Patchwork [RFC,v4,04/24] sysdeps/wait: Use waitid if avaliable

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Submitter Alistair Francis
Date Aug. 10, 2019, 12:59 a.m.
Message ID <c4e8eb69ee269277b6f6cb72dab4023f76f57fea.1565398513.git.alistair.francis@wdc.com>
Download mbox | patch
Permalink /patch/34031/
State New
Headers show

Comments

Alistair Francis - Aug. 10, 2019, 12:59 a.m.
If the waitid syscall is avaliable let's use that as waitpid
and wait4 aren't always avaliable (they aren't avaliable on RV32).

Unfortunately waitid is substantially differnt to waitpid and wait4, so
the conversion ends up being complex.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 ChangeLog                                  |  3 ++
 sysdeps/unix/sysv/linux/wait.c             | 41 +++++++++++++--
 sysdeps/unix/sysv/linux/waitpid.c          | 58 +++++++++++++++++++++-
 sysdeps/unix/sysv/linux/waitpid_nocancel.c | 55 +++++++++++++++++++-
 4 files changed, 152 insertions(+), 5 deletions(-)

Patch

diff --git a/ChangeLog b/ChangeLog
index 82a2cdc746d..6daa6f259e1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1425,6 +1425,9 @@ 
 	* sysdeps/unix/sysv/linux/nanosleep.c: Likewise.
 	* sysdeps/unix/sysv/linux/nanosleep_nocancel.c: Likewise.
 	* sysdeps/unix/sysv/linux/gettimeofday.c: Use clock_gettime64 syscall for gettimeofday.
+	* sysdeps/unix/sysv/linux/wait.c: Use __NR_waitid if avaliable.
+	* sysdeps/unix/sysv/linux/waitpid.c: Likewise.
+	* sysdeps/unix/sysv/linux/waitpid_nocancel.c: Likewise.
 
 2019-06-20  Dmitry V. Levin  <ldv@altlinux.org>
 	    Florian Weimer  <fweimer@redhat.com>
diff --git a/sysdeps/unix/sysv/linux/wait.c b/sysdeps/unix/sysv/linux/wait.c
index 498bd1c095e..cd124ed11fb 100644
--- a/sysdeps/unix/sysv/linux/wait.c
+++ b/sysdeps/unix/sysv/linux/wait.c
@@ -26,9 +26,44 @@ 
 pid_t
 __libc_wait (int *stat_loc)
 {
-  pid_t result = SYSCALL_CANCEL (wait4, WAIT_ANY, stat_loc, 0,
-				 (struct rusage *) NULL);
-  return result;
+#ifdef __NR_wait4
+  return SYSCALL_CANCEL (wait4, WAIT_ANY, stat_loc, 0,
+                         (struct rusage *) NULL);
+#else
+  siginfo_t infop;
+  __pid_t ret;
+
+  ret = SYSCALL_CANCEL (waitid, P_ALL, 0, &infop, WEXITED, NULL);
+
+  if (ret < 0)
+      return ret;
+
+  if (stat_loc)
+    {
+      *stat_loc = 0;
+      switch (infop.si_code)
+      {
+        case CLD_EXITED:
+            *stat_loc = infop.si_status << 8;
+            break;
+        case CLD_DUMPED:
+            *stat_loc = 0x80;
+            /* Fallthrough */
+        case CLD_KILLED:
+            *stat_loc |= infop.si_status;
+            break;
+        case CLD_TRAPPED:
+        case CLD_STOPPED:
+            *stat_loc = infop.si_status << 8 | 0x7f;
+            break;
+        case CLD_CONTINUED:
+            *stat_loc = 0xffff;
+            break;
+      }
+    }
+
+  return infop.si_pid;
+#endif
 }
 
 weak_alias (__libc_wait, __wait)
diff --git a/sysdeps/unix/sysv/linux/waitpid.c b/sysdeps/unix/sysv/linux/waitpid.c
index f0897574c0b..2add17b3023 100644
--- a/sysdeps/unix/sysv/linux/waitpid.c
+++ b/sysdeps/unix/sysv/linux/waitpid.c
@@ -20,14 +20,70 @@ 
 #include <sysdep-cancel.h>
 #include <stdlib.h>
 #include <sys/wait.h>
+#include <unistd.h>
 
 __pid_t
 __waitpid (__pid_t pid, int *stat_loc, int options)
 {
 #ifdef __NR_waitpid
   return SYSCALL_CANCEL (waitpid, pid, stat_loc, options);
-#else
+#elif defined(__NR_wait4)
   return SYSCALL_CANCEL (wait4, pid, stat_loc, options, NULL);
+#else
+  __pid_t ret;
+  idtype_t idtype = P_PID;
+  siginfo_t infop;
+
+  if (pid < -1)
+    {
+      idtype = P_PGID;
+      pid *= -1;
+    }
+  else if (pid == -1)
+    {
+      idtype = P_ALL;
+    }
+  else if (pid == 0)
+    {
+      /* FIXME: This can lead to a race condition */
+      idtype = P_PGID;
+      pid = getpgrp();
+    }
+
+  options |= WEXITED;
+
+  ret = SYSCALL_CANCEL (waitid, idtype, pid, &infop, options, NULL);
+
+  if (ret < 0)
+    {
+      return ret;
+    }
+
+  if (stat_loc)
+    {
+      *stat_loc = 0;
+      switch (infop.si_code)
+        {
+        case CLD_EXITED:
+            *stat_loc = infop.si_status << 8;
+            break;
+        case CLD_DUMPED:
+            *stat_loc = 0x80;
+            /* Fallthrough */
+        case CLD_KILLED:
+            *stat_loc |= infop.si_status;
+            break;
+        case CLD_TRAPPED:
+        case CLD_STOPPED:
+            *stat_loc = infop.si_status << 8 | 0x7f;
+            break;
+        case CLD_CONTINUED:
+            *stat_loc = 0xffff;
+            break;
+        }
+    }
+
+  return infop.si_pid;
 #endif
 }
 libc_hidden_def (__waitpid)
diff --git a/sysdeps/unix/sysv/linux/waitpid_nocancel.c b/sysdeps/unix/sysv/linux/waitpid_nocancel.c
index 89e36a5c0b1..00d566a9931 100644
--- a/sysdeps/unix/sysv/linux/waitpid_nocancel.c
+++ b/sysdeps/unix/sysv/linux/waitpid_nocancel.c
@@ -27,8 +27,61 @@  __waitpid_nocancel (__pid_t pid, int *stat_loc, int options)
 {
 #ifdef __NR_waitpid
   return INLINE_SYSCALL_CALL (waitpid, pid, stat_loc, options);
-#else
+#elif defined (__NR_wait4)
   return INLINE_SYSCALL_CALL (wait4, pid, stat_loc, options, NULL);
+#else
+  __pid_t ret;
+  idtype_t idtype = P_PID;
+  siginfo_t infop;
+
+  if (pid < -1)
+    {
+      idtype = P_PGID;
+      pid *= -1;
+    }
+  else if (pid == -1)
+    {
+      idtype = P_ALL;
+    }
+  else if (pid == 0)
+    {
+      /* FIXME: This can lead to a race condition */
+      idtype = P_PGID;
+      pid = getpgrp();
+    }
+
+  options |= WEXITED;
+
+  ret = INLINE_SYSCALL_CALL (waitid, idtype, pid, &infop, options, NULL);
+
+  if (ret < 0)
+      return ret;
+
+  if (stat_loc)
+    {
+      *stat_loc = 0;
+      switch (infop.si_code)
+        {
+        case CLD_EXITED:
+            *stat_loc = infop.si_status << 8;
+            break;
+        case CLD_DUMPED:
+            *stat_loc = 0x80;
+            /* Fallthrough */
+        case CLD_KILLED:
+            *stat_loc |= infop.si_status;
+            break;
+        case CLD_TRAPPED:
+        case CLD_STOPPED:
+            *stat_loc = infop.si_status << 8 | 0x7f;
+            break;
+        case CLD_CONTINUED:
+            *stat_loc = 0xffff;
+            break;
+        }
+    }
+
+  return infop.si_pid;
 #endif
 }
 libc_hidden_def (__waitpid_nocancel)