posix: Add wait4 test case

Add a wait4 test case based on the waitid test case.

posix/Makefile

@@ -82,7 +82,8 @@ tests		:= test-errno tstgetopt testfnm runtests runptests \
 		   bug-regex29 bug-regex30 bug-regex31 bug-regex32 \
 		   tst-nice tst-nanosleep tst-regex2 \
 		   transbug tst-rxspencer tst-pcre tst-boost \
-		   bug-ga1 tst-vfork1 tst-vfork2 tst-vfork3 tst-waitid \
+		   bug-ga1 tst-vfork1 tst-vfork2 tst-vfork3 \
+		   tst-waitid tst-wait4 \
 		   tst-getaddrinfo2 bug-glob2 bug-glob3 tst-sysconf \
 		   tst-execvp1 tst-execvp2 tst-execlp1 tst-execlp2 \
 		   tst-execv1 tst-execv2 tst-execl1 tst-execl2 \

posix/tst-wait4.c

@@ -0,0 +1,209 @@
+/* Tests for wait4.
+   Copyright (C) 2020 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 <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <sys/resource.h>
+#include <signal.h>
+#include <time.h>
+#include <stdatomic.h>
+#include <stdbool.h>
+
+#include <support/xsignal.h>
+#include <support/xunistd.h>
+#include <support/check.h>
+#include <support/process_state.h>
+
+static void
+test_child (void)
+{
+  /* First thing, we stop ourselves.  */
+  raise (SIGSTOP);
+
+  /* Hey, we got continued!  */
+  while (1)
+    pause ();
+}
+
+#ifndef WEXITED
+# define WEXITED        0
+# define WCONTINUED     0
+# define WSTOPPED       WUNTRACED
+#endif
+
+/* Set with only SIGCHLD on do_test_waitid.  */
+static sigset_t chldset;
+
+#ifdef SA_SIGINFO
+static void
+sigchld (int signo, siginfo_t *info, void *ctx)
+{
+}
+#endif
+
+static void
+check_sigchld (int code, int status, pid_t pid)
+{
+#ifdef SA_SIGINFO
+  siginfo_t siginfo;
+  TEST_COMPARE (sigwaitinfo (&chldset, &siginfo), SIGCHLD);
+
+  TEST_COMPARE (siginfo.si_signo, SIGCHLD);
+  TEST_COMPARE (siginfo.si_code, code);
+  TEST_COMPARE (siginfo.si_status, status);
+  TEST_COMPARE (siginfo.si_pid, pid);
+#endif
+}
+
+static int
+do_test_wait4 (pid_t pid)
+{
+  /* 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;
+
+  support_process_state_wait (pid, stop_state);
+
+  check_sigchld (CLD_STOPPED, SIGSTOP, pid);
+
+  pid_t ret;
+  int wstatus;
+  struct rusage rusage;
+
+  ret = wait4 (pid, &wstatus, WUNTRACED|WCONTINUED|WNOHANG, NULL);
+  if (ret == -1 && errno == ENOTSUP)
+    FAIL_RET ("waitid WNOHANG on stopped: %m");
+  TEST_COMPARE (ret, pid);
+  TEST_VERIFY (WIFSTOPPED (wstatus));
+
+  /* Issue again but with struct rusage input.  */
+  ret = wait4 (pid, &wstatus, WUNTRACED|WCONTINUED|WNOHANG, &rusage);
+  /* With WNOHANG and WUNTRACED, if the children has not changes its state
+     since previous call the expected result it 0.  */
+  TEST_COMPARE (ret, 0);
+
+  /* Some sanity tests to check if 'wtatus' and 'rusage' possible
+     input values.  */
+  ret = wait4 (pid, NULL, WUNTRACED|WCONTINUED|WNOHANG, &rusage);
+  TEST_COMPARE (ret, 0);
+  ret = wait4 (pid, NULL, WUNTRACED|WCONTINUED|WNOHANG, NULL);
+  TEST_COMPARE (ret, 0);
+
+  if (kill (pid, SIGCONT) != 0)
+    FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);
+
+  /* Wait for the child to have continued.  */
+  support_process_state_wait (pid, support_process_state_sleeping);
+
+#if WCONTINUED != 0
+  check_sigchld (CLD_CONTINUED, SIGCONT, pid);
+
+  ret = wait4 (pid, &wstatus, WCONTINUED|WNOHANG, NULL);
+  TEST_COMPARE (ret, pid);
+  TEST_VERIFY (WIFCONTINUED (wstatus));
+
+  /* Issue again but with struct rusage input.  */
+  ret = wait4 (pid, &wstatus, WUNTRACED|WCONTINUED|WNOHANG, &rusage);
+  /* With WNOHANG and WUNTRACED, if the children has not changes its state
+     since previous call the expected result it 0.  */
+  TEST_COMPARE (ret, 0);
+
+  /* Now stop him again and test waitpid with WCONTINUED.  */
+  if (kill (pid, SIGSTOP) != 0)
+    FAIL_RET ("kill (%d, SIGSTOP): %m\n", pid);
+
+  /* Wait the child stop.  The waitid call below will block until it has
+     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);
+
+  ret = wait4 (pid, &wstatus, WUNTRACED|WNOHANG, &rusage);
+  TEST_COMPARE (ret, pid);
+
+  check_sigchld (CLD_STOPPED, SIGSTOP, pid);
+
+  if (kill (pid, SIGCONT) != 0)
+    FAIL_RET ("kill (%d, SIGCONT): %m\n", pid);
+
+  /* Wait for the child to have continued.  */
+  support_process_state_wait (pid, support_process_state_sleeping);
+
+  check_sigchld (CLD_CONTINUED, SIGCONT, pid);
+
+  ret = wait4 (pid, &wstatus, WCONTINUED|WNOHANG, NULL);
+  TEST_COMPARE (ret, pid);
+  TEST_VERIFY (WIFCONTINUED (wstatus));
+#endif
+
+  /* Die, child, die!  */
+  if (kill (pid, SIGKILL) != 0)
+    FAIL_RET ("kill (%d, SIGKILL): %m\n", pid);
+
+  support_process_state_wait (pid, support_process_state_zombie);
+
+  ret = wait4 (pid, &wstatus, 0, &rusage);
+  TEST_COMPARE (ret, pid);
+  TEST_VERIFY (WIFSIGNALED (wstatus));
+  TEST_VERIFY (WTERMSIG (wstatus) == SIGKILL);
+
+  check_sigchld (CLD_KILLED, SIGKILL, pid);
+
+  return 0;
+}
+
+static int
+do_test (void)
+{
+#ifdef SA_SIGINFO
+  {
+    struct sigaction sa;
+    sa.sa_flags = SA_SIGINFO | SA_RESTART;
+    sa.sa_sigaction = sigchld;
+    sigemptyset (&sa.sa_mask);
+    xsigaction (SIGCHLD, &sa, NULL);
+  }
+#endif
+
+  sigemptyset (&chldset);
+  sigaddset (&chldset, SIGCHLD);
+
+  /* The SIGCHLD shall has blocked at the time of the call to sigwait;
+     otherwise, the behavior is undefined.  */
+  sigprocmask (SIG_BLOCK, &chldset, NULL);
+
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      test_child ();
+      _exit (127);
+    }
+
+  do_test_wait4 (pid);
+
+  xsignal (SIGCHLD, SIG_IGN);
+  kill (pid, SIGKILL);          /* Make sure it's dead if we bailed early.  */
+
+  return 0;
+}
+
+#include <support/test-driver.c>