When interrupting Win32 processes, kill their child processes, too

winsup/cygwin/common.din

@@ -33,6 +33,7 @@ sys_errlist = _sys_errlist DATA
 sys_nerr = _sys_nerr DATA
 sys_sigabbrev DATA
 sys_siglist DATA
+kill_process_tree DATA
 
 # Exported functions
 _Exit SIGFE

winsup/cygwin/exceptions.cc

@@ -1479,7 +1479,10 @@ sigpacket::process ()
   if (have_execed)
     {
       sigproc_printf ("terminating captive process");
-      TerminateProcess (ch_spawn, sigExeced = si.si_signo);
+      if ((sigExeced = si.si_signo) == SIGINT)
+        kill_process_tree (GetProcessId (ch_spawn), sigExeced = si.si_signo);
+      else
+        TerminateProcess (ch_spawn, sigExeced = si.si_signo);
     }
   /* Dispatch to the appropriate function. */
   sigproc_printf ("signal %d, signal handler %p", si.si_signo, handler);

winsup/cygwin/include/cygwin/signal.h

@@ -396,9 +396,11 @@ int siginterrupt (int, int);
 #ifdef __INSIDE_CYGWIN__
 extern const char *sys_sigabbrev[];
 extern const char *sys_siglist[];
+extern void kill_process_tree(pid_t pid, int sig);
 #else
 extern const char __declspec(dllimport) *sys_sigabbrev[];
 extern const char __declspec(dllimport) *sys_siglist[];
+extern void __declspec(dllimport) kill_process_tree(pid_t pid, int sig);
 #endif
 
 #ifdef __cplusplus

winsup/cygwin/include/cygwin/version.h

@@ -469,12 +469,13 @@ details. */
       285: Export wcstold.
       286: Export cabsl, cimagl, creall, finitel, hypotl, sqrtl.
       287: Export issetugid.
+      288: Export kill_process_tree.
      */
 
      /* Note that we forgot to bump the api for ualarm, strtoll, strtoull */
 
 #define CYGWIN_VERSION_API_MAJOR 0
-#define CYGWIN_VERSION_API_MINOR 287
+#define CYGWIN_VERSION_API_MINOR 288
 
      /* There is also a compatibity version number associated with the
 	shared memory regions.  It is incremented when incompatible

winsup/cygwin/signal.cc

@@ -13,6 +13,7 @@ Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
 details. */
 
 #include "winsup.h"
+#include <tlhelp32.h>
 #include <stdlib.h>
 #include <sys/cygwin.h>
 #include "pinfo.h"
@@ -361,6 +362,62 @@ killpg (pid_t pgrp, int sig)
   return kill (-pgrp, sig);
 }
 
+/**
+ * Terminates the process corresponding to the process ID and all of its
+ * directly and indirectly spawned subprocesses.
+ */
+extern "C" void
+kill_process_tree(pid_t pid, int sig)
+{
+	HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
+	PROCESSENTRY32 entry;
+	DWORD pids[16384];
+	int max_len = sizeof(pids) / sizeof(*pids), i, len;
+
+	pids[0] = (DWORD) pid;
+	len = 1;
+
+	/*
+	 * Even if Process32First()/Process32Next() seem to traverse the
+	 * processes in topological order (i.e. parent processes before
+	 * child processes), there is nothing in the Win32 API documentation
+	 * suggesting that this is guaranteed.
+	 *
+	 * Therefore, run through them at least twice and stop when no more
+	 * process IDs were added to the list.
+	 */
+	for (;;) {
+		int orig_len = len;
+
+		memset(&entry, 0, sizeof(entry));
+		entry.dwSize = sizeof(entry);
+
+		if (!Process32First(snapshot, &entry))
+			break;
+
+		do {
+			for (i = len - 1; i >= 0; i--) {
+				if (pids[i] == entry.th32ProcessID)
+					break;
+				if (pids[i] == entry.th32ParentProcessID)
+					pids[len++] = entry.th32ProcessID;
+			}
+		} while (len < max_len && Process32Next(snapshot, &entry));
+
+		if (orig_len == len || len >= max_len)
+			break;
+	}
+
+	for (i = len - 1; i >= 0; i--) {
+		HANDLE process = OpenProcess(PROCESS_TERMINATE, FALSE, pids[i]);
+
+		if (process) {
+			TerminateProcess(process, sig << 8);
+			CloseHandle(process);
+		}
+	}
+}
+
 extern "C" void
 abort (void)
 {

winsup/utils/kill.cc

@@ -174,10 +174,14 @@ forcekill (int pid, int sig, int wait)
       return;
     }
   if (!wait || WaitForSingleObject (h, 200) != WAIT_OBJECT_0)
-    if (sig && !TerminateProcess (h, sig << 8)
-	&& WaitForSingleObject (h, 200) != WAIT_OBJECT_0)
-      fprintf (stderr, "%s: couldn't kill pid %u, %u\n",
+    {
+      if (sig == SIGINT || sig == SIGTERM)
+        kill_process_tree (dwpid, sig);
+      else if (sig && !TerminateProcess (h, sig << 8)
+          && WaitForSingleObject (h, 200) != WAIT_OBJECT_0)
+        fprintf (stderr, "%s: couldn't kill pid %u, %u\n",
 	       prog_name, (unsigned) dwpid, (unsigned int) GetLastError ());
+    }
   CloseHandle (h);
 }