forkfd: use wait4 to get the process status instead of waitid

wait4 gives us the struct rusage contents for us, which may contain
interesting data for other users of forkfd (not Qt, though).

Change-Id: Iee8cbc07c4434ce9b560ffff13cb4aa28e18e790
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>

1 files changed, 34 insertions, 19 deletions

diff --git a/src/3rdparty/forkfd/forkfd.c b/src/3rdparty/forkfd/forkfd.c
index 86e109358c..5d62f88149 100644
--- a/src/3rdparty/forkfd/forkfd.c
+++ b/src/3rdparty/forkfd/forkfd.c
@@ -25,9 +25,8 @@
 
 #ifndef _GNU_SOURCE
 #  define _GNU_SOURCE
-#  define _POSIX_C_SOURCE 200809L
-#  define _XOPEN_SOURCE 700
 #endif
+
 #include "forkfd.h"
 
 #include <sys/types.h>
@@ -44,6 +43,7 @@
 #include <unistd.h>
 
 #ifdef __linux__
+#  define HAVE_WAIT4    1
 #  if (defined(__GLIBC__) && (__GLIBC__ << 16) + __GLIBC_MINOR__ >= 0x207) || defined(__BIONIC__)
 #    include <sys/eventfd.h>
 #    define HAVE_EVENTFD  1
@@ -56,6 +56,10 @@
 #if _POSIX_VERSION-0 >= 200809L || _XOPEN_VERSION-0 >= 500
 #  define HAVE_WAITID   1
 #endif
+#if defined(__FreeBSD__) || defined(__DragonFly__) || defined(__FreeBSD_kernel__) || \
+    defined(__OpenBSD__) || defined(__NetBSD__) || defined(__APPLE__)
+#  define HAVE_WAIT4    1
+#endif
 
 #if defined(__APPLE__)
 /* Up until OS X 10.7, waitid(P_ALL, ...) will return success, but will not
@@ -188,12 +192,33 @@ static int isChildReady(pid_t pid, siginfo_t *info)
 }
 #endif
 
+static void convertStatusToForkfdInfo(int status, struct forkfd_info *info)
+{
+    if (WIFEXITED(status)) {
+        info->code = CLD_EXITED;
+        info->status = WEXITSTATUS(status);
+    } else if (WIFSIGNALED(status)) {
+        info->code = CLD_KILLED;
+#  ifdef WCOREDUMP
+        if (WCOREDUMP(status))
+            info->code = CLD_DUMPED;
+#  endif
+        info->status = WTERMSIG(status);
+    }
+}
+
 static int tryReaping(pid_t pid, struct pipe_payload *payload)
 {
     /* reap the child */
-#ifdef HAVE_WAITID
+#if defined(HAVE_WAIT4)
+    int status;
+    if (wait4(pid, &status, WNOHANG, &payload->rusage) <= 0)
+        return 0;
+    convertStatusToForkfdInfo(status, &payload->info);
+#else
+#  if defined(HAVE_WAITID)
     if (waitid_works) {
-        // we have waitid(2), which fills in siginfo_t for us
+        /* we have waitid(2), which gets us some payload values on some systems */
         siginfo_t info;
         info.si_pid = 0;
         int ret = waitid(P_PID, pid, &info, WEXITED | WNOHANG) == 0 && info.si_pid == pid;
@@ -202,30 +227,20 @@ static int tryReaping(pid_t pid, struct pipe_payload *payload)
 
         payload->info.code = info.si_code;
         payload->info.status = info.si_status;
-#  ifdef __linux__
+#    ifdef __linux__
         payload->rusage.ru_utime.tv_sec = info.si_utime / CLOCKS_PER_SEC;
         payload->rusage.ru_utime.tv_usec = info.si_utime % CLOCKS_PER_SEC;
         payload->rusage.ru_stime.tv_sec = info.si_stime / CLOCKS_PER_SEC;
         payload->rusage.ru_stime.tv_usec = info.si_stime % CLOCKS_PER_SEC;
-#  endif
+#    endif
         return 1;
     }
-#endif
+#  endif // HAVE_WAITID
     int status;
     if (waitpid(pid, &status, WNOHANG) <= 0)
         return 0;     // child did not change state
-
-    if (WIFEXITED(status)) {
-        payload->info.code = CLD_EXITED;
-        payload->info.status = WEXITSTATUS(status);
-    } else if (WIFSIGNALED(status)) {
-        payload->info.code = CLD_KILLED;
-#  ifdef WCOREDUMP
-        if (WCOREDUMP(status))
-            payload->info.code = CLD_DUMPED;
-#  endif
-        payload->info.status = WTERMSIG(status);
-    }
+    convertStatusToForkfdInfo(status, &payload->info);
+#endif // !HAVE_WAIT4
 
     return 1;
 }