[v2,3/3] posix: Remove posix waitid

Message ID 20200218140205.18263-3-adhemerval.zanella@linaro.org
State New
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Series
  • [v2,1/3] support: Add support_process_state_wait
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Commit Message

Adhemerval Zanella Feb. 18, 2020, 2:02 p.m.
The POSIX waitid implementation is problematic in some ways:

  - It emulates using waitpid, which default implementation calls
    wait4 and wait4 returns ENOSYS as default.

  - Also by using waitpid it does not allod support the WNOWAIT,
    WEXITED, WSTOPPED, or WCONTINUED flag.  With current POSIX
    specification the flags are no longer marked as optional.

Also due BZ#23091 Hurd still uses the implementation, so it is moved
to as a Hurd arch-specific folder (with some minor cleanups).

Checked against a i686-gnu (run-built-tests=no)
---
 posix/tst-waitid.c                    | 14 +++---
 sysdeps/{posix => mach/hurd}/waitid.c | 70 ++++-----------------------
 2 files changed, 16 insertions(+), 68 deletions(-)
 rename sysdeps/{posix => mach/hurd}/waitid.c (65%)

-- 
2.17.1

Comments

Adhemerval Zanella Feb. 18, 2020, 5:47 p.m. | #1
On 18/02/2020 11:02, Adhemerval Zanella wrote:
> The POSIX waitid implementation is problematic in some ways:

> 

>   - It emulates using waitpid, which default implementation calls

>     wait4 and wait4 returns ENOSYS as default.

> 

>   - Also by using waitpid it does not allod support the WNOWAIT,

>     WEXITED, WSTOPPED, or WCONTINUED flag.  With current POSIX

>     specification the flags are no longer marked as optional.

> 

> Also due BZ#23091 Hurd still uses the implementation, so it is moved

> to as a Hurd arch-specific folder (with some minor cleanups).

> 

> Checked against a i686-gnu (run-built-tests=no)

> ---

>  posix/tst-waitid.c                    | 14 +++---


Ok, the changes on tst-waitid.c shouldn't be in this patch, but rather
on the second one.

>  sysdeps/{posix => mach/hurd}/waitid.c | 70 ++++-----------------------

>  2 files changed, 16 insertions(+), 68 deletions(-)

>  rename sysdeps/{posix => mach/hurd}/waitid.c (65%)

> 

> diff --git a/posix/tst-waitid.c b/posix/tst-waitid.c

> index 2331c42e66..380d807498 100644

> --- a/posix/tst-waitid.c

> +++ b/posix/tst-waitid.c

> @@ -80,10 +80,10 @@ do_test_waitd_common (idtype_t type, pid_t pid)

>  {

>    /* 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;

> +  enum support_process_state stop_state

> +    = support_process_state_stopped | support_process_state_tracing_stop;

>  

> -  support_process_state_wait (pid, stop_state);

> +  support_process_state_wait (pid, stop_state, NULL);

>  

>    check_sigchld (CLD_STOPPED, SIGSTOP, pid);

>  

> @@ -117,7 +117,7 @@ do_test_waitd_common (idtype_t type, pid_t pid)

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

>  

>    /* Wait for the child to have continued.  */

> -  support_process_state_wait (pid, process_state_sleeping);

> +  support_process_state_wait (pid, support_process_state_sleeping, NULL);

>  

>  #if WCONTINUED != 0

>    {

> @@ -175,7 +175,7 @@ do_test_waitd_common (idtype_t type, pid_t pid)

>       stopped, but if we are real quick and enter the waitid system call

>       before the SIGCHLD has been generated, then it will be discarded and

>       never delivered.  */

> -  support_process_state_wait (pid, stop_state);

> +  support_process_state_wait (pid, stop_state, NULL);

>  

>    fail = waitid (type, pid, &info, WEXITED|WSTOPPED);

>    TEST_COMPARE (fail, 0);

> @@ -190,7 +190,7 @@ do_test_waitd_common (idtype_t type, pid_t pid)

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

>  

>    /* Wait for the child to have continued.  */

> -  support_process_state_wait (pid, process_state_sleeping);

> +  support_process_state_wait (pid, support_process_state_sleeping, NULL);

>  

>    check_sigchld (CLD_CONTINUED, SIGCONT, pid);

>  

> @@ -219,7 +219,7 @@ do_test_waitd_common (idtype_t type, pid_t pid)

>    TEST_COMPARE (info.si_status, SIGKILL);

>    TEST_COMPARE (info.si_pid, pid);

>  #else

> -  support_process_state_wait (pid, process_state_zombie);

> +  support_process_state_wait (pid, support_process_state_zombie, NULL);

>  #endif

>    check_sigchld (CLD_KILLED, SIGKILL, pid);

>  

> diff --git a/sysdeps/posix/waitid.c b/sysdeps/mach/hurd/waitid.c

> similarity index 65%

> rename from sysdeps/posix/waitid.c

> rename to sysdeps/mach/hurd/waitid.c

> index f752076735..dce72339dd 100644

> --- a/sysdeps/posix/waitid.c

> +++ b/sysdeps/mach/hurd/waitid.c

> @@ -17,25 +17,11 @@

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

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

>  

> -#include <assert.h>

>  #include <errno.h>

> -#include <signal.h>

> -#define __need_NULL

> -#include <stddef.h>

>  #include <sys/wait.h>

> -#include <sys/types.h>

> -#include <sysdep-cancel.h>

>  

> -

> -#ifdef DO_WAITID

> -# define OUR_WAITID DO_WAITID

> -#elif !defined NO_DO_WAITID

> -# define OUR_WAITID do_waitid

> -#endif

> -

> -#ifdef OUR_WAITID

> -static int

> -OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)

> +int

> +__waitid (idtype_t idtype, id_t id, siginfo_t *infop, int options)

>  {

>    pid_t pid, child;

>    int status;

> @@ -43,7 +29,7 @@ OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)

>    switch (idtype)

>      {

>      case P_PID:

> -      if(id <= 0)

> +      if (id <= 0)

>  	goto invalid;

>        pid = (pid_t) id;

>        break;

> @@ -72,31 +58,10 @@ OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)

>        return -1;

>      }

>  

> -  /* This emulation using waitpid cannot support the waitid modes in which

> -     we do not reap the child, or match only stopped and not dead children.  */

> -  if (0

> -#ifdef WNOWAIT

> -      || (options & WNOWAIT)

> -#endif

> -#ifdef WEXITED

> -      || ((options & (WEXITED|WSTOPPED|WCONTINUED))

> -	  != (WEXITED | (options & WSTOPPED)))

> -#endif

> -      )

> -    {

> -      __set_errno (ENOTSUP);

> -      return -1;

> -    }

> -

>    /* Note the waitid() is a cancellation point.  But since we call

>       waitpid() which itself is a cancellation point we do not have

>       to do anything here.  */

> -  child = __waitpid (pid, &status,

> -		     options

> -#ifdef WEXITED

> -		     &~ WEXITED

> -#endif

> -		     );

> +  child = __waitpid (pid, &status, options);

>  

>    if (child == -1)

>      /* `waitpid' set `errno' for us.  */

> @@ -104,9 +69,11 @@ OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)

>  

>    if (child == 0)

>      {

> -      /* The WHOHANG bit in OPTIONS is set and there are children available

> -	 but none has a status for us.  The XPG docs do not mention this

> -	 case so we clear the `siginfo_t' struct and return successfully.  */

> +      /* POSIX.1-2008, Technical Corrigendum 1 XSH/TC1-2008/0713 [153] states

> +	 that if waitid returns because WNOHANG was specified and status is

> +	 not available for any process specified by idtype and id, then the

> +	 si_signo and si_pid members of the structure pointed to by infop

> +	 shall be set to zero.  */

>        infop->si_signo = 0;

>        infop->si_code = 0;

>        return 0;

> @@ -132,27 +99,8 @@ OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)

>        infop->si_code = CLD_STOPPED;

>        infop->si_status = WSTOPSIG (status);

>      }

> -#ifdef WIFCONTINUED

> -  else if (WIFCONTINUED (status))

> -    {

> -      infop->si_code = CLD_CONTINUED;

> -      infop->si_status = SIGCONT;

> -    }

> -#endif

> -  else

> -    /* Can't happen. */

> -    assert (! "What?");

>  

>    return 0;

>  }

> -#endif

> -

> -

> -int

> -__waitid (idtype_t idtype, id_t id, siginfo_t *infop, int options)

> -{

> -  /* __waitpid should be a cancellation point.  */

> -  return do_waitid (idtype, id, infop, options);

> -}

>  weak_alias (__waitid, waitid)

>  strong_alias (__waitid, __libc_waitid)

>
Adhemerval Zanella Feb. 27, 2020, 4:45 p.m. | #2
On 18/02/2020 14:47, Adhemerval Zanella wrote:
> 

> 

> On 18/02/2020 11:02, Adhemerval Zanella wrote:

>> The POSIX waitid implementation is problematic in some ways:

>>

>>   - It emulates using waitpid, which default implementation calls

>>     wait4 and wait4 returns ENOSYS as default.

>>

>>   - Also by using waitpid it does not allod support the WNOWAIT,

>>     WEXITED, WSTOPPED, or WCONTINUED flag.  With current POSIX

>>     specification the flags are no longer marked as optional.

>>

>> Also due BZ#23091 Hurd still uses the implementation, so it is moved

>> to as a Hurd arch-specific folder (with some minor cleanups).

>>

>> Checked against a i686-gnu (run-built-tests=no)

>> ---

>>  posix/tst-waitid.c                    | 14 +++---

> 

> Ok, the changes on tst-waitid.c shouldn't be in this patch, but rather

> on the second one.



I will commit this patch shortly if no one opposes it.

Patch

diff --git a/posix/tst-waitid.c b/posix/tst-waitid.c
index 2331c42e66..380d807498 100644
--- a/posix/tst-waitid.c
+++ b/posix/tst-waitid.c
@@ -80,10 +80,10 @@  do_test_waitd_common (idtype_t type, pid_t pid)
 {
   /* 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;
+  enum support_process_state stop_state
+    = support_process_state_stopped | support_process_state_tracing_stop;
 
-  support_process_state_wait (pid, stop_state);
+  support_process_state_wait (pid, stop_state, NULL);
 
   check_sigchld (CLD_STOPPED, SIGSTOP, pid);
 
@@ -117,7 +117,7 @@  do_test_waitd_common (idtype_t type, pid_t pid)
     FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);
 
   /* Wait for the child to have continued.  */
-  support_process_state_wait (pid, process_state_sleeping);
+  support_process_state_wait (pid, support_process_state_sleeping, NULL);
 
 #if WCONTINUED != 0
   {
@@ -175,7 +175,7 @@  do_test_waitd_common (idtype_t type, pid_t pid)
      stopped, but if we are real quick and enter the waitid system call
      before the SIGCHLD has been generated, then it will be discarded and
      never delivered.  */
-  support_process_state_wait (pid, stop_state);
+  support_process_state_wait (pid, stop_state, NULL);
 
   fail = waitid (type, pid, &info, WEXITED|WSTOPPED);
   TEST_COMPARE (fail, 0);
@@ -190,7 +190,7 @@  do_test_waitd_common (idtype_t type, pid_t pid)
     FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);
 
   /* Wait for the child to have continued.  */
-  support_process_state_wait (pid, process_state_sleeping);
+  support_process_state_wait (pid, support_process_state_sleeping, NULL);
 
   check_sigchld (CLD_CONTINUED, SIGCONT, pid);
 
@@ -219,7 +219,7 @@  do_test_waitd_common (idtype_t type, pid_t pid)
   TEST_COMPARE (info.si_status, SIGKILL);
   TEST_COMPARE (info.si_pid, pid);
 #else
-  support_process_state_wait (pid, process_state_zombie);
+  support_process_state_wait (pid, support_process_state_zombie, NULL);
 #endif
   check_sigchld (CLD_KILLED, SIGKILL, pid);
 
diff --git a/sysdeps/posix/waitid.c b/sysdeps/mach/hurd/waitid.c
similarity index 65%
rename from sysdeps/posix/waitid.c
rename to sysdeps/mach/hurd/waitid.c
index f752076735..dce72339dd 100644
--- a/sysdeps/posix/waitid.c
+++ b/sysdeps/mach/hurd/waitid.c
@@ -17,25 +17,11 @@ 
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <assert.h>
 #include <errno.h>
-#include <signal.h>
-#define __need_NULL
-#include <stddef.h>
 #include <sys/wait.h>
-#include <sys/types.h>
-#include <sysdep-cancel.h>
 
-
-#ifdef DO_WAITID
-# define OUR_WAITID DO_WAITID
-#elif !defined NO_DO_WAITID
-# define OUR_WAITID do_waitid
-#endif
-
-#ifdef OUR_WAITID
-static int
-OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)
+int
+__waitid (idtype_t idtype, id_t id, siginfo_t *infop, int options)
 {
   pid_t pid, child;
   int status;
@@ -43,7 +29,7 @@  OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)
   switch (idtype)
     {
     case P_PID:
-      if(id <= 0)
+      if (id <= 0)
 	goto invalid;
       pid = (pid_t) id;
       break;
@@ -72,31 +58,10 @@  OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)
       return -1;
     }
 
-  /* This emulation using waitpid cannot support the waitid modes in which
-     we do not reap the child, or match only stopped and not dead children.  */
-  if (0
-#ifdef WNOWAIT
-      || (options & WNOWAIT)
-#endif
-#ifdef WEXITED
-      || ((options & (WEXITED|WSTOPPED|WCONTINUED))
-	  != (WEXITED | (options & WSTOPPED)))
-#endif
-      )
-    {
-      __set_errno (ENOTSUP);
-      return -1;
-    }
-
   /* Note the waitid() is a cancellation point.  But since we call
      waitpid() which itself is a cancellation point we do not have
      to do anything here.  */
-  child = __waitpid (pid, &status,
-		     options
-#ifdef WEXITED
-		     &~ WEXITED
-#endif
-		     );
+  child = __waitpid (pid, &status, options);
 
   if (child == -1)
     /* `waitpid' set `errno' for us.  */
@@ -104,9 +69,11 @@  OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)
 
   if (child == 0)
     {
-      /* The WHOHANG bit in OPTIONS is set and there are children available
-	 but none has a status for us.  The XPG docs do not mention this
-	 case so we clear the `siginfo_t' struct and return successfully.  */
+      /* POSIX.1-2008, Technical Corrigendum 1 XSH/TC1-2008/0713 [153] states
+	 that if waitid returns because WNOHANG was specified and status is
+	 not available for any process specified by idtype and id, then the
+	 si_signo and si_pid members of the structure pointed to by infop
+	 shall be set to zero.  */
       infop->si_signo = 0;
       infop->si_code = 0;
       return 0;
@@ -132,27 +99,8 @@  OUR_WAITID (idtype_t idtype, id_t id, siginfo_t *infop, int options)
       infop->si_code = CLD_STOPPED;
       infop->si_status = WSTOPSIG (status);
     }
-#ifdef WIFCONTINUED
-  else if (WIFCONTINUED (status))
-    {
-      infop->si_code = CLD_CONTINUED;
-      infop->si_status = SIGCONT;
-    }
-#endif
-  else
-    /* Can't happen. */
-    assert (! "What?");
 
   return 0;
 }
-#endif
-
-
-int
-__waitid (idtype_t idtype, id_t id, siginfo_t *infop, int options)
-{
-  /* __waitpid should be a cancellation point.  */
-  return do_waitid (idtype, id, infop, options);
-}
 weak_alias (__waitid, waitid)
 strong_alias (__waitid, __libc_waitid)