process: implement UV_PROCESS_DETACHED flag for uv_spawn

include/uv.h

@@ -1246,7 +1246,15 @@ enum uv_process_flags {
    * converting the argument list into a command line string. This option is
    * only meaningful on Windows systems. On unix it is silently ignored.
    */
-  UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS = (1 << 2)
+  UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS = (1 << 2),
+  /*
+   * Spawn the child process in a detached state - this will make it a process
+   * group leader, and will effectively enable the child to keep running after
+   * the parent exits.  Note that the child process will still keep the
+   * parent's event loop alive unless the parent process calls uv_unref() on
+   * the child's process handle.
+   */
+  UV_PROCESS_DETACHED = (1 << 3)
 };
 
 /*

src/unix/process.c

@@ -240,6 +240,7 @@ int uv_spawn(uv_loop_t* loop, uv_process_t* process,
 
   assert(options.file != NULL);
   assert(!(options.flags & ~(UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS |
+                             UV_PROCESS_DETACHED |
                              UV_PROCESS_SETGID |
                              UV_PROCESS_SETUID)));
 
@@ -301,6 +302,9 @@ int uv_spawn(uv_loop_t* loop, uv_process_t* process,
 
   if (pid == 0) {
     /* Child */
+    if (options.flags & UV_PROCESS_DETACHED) {
+      setsid();
+    }
 
     /* Dup fds */
     for (i = 0; i < options.stdio_count; i++) {

src/win/process.c

@@ -869,7 +869,8 @@ int uv_spawn(uv_loop_t* loop, uv_process_t* process,
   int err = 0, keep_child_stdio_open = 0;
   wchar_t* path = NULL;
   int size, i, overlapped;
-  DWORD server_access, child_access;
+  DWORD server_access, child_access,
+        process_flags = CREATE_UNICODE_ENVIRONMENT;
   BOOL result;
   wchar_t* application_path = NULL, *application = NULL, *arguments = NULL,
     *env = NULL, *cwd = NULL;
@@ -891,6 +892,7 @@ int uv_spawn(uv_loop_t* loop, uv_process_t* process,
 
   assert(options.file != NULL);
   assert(!(options.flags & ~(UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS |
+                             UV_PROCESS_DETACHED |
                              UV_PROCESS_SETGID |
                              UV_PROCESS_SETUID)));
 
@@ -1005,12 +1007,16 @@ int uv_spawn(uv_loop_t* loop, uv_process_t* process,
   startup.hStdOutput = child_stdio[1];
   startup.hStdError = child_stdio[2];
 
+  if (options.flags & UV_PROCESS_DETACHED) {
+    process_flags |= DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP;
+  }
+
   if (CreateProcessW(application_path,
                      arguments,
                      NULL,
                      NULL,
                      1,
-                     CREATE_UNICODE_ENVIRONMENT,
+                     process_flags,
                      env,
                      cwd,
                      &startup,

test/test-list.h

@@ -120,6 +120,7 @@ TEST_DECLARE   (spawn_exit_code)
 TEST_DECLARE   (spawn_stdout)
 TEST_DECLARE   (spawn_stdin)
 TEST_DECLARE   (spawn_and_kill)
+TEST_DECLARE   (spawn_detached)
 TEST_DECLARE   (spawn_and_kill_with_std)
 TEST_DECLARE   (spawn_and_ping)
 TEST_DECLARE   (spawn_setuid_fails)
@@ -333,6 +334,7 @@ TASK_LIST_START
   TEST_ENTRY  (spawn_stdout)
   TEST_ENTRY  (spawn_stdin)
   TEST_ENTRY  (spawn_and_kill)
+  TEST_ENTRY  (spawn_detached)
   TEST_ENTRY  (spawn_and_kill_with_std)
   TEST_ENTRY  (spawn_and_ping)
   TEST_ENTRY  (spawn_setuid_fails)

test/test-spawn.c

@@ -99,6 +99,11 @@ static void kill_cb(uv_process_t* process, int exit_status, int term_signal) {
   ASSERT(err.code == UV_ESRCH);
 }
 
+static void detach_failure_cb(uv_process_t* process, int exit_status, int term_signal) {
+  uv_err_t err;
+  printf("detach_cb\n");
+  exit_cb_called++;
+}
 
 static uv_buf_t on_alloc(uv_handle_t* handle, size_t suggested_size) {
   uv_buf_t buf;
@@ -314,6 +319,32 @@ TEST_IMPL(spawn_and_kill) {
   return 0;
 }
 
+TEST_IMPL(spawn_detached) {
+  int r;
+  uv_err_t err;
+
+  init_process_options("spawn_helper4", detach_failure_cb);
+
+  options.flags |= UV_PROCESS_DETACHED;
+
+  r = uv_spawn(uv_default_loop(), &process, options);
+  ASSERT(r == 0);
+
+  uv_unref((uv_handle_t*)&process);
+
+  r = uv_run(uv_default_loop());
+  ASSERT(r == 0);
+
+  ASSERT(exit_cb_called == 0);
+
+  err = uv_kill(process.pid, 0);
+  ASSERT(err.code == 0);
+
+  err = uv_kill(process.pid, 15);
+  ASSERT(err.code == 0);
+
+  return 0;
+}
 
 TEST_IMPL(spawn_and_kill_with_std) {
   int r;