Make ProcessWaitState store ProcessExitStatus instead of int? exit code

src/libraries/Common/src/Interop/Unix/System.Native/Interop.WaitPid.cs

@@ -18,6 +18,6 @@ internal static partial class Sys
         /// 4) on error, -1 is returned.
         /// </returns>
         [LibraryImport(Libraries.SystemNative, EntryPoint = "SystemNative_WaitPidExitedNoHang", SetLastError = true)]
-        internal static partial int WaitPidExitedNoHang(int pid, out int exitCode);
+        internal static partial int WaitPidExitedNoHang(int pid, out int exitCode, out int terminatingSignal);
     }
 }

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Unix.cs

@@ -223,11 +223,11 @@ public ProcessModule? MainModule
         /// <summary>Checks whether the process has exited and updates state accordingly.</summary>
         private void UpdateHasExited()
         {
-            int? exitCode;
-            _exited = GetWaitState().GetExited(out exitCode, refresh: true);
-            if (_exited && exitCode != null)
+            ProcessExitStatus? exitStatus;
+            _exited = GetWaitState().GetExited(out exitStatus, refresh: true);
+            if (_exited && exitStatus is not null)
             {
-                _exitCode = exitCode.Value;
+                _exitCode = exitStatus.ExitCode;
             }
         }
 

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/ProcessWaitState.Unix.cs

@@ -208,8 +208,8 @@ internal void ReleaseRef()
 
         /// <summary>Whether the associated process exited.</summary>
         private bool _exited;
-        /// <summary>If the process exited, it's exit code, or null if we were unable to determine one.</summary>
-        private int? _exitCode;
+        /// <summary>If the process exited, its exit status, or null if we were unable to determine one.</summary>
+        private ProcessExitStatus? _exitStatus;
         /// <summary>
         /// The approximate time the process exited.  We do not have the ability to know exact time a process
         /// exited, so we approximate it by storing the time that we discovered it exited.
@@ -310,22 +310,22 @@ internal bool HasExited
             }
         }
 
-        internal bool GetExited(out int? exitCode, bool refresh)
+        internal bool GetExited(out ProcessExitStatus? exitStatus, bool refresh)
         {
             lock (_gate)
             {
                 // Have we already exited?  If so, return the cached results.
                 if (_exited)
                 {
-                    exitCode = _exitCode;
+                    exitStatus = _exitStatus;
                     return true;
                 }
 
                 // Is another wait operation in progress?  If so, then we haven't exited,
                 // and that task owns the right to call CheckForNonChildExit.
                 if (!_waitInProgress.IsCompleted)
                 {
-                    exitCode = null;
+                    exitStatus = null;
                     return false;
                 }
 
@@ -338,7 +338,7 @@ internal bool GetExited(out int? exitCode, bool refresh)
 
                 // We now have an up-to-date snapshot for whether we've exited,
                 // and if we have, what the exit code is (if we were able to find out).
-                exitCode = _exitCode;
+                exitStatus = _exitStatus;
                 return _exited;
             }
         }
@@ -539,13 +539,14 @@ private async Task WaitForExitAsync(CancellationToken cancellationToken)
             }
         }
 
-        private void ChildReaped(int exitCode, bool configureConsole)
+        private void ChildReaped(int exitCode, int terminatingSignal, bool configureConsole)
         {
             lock (_gate)
             {
                 Debug.Assert(!_exited);
 
-                _exitCode = exitCode;
+                PosixSignal? signal = terminatingSignal != 0 ? (PosixSignal)terminatingSignal : null;
+                _exitStatus = new ProcessExitStatus(exitCode, canceled: false, signal);
 
                 if (_usesTerminal)
                 {
@@ -568,11 +569,12 @@ private bool TryReapChild(bool configureConsole)
 
                 // Try to get the state of the child process
                 int exitCode;
-                int waitResult = Interop.Sys.WaitPidExitedNoHang(_processId, out exitCode);
+                int terminatingSignal;
+                int waitResult = Interop.Sys.WaitPidExitedNoHang(_processId, out exitCode, out terminatingSignal);
 
                 if (waitResult == _processId)
                 {
-                    ChildReaped(exitCode, configureConsole);
+                    ChildReaped(exitCode, terminatingSignal, configureConsole);
                     return true;
                 }
                 else if (waitResult == 0)
@@ -673,7 +675,8 @@ internal static void CheckChildren(bool reapAll, bool configureConsole)
                     do
                     {
                         int exitCode;
-                        pid = Interop.Sys.WaitPidExitedNoHang(-1, out exitCode);
+                        int terminatingSignal;
+                        pid = Interop.Sys.WaitPidExitedNoHang(-1, out exitCode, out terminatingSignal);
                         if (pid <= 0)
                         {
                             break;
@@ -682,7 +685,7 @@ internal static void CheckChildren(bool reapAll, bool configureConsole)
                         // Check if the process is a child that has just terminated.
                         if (s_childProcessWaitStates.TryGetValue(pid, out ProcessWaitState? pws))
                         {
-                            pws.ChildReaped(exitCode, configureConsole);
+                            pws.ChildReaped(exitCode, terminatingSignal, configureConsole);
                             pws.ReleaseRef();
                         }
                     } while (true);

src/native/libs/System.Native/pal_process.c

@@ -3,6 +3,7 @@
 
 #include "pal_config.h"
 #include "pal_process.h"
+#include "pal_signal.h"
 #include "pal_io.h"
 #include "pal_utilities.h"
 
@@ -929,9 +930,10 @@ int32_t SystemNative_WaitIdAnyExitedNoHangNoWait(void)
     return result;
 }
 
-int32_t SystemNative_WaitPidExitedNoHang(int32_t pid, int32_t* exitCode)
+int32_t SystemNative_WaitPidExitedNoHang(int32_t pid, int32_t* exitCode, int32_t* terminatingSignal)
 {
     assert(exitCode != NULL);
+    assert(terminatingSignal != NULL);
 
     int32_t result;
     int status;
@@ -942,11 +944,16 @@ int32_t SystemNative_WaitPidExitedNoHang(int32_t pid, int32_t* exitCode)
         {
             // the child terminated normally.
             *exitCode = WEXITSTATUS(status);
+            *terminatingSignal = 0;
         }
         else if (WIFSIGNALED(status))
         {
             // child process was terminated by a signal.
-            *exitCode = 128 + WTERMSIG(status);
+            int sig = WTERMSIG(status);
+            *exitCode = 128 + sig;
+            PosixSignal posixSignal = PosixSignalInvalid;
+            TryConvertSignalCodeToPosixSignal(sig, &posixSignal);
+            *terminatingSignal = (int32_t)posixSignal;
         }
         else
         {

src/native/libs/System.Native/pal_process.h

@@ -186,8 +186,12 @@ PALEXPORT int32_t SystemNative_WaitIdAnyExitedNoHangNoWait(void);
  * 2) if pid is not a child or there are no unwaited-for children, -1 is returned (errno=ECHILD)
  * 3) if the child has not yet terminated, 0 is returned
  * 4) on error, -1 is returned.
+ *
+ * exitCode: set to WEXITSTATUS on normal exit, or 128 + signal number on signal termination.
+ * terminatingSignal: set to 0 on normal exit, or the PosixSignal value on signal termination.
+ *                    For signals not in the known PosixSignal set, this is the raw signal number.
  */
-PALEXPORT int32_t SystemNative_WaitPidExitedNoHang(int32_t pid, int32_t* exitCode);
+PALEXPORT int32_t SystemNative_WaitPidExitedNoHang(int32_t pid, int32_t* exitCode, int32_t* terminatingSignal);
 
 /**
  * Gets the configurable limit or variable for system path or file descriptor options.

src/native/libs/System.Native/pal_process_wasi.c

@@ -76,7 +76,7 @@ int32_t SystemNative_WaitIdAnyExitedNoHangNoWait(void)
     return -1;
 }
 
-int32_t SystemNative_WaitPidExitedNoHang(int32_t pid, int32_t* exitCode)
+int32_t SystemNative_WaitPidExitedNoHang(int32_t pid, int32_t* exitCode, int32_t* terminatingSignal)
 {
     return -1;
 }

src/native/libs/System.Native/pal_signal.c

@@ -83,7 +83,7 @@ static bool IsSigIgn(struct sigaction* action)
             action->sa_handler == SIG_IGN;
 }
 
-static bool TryConvertSignalCodeToPosixSignal(int signalCode, PosixSignal* posixSignal)
+bool TryConvertSignalCodeToPosixSignal(int signalCode, PosixSignal* posixSignal)
 {
     assert(posixSignal != NULL);
 

src/native/libs/System.Native/pal_signal.h

@@ -83,6 +83,14 @@ PALEXPORT void SystemNative_DisablePosixSignalHandling(int signalCode);
  */
 PALEXPORT void SystemNative_HandleNonCanceledPosixSignal(int32_t signalCode);
 
+/**
+ * Converts a native signal code to PosixSignal.
+ *
+ * Returns true if the signal code was mapped to a known PosixSignal.
+ * Returns false if the signal is not in the known set (posixSignal is set to the raw signal code).
+ */
+bool TryConvertSignalCodeToPosixSignal(int signalCode, PosixSignal* posixSignal);
+
 typedef void (*ConsoleSigTtouHandler)(void);
 
 /**