[1/3] support: Add support_process_state_wait

Message ID 20191120141535.5303-1-adhemerval.zanella@linaro.org
State New
Headers show
Series
  • [1/3] support: Add support_process_state_wait
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Commit Message

Adhemerval Zanella Nov. 20, 2019, 2:15 p.m.
It allows parent process to wait for children state using a polling
strategy over procfs on Linux.  The polling is used over ptrace to
avoid the need to handle signals on the target pid and to handle some
system specific limitations (such as YAMA).

The polling has some limitations, such as resource consumption due
the procfs read in a loop and the lack of synchronization after the
state is obtained.

The interface idea is to simplify some sleep synchronization in waitid
tests.
---
 support/Makefile                    |   2 +
 support/process_state.h             |  41 +++++++++++
 support/support_process_state.c     |  89 ++++++++++++++++++++++++
 support/tst-support-process_state.c | 101 ++++++++++++++++++++++++++++
 4 files changed, 233 insertions(+)
 create mode 100644 support/process_state.h
 create mode 100644 support/support_process_state.c
 create mode 100644 support/tst-support-process_state.c

-- 
2.17.1

Comments

Adhemerval Zanella Dec. 20, 2019, 12:35 p.m. | #1
Ping.

On 20/11/2019 11:15, Adhemerval Zanella wrote:
> It allows parent process to wait for children state using a polling

> strategy over procfs on Linux.  The polling is used over ptrace to

> avoid the need to handle signals on the target pid and to handle some

> system specific limitations (such as YAMA).

> 

> The polling has some limitations, such as resource consumption due

> the procfs read in a loop and the lack of synchronization after the

> state is obtained.

> 

> The interface idea is to simplify some sleep synchronization in waitid

> tests.

> ---

>  support/Makefile                    |   2 +

>  support/process_state.h             |  41 +++++++++++

>  support/support_process_state.c     |  89 ++++++++++++++++++++++++

>  support/tst-support-process_state.c | 101 ++++++++++++++++++++++++++++

>  4 files changed, 233 insertions(+)

>  create mode 100644 support/process_state.h

>  create mode 100644 support/support_process_state.c

>  create mode 100644 support/tst-support-process_state.c

> 

> diff --git a/support/Makefile b/support/Makefile

> index 23c6d74627..b0d28200af 100644

> --- a/support/Makefile

> +++ b/support/Makefile

> @@ -56,6 +56,7 @@ libsupport-routines = \

>    support_format_hostent \

>    support_format_netent \

>    support_isolate_in_subprocess \

> +  support_process_state \

>    support_ptrace \

>    support_openpty \

>    support_paths \

> @@ -223,6 +224,7 @@ tests = \

>    tst-support_capture_subprocess \

>    tst-support_descriptors \

>    tst-support_format_dns_packet \

> +  tst-support-process_state \

>    tst-support_quote_blob \

>    tst-support_quote_string \

>    tst-support_record_failure \

> diff --git a/support/process_state.h b/support/process_state.h

> new file mode 100644

> index 0000000000..d616f0e3e6

> --- /dev/null

> +++ b/support/process_state.h

> @@ -0,0 +1,41 @@

> +/* Wait for process state.

> +   Copyright (C) 2019 Free Software Foundation, Inc.

> +   This file is part of the GNU C Library.

> +

> +   The GNU C Library is free software; you can redistribute it and/or

> +   modify it under the terms of the GNU Lesser General Public

> +   License as published by the Free Software Foundation; either

> +   version 2.1 of the License, or (at your option) any later version.

> +

> +   The GNU C Library is distributed in the hope that it will be useful,

> +   but WITHOUT ANY WARRANTY; without even the implied warranty of

> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

> +   Lesser General Public License for more details.

> +

> +   You should have received a copy of the GNU Lesser General Public

> +   License along with the GNU C Library; if not, see

> +   <https://www.gnu.org/licenses/>.  */

> +

> +#ifndef SUPPORT_PROCESS_STATE_H

> +#define SUPPORT_PROCESS_STATE_H

> +

> +#include <sys/types.h>

> +

> +enum process_state_t

> +{

> +  process_state_running      = 0x01,  /* R (running)  */

> +  process_state_sleeping     = 0x02,  /* S (sleeping)  */

> +  process_state_disk_sleep   = 0x04,  /* D (disk sleep)  */

> +  process_state_stopped      = 0x08,  /* T (stopped)  */

> +  process_state_tracing_stop = 0x10,  /* t (tracing stop)  */

> +  process_state_dead         = 0x20,  /* X (dead)  */

> +  process_state_zombie       = 0x40,  /* Z (zombie)  */

> +  process_state_parked       = 0x80,  /* P (parked)  */

> +};

> +

> +/* Wait for process PID to reach state STATE.  It can be a combination of

> +   multiple possible states ('process_state_running | process_state_sleeping')

> +   where the function return when any of these state are observed.  */

> +void support_process_state_wait (pid_t pid, enum process_state_t state);

> +

> +#endif

> diff --git a/support/support_process_state.c b/support/support_process_state.c

> new file mode 100644

> index 0000000000..77c684c49c

> --- /dev/null

> +++ b/support/support_process_state.c

> @@ -0,0 +1,89 @@

> +/* Wait for process state.

> +   Copyright (C) 2019 Free Software Foundation, Inc.

> +   This file is part of the GNU C Library.

> +

> +   The GNU C Library is free software; you can redistribute it and/or

> +   modify it under the terms of the GNU Lesser General Public

> +   License as published by the Free Software Foundation; either

> +   version 2.1 of the License, or (at your option) any later version.

> +

> +   The GNU C Library is distributed in the hope that it will be useful,

> +   but WITHOUT ANY WARRANTY; without even the implied warranty of

> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

> +   Lesser General Public License for more details.

> +

> +   You should have received a copy of the GNU Lesser General Public

> +   License along with the GNU C Library; if not, see

> +   <https://www.gnu.org/licenses/>.  */

> +

> +#include <stdio.h>

> +#include <fcntl.h>

> +#include <time.h>

> +

> +#include <array_length.h>

> +

> +#include <support/process_state.h>

> +#include <support/xunistd.h>

> +#include <support/check.h>

> +

> +void

> +support_process_state_wait (pid_t pid, enum process_state_t state)

> +{

> +#ifdef __linux__

> +  /* For Linux it does a polling check on /proc/<pid>/status checking on

> +     third field.  */

> +

> +  /* It mimics the kernel states from fs/proc/array.c  */

> +  static struct process_states_t

> +  {

> +    enum process_state_t s;

> +    char v;

> +  } process_states[] = {

> +    { process_state_running,      'R' },

> +    { process_state_sleeping,     'S' },

> +    { process_state_disk_sleep,   'D' },

> +    { process_state_stopped,      'T' },

> +    { process_state_tracing_stop, 't' },

> +    { process_state_dead,         'X' },

> +    { process_state_zombie,       'Z' },

> +    { process_state_parked,       'P' },

> +  };

> +

> +  char proc_path[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/stat")

> +		 + 1];

> +  snprintf (proc_path, sizeof (proc_path), "/proc/%i/stat", pid);

> +

> +  int fd = xopen (proc_path, O_RDONLY, 0600);

> +

> +  char statbuf[3 * sizeof (pid_t)  /* pid.  */

> +               + 2                 /* ' (' */

> +               + 64                /* task name.  */

> +               + 2                 /* ' )'  */

> +               + 1                 /* <state>, 1 char.  */

> +               + 1];               /* Final \0.  */

> +  for (;;)

> +    {

> +      ssize_t ret = read (fd, statbuf, sizeof (statbuf) - 1);

> +      TEST_VERIFY (ret >= 0);

> +      statbuf[ret] = '\0';

> +

> +      char cur_state;

> +      int sret = sscanf (statbuf, "%*i %*s %c", &cur_state);

> +      TEST_VERIFY (sret == 1);

> +

> +      for (size_t i = 0; i < array_length (process_states); ++i)

> +	if (state & process_states[i].s && cur_state == process_states[i].v)

> +	  {

> +	    close (fd);

> +	    return;

> +	  }

> +

> +      xlseek (fd, 0, SEEK_SET);

> +      nanosleep (&(struct timespec) { 0, 10000000 }, NULL);

> +    }

> +

> +  close (fd);

> +#else

> +  sleep (2);

> +#endif

> +}

> diff --git a/support/tst-support-process_state.c b/support/tst-support-process_state.c

> new file mode 100644

> index 0000000000..3482f12fa5

> --- /dev/null

> +++ b/support/tst-support-process_state.c

> @@ -0,0 +1,101 @@

> +/* Wait for process state tests.

> +   Copyright (C) 2019 Free Software Foundation, Inc.

> +   This file is part of the GNU C Library.

> +

> +   The GNU C Library is free software; you can redistribute it and/or

> +   modify it under the terms of the GNU Lesser General Public

> +   License as published by the Free Software Foundation; either

> +   version 2.1 of the License, or (at your option) any later version.

> +

> +   The GNU C Library is distributed in the hope that it will be useful,

> +   but WITHOUT ANY WARRANTY; without even the implied warranty of

> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

> +   Lesser General Public License for more details.

> +

> +   You should have received a copy of the GNU Lesser General Public

> +   License along with the GNU C Library; if not, see

> +   <https://www.gnu.org/licenses/>.  */

> +

> +#include <stdio.h>

> +#include <sys/wait.h>

> +#include <unistd.h>

> +#include <errno.h>

> +

> +#include <support/test-driver.h>

> +#include <support/process_state.h>

> +#include <support/check.h>

> +#include <support/xsignal.h>

> +#include <support/xunistd.h>

> +

> +static void

> +sigusr1_handler (int signo)

> +{

> +}

> +

> +static void

> +test_child (void)

> +{

> +  xsignal (SIGUSR1, sigusr1_handler);

> +

> +  raise (SIGSTOP);

> +

> +  TEST_COMPARE (pause (), -1);

> +  TEST_COMPARE (errno, EINTR);

> +

> +  while (1)

> +    asm ("");

> +}

> +

> +static int

> +do_test (void)

> +{

> +  pid_t pid = xfork ();

> +  if (pid == 0)

> +    {

> +      test_child ();

> +      _exit (127);

> +    }

> +

> +  /* Adding process_state_tracing_stop ('t') allows the test to work under

> +     trace programs such as ptrace.  */

> +  enum process_state_t stop_state = process_state_stopped

> +				    | process_state_tracing_stop;

> +

> +  if (test_verbose)

> +    printf ("info: waiting pid %d, state_stopped/state_tracing_stop\n",

> +	    (int) pid);

> +  support_process_state_wait (pid, stop_state);

> +

> +  if (kill (pid, SIGCONT) != 0)

> +    FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);

> +

> +  if (test_verbose)

> +    printf ("info: waiting pid %d, state_sleeping\n", (int) pid);

> +  support_process_state_wait (pid, process_state_sleeping);

> +

> +  if (kill (pid, SIGUSR1) != 0)

> +    FAIL_RET ("kill (%d, SIGUSR1): %m\n", pid);

> +

> +  if (test_verbose)

> +    printf ("info: waiting pid %d, state_running\n", (int) pid);

> +  support_process_state_wait (pid, process_state_running);

> +

> +  if (kill (pid, SIGKILL) != 0)

> +    FAIL_RET ("kill (%d, SIGKILL): %m\n", pid);

> +

> +  if (test_verbose)

> +    printf ("info: waiting pid %d, state_zombie\n", (int) pid);

> +  support_process_state_wait (pid, process_state_zombie);

> +

> +  siginfo_t info;

> +  int r = waitid (P_PID, pid, &info, WEXITED);

> +  TEST_COMPARE (r, 0);

> +  TEST_COMPARE (info.si_signo, SIGCHLD);

> +  TEST_COMPARE (info.si_code, CLD_KILLED);

> +  TEST_COMPARE (info.si_status, SIGKILL);

> +  TEST_COMPARE (info.si_pid, pid);

> +

> +  return 0;

> +}

> +

> +#include <support/test-driver.c>

>
Florian Weimer Dec. 20, 2019, 2:09 p.m. | #2
* Adhemerval Zanella:

> It allows parent process to wait for children state using a polling

> strategy over procfs on Linux.  The polling is used over ptrace to

> avoid the need to handle signals on the target pid and to handle some

> system specific limitations (such as YAMA).

>

> The polling has some limitations, such as resource consumption due

> the procfs read in a loop and the lack of synchronization after the

> state is obtained.

>

> The interface idea is to simplify some sleep synchronization in waitid

> tests.


The goal is to reduce timeouts, I assume, replacing arbitrary two-second
waits.

> diff --git a/support/process_state.h b/support/process_state.h

> new file mode 100644

> index 0000000000..d616f0e3e6

> --- /dev/null

> +++ b/support/process_state.h

> @@ -0,0 +1,41 @@


> +enum process_state_t

> +{

> +  process_state_running      = 0x01,  /* R (running)  */

> +  process_state_sleeping     = 0x02,  /* S (sleeping)  */

> +  process_state_disk_sleep   = 0x04,  /* D (disk sleep)  */

> +  process_state_stopped      = 0x08,  /* T (stopped)  */

> +  process_state_tracing_stop = 0x10,  /* t (tracing stop)  */

> +  process_state_dead         = 0x20,  /* X (dead)  */

> +  process_state_zombie       = 0x40,  /* Z (zombie)  */

> +  process_state_parked       = 0x80,  /* P (parked)  */

> +};


Maybe drop the reversed _t suffix and add a support_ prefix?

> +

> +/* Wait for process PID to reach state STATE.  It can be a combination of

> +   multiple possible states ('process_state_running | process_state_sleeping')

> +   where the function return when any of these state are observed.  */

> +void support_process_state_wait (pid_t pid, enum process_state_t state);


This interface does not allow to poll for a process not to have a
specific state.  I guess we can adjust it once the need arises, so you
can leave it for now.

> --- /dev/null

> +++ b/support/support_process_state.c

> @@ -0,0 +1,89 @@


> +void

> +support_process_state_wait (pid_t pid, enum process_state_t state)

> +{

> +#ifdef __linux__

> +  /* For Linux it does a polling check on /proc/<pid>/status checking on

> +     third field.  */

> +

> +  /* It mimics the kernel states from fs/proc/array.c  */

> +  static struct process_states_t

> +  {

> +    enum process_state_t s;

> +    char v;

> +  } process_states[] = {

> +    { process_state_running,      'R' },

> +    { process_state_sleeping,     'S' },

> +    { process_state_disk_sleep,   'D' },

> +    { process_state_stopped,      'T' },

> +    { process_state_tracing_stop, 't' },

> +    { process_state_dead,         'X' },

> +    { process_state_zombie,       'Z' },

> +    { process_state_parked,       'P' },

> +  };


Should be const.

> +  char proc_path[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/stat")

> +		 + 1];

> +  snprintf (proc_path, sizeof (proc_path), "/proc/%i/stat", pid);

> +

> +  int fd = xopen (proc_path, O_RDONLY, 0600);

> +

> +  char statbuf[3 * sizeof (pid_t)  /* pid.  */

> +               + 2                 /* ' (' */

> +               + 64                /* task name.  */

> +               + 2                 /* ' )'  */

> +               + 1                 /* <state>, 1 char.  */

> +               + 1];               /* Final \0.  */

> +  for (;;)

> +    {

> +      ssize_t ret = read (fd, statbuf, sizeof (statbuf) - 1);

> +      TEST_VERIFY (ret >= 0);

> +      statbuf[ret] = '\0';

> +

> +      char cur_state;

> +      int sret = sscanf (statbuf, "%*i %*s %c", &cur_state);

> +      TEST_VERIFY (sret == 1);


Hmm.  Does this work if COMM includes a space?  I think it's safer to
parse /proc/PID/status.

> +      for (size_t i = 0; i < array_length (process_states); ++i)

> +	if (state & process_states[i].s && cur_state == process_states[i].v)

> +	  {

> +	    close (fd);

> +	    return;

> +	  }

> +

> +      xlseek (fd, 0, SEEK_SET);

> +      nanosleep (&(struct timespec) { 0, 10000000 }, NULL);

> +    }

> +

> +  close (fd);


Should this have a fallback timeout?

The sleep should probably be usleep or nanosleep, to avoid interfering
with laram.

The test looks reasonable.

Thanks,
Florian
Adhemerval Zanella Dec. 20, 2019, 8:19 p.m. | #3
On 20/12/2019 11:09, Florian Weimer wrote:
> * Adhemerval Zanella:

> 

>> It allows parent process to wait for children state using a polling

>> strategy over procfs on Linux.  The polling is used over ptrace to

>> avoid the need to handle signals on the target pid and to handle some

>> system specific limitations (such as YAMA).

>>

>> The polling has some limitations, such as resource consumption due

>> the procfs read in a loop and the lack of synchronization after the

>> state is obtained.

>>

>> The interface idea is to simplify some sleep synchronization in waitid

>> tests.

> 

> The goal is to reduce timeouts, I assume, replacing arbitrary two-second

> waits.


Indeed, I updated the commit message.

> 

>> diff --git a/support/process_state.h b/support/process_state.h

>> new file mode 100644

>> index 0000000000..d616f0e3e6

>> --- /dev/null

>> +++ b/support/process_state.h

>> @@ -0,0 +1,41 @@

> 

>> +enum process_state_t

>> +{

>> +  process_state_running      = 0x01,  /* R (running)  */

>> +  process_state_sleeping     = 0x02,  /* S (sleeping)  */

>> +  process_state_disk_sleep   = 0x04,  /* D (disk sleep)  */

>> +  process_state_stopped      = 0x08,  /* T (stopped)  */

>> +  process_state_tracing_stop = 0x10,  /* t (tracing stop)  */

>> +  process_state_dead         = 0x20,  /* X (dead)  */

>> +  process_state_zombie       = 0x40,  /* Z (zombie)  */

>> +  process_state_parked       = 0x80,  /* P (parked)  */

>> +};

> 

> Maybe drop the reversed _t suffix and add a support_ prefix?


Ack.

> 

>> +

>> +/* Wait for process PID to reach state STATE.  It can be a combination of

>> +   multiple possible states ('process_state_running | process_state_sleeping')

>> +   where the function return when any of these state are observed.  */

>> +void support_process_state_wait (pid_t pid, enum process_state_t state);

> 

> This interface does not allow to poll for a process not to have a

> specific state.  I guess we can adjust it once the need arises, so you

> can leave it for now.


Ok.

> 

>> --- /dev/null

>> +++ b/support/support_process_state.c

>> @@ -0,0 +1,89 @@

> 

>> +void

>> +support_process_state_wait (pid_t pid, enum process_state_t state)

>> +{

>> +#ifdef __linux__

>> +  /* For Linux it does a polling check on /proc/<pid>/status checking on

>> +     third field.  */

>> +

>> +  /* It mimics the kernel states from fs/proc/array.c  */

>> +  static struct process_states_t

>> +  {

>> +    enum process_state_t s;

>> +    char v;

>> +  } process_states[] = {

>> +    { process_state_running,      'R' },

>> +    { process_state_sleeping,     'S' },

>> +    { process_state_disk_sleep,   'D' },

>> +    { process_state_stopped,      'T' },

>> +    { process_state_tracing_stop, 't' },

>> +    { process_state_dead,         'X' },

>> +    { process_state_zombie,       'Z' },

>> +    { process_state_parked,       'P' },

>> +  };

> 

> Should be const.


Ack.

> 

>> +  char proc_path[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/stat")

>> +		 + 1];

>> +  snprintf (proc_path, sizeof (proc_path), "/proc/%i/stat", pid);

>> +

>> +  int fd = xopen (proc_path, O_RDONLY, 0600);

>> +

>> +  char statbuf[3 * sizeof (pid_t)  /* pid.  */

>> +               + 2                 /* ' (' */

>> +               + 64                /* task name.  */

>> +               + 2                 /* ' )'  */

>> +               + 1                 /* <state>, 1 char.  */

>> +               + 1];               /* Final \0.  */

>> +  for (;;)

>> +    {

>> +      ssize_t ret = read (fd, statbuf, sizeof (statbuf) - 1);

>> +      TEST_VERIFY (ret >= 0);

>> +      statbuf[ret] = '\0';

>> +

>> +      char cur_state;

>> +      int sret = sscanf (statbuf, "%*i %*s %c", &cur_state);

>> +      TEST_VERIFY (sret == 1);

> 

> Hmm.  Does this work if COMM includes a space?  I think it's safer to

> parse /proc/PID/status.


It does not, I updated to parse /proc/PID/status.

> 

>> +      for (size_t i = 0; i < array_length (process_states); ++i)

>> +	if (state & process_states[i].s && cur_state == process_states[i].v)

>> +	  {

>> +	    close (fd);

>> +	    return;

>> +	  }

>> +

>> +      xlseek (fd, 0, SEEK_SET);

>> +      nanosleep (&(struct timespec) { 0, 10000000 }, NULL);

>> +    }

>> +

>> +  close (fd);

> 

> Should this have a fallback timeout?


Do you mean if it can not get the process state? Currently
support_process_state_wait fails either if it can not open the status
file or if it can't find 'State:' field. Should we add a fallback for
each case?

> 

> The sleep should probably be usleep or nanosleep, to avoid interfering

> with laram.


Ok.

> 

> The test looks reasonable.



Updated patch below:

--

diff --git a/support/Makefile b/support/Makefile
index 23c6d74627..b0d28200af 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -56,6 +56,7 @@ libsupport-routines = \
   support_format_hostent \
   support_format_netent \
   support_isolate_in_subprocess \
+  support_process_state \
   support_ptrace \
   support_openpty \
   support_paths \
@@ -223,6 +224,7 @@ tests = \
   tst-support_capture_subprocess \
   tst-support_descriptors \
   tst-support_format_dns_packet \
+  tst-support-process_state \
   tst-support_quote_blob \
   tst-support_quote_string \
   tst-support_record_failure \
diff --git a/support/process_state.h b/support/process_state.h
new file mode 100644
index 0000000000..d983197247
--- /dev/null
+++ b/support/process_state.h
@@ -0,0 +1,45 @@
+/* Wait for process state.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_PROCESS_STATE_H
+#define SUPPORT_PROCESS_STATE_H
+
+#include <sys/types.h>
+
+enum support_process_state
+{
+  support_process_state_running      = 0x01,  /* R (running).  */
+  support_process_state_sleeping     = 0x02,  /* S (sleeping).  */
+  support_process_state_disk_sleep   = 0x04,  /* D (disk sleep).  */
+  support_process_state_stopped      = 0x08,  /* T (stopped).  */
+  support_process_state_tracing_stop = 0x10,  /* t (tracing stop).  */
+  support_process_state_dead         = 0x20,  /* X (dead).  */
+  support_process_state_zombie       = 0x40,  /* Z (zombie).  */
+  support_process_state_parked       = 0x80,  /* P (parked).  */
+};
+
+/* Wait for process PID to reach state STATE.  It can be a combination of
+   multiple possible states ('process_state_running | process_state_sleeping')
+   where the function return when any of these state are observed.
+   The timeout POLL_TS might be used to wait before polling the PID status
+   information from the kernel.  A NULL value will set to use a default
+   value (10000000 ns).  */
+void support_process_state_wait (pid_t pid, enum support_process_state state,
+				 struct timespec *poll_ts);
+
+#endif
diff --git a/support/support_process_state.c b/support/support_process_state.c
new file mode 100644
index 0000000000..16c2c3642e
--- /dev/null
+++ b/support/support_process_state.c
@@ -0,0 +1,102 @@
+/* Wait for process state.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <time.h>
+#include <string.h>
+
+#include <array_length.h>
+
+#include <support/process_state.h>
+#include <support/xunistd.h>
+#include <support/check.h>
+
+/* Returns the character representing the task state from FD.  */
+static char find_state (int fd)
+{
+  char statusbuf[strlen ("Name:\t")
+		 + 64                   /* task name.  */
+		 + strlen ("Umask:\t")  /* optional.  */
+		 + 4                    /* umask size.  */
+		 + strlen ("State:\t")
+		 + 1                    /* <state>, 1 char.  */
+		 + 1];                  /* Final \0.  */
+
+  ssize_t ret = read (fd, statusbuf, sizeof (statusbuf) - 1);
+  TEST_VERIFY (ret >= 0);
+  statusbuf[ret] = '\0';
+
+  char *statestr = strstr (statusbuf, "State:\t");
+  TEST_VERIFY (statestr != NULL);
+  char state;
+  int sret = sscanf (statestr, "%*s %c", &state);
+  TEST_VERIFY (sret == 1);
+
+  return state;
+}
+
+void
+support_process_state_wait (pid_t pid, enum support_process_state state,
+			    struct timespec *poll_ts)
+{
+#ifdef __linux__
+  /* For Linux it does a polling check on /proc/<pid>/status checking on
+     third field.  */
+
+  /* It mimics the kernel states from fs/proc/array.c  */
+  static const struct process_states_t
+  {
+    enum support_process_state s;
+    char v;
+  } process_states[] = {
+    { support_process_state_running,      'R' },
+    { support_process_state_sleeping,     'S' },
+    { support_process_state_disk_sleep,   'D' },
+    { support_process_state_stopped,      'T' },
+    { support_process_state_tracing_stop, 't' },
+    { support_process_state_dead,         'X' },
+    { support_process_state_zombie,       'Z' },
+    { support_process_state_parked,       'P' },
+  };
+
+  char proc_path[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/stat")
+		 + 1];
+  snprintf (proc_path, sizeof (proc_path), "/proc/%i/status", pid);
+
+  int fd = xopen (proc_path, O_RDONLY, 0600);
+
+  for (;;)
+    {
+      char cur_state = find_state (fd);
+
+      for (size_t i = 0; i < array_length (process_states); ++i)
+	if (state & process_states[i].s && cur_state == process_states[i].v)
+	  goto found;
+
+      xlseek (fd, 0, SEEK_SET);
+
+      nanosleep (poll_ts ? poll_ts : &(struct timespec) { 0, 10000000 }, NULL);
+    }
+
+found:
+  xclose (fd);
+#else
+  nanosleep (&(struct timespec) { 2, 0 }, NULL);
+#endif
+}
diff --git a/support/tst-support-process_state.c b/support/tst-support-process_state.c
new file mode 100644
index 0000000000..d0aa142c76
--- /dev/null
+++ b/support/tst-support-process_state.c
@@ -0,0 +1,101 @@
+/* Wait for process state tests.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <support/test-driver.h>
+#include <support/process_state.h>
+#include <support/check.h>
+#include <support/xsignal.h>
+#include <support/xunistd.h>
+
+static void
+sigusr1_handler (int signo)
+{
+}
+
+static void
+test_child (void)
+{
+  xsignal (SIGUSR1, sigusr1_handler);
+
+  raise (SIGSTOP);
+
+  TEST_COMPARE (pause (), -1);
+  TEST_COMPARE (errno, EINTR);
+
+  while (1)
+    asm ("");
+}
+
+static int
+do_test (void)
+{
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      test_child ();
+      _exit (127);
+    }
+
+  /* Adding process_state_tracing_stop ('t') allows the test to work under
+     trace programs such as ptrace.  */
+  enum support_process_state stop_state = support_process_state_stopped
+				    | support_process_state_tracing_stop;
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_stopped/state_tracing_stop\n",
+	    (int) pid);
+  support_process_state_wait (pid, stop_state, NULL);
+
+  if (kill (pid, SIGCONT) != 0)
+    FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_sleeping\n", (int) pid);
+  support_process_state_wait (pid, support_process_state_sleeping, NULL);
+
+  if (kill (pid, SIGUSR1) != 0)
+    FAIL_RET ("kill (%d, SIGUSR1): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_running\n", (int) pid);
+  support_process_state_wait (pid, support_process_state_running, NULL);
+
+  if (kill (pid, SIGKILL) != 0)
+    FAIL_RET ("kill (%d, SIGKILL): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_zombie\n", (int) pid);
+  support_process_state_wait (pid, support_process_state_zombie, NULL);
+
+  siginfo_t info;
+  int r = waitid (P_PID, pid, &info, WEXITED);
+  TEST_COMPARE (r, 0);
+  TEST_COMPARE (info.si_signo, SIGCHLD);
+  TEST_COMPARE (info.si_code, CLD_KILLED);
+  TEST_COMPARE (info.si_status, SIGKILL);
+  TEST_COMPARE (info.si_pid, pid);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
Florian Weimer Dec. 20, 2019, 8:32 p.m. | #4
* Adhemerval Zanella:

> diff --git a/support/process_state.h b/support/process_state.h

> new file mode 100644

> index 0000000000..d983197247

> --- /dev/null

> +++ b/support/process_state.h

> @@ -0,0 +1,45 @@


> +#ifndef SUPPORT_PROCESS_STATE_H

> +#define SUPPORT_PROCESS_STATE_H

> +

> +#include <sys/types.h>


I think you also need to include <time.h> for struct timespec,
strictly speaking.

> diff --git a/support/support_process_state.c b/support/support_process_state.c

> new file mode 100644

> index 0000000000..16c2c3642e

> --- /dev/null

> +++ b/support/support_process_state.c


> +/* Returns the character representing the task state from FD.  */

> +static char find_state (int fd)

> +{

> +  char statusbuf[strlen ("Name:\t")

> +		 + 64                   /* task name.  */

> +		 + strlen ("Umask:\t")  /* optional.  */

> +		 + 4                    /* umask size.  */

> +		 + strlen ("State:\t")

> +		 + 1                    /* <state>, 1 char.  */

> +		 + 1];                  /* Final \0.  */

> +

> +  ssize_t ret = read (fd, statusbuf, sizeof (statusbuf) - 1);

> +  TEST_VERIFY (ret >= 0);

> +  statusbuf[ret] = '\0';

> +

> +  char *statestr = strstr (statusbuf, "State:\t");

> +  TEST_VERIFY (statestr != NULL);

> +  char state;

> +  int sret = sscanf (statestr, "%*s %c", &state);

> +  TEST_VERIFY (sret == 1);

> +

> +  return state;

> +}


I think the expectation here is that more things will be inserted
after Name:.  As you note, Umask: is already a late arrival.

So if simplicity is a concern, I would just read 4 KiB or so, and then
use strstr with "\nState:\t" (note the \n).  The sscanf seems
superfluous in this context.  Every else heads in the direction of
getline …

I think it also makes sense to return 0 in case the state cannot be
determined, rather than an indeterminate value.

> +void

> +support_process_state_wait (pid_t pid, enum support_process_state state,

> +			    struct timespec *poll_ts)

> +{

> +#ifdef __linux__

> +  /* For Linux it does a polling check on /proc/<pid>/status checking on

> +     third field.  */

> +

> +  /* It mimics the kernel states from fs/proc/array.c  */

> +  static const struct process_states_t

> +  {

> +    enum support_process_state s;

> +    char v;

> +  } process_states[] = {

> +    { support_process_state_running,      'R' },

> +    { support_process_state_sleeping,     'S' },

> +    { support_process_state_disk_sleep,   'D' },

> +    { support_process_state_stopped,      'T' },

> +    { support_process_state_tracing_stop, 't' },

> +    { support_process_state_dead,         'X' },

> +    { support_process_state_zombie,       'Z' },

> +    { support_process_state_parked,       'P' },

> +  };

> +

> +  char proc_path[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/stat")

> +		 + 1];

> +  snprintf (proc_path, sizeof (proc_path), "/proc/%i/status", pid);

> +

> +  int fd = xopen (proc_path, O_RDONLY, 0600);

> +

> +  for (;;)

> +    {

> +      char cur_state = find_state (fd);

> +

> +      for (size_t i = 0; i < array_length (process_states); ++i)

> +	if (state & process_states[i].s && cur_state == process_states[i].v)

> +	  goto found;


I missed that before, I think we should error out if the state is
completely unknown.  Maybe use strchr on "RSDTtXZP" instead, and use
that for the shift? 8-)
Adhemerval Zanella Dec. 26, 2019, 2:20 p.m. | #5
On 20/12/2019 17:32, Florian Weimer wrote:
> * Adhemerval Zanella:

> 

>> diff --git a/support/process_state.h b/support/process_state.h

>> new file mode 100644

>> index 0000000000..d983197247

>> --- /dev/null

>> +++ b/support/process_state.h

>> @@ -0,0 +1,45 @@

> 

>> +#ifndef SUPPORT_PROCESS_STATE_H

>> +#define SUPPORT_PROCESS_STATE_H

>> +

>> +#include <sys/types.h>

> 

> I think you also need to include <time.h> for struct timespec,

> strictly speaking.


Ack.

> 

>> diff --git a/support/support_process_state.c b/support/support_process_state.c

>> new file mode 100644

>> index 0000000000..16c2c3642e

>> --- /dev/null

>> +++ b/support/support_process_state.c

> 

>> +/* Returns the character representing the task state from FD.  */

>> +static char find_state (int fd)

>> +{

>> +  char statusbuf[strlen ("Name:\t")

>> +		 + 64                   /* task name.  */

>> +		 + strlen ("Umask:\t")  /* optional.  */

>> +		 + 4                    /* umask size.  */

>> +		 + strlen ("State:\t")

>> +		 + 1                    /* <state>, 1 char.  */

>> +		 + 1];                  /* Final \0.  */

>> +

>> +  ssize_t ret = read (fd, statusbuf, sizeof (statusbuf) - 1);

>> +  TEST_VERIFY (ret >= 0);

>> +  statusbuf[ret] = '\0';

>> +

>> +  char *statestr = strstr (statusbuf, "State:\t");

>> +  TEST_VERIFY (statestr != NULL);

>> +  char state;

>> +  int sret = sscanf (statestr, "%*s %c", &state);

>> +  TEST_VERIFY (sret == 1);

>> +

>> +  return state;

>> +}

> 

> I think the expectation here is that more things will be inserted

> after Name:.  As you note, Umask: is already a late arrival.

> 

> So if simplicity is a concern, I would just read 4 KiB or so, and then

> use strstr with "\nState:\t" (note the \n).  The sscanf seems

> superfluous in this context.  Every else heads in the direction of

> getline …

> 

> I think it also makes sense to return 0 in case the state cannot be

> determined, rather than an indeterminate value.


I was trying more to make support_process_state_wait not consume much
resources, but it seems since /proc/pid/status does not have a
stable format we will need to parse it in the end.  I have adjusted
to use getline.

> 

>> +void

>> +support_process_state_wait (pid_t pid, enum support_process_state state,

>> +			    struct timespec *poll_ts)

>> +{

>> +#ifdef __linux__

>> +  /* For Linux it does a polling check on /proc/<pid>/status checking on

>> +     third field.  */

>> +

>> +  /* It mimics the kernel states from fs/proc/array.c  */

>> +  static const struct process_states_t

>> +  {

>> +    enum support_process_state s;

>> +    char v;

>> +  } process_states[] = {

>> +    { support_process_state_running,      'R' },

>> +    { support_process_state_sleeping,     'S' },

>> +    { support_process_state_disk_sleep,   'D' },

>> +    { support_process_state_stopped,      'T' },

>> +    { support_process_state_tracing_stop, 't' },

>> +    { support_process_state_dead,         'X' },

>> +    { support_process_state_zombie,       'Z' },

>> +    { support_process_state_parked,       'P' },

>> +  };

>> +

>> +  char proc_path[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/stat")

>> +		 + 1];

>> +  snprintf (proc_path, sizeof (proc_path), "/proc/%i/status", pid);

>> +

>> +  int fd = xopen (proc_path, O_RDONLY, 0600);

>> +

>> +  for (;;)

>> +    {

>> +      char cur_state = find_state (fd);

>> +

>> +      for (size_t i = 0; i < array_length (process_states); ++i)

>> +	if (state & process_states[i].s && cur_state == process_states[i].v)

>> +	  goto found;

> 

> I missed that before, I think we should error out if the state is

> completely unknown.  Maybe use strchr on "RSDTtXZP" instead, and use

> that for the shift? 8-)

> 


What I did instead is to to fallback to nanosleep (2s) for such case
(another possibility would be to just assert/abort).

--

diff --git a/support/Makefile b/support/Makefile
index 23c6d74627..5a3bdd8e9f 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -56,6 +56,7 @@ libsupport-routines = \
   support_format_hostent \
   support_format_netent \
   support_isolate_in_subprocess \
+  support_process_state \
   support_ptrace \
   support_openpty \
   support_paths \
@@ -95,6 +96,7 @@ libsupport-routines = \
   xfopen \
   xfork \
   xftruncate \
+  xgetline \
   xgetsockname \
   xlisten \
   xlseek \
@@ -223,6 +225,7 @@ tests = \
   tst-support_capture_subprocess \
   tst-support_descriptors \
   tst-support_format_dns_packet \
+  tst-support-process_state \
   tst-support_quote_blob \
   tst-support_quote_string \
   tst-support_record_failure \
diff --git a/support/process_state.h b/support/process_state.h
new file mode 100644
index 0000000000..4325909efd
--- /dev/null
+++ b/support/process_state.h
@@ -0,0 +1,47 @@
+/* Wait for process state.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_PROCESS_STATE_H
+#define SUPPORT_PROCESS_STATE_H
+
+#include <sys/types.h>
+
+enum support_process_state
+{
+  support_process_state_running      = 0x01,  /* R (running).  */
+  support_process_state_sleeping     = 0x02,  /* S (sleeping).  */
+  support_process_state_disk_sleep   = 0x04,  /* D (disk sleep).  */
+  support_process_state_stopped      = 0x08,  /* T (stopped).  */
+  support_process_state_tracing_stop = 0x10,  /* t (tracing stop).  */
+  support_process_state_dead         = 0x20,  /* X (dead).  */
+  support_process_state_zombie       = 0x40,  /* Z (zombie).  */
+  support_process_state_parked       = 0x80,  /* P (parked).  */
+};
+
+/* Wait for process PID to reach state STATE.  It can be a combination of
+   multiple possible states ('process_state_running | process_state_sleeping')
+   where the function return when any of these state are observed.
+   The timeout POLL_TS might be used to wait before polling the PID status
+   information from the kernel.  A NULL value will set to use a default
+   value (10000000 ns).
+   For an invalid state not represented by SUPPORT_PROCESS_STATE, it fallbacks
+   to a 2 second sleep.  */
+void support_process_state_wait (pid_t pid, enum support_process_state state,
+				 struct timespec *poll_ts);
+
+#endif
diff --git a/support/support_process_state.c b/support/support_process_state.c
new file mode 100644
index 0000000000..6a6dbc6287
--- /dev/null
+++ b/support/support_process_state.c
@@ -0,0 +1,91 @@
+/* Wait for process state.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include <time.h>
+#include <string.h>
+
+#include <array_length.h>
+
+#include <support/process_state.h>
+#include <support/xstdio.h>
+#include <support/check.h>
+
+void
+support_process_state_wait (pid_t pid, enum support_process_state state,
+			    struct timespec *poll_ts)
+{
+#ifdef __linux__
+  /* For Linux it does a polling check on /proc/<pid>/status checking on
+     third field.  */
+
+  /* It mimics the kernel states from fs/proc/array.c  */
+  static struct process_states
+  {
+    enum support_process_state s;
+    char v;
+  } process_states[] = {
+    { support_process_state_running,      'R' },
+    { support_process_state_sleeping,     'S' },
+    { support_process_state_disk_sleep,   'D' },
+    { support_process_state_stopped,      'T' },
+    { support_process_state_tracing_stop, 't' },
+    { support_process_state_dead,         'X' },
+    { support_process_state_zombie,       'Z' },
+    { support_process_state_parked,       'P' },
+  };
+
+  char spath[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/status") + 1];
+  snprintf (spath, sizeof (spath), "/proc/%i/status", pid);
+
+  FILE *fstatus = xfopen (spath, "r");
+  char *line = NULL;
+  size_t linesiz = 0;
+
+  for (;;)
+    {
+      char cur_state = -1;
+      while (xgetline (&line, &linesiz, fstatus) != -1)
+	if (strncmp (line, "State:", strlen ("State:")) == 0)
+	  {
+	    TEST_COMPARE (sscanf (line, "%*s %c", &cur_state), 1);
+	    break;
+	  }
+      if (cur_state == -1)
+	break;
+
+      for (size_t i = 0; i < array_length (process_states); ++i)
+	if (state & process_states[i].s && cur_state == process_states[i].v)
+	  {
+	    free (line);
+	    xfclose (fstatus);
+	    return;
+	  }
+
+      rewind (fstatus);
+      fflush (fstatus);
+
+      nanosleep (poll_ts ? poll_ts : &(struct timespec) { 0, 10000000 }, NULL);
+    }
+
+  free (line);
+  xfclose (fstatus);
+  /* Fallback to nanosleep if an invalid state is found.  */
+#endif
+  nanosleep (&(struct timespec) { 2, 0 }, NULL);
+}
diff --git a/support/tst-support-process_state.c b/support/tst-support-process_state.c
new file mode 100644
index 0000000000..3615bbe192
--- /dev/null
+++ b/support/tst-support-process_state.c
@@ -0,0 +1,105 @@
+/* Wait for process state tests.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <support/test-driver.h>
+#include <support/process_state.h>
+#include <support/check.h>
+#include <support/xsignal.h>
+#include <support/xunistd.h>
+
+#ifndef WEXITED
+# define WEXITED	0
+#endif
+
+static void
+sigusr1_handler (int signo)
+{
+}
+
+static void
+test_child (void)
+{
+  xsignal (SIGUSR1, sigusr1_handler);
+
+  raise (SIGSTOP);
+
+  TEST_COMPARE (pause (), -1);
+  TEST_COMPARE (errno, EINTR);
+
+  while (1)
+    asm ("");
+}
+
+static int
+do_test (void)
+{
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      test_child ();
+      _exit (127);
+    }
+
+  /* Adding process_state_tracing_stop ('t') allows the test to work under
+     trace programs such as ptrace.  */
+  enum support_process_state stop_state = support_process_state_stopped
+				    | support_process_state_tracing_stop;
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_stopped/state_tracing_stop\n",
+	    (int) pid);
+  support_process_state_wait (pid, stop_state, NULL);
+
+  if (kill (pid, SIGCONT) != 0)
+    FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_sleeping\n", (int) pid);
+  support_process_state_wait (pid, support_process_state_sleeping, NULL);
+
+  if (kill (pid, SIGUSR1) != 0)
+    FAIL_RET ("kill (%d, SIGUSR1): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_running\n", (int) pid);
+  support_process_state_wait (pid, support_process_state_running, NULL);
+
+  if (kill (pid, SIGKILL) != 0)
+    FAIL_RET ("kill (%d, SIGKILL): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_zombie\n", (int) pid);
+  support_process_state_wait (pid, support_process_state_zombie, NULL);
+
+  siginfo_t info;
+  int r = waitid (P_PID, pid, &info, WEXITED);
+  TEST_COMPARE (r, 0);
+  TEST_COMPARE (info.si_signo, SIGCHLD);
+  TEST_COMPARE (info.si_code, CLD_KILLED);
+  TEST_COMPARE (info.si_status, SIGKILL);
+  TEST_COMPARE (info.si_pid, pid);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/support/xgetline.c b/support/xgetline.c
new file mode 100644
index 0000000000..5b010bcf56
--- /dev/null
+++ b/support/xgetline.c
@@ -0,0 +1,34 @@
+/* fopen with error checking.
+   Copyright (C) 2016-2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <support/xstdio.h>
+
+#include <support/check.h>
+#include <errno.h>
+
+ssize_t
+xgetline (char **lineptr, size_t *n, FILE *stream)
+{
+  int old_errno = errno;
+  errno = 0;
+  ssize_t ret = getline (lineptr, n, stream);
+  if (ret == -1 && errno != 0)
+    FAIL_EXIT1 ("getline failed: %m");
+  errno = old_errno;
+  return ret;
+}
diff --git a/support/xstdio.h b/support/xstdio.h
index e4e52b4c7e..df6ee27711 100644
--- a/support/xstdio.h
+++ b/support/xstdio.h
@@ -27,6 +27,8 @@ __BEGIN_DECLS
 FILE *xfopen (const char *path, const char *mode);
 void xfclose (FILE *);
 
+ssize_t xgetline (char **lineptr, size_t *n, FILE *stream);
+
 __END_DECLS
 
 #endif /* SUPPORT_XSTDIO_H */

Patch

diff --git a/support/Makefile b/support/Makefile
index 23c6d74627..b0d28200af 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -56,6 +56,7 @@  libsupport-routines = \
   support_format_hostent \
   support_format_netent \
   support_isolate_in_subprocess \
+  support_process_state \
   support_ptrace \
   support_openpty \
   support_paths \
@@ -223,6 +224,7 @@  tests = \
   tst-support_capture_subprocess \
   tst-support_descriptors \
   tst-support_format_dns_packet \
+  tst-support-process_state \
   tst-support_quote_blob \
   tst-support_quote_string \
   tst-support_record_failure \
diff --git a/support/process_state.h b/support/process_state.h
new file mode 100644
index 0000000000..d616f0e3e6
--- /dev/null
+++ b/support/process_state.h
@@ -0,0 +1,41 @@ 
+/* Wait for process state.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_PROCESS_STATE_H
+#define SUPPORT_PROCESS_STATE_H
+
+#include <sys/types.h>
+
+enum process_state_t
+{
+  process_state_running      = 0x01,  /* R (running)  */
+  process_state_sleeping     = 0x02,  /* S (sleeping)  */
+  process_state_disk_sleep   = 0x04,  /* D (disk sleep)  */
+  process_state_stopped      = 0x08,  /* T (stopped)  */
+  process_state_tracing_stop = 0x10,  /* t (tracing stop)  */
+  process_state_dead         = 0x20,  /* X (dead)  */
+  process_state_zombie       = 0x40,  /* Z (zombie)  */
+  process_state_parked       = 0x80,  /* P (parked)  */
+};
+
+/* Wait for process PID to reach state STATE.  It can be a combination of
+   multiple possible states ('process_state_running | process_state_sleeping')
+   where the function return when any of these state are observed.  */
+void support_process_state_wait (pid_t pid, enum process_state_t state);
+
+#endif
diff --git a/support/support_process_state.c b/support/support_process_state.c
new file mode 100644
index 0000000000..77c684c49c
--- /dev/null
+++ b/support/support_process_state.c
@@ -0,0 +1,89 @@ 
+/* Wait for process state.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <time.h>
+
+#include <array_length.h>
+
+#include <support/process_state.h>
+#include <support/xunistd.h>
+#include <support/check.h>
+
+void
+support_process_state_wait (pid_t pid, enum process_state_t state)
+{
+#ifdef __linux__
+  /* For Linux it does a polling check on /proc/<pid>/status checking on
+     third field.  */
+
+  /* It mimics the kernel states from fs/proc/array.c  */
+  static struct process_states_t
+  {
+    enum process_state_t s;
+    char v;
+  } process_states[] = {
+    { process_state_running,      'R' },
+    { process_state_sleeping,     'S' },
+    { process_state_disk_sleep,   'D' },
+    { process_state_stopped,      'T' },
+    { process_state_tracing_stop, 't' },
+    { process_state_dead,         'X' },
+    { process_state_zombie,       'Z' },
+    { process_state_parked,       'P' },
+  };
+
+  char proc_path[sizeof ("/proc/" + 3) * sizeof (pid_t) + sizeof ("/stat")
+		 + 1];
+  snprintf (proc_path, sizeof (proc_path), "/proc/%i/stat", pid);
+
+  int fd = xopen (proc_path, O_RDONLY, 0600);
+
+  char statbuf[3 * sizeof (pid_t)  /* pid.  */
+               + 2                 /* ' (' */
+               + 64                /* task name.  */
+               + 2                 /* ' )'  */
+               + 1                 /* <state>, 1 char.  */
+               + 1];               /* Final \0.  */
+  for (;;)
+    {
+      ssize_t ret = read (fd, statbuf, sizeof (statbuf) - 1);
+      TEST_VERIFY (ret >= 0);
+      statbuf[ret] = '\0';
+
+      char cur_state;
+      int sret = sscanf (statbuf, "%*i %*s %c", &cur_state);
+      TEST_VERIFY (sret == 1);
+
+      for (size_t i = 0; i < array_length (process_states); ++i)
+	if (state & process_states[i].s && cur_state == process_states[i].v)
+	  {
+	    close (fd);
+	    return;
+	  }
+
+      xlseek (fd, 0, SEEK_SET);
+      nanosleep (&(struct timespec) { 0, 10000000 }, NULL);
+    }
+
+  close (fd);
+#else
+  sleep (2);
+#endif
+}
diff --git a/support/tst-support-process_state.c b/support/tst-support-process_state.c
new file mode 100644
index 0000000000..3482f12fa5
--- /dev/null
+++ b/support/tst-support-process_state.c
@@ -0,0 +1,101 @@ 
+/* Wait for process state tests.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <support/test-driver.h>
+#include <support/process_state.h>
+#include <support/check.h>
+#include <support/xsignal.h>
+#include <support/xunistd.h>
+
+static void
+sigusr1_handler (int signo)
+{
+}
+
+static void
+test_child (void)
+{
+  xsignal (SIGUSR1, sigusr1_handler);
+
+  raise (SIGSTOP);
+
+  TEST_COMPARE (pause (), -1);
+  TEST_COMPARE (errno, EINTR);
+
+  while (1)
+    asm ("");
+}
+
+static int
+do_test (void)
+{
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      test_child ();
+      _exit (127);
+    }
+
+  /* Adding process_state_tracing_stop ('t') allows the test to work under
+     trace programs such as ptrace.  */
+  enum process_state_t stop_state = process_state_stopped
+				    | process_state_tracing_stop;
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_stopped/state_tracing_stop\n",
+	    (int) pid);
+  support_process_state_wait (pid, stop_state);
+
+  if (kill (pid, SIGCONT) != 0)
+    FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_sleeping\n", (int) pid);
+  support_process_state_wait (pid, process_state_sleeping);
+
+  if (kill (pid, SIGUSR1) != 0)
+    FAIL_RET ("kill (%d, SIGUSR1): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_running\n", (int) pid);
+  support_process_state_wait (pid, process_state_running);
+
+  if (kill (pid, SIGKILL) != 0)
+    FAIL_RET ("kill (%d, SIGKILL): %m\n", pid);
+
+  if (test_verbose)
+    printf ("info: waiting pid %d, state_zombie\n", (int) pid);
+  support_process_state_wait (pid, process_state_zombie);
+
+  siginfo_t info;
+  int r = waitid (P_PID, pid, &info, WEXITED);
+  TEST_COMPARE (r, 0);
+  TEST_COMPARE (info.si_signo, SIGCHLD);
+  TEST_COMPARE (info.si_code, CLD_KILLED);
+  TEST_COMPARE (info.si_status, SIGKILL);
+  TEST_COMPARE (info.si_pid, pid);
+
+  return 0;
+}
+
+#include <support/test-driver.c>