From adbe5a2f2e835718a6e6a5d152c0cf2ca41a6ac1 Mon Sep 17 00:00:00 2001
From: Manoj Ampalam <manojampalam@live.com>
Date: Fri, 13 Jan 2017 13:25:31 -0800
Subject: [PATCH] Fixed issue: sshd service terminates after a brief period of
 time (https://github.com/PowerShell/Win32-OpenSSH/issues/241)

---
 contrib/win32/win32compat/misc.c            |  5 ++-
 contrib/win32/win32compat/signal.c          |  2 +-
 contrib/win32/win32compat/signal_internal.h |  7 +++-
 contrib/win32/win32compat/signal_sigchld.c  | 42 +++++++++++++--------
 4 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/contrib/win32/win32compat/misc.c b/contrib/win32/win32compat/misc.c
index 43d180a57..224baccf1 100644
--- a/contrib/win32/win32compat/misc.c
+++ b/contrib/win32/win32compat/misc.c
@@ -472,14 +472,15 @@ settimes(wchar_t * path, FILETIME *cretime, FILETIME *acttime, FILETIME *modtime
 		NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
 
 	if (handle == INVALID_HANDLE_VALUE) {
-		errno = GetLastError;
+		/* TODO - convert Win32 error to errno */
+		errno = GetLastError();
 		debug("w32_settimes - CreateFileW ERROR:%d", errno);
 		return -1;
 	}
 
 	if (SetFileTime(handle, cretime, acttime, modtime) == 0)
 	{
-		errno = GetLastError;
+		errno = GetLastError();
 		debug("w32_settimes - SetFileTime ERROR:%d", errno);
 		CloseHandle(handle);
 		return -1;
diff --git a/contrib/win32/win32compat/signal.c b/contrib/win32/win32compat/signal.c
index 8a74da9a3..d84f5412f 100644
--- a/contrib/win32/win32compat/signal.c
+++ b/contrib/win32/win32compat/signal.c
@@ -258,7 +258,7 @@ wait_for_any_event(HANDLE* events, int num_events, DWORD milli_seconds)
 		if ((ret >= WAIT_OBJECT_0) && (ret <= WAIT_OBJECT_0 + num_all_events - 1)) {
 			//woken up by event signalled
 			/* is this due to a child process going down*/
-			if (children.num_children && ((ret - WAIT_OBJECT_0) < children.num_children)) {
+			if (live_children && ((ret - WAIT_OBJECT_0) < live_children)) {
 				sigaddset(&pending_signals, W32_SIGCHLD);
 				sw_child_to_zombie(ret - WAIT_OBJECT_0);
 			}
diff --git a/contrib/win32/win32compat/signal_internal.h b/contrib/win32/win32compat/signal_internal.h
index 826ca9574..4bd7f2093 100644
--- a/contrib/win32/win32compat/signal_internal.h
+++ b/contrib/win32/win32compat/signal_internal.h
@@ -11,12 +11,17 @@ int sw_kill(int pid, int sig);
 /* child processes */
 #define MAX_CHILDREN 50
 struct _children {
+	/* 
+	 * array of handles and process_ids. 
+	 * intial (num_children - num_zombies) are alive 
+	 * rest are zombies 
+	 */
 	HANDLE handles[MAX_CHILDREN];
 	DWORD process_id[MAX_CHILDREN];
 	/* total children */
 	DWORD num_children;
 	/* #zombies */
-	/* (num_chileren - zombies) are live children */
+	/* (num_children - zombies) are live children */
 	DWORD num_zombies;
 };
 
diff --git a/contrib/win32/win32compat/signal_sigchld.c b/contrib/win32/win32compat/signal_sigchld.c
index afd0242f4..53c6c2d76 100644
--- a/contrib/win32/win32compat/signal_sigchld.c
+++ b/contrib/win32/win32compat/signal_sigchld.c
@@ -101,7 +101,7 @@ sw_remove_child_at_index(DWORD index) {
 
 int
 sw_child_to_zombie(DWORD index) {
-	DWORD last_non_zombie, last_child, zombie_pid;
+	DWORD last_non_zombie, zombie_pid;
 	HANDLE zombie_handle;
 
 	debug("zombie'ing child at index %d, %d zombies of %d", index,
@@ -112,17 +112,17 @@ sw_child_to_zombie(DWORD index) {
 		return -1;
 	}
 
-	zombie_pid = children.process_id[index];
-	zombie_handle = children.handles[index];
 	last_non_zombie = children.num_children - children.num_zombies - 1;
-	last_child = children.num_children - 1;
-
-	children.handles[index] = children.handles[last_non_zombie];
-	children.process_id[index] = children.process_id[last_non_zombie];
-
-	children.handles[last_non_zombie] = children.handles[index];
-	children.process_id[last_non_zombie] = children.process_id[index];
-
+	
+	if (last_non_zombie != index) {
+		/* swap */
+		zombie_pid = children.process_id[index];
+		zombie_handle = children.handles[index];
+		children.handles[index] = children.handles[last_non_zombie];
+		children.process_id[index] = children.process_id[last_non_zombie];
+		children.handles[last_non_zombie] = zombie_handle;
+		children.process_id[last_non_zombie] = zombie_pid;
+	}
 	children.num_zombies++;
 	return 0;
 }
@@ -185,10 +185,13 @@ int waitpid(int pid, int *status, int options) {
 			return -1;
 		}
 
-		process = children.handles[index];
-		ret = WaitForSingleObject(process, INFINITE);
-		if (ret != WAIT_OBJECT_0)
-			DebugBreak();//fatal
+		/* wait if process is still alive */
+		if (index < children.num_children - children.num_zombies) {
+			process = children.handles[index];
+			ret = WaitForSingleObject(process, INFINITE);
+			if (ret != WAIT_OBJECT_0)
+				DebugBreak();//fatal
+		}
 
 		ret_id = children.process_id[index];
 		GetExitCodeProcess(process, &exit_code);
@@ -200,6 +203,15 @@ int waitpid(int pid, int *status, int options) {
 	}
 
 	/* pid = -1*/
+	/* are there any existing zombies */
+	if (children.num_zombies) {
+		/* return one of them */
+		ret_id = children.process_id[children.num_children - 1];
+		sw_remove_child_at_index(children.num_children - 1);
+		return ret_id;
+	}
+	
+	/* all children are alive. wait for one of them to exit */
 	timeout = INFINITE;
 	if (options & WNOHANG)
 		timeout = 0;