1 files changed, 84 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/wait4.c b/sysdeps/unix/sysv/linux/wait4.c
new file mode 100644
index 0000000000..c97e212b54
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/wait4.c
@@ -0,0 +1,84 @@
+/* Wait for process to change state.  Linux version.
+   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 <sys/wait.h>
+#include <sys/resource.h>
+#include <sysdep-cancel.h>
+
+pid_t
+__wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
+{
+#ifdef __NR_wait4
+  return SYSCALL_CANCEL (wait4, pid, stat_loc, options, usage);
+#elif defined (__ASSUME_WAITID_PID0_P_PGID)
+  idtype_t idtype = P_PID;
+
+  if (pid < -1)
+    {
+      idtype = P_PGID;
+      pid *= -1;
+    }
+  else if (pid == -1)
+    idtype = P_ALL;
+  else if (pid == 0)
+    idtype = P_PGID;
+
+  options |= WEXITED;
+
+  siginfo_t infop;
+  if (SYSCALL_CANCEL (waitid, idtype, pid, &infop, options, usage) < 0)
+    return -1;
+
+  if (stat_loc)
+    {
+      switch (infop.si_code)
+        {
+        case CLD_EXITED:
+          *stat_loc = W_EXITCODE (infop.si_status, 0);
+          break;
+        case CLD_DUMPED:
+          *stat_loc = WCOREFLAG | infop.si_status;
+	  break;
+        case CLD_KILLED:
+          *stat_loc = infop.si_status;
+          break;
+        case CLD_TRAPPED:
+        case CLD_STOPPED:
+          *stat_loc = W_STOPCODE (infop.si_status);
+          break;
+        case CLD_CONTINUED:
+          *stat_loc = __W_CONTINUED;
+          break;
+	default:
+	  *stat_loc = 0;
+	  break;
+        }
+    }
+
+  return infop.si_pid;
+# else
+/* Linux waitid prior kernel 5.4 does not support waiting for the current
+   process.  It is possible to emulate wait4 it by calling getpgid for
+   PID 0, however, it would require an additional syscall and it is inherent
+   racy: after the current process group is received and before it is passed
+   to waitid a signal could arrive causing the current process group to
+   change.  */
+# error "The kernel ABI does not provide a way to implement wait4"
+#endif
+}
+weak_alias (__wait4, wait4)