 55 insertions(+), 30 deletions(-)
diff --git a/misc/tst-select.c b/misc/tst-select.c
index 7c310256c5..530181c264 100644
--- a/misc/tst-select.c
+++ b/misc/tst-select.c
@@ -16,54 +16,79 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <time.h>
#include <errno.h>
-#include <stdbool.h>
-#include <sys/select.h>
+#include <support/capture_subprocess.h>
#include <support/check.h>
-#include <support/xtime.h>
#include <support/timespec.h>
+#include <support/xunistd.h>
+#include <support/xtime.h>
-#define TST_SELECT_TIMEOUT 1
-#define TST_SELECT_FD_ERR 2
+struct child_args
+{
+ int fds[2][2];
+ struct timeval tmo;
+};
-static int
-test_select_timeout (bool zero_tmo)
+static void
+do_test_child (void *clousure)
{
- const int fds = TST_SELECT_FD_ERR;
- int timeout = TST_SELECT_TIMEOUT;
- struct timeval to = { 0, 0 };
- struct timespec ts;
- fd_set rfds;
+ struct child_args *args = (struct child_args *) clousure;
- FD_ZERO (&rfds);
- FD_SET (fds, &rfds);
+ close (args->fds[0][1]);
+ close (args->fds[1][0]);
- if (zero_tmo)
- timeout = 0;
+ fd_set rfds;
+ FD_ZERO (&rfds);
+ FD_SET (args->fds[0][0], &rfds);
- to.tv_sec = timeout;
- ts = xclock_now (CLOCK_REALTIME);
- ts = timespec_add (ts, (struct timespec) { timeout, 0 });
+ struct timespec ts = xclock_now (CLOCK_REALTIME);
+ ts = timespec_add (ts, (struct timespec) { args->tmo.tv_sec, 0 });
- /* Wait for timeout. */
- int ret = select (fds + 1, &rfds, NULL, NULL, &to);
- if (ret == -1)
- FAIL_EXIT1 ("select failed: %m\n");
+ int r = select (args->fds[0][0] + 1, &rfds, NULL, NULL, &args->tmo);
+ TEST_COMPARE (r, 0);
TEST_TIMESPEC_NOW_OR_AFTER (CLOCK_REALTIME, ts);
- return 0;
+ xwrite (args->fds[1][1], "foo", 3);
}
static int
do_test (void)
{
- /* Check if select exits immediately. */
- test_select_timeout (true);
-
- /* Check if select exits after specified timeout. */
- test_select_timeout (false);
+ struct child_args args;
+
+ xpipe (args.fds[0]);
+ xpipe (args.fds[1]);
+
+ /* The child select should timeout and write on its pipe end. */
+ args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 250000 };
+ {
+ struct support_capture_subprocess result;
+ result = support_capture_subprocess (do_test_child, &args);
+ support_capture_subprocess_check (&result, "tst-select-child", 0,
+ sc_allow_none);
+ }
+
+ /* Same with simulating a polling. */
+ args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 0 };
+ {
+ struct support_capture_subprocess result;
+ result = support_capture_subprocess (do_test_child, &args);
+ support_capture_subprocess_check (&result, "tst-select-child", 0,
+ sc_allow_none);
+ }
+
+ xclose (args.fds[0][0]);
+ xclose (args.fds[1][1]);
+
+ {
+ fd_set rfds;
+ FD_ZERO (&rfds);
+ FD_SET (args.fds[1][0], &rfds);
+
+ int r = select (args.fds[1][0] + 1, &rfds, NULL, NULL, &args.tmo);
+ TEST_COMPARE (r, 1);
+ }
return 0;
}
--
2.27.0
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] misc: Fix tst-select timeout handling (BZ#27648)
2021-03-25 20:00 [PATCH] misc: Fix tst-select timeout handling (BZ#27648) Adhemerval Zanella
@ 2021-03-25 21:06 ` H.J. Lu
2021-03-26 9:43 ` Lukasz Majewski
1 sibling, 0 replies; 4+ messages in thread
From: H.J. Lu @ 2021-03-25 21:06 UTC (permalink / raw)
To: Adhemerval Zanella; +Cc: GNU C Library
On Thu, Mar 25, 2021 at 1:00 PM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> Instead of polling the stderr, create two pipes and fork to check
> if child timeout as expected similar to tst-pselect.c. Also lower
> the timeout value.
>
> Checked on x86_64-linux-gnu.
> ---
> misc/tst-select.c | 85 ++++++++++++++++++++++++++++++-----------------
> 1 file changed, 55 insertions(+), 30 deletions(-)
>
> diff --git a/misc/tst-select.c b/misc/tst-select.c
> index 7c310256c5..530181c264 100644
> --- a/misc/tst-select.c
> +++ b/misc/tst-select.c
> @@ -16,54 +16,79 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> -#include <time.h>
> #include <errno.h>
> -#include <stdbool.h>
> -#include <sys/select.h>
> +#include <support/capture_subprocess.h>
> #include <support/check.h>
> -#include <support/xtime.h>
> #include <support/timespec.h>
> +#include <support/xunistd.h>
> +#include <support/xtime.h>
>
> -#define TST_SELECT_TIMEOUT 1
> -#define TST_SELECT_FD_ERR 2
> +struct child_args
> +{
> + int fds[2][2];
> + struct timeval tmo;
> +};
>
> -static int
> -test_select_timeout (bool zero_tmo)
> +static void
> +do_test_child (void *clousure)
> {
> - const int fds = TST_SELECT_FD_ERR;
> - int timeout = TST_SELECT_TIMEOUT;
> - struct timeval to = { 0, 0 };
> - struct timespec ts;
> - fd_set rfds;
> + struct child_args *args = (struct child_args *) clousure;
>
> - FD_ZERO (&rfds);
> - FD_SET (fds, &rfds);
> + close (args->fds[0][1]);
> + close (args->fds[1][0]);
>
> - if (zero_tmo)
> - timeout = 0;
> + fd_set rfds;
> + FD_ZERO (&rfds);
> + FD_SET (args->fds[0][0], &rfds);
>
> - to.tv_sec = timeout;
> - ts = xclock_now (CLOCK_REALTIME);
> - ts = timespec_add (ts, (struct timespec) { timeout, 0 });
> + struct timespec ts = xclock_now (CLOCK_REALTIME);
> + ts = timespec_add (ts, (struct timespec) { args->tmo.tv_sec, 0 });
>
> - /* Wait for timeout. */
> - int ret = select (fds + 1, &rfds, NULL, NULL, &to);
> - if (ret == -1)
> - FAIL_EXIT1 ("select failed: %m\n");
> + int r = select (args->fds[0][0] + 1, &rfds, NULL, NULL, &args->tmo);
> + TEST_COMPARE (r, 0);
>
> TEST_TIMESPEC_NOW_OR_AFTER (CLOCK_REALTIME, ts);
>
> - return 0;
> + xwrite (args->fds[1][1], "foo", 3);
> }
>
> static int
> do_test (void)
> {
> - /* Check if select exits immediately. */
> - test_select_timeout (true);
> -
> - /* Check if select exits after specified timeout. */
> - test_select_timeout (false);
> + struct child_args args;
> +
> + xpipe (args.fds[0]);
> + xpipe (args.fds[1]);
> +
> + /* The child select should timeout and write on its pipe end. */
> + args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 250000 };
> + {
> + struct support_capture_subprocess result;
> + result = support_capture_subprocess (do_test_child, &args);
> + support_capture_subprocess_check (&result, "tst-select-child", 0,
> + sc_allow_none);
> + }
> +
> + /* Same with simulating a polling. */
> + args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 0 };
> + {
> + struct support_capture_subprocess result;
> + result = support_capture_subprocess (do_test_child, &args);
> + support_capture_subprocess_check (&result, "tst-select-child", 0,
> + sc_allow_none);
> + }
> +
> + xclose (args.fds[0][0]);
> + xclose (args.fds[1][1]);
> +
> + {
> + fd_set rfds;
> + FD_ZERO (&rfds);
> + FD_SET (args.fds[1][0], &rfds);
> +
> + int r = select (args.fds[1][0] + 1, &rfds, NULL, NULL, &args.tmo);
> + TEST_COMPARE (r, 1);
> + }
>
> return 0;
> }
> --
> 2.27.0
>
LGTM.
Thanks.
--
H.J.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] misc: Fix tst-select timeout handling (BZ#27648)
2021-03-25 20:00 [PATCH] misc: Fix tst-select timeout handling (BZ#27648) Adhemerval Zanella
2021-03-25 21:06 ` H.J. Lu
@ 2021-03-26 9:43 ` Lukasz Majewski
2021-03-26 17:15 ` Adhemerval Zanella
1 sibling, 1 reply; 4+ messages in thread
From: Lukasz Majewski @ 2021-03-26 9:43 UTC (permalink / raw)
To: Adhemerval Zanella via Libc-alpha
[-- Attachment #1: Type: text/plain, Size: 529 bytes --]
Hi Adhemerval,
> Instead of polling the stderr, create two pipes and fork to check
> if child timeout as expected similar to tst-pselect.c. Also lower
> the timeout value.
I'm just wondering why this approach (with pipes) is more safe than
polling stderr?
Best regards,
Lukasz Majewski
--
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] misc: Fix tst-select timeout handling (BZ#27648)
2021-03-26 9:43 ` Lukasz Majewski
@ 2021-03-26 17:15 ` Adhemerval Zanella
0 siblings, 0 replies; 4+ messages in thread
From: Adhemerval Zanella @ 2021-03-26 17:15 UTC (permalink / raw)
To: Lukasz Majewski, Adhemerval Zanella via Libc-alpha
On 26/03/2021 06:43, Lukasz Majewski wrote:
> Hi Adhemerval,
>
>> Instead of polling the stderr, create two pipes and fork to check
>> if child timeout as expected similar to tst-pselect.c. Also lower
>> the timeout value.
>
> I'm just wondering why this approach (with pipes) is more safe than
> polling stderr?
Using the standard file descriptor is tricky because they can be
either closed or redirected by the parent.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-03-25 20:00 [PATCH] misc: Fix tst-select timeout handling (BZ#27648) Adhemerval Zanella
2021-03-25 21:06 ` H.J. Lu
2021-03-26 9:43 ` Lukasz Majewski
2021-03-26 17:15 ` Adhemerval Zanella
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