SIGCHLD and waitpid implementation with sshd on board

Author: manojampalam

contrib/win32/win32compat/fileio.c

@@ -373,8 +373,7 @@ fileio_read(struct w32_io* pio, void *dst, unsigned int max) {
 		}
 
 		/* pick up APC if IO has completed */
-		if (-1 == wait_for_any_event(NULL, 0, 0))
-			return -1;
+		SleepEx(0, TRUE);
 
 		if (w32_io_is_blocking(pio)) {
 			while (fileio_is_io_available(pio, TRUE) == FALSE) {
@@ -519,12 +518,7 @@ fileio_write(struct w32_io* pio, const void *buf, unsigned int max) {
 		}
 	}
 	/* execute APC to give a chance for write to complete */
-	else if (wait_for_any_event(NULL, 0, 0) == -1) {
-		/* if interrupted but write has completed, we are good*/
-		if ((errno != EINTR) || (pio->write_details.pending))
-			return -1;
-		errno = 0;
-	}
+	SleepEx(0, TRUE);
 
 	/* if write has completed, pick up any error reported*/
 	if (!pio->write_details.pending && pio->write_details.error) {

contrib/win32/win32compat/inc/defs.h

@@ -70,4 +70,7 @@ typedef int sigset_t;
 
 typedef unsigned short _mode_t;
 typedef _mode_t mode_t;
-typedef unsigned long pid_t;
+typedef int pid_t;
+
+/* wait pid options */
+#define WNOHANG 1

contrib/win32/win32compat/inc/sys/wait.h

@@ -1,14 +1,17 @@
 #pragma once
 #include "..\w32posix.h"
 
-#define _W_INT(w)	(*(int*)&(w))	/* convert union wait to int */
-#define WIFEXITED(w)	(!((_W_INT(w)) & 0377))
-#define WIFSTOPPED(w)	((_W_INT(w)) & 0100)
-#define WIFSIGNALED(w)	(!WIFEXITED(w) && !WIFSTOPPED(w))
-#define WEXITSTATUS(w)	(int)(WIFEXITED(w) ? ((_W_INT(w) >> 8) & 0377) : -1)
-#define WTERMSIG(w)	(int)(WIFSIGNALED(w) ? (_W_INT(w) & 0177) : -1)
+//#define _W_INT(w)	(*(int*)&(w))	/* convert union wait to int */
+//#define WIFEXITED(w)	(!((_W_INT(w)) & 0377))
+//#define WIFSTOPPED(w)	((_W_INT(w)) & 0100)
+//#define WIFSIGNALED(w)	(!WIFEXITED(w) && !WIFSTOPPED(w))
+//#define WEXITSTATUS(w)	(int)(WIFEXITED(w) ? ((_W_INT(w) >> 8) & 0377) : -1)
+//#define WTERMSIG(w)	(int)(WIFSIGNALED(w) ? (_W_INT(w) & 0177) : -1)
 
-/* wait pid options */
-#define WNOHANG 1
+#define WIFEXITED(w)	TRUE
+#define WIFSTOPPED(w)	TRUE
+#define WIFSIGNALED(w)	FALSE
+#define WEXITSTATUS(w)	w
+#define WTERMSIG(w)	-1
 
-pid_t waitpid(pid_t pid, int *status, int options);
+int waitpid(int pid, int *status, int options);

contrib/win32/win32compat/inc/w32posix.h

@@ -107,7 +107,7 @@ int w32_temp_DelChildToWatch(HANDLE processtowatch);
 int w32_temp_AddChildToWatch(HANDLE processtowatch);
 HANDLE w32_fd_to_handle(int fd);
 int w32_allocate_fd_for_handle(HANDLE h, BOOL is_sock);
-int sw_add_child(HANDLE child);
+int sw_add_child(HANDLE child, DWORD pid);
 
 /* temporary definitions to aid in transition */
 #define WSHELPDelChildToWatch(a) w32_temp_DelChildToWatch((a))

contrib/win32/win32compat/misc.c

@@ -8,11 +8,6 @@ int usleep(unsigned int useconds)
 	return 1;
 }
 
-pid_t waitpid(pid_t pid, int *status, int options) {
-	/* TODO - implement this*/
-	return 0;
-}
-
 void
 explicit_bzero(void *b, size_t len) {
 	SecureZeroMemory(b, len);

contrib/win32/win32compat/signal.c

@@ -70,17 +70,19 @@ sw_init_signal_handler_table() {
 #define MAX_CHILDREN 50
 struct _children {
 	HANDLE handles[MAX_CHILDREN];
-	//DWORD process_id[MAX_CHILDREN];
+	DWORD process_id[MAX_CHILDREN];
 	DWORD num_children;
 } children;
 
 int
-sw_add_child(HANDLE child) {
+sw_add_child(HANDLE child, DWORD pid) {
 	if (children.num_children == MAX_CHILDREN) {
 		errno = ENOTSUP;
 		return -1;
 	}
-	children.handles[children.num_children++] = child;
+	children.handles[children.num_children] = child;
+	children.process_id[children.num_children] = pid;
+	children.num_children++;
 	return 0;
 }
 
@@ -100,7 +102,6 @@ sw_remove_child_at_index(DWORD index) {
 	return 0;
 }
 
-
 int
 sw_remove_child(HANDLE child) {
 	HANDLE* handles = children.handles;
@@ -117,6 +118,90 @@ sw_remove_child(HANDLE child) {
 	return -1;
 }
 
+int waitpid(int pid, int *status, int options) {
+	DWORD index, ret, ret_id, exit_code, timeout = 0;
+	HANDLE process = NULL;
+
+	if (options & (~WNOHANG)) {
+		errno = ENOTSUP;
+		DebugBreak();
+		return -1;
+	}
+
+	if ((pid < -1) || (pid == 0)) {
+		errno = ENOTSUP;
+		DebugBreak();
+		return -1;
+	}
+
+	if (children.num_children == 0) {
+		errno = ECHILD;
+		return -1;
+	}
+
+	if (pid > 0) {
+		if (options != 0) {
+			errno = ENOTSUP;
+			DebugBreak();
+			return -1;
+		}
+		/* find entry in table */
+		for (index = 0; index < children.num_children; index++)
+			if (children.process_id[index] == pid)				
+				break;
+		
+		if (index == children.num_children) {
+			errno = ECHILD;
+			return -1;
+		}
+
+		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);
+		CloseHandle(process);
+		sw_remove_child_at_index(index);
+		if (status)
+			*status = exit_code;
+		return ret_id;
+	}
+
+	/* pid = -1*/
+	timeout = INFINITE;
+	if (options & WNOHANG)
+		timeout = 0;
+	ret = WaitForMultipleObjects(children.num_children, children.handles, FALSE, timeout);
+	if ((ret >= WAIT_OBJECT_0) && (ret < (WAIT_OBJECT_0 + children.num_children))) {
+		index = ret - WAIT_OBJECT_0;
+		process = children.handles[index];
+		ret_id = children.process_id[index];
+		GetExitCodeProcess(process, &exit_code);
+		CloseHandle(process);
+		sw_remove_child_at_index(index);
+		if (status)
+			*status = exit_code;
+		return ret_id;
+	}
+	else if (ret == WAIT_TIMEOUT) {
+		/* assert that WNOHANG  was specified*/
+		return 0;
+	}
+
+	DebugBreak();//fatal
+	return -1;
+}
+
+static void
+sw_cleanup_child_zombies() {
+	int pid = 1;
+	while (pid > 0) {
+		pid = waitpid(-1, NULL, WNOHANG);
+	}
+}
+
 struct {
 	HANDLE timer;
 	ULONGLONG ticks_at_start; /* 0 if timer is not live */
@@ -223,7 +308,7 @@ sw_raise(int sig) {
 	/* execute any default handlers */
 	switch (sig) {
 	case W32_SIGCHLD:
-		/*TODO - execute sigchild default handler */
+		sw_cleanup_child_zombies();
 		break;
 	case W32_SIGINT:
 		/* TODO - execute sigint default handler */
@@ -274,9 +359,6 @@ sw_process_pending_signals() {
 				sw_raise(exp[i]);
 				sig_int = TRUE;
 			}
-			else {/* disposition is W32_SIG_IGN */
-				/* TODO for SIG_CHLD - do clean up of Zombies */
-			}
 
 			sigdelset(&pending_tmp, exp[i]);
 		}
@@ -313,7 +395,9 @@ int
 wait_for_any_event(HANDLE* events, int num_events, DWORD milli_seconds)
 {
 	HANDLE all_events[MAXIMUM_WAIT_OBJECTS];
-	DWORD num_all_events = num_events + children.num_children;
+	DWORD num_all_events;
+
+	num_all_events = num_events + children.num_children;
 
 	if (num_all_events > MAXIMUM_WAIT_OBJECTS) {
 		errno = ENOTSUP;
@@ -335,11 +419,9 @@ wait_for_any_event(HANDLE* events, int num_events, DWORD milli_seconds)
 			//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)) {
-				/* TODO - enable this once all direct closes are removed in core code*/
-				//sigaddset(&pending_signals, W32_SIGCHLD);
-				//sw_remove_child(ret - WAIT_OBJECT_0);
-				errno = EINTR;
-				return -1;
+				sigaddset(&pending_signals, W32_SIGCHLD);
+				//errno = EINTR;
+				//return -1;
 			}
 		}
 		else if (ret == WAIT_IO_COMPLETION) {

contrib/win32/win32compat/socketio.c

@@ -421,8 +421,7 @@ socketio_recv(struct w32_io* pio, void *buf, size_t len, int flags) {
 	if (completed) {
 		/* Let APC be scheduled */
 		debug2("recv - Letting APC to execute, io:%p", pio);
-		if (wait_for_any_event(NULL, 0, 0) == -1)
-			return -1;
+		SleepEx(0, TRUE);
 		if (pio->read_details.pending) {
 			/* this shouldn't be happening */
 			errno = EOTHER;
@@ -588,13 +587,7 @@ socketio_send(struct w32_io* pio, const void *buf, size_t len, int flags) {
 		debug2("send - WSASend() returned 0, APC scheduled io:%p", pio);
 		pio->write_details.pending = TRUE;
 		pio->write_details.remaining = wsabuf.len;
-		if (wait_for_any_event(NULL, 0, 0) == -1) {
-			//interrupted but send went through
-			if (errno == EINTR)
-				errno = 0;
-			else
-				return -1;
-		}
+		SleepEx(0, TRUE);
 		if ((pio->write_details.pending) || (pio->write_details.remaining != 0)) {
 			errno = EOTHER;
 			debug("send - ERROR: Unexpected IO state, io:%p", pio);

contrib/win32/win32compat/w32fd.h

@@ -123,7 +123,7 @@ int termio_close(struct w32_io* pio);
 
 /* signal related APIs*/
 int sw_initialize();
-int sw_add_child(HANDLE child);
+int sw_add_child(HANDLE child, DWORD pid);
 int sw_remove_child(HANDLE child);
 unsigned int sw_alarm(unsigned int seconds);
 sighandler_t sw_signal(int signum, sighandler_t handler);

session.c

@@ -843,9 +843,8 @@ do_exec_no_pty(Session *s, const char *command)
    * Log the process handle (fake it as the pid) for termination lookups 
    */
 
-  s -> pid = pi.hProcess;
-  s -> processId = pi.dwProcessId;
-  sw_add_child(pi.hProcess);
+  s -> pid = pi.dwProcessId;
+  sw_add_child(pi.hProcess, pi.dwProcessId);
 
   // Add the child process created to select mux so that during our select data call we know if the process has exited
   /* TODO - fix thi s*/
@@ -2877,10 +2876,12 @@ session_pty_cleanup2(Session *s)
 
     debug("Sending exit signal to child process [pid = %u]...", s -> pid);
 
-    if (!GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, s -> processId))
-    {
-      debug("ERROR. Cannot send signal to process.");
-    }
+    //if (!GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, s -> processId))
+    //{
+    //  debug("ERROR. Cannot send signal to process.");
+    //}
+
+    kill(s->pid, SIGTERM);
 
     /*
      * Try wait 100 ms until child finished.
@@ -2991,11 +2992,11 @@ session_close_single_x11(int id, void *arg)
     {
       debug("Sending exit signal to child process [pid = %u]...", s -> pid);
 
-      if (!GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, s -> processId))
-      {
-        debug("ERROR. Cannot send signal to process.");
-      }  
-  
+      //if (!GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, s -> processId))
+      //{
+      //  debug("ERROR. Cannot send signal to process.");
+      //}  
+      kill(s->pid, SIGTERM);
       /*
        * Try wait 100 ms until child finished.
        */

session.h

@@ -35,10 +35,6 @@ struct Session {
 	struct passwd *pw;
 	Authctxt *authctxt;
 	pid_t	pid;
-	
-  #ifdef WIN32_FIXME
-  DWORD processId;
-  #endif
 
 	/* tty */
 	char	*term;