New piece of Windows infrastructure: winhandl.c takes Plink's

thread-based approach to stdin and stdout, wraps it in a halfway
sensible API, and makes it a globally available service across all
network tools.

There is no direct functionality enhancement from this checkin:
winplink.c now talks to the new API instead of doing it all
internally, but does nothing different as a result.

However, this should lay the groundwork for several diverse pieces
of work in future: pipe-based ProxyCommand on Windows, a serial port
back end, and (hopefully) a pipe-based means of communicating with
Pageant, which should have sensible blocking behaviour and hence
permit asynchronous agent requests and decrypt-on-demand.

[originally from svn r6797]

Recipe

@@ -244,7 +244,7 @@ SFTP     = sftp int64 logging
 # Miscellaneous objects appearing in all the network utilities (not
 # Pageant or PuTTYgen).
 MISC     = timing misc version settings tree234 proxy
-WINMISC  = MISC winstore winnet cmdline windefs winmisc pproxy wintime
+WINMISC  = MISC winstore winnet winhandl cmdline windefs winmisc pproxy wintime
 UXMISC   = MISC uxstore uxsel uxnet cmdline uxmisc uxproxy time
 OSXMISC  = MISC uxstore uxsel osxsel uxnet uxmisc uxproxy time
 MACMISC  = MISC macstore macnet mtcpnet otnet macmisc macabout pproxy

windows/window.c

@@ -816,8 +816,29 @@ int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmdline, int show)
     term_set_focus(term, GetForegroundWindow() == hwnd);
     UpdateWindow(hwnd);
 
-    if (GetMessage(&msg, NULL, 0, 0) == 1) {
+    while (1) {
-	while (msg.message != WM_QUIT) {
+	HANDLE *handles;
+	int nhandles, n;
+
+	handles = handle_get_events(&nhandles);
+
+	n = MsgWaitForMultipleObjects(nhandles, handles, FALSE, INFINITE,
+				      QS_ALLINPUT);
+
+	if ((unsigned)(n - WAIT_OBJECT_0) < (unsigned)nhandles) {
+	    handle_got_event(handles[n - WAIT_OBJECT_0]);
+	    sfree(handles);
+	    continue;
+	}
+
+	sfree(handles);
+
+	if (GetMessage(&msg, NULL, 0, 0) != 1)
+	    break;
+	do {
+	    if (msg.message == WM_QUIT)
+		goto finished;	       /* two-level break */
+
 	    if (!(IsWindow(logbox) && IsDialogMessage(logbox, &msg)))
 		DispatchMessage(&msg);
 	    /* Send the paste buffer if there's anything to send */
@@ -826,23 +847,15 @@ int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmdline, int show)
 	     * we've delayed, reading the socket, writing, and repainting
 	     * the window.
 	     */
-	    if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
+	} while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE));
-		continue;
 
-	    /* The messages seem unreliable; especially if we're being tricky */
+	/* The messages seem unreliable; especially if we're being tricky */
-	    term_set_focus(term, GetForegroundWindow() == hwnd);
+	term_set_focus(term, GetForegroundWindow() == hwnd);
 
-	    net_pending_errors();
+	net_pending_errors();
-
-	    /* There's no point rescanning everything in the message queue
-	     * so we do an apparently unnecessary wait here
-	     */
-	    WaitMessage();
-	    if (GetMessage(&msg, NULL, 0, 0) != 1)
-		break;
-	}
     }
 
+    finished:
     cleanup_exit(msg.wParam);	       /* this doesn't return... */
     return msg.wParam;		       /* ... but optimiser doesn't know */
 }

windows/winhandl.c

@@ -0,0 +1,486 @@
+/*
+ * winhandl.c: Module to give Windows front ends the general
+ * ability to deal with consoles, pipes, serial ports, or any other
+ * type of data stream accessed through a Windows API HANDLE rather
+ * than a WinSock SOCKET.
+ *
+ * We do this by spawning a subthread to continuously try to read
+ * from the handle. Every time a read successfully returns some
+ * data, the subthread sets an event object which is picked up by
+ * the main thread, and the main thread then sets an event in
+ * return to instruct the subthread to resume reading.
+ * 
+ * Output works precisely the other way round, in a second
+ * subthread. The output subthread should not be attempting to
+ * write all the time, because it hasn't always got data _to_
+ * write; so the output thread waits for an event object notifying
+ * it to _attempt_ a write, and then it sets an event in return
+ * when one completes.
+ */
+
+/*
+ * TODO:
+ *
+ *  - could do with some sort of private-data field in each handle
+ *    structure.
+ */
+
+#include <assert.h>
+
+#include "putty.h"
+
+/* ----------------------------------------------------------------------
+ * Generic definitions.
+ */
+
+/*
+ * Maximum amount of backlog we will allow to build up on an input
+ * handle before we stop reading from it.
+ */
+#define MAX_BACKLOG 32768
+
+struct handle_generic {
+    /*
+     * Initial fields common to both handle_input and handle_output
+     * structures.
+     * 
+     * The three HANDLEs are set up at initialisation time and are
+     * thereafter read-only to both main thread and subthread.
+     * `moribund' is only used by the main thread; `done' is
+     * written by the main thread before signalling to the
+     * subthread. `defunct' and `busy' are used only by the main
+     * thread.
+     */
+    HANDLE h;			       /* the handle itself */
+    HANDLE ev_to_main;		       /* event used to signal main thread */
+    HANDLE ev_from_main;	       /* event used to signal back to us */
+    int moribund;		       /* are we going to kill this soon? */
+    int done;			       /* request subthread to terminate */
+    int defunct;		       /* has the subthread already gone? */
+    int busy;			       /* operation currently in progress? */
+};
+
+/* ----------------------------------------------------------------------
+ * Input threads.
+ */
+
+/*
+ * Data required by an input thread.
+ */
+struct handle_input {
+    /*
+     * Copy of the handle_generic structure.
+     */
+    HANDLE h;			       /* the handle itself */
+    HANDLE ev_to_main;		       /* event used to signal main thread */
+    HANDLE ev_from_main;	       /* event used to signal back to us */
+    int moribund;		       /* are we going to kill this soon? */
+    int done;			       /* request subthread to terminate */
+    int defunct;		       /* has the subthread already gone? */
+    int busy;			       /* operation currently in progress? */
+
+    /*
+     * Data set by the input thread before signalling ev_to_main,
+     * and read by the main thread after receiving that signal.
+     */
+    char buffer[4096];		       /* the data read from the handle */
+    DWORD len;			       /* how much data that was */
+    int readret;		       /* lets us know about read errors */
+
+    /*
+     * Callback function called by this module when data arrives on
+     * an input handle.
+     */
+    handle_inputfn_t gotdata;
+};
+
+/*
+ * The actual thread procedure for an input thread.
+ */
+static DWORD WINAPI handle_input_threadfunc(void *param)
+{
+    struct handle_input *ctx = (struct handle_input *) param;
+
+    while (1) {
+	ctx->readret = ReadFile(ctx->h, ctx->buffer, sizeof(ctx->buffer),
+				&ctx->len, NULL);
+	if (!ctx->readret)
+	    ctx->len = 0;
+
+	SetEvent(ctx->ev_to_main);
+
+	if (!ctx->len)
+	    break;
+
+	WaitForSingleObject(ctx->ev_from_main, INFINITE);
+	if (ctx->done)
+	    break;		       /* main thread told us to shut down */
+    }
+
+    return 0;
+}
+
+/*
+ * This is called after a succcessful read, or from the
+ * `unthrottle' function. It decides whether or not to begin a new
+ * read operation.
+ */
+static void handle_throttle(struct handle_input *ctx, int backlog)
+{
+    assert(!ctx->defunct);
+
+    /*
+     * If there's a read operation already in progress, do nothing:
+     * when that completes, we'll come back here and be in a
+     * position to make a better decision.
+     */
+    if (ctx->busy)
+	return;
+
+    /*
+     * Otherwise, we must decide whether to start a new read based
+     * on the size of the backlog.
+     */
+    if (backlog < MAX_BACKLOG) {
+	SetEvent(ctx->ev_from_main);
+	ctx->busy = TRUE;
+    }
+}
+
+/* ----------------------------------------------------------------------
+ * Output threads.
+ */
+
+/*
+ * Data required by an output thread.
+ */
+struct handle_output {
+    /*
+     * Copy of the handle_generic structure.
+     */
+    HANDLE h;			       /* the handle itself */
+    HANDLE ev_to_main;		       /* event used to signal main thread */
+    HANDLE ev_from_main;	       /* event used to signal back to us */
+    int moribund;		       /* are we going to kill this soon? */
+    int done;			       /* request subthread to terminate */
+    int defunct;		       /* has the subthread already gone? */
+    int busy;			       /* operation currently in progress? */
+
+    /*
+     * Data set by the main thread before signalling ev_from_main,
+     * and read by the input thread after receiving that signal.
+     */
+    char *buffer;		       /* the data to write */
+    DWORD len;			       /* how much data there is */
+
+    /*
+     * Data set by the input thread before signalling ev_to_main,
+     * and read by the main thread after receiving that signal.
+     */
+    DWORD lenwritten;		       /* how much data we actually wrote */
+    int writeret;		       /* return value from WriteFile */
+
+    /*
+     * Data only ever read or written by the main thread.
+     */
+    bufchain queued_data;	       /* data still waiting to be written */
+
+    /*
+     * Callback function called when the backlog in the bufchain
+     * drops.
+     */
+    handle_outputfn_t sentdata;
+};
+
+static DWORD WINAPI handle_output_threadfunc(void *param)
+{
+    struct handle_output *ctx = (struct handle_output *) param;
+
+    while (1) {
+	WaitForSingleObject(ctx->ev_from_main, INFINITE);
+	if (ctx->done) {
+	    SetEvent(ctx->ev_to_main);
+	    break;
+	}
+	ctx->writeret = WriteFile(ctx->h, ctx->buffer, ctx->len,
+				  &ctx->lenwritten, NULL);
+	SetEvent(ctx->ev_to_main);
+	if (!ctx->writeret)
+	    break;
+    }
+
+    return 0;
+}
+
+static void handle_try_output(struct handle_output *ctx)
+{
+    void *senddata;
+    int sendlen;
+
+    if (!ctx->busy && bufchain_size(&ctx->queued_data)) {
+	bufchain_prefix(&ctx->queued_data, &senddata, &sendlen);
+	ctx->buffer = senddata;
+	ctx->len = sendlen;
+	SetEvent(ctx->ev_from_main);
+	ctx->busy = TRUE;
+    }
+}
+
+/* ----------------------------------------------------------------------
+ * Unified code handling both input and output threads.
+ */
+
+struct handle {
+    int output;
+    union {
+	struct handle_generic g;
+	struct handle_input i;
+	struct handle_output o;
+    } u;
+};
+
+static tree234 *handles_by_evtomain;
+
+static int handle_cmp_evtomain(void *av, void *bv)
+{
+    struct handle *a = (struct handle *)av;
+    struct handle *b = (struct handle *)bv;
+
+    if ((unsigned)a->u.g.ev_to_main < (unsigned)b->u.g.ev_to_main)
+	return -1;
+    else if ((unsigned)a->u.g.ev_to_main > (unsigned)b->u.g.ev_to_main)
+	return +1;
+    else
+	return 0;
+}
+
+static int handle_find_evtomain(void *av, void *bv)
+{
+    HANDLE *a = (HANDLE *)av;
+    struct handle *b = (struct handle *)bv;
+
+    if ((unsigned)*a < (unsigned)b->u.g.ev_to_main)
+	return -1;
+    else if ((unsigned)*a > (unsigned)b->u.g.ev_to_main)
+	return +1;
+    else
+	return 0;
+}
+
+struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata)
+{
+    struct handle *h = snew(struct handle);
+
+    h->output = FALSE;
+    h->u.i.h = handle;
+    h->u.i.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL);
+    h->u.i.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL);
+    h->u.i.gotdata = gotdata;
+    h->u.i.busy = FALSE;
+    h->u.i.defunct = FALSE;
+    h->u.i.moribund = FALSE;
+    h->u.i.done = FALSE;
+
+    if (!handles_by_evtomain)
+	handles_by_evtomain = newtree234(handle_cmp_evtomain);
+    add234(handles_by_evtomain, h);
+
+    CreateThread(NULL, 0, handle_input_threadfunc,
+		 &h->u.i, 0, NULL);
+
+    handle_throttle(&h->u.i, 0);       /* start first read operation */
+
+    return h;
+}
+
+struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata)
+{
+    struct handle *h = snew(struct handle);
+
+    h->output = TRUE;
+    h->u.o.h = handle;
+    h->u.o.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL);
+    h->u.o.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL);
+    h->u.o.busy = FALSE;
+    h->u.o.defunct = FALSE;
+    h->u.o.moribund = FALSE;
+    h->u.o.done = FALSE;
+    bufchain_init(&h->u.o.queued_data);
+    h->u.o.sentdata = sentdata;
+
+    if (!handles_by_evtomain)
+	handles_by_evtomain = newtree234(handle_cmp_evtomain);
+    add234(handles_by_evtomain, h);
+
+    CreateThread(NULL, 0, handle_output_threadfunc,
+		 &h->u.i, 0, NULL);
+
+    return h;
+}
+
+int handle_write(struct handle *h, const void *data, int len)
+{
+    assert(h->output);
+    bufchain_add(&h->u.o.queued_data, data, len);
+    handle_try_output(&h->u.o);
+    return bufchain_size(&h->u.o.queued_data);
+}
+
+HANDLE *handle_get_events(int *nevents)
+{
+    HANDLE *ret;
+    struct handle *h;
+    int i, n, size;
+
+    /*
+     * Go through our tree counting the handle objects currently
+     * engaged in useful activity.
+     */
+    ret = NULL;
+    n = size = 0;
+    if (handles_by_evtomain) {
+	for (i = 0; (h = index234(handles_by_evtomain, i)) != NULL; i++) {
+	    if (h->u.g.busy) {
+		if (n >= size) {
+		    size += 32;
+		    ret = sresize(ret, size, HANDLE);
+		}
+		ret[n++] = h->u.g.ev_to_main;
+	    }
+	}
+    }
+
+    *nevents = n;
+    return ret;
+}
+
+static void handle_destroy(struct handle *h)
+{
+    if (h->output)
+	bufchain_clear(&h->u.o.queued_data);
+    CloseHandle(h->u.g.ev_from_main);
+    CloseHandle(h->u.g.ev_to_main);
+    del234(handles_by_evtomain, h);
+    sfree(h);
+}
+
+void handle_free(struct handle *h)
+{
+    /*
+     * If the handle is currently busy, we cannot immediately free
+     * it. Instead we must wait until it's finished its current
+     * operation, because otherwise the subthread will write to
+     * invalid memory after we free its context from under it.
+     */
+    assert(h && !h->u.g.moribund);
+    if (h->u.g.busy) {
+	/*
+	 * Just set the moribund flag, which will be noticed next
+	 * time an operation completes.
+	 */
+	h->u.g.moribund = TRUE;
+    } else if (h->u.g.defunct) {
+	/*
+	 * There isn't even a subthread; we can go straight to
+	 * handle_destroy.
+	 */
+	handle_destroy(h);
+    } else {
+	/*
+	 * The subthread is alive but not busy, so we now signal it
+	 * to die. Set the moribund flag to indicate that it will
+	 * want destroying after that.
+	 */
+	h->u.g.moribund = TRUE;
+	h->u.g.done = TRUE;
+	SetEvent(h->u.g.ev_from_main);
+    }
+}
+
+void handle_got_event(HANDLE event)
+{
+    struct handle *h;
+
+    assert(handles_by_evtomain);
+    h = find234(handles_by_evtomain, &event, handle_find_evtomain);
+    if (!h) {
+	/*
+	 * This isn't an error condition. If two or more event
+	 * objects were signalled during the same select operation,
+	 * and processing of the first caused the second handle to
+	 * be closed, then it will sometimes happen that we receive
+	 * an event notification here for a handle which is already
+	 * deceased. In that situation we simply do nothing.
+	 */
+	return;
+    }
+
+    if (h->u.g.moribund) {
+	/*
+	 * A moribund handle is already treated as dead from the
+	 * external user's point of view, so do nothing with the
+	 * actual event. Just signal the thread to die if
+	 * necessary, or destroy the handle if not.
+	 */
+	if (h->u.g.done) {
+	    handle_destroy(h);
+	} else {
+	    h->u.g.done = TRUE;
+	    SetEvent(h->u.g.ev_from_main);
+	}
+	return;
+    }
+
+    if (!h->output) {
+	int backlog;
+
+	h->u.i.busy = FALSE;
+
+	/*
+	 * A signal on an input handle means data has arrived.
+	 */
+	if (h->u.i.len == 0) {
+	    /*
+	     * EOF, or (nearly equivalently) read error.
+	     */
+	    h->u.i.gotdata(h, NULL, (h->u.i.readret ? 0 : -1));
+	    h->u.i.defunct = TRUE;
+	} else {
+	    backlog = h->u.i.gotdata(h, h->u.i.buffer, h->u.i.len);
+	    handle_throttle(&h->u.i, backlog);
+	}
+    } else {
+	h->u.o.busy = FALSE;
+
+	/*
+	 * A signal on an output handle means we have completed a
+	 * write. Call the callback to indicate that the output
+	 * buffer size has decreased, or to indicate an error.
+	 */
+	if (!h->u.o.writeret) {
+	    /*
+	     * Write error. Send a negative value to the callback,
+	     * and mark the thread as defunct (because the output
+	     * thread is terminating by now).
+	     */
+	    h->u.o.sentdata(h, -1);
+	    h->u.o.defunct = TRUE;
+	} else {
+	    bufchain_consume(&h->u.o.queued_data, h->u.o.lenwritten);
+	    h->u.o.sentdata(h, bufchain_size(&h->u.o.queued_data));
+	    handle_try_output(&h->u.o);
+	}
+    }
+}
+
+void handle_unthrottle(struct handle *h, int backlog)
+{
+    assert(!h->output);
+    handle_throttle(&h->u.i, backlog);
+}
+
+int handle_backlog(struct handle *h)
+{
+    assert(h->output);
+    return bufchain_size(&h->u.o.queued_data);
+}

windows/winplink.c

@@ -14,8 +14,6 @@
 
 #define WM_AGENT_CALLBACK (WM_APP + 4)
 
-#define MAX_STDIN_BACKLOG 4096
-
 struct agent_callback {
     void (*callback)(void *, void *, int);
     void *callback_ctx;
@@ -65,7 +63,9 @@ void cmdline_error(char *p, ...)
 }
 
 HANDLE inhandle, outhandle, errhandle;
+struct handle *stdin_handle, *stdout_handle, *stderr_handle;
 DWORD orig_console_mode;
+int connopen;
 
 WSAEVENT netevent;
 
@@ -96,97 +96,16 @@ void ldisc_update(void *frontend, int echo, int edit)
 
 char *get_ttymode(void *frontend, const char *mode) { return NULL; }
 
-struct input_data {
-    DWORD len;
-    char buffer[4096];
-    HANDLE event, eventback;
-};
-
-static DWORD WINAPI stdin_read_thread(void *param)
-{
-    struct input_data *idata = (struct input_data *) param;
-    HANDLE inhandle;
-
-    inhandle = GetStdHandle(STD_INPUT_HANDLE);
-
-    while (ReadFile(inhandle, idata->buffer, sizeof(idata->buffer),
-		    &idata->len, NULL) && idata->len > 0) {
-	SetEvent(idata->event);
-	WaitForSingleObject(idata->eventback, INFINITE);
-    }
-
-    idata->len = 0;
-    SetEvent(idata->event);
-
-    return 0;
-}
-
-struct output_data {
-    DWORD len, lenwritten;
-    int writeret;
-    char *buffer;
-    int is_stderr, done;
-    HANDLE event, eventback;
-    int busy;
-};
-
-static DWORD WINAPI stdout_write_thread(void *param)
-{
-    struct output_data *odata = (struct output_data *) param;
-    HANDLE outhandle, errhandle;
-
-    outhandle = GetStdHandle(STD_OUTPUT_HANDLE);
-    errhandle = GetStdHandle(STD_ERROR_HANDLE);
-
-    while (1) {
-	WaitForSingleObject(odata->eventback, INFINITE);
-	if (odata->done)
-	    break;
-	odata->writeret =
-	    WriteFile(odata->is_stderr ? errhandle : outhandle,
-		      odata->buffer, odata->len, &odata->lenwritten, NULL);
-	SetEvent(odata->event);
-    }
-
-    return 0;
-}
-
-bufchain stdout_data, stderr_data;
-struct output_data odata, edata;
-
-void try_output(int is_stderr)
-{
-    struct output_data *data = (is_stderr ? &edata : &odata);
-    void *senddata;
-    int sendlen;
-
-    if (!data->busy) {
-	bufchain_prefix(is_stderr ? &stderr_data : &stdout_data,
-			&senddata, &sendlen);
-	data->buffer = senddata;
-	data->len = sendlen;
-	SetEvent(data->eventback);
-	data->busy = 1;
-    }
-}
-
 int from_backend(void *frontend_handle, int is_stderr,
 		 const char *data, int len)
 {
-    int osize, esize;
-
     if (is_stderr) {
-	bufchain_add(&stderr_data, data, len);
+	handle_write(stderr_handle, data, len);
-	try_output(1);
     } else {
-	bufchain_add(&stdout_data, data, len);
+	handle_write(stdout_handle, data, len);
-	try_output(0);
     }
 
-    osize = bufchain_size(&stdout_data);
+    return handle_backlog(stdout_handle) + handle_backlog(stderr_handle);
-    esize = bufchain_size(&stderr_data);
-
-    return osize + esize;
 }
 
 int from_backend_untrusted(void *frontend_handle, const char *data, int len)
@@ -289,18 +208,49 @@ char *do_select(SOCKET skt, int startup)
     return NULL;
 }
 
+int stdin_gotdata(struct handle *h, void *data, int len)
+{
+    if (len < 0) {
+	/*
+	 * Special case: report read error.
+	 */
+	fprintf(stderr, "Unable to read from standard input\n");
+	cleanup_exit(0);
+    }
+    noise_ultralight(len);
+    if (connopen && back->socket(backhandle) != NULL) {
+	if (len > 0) {
+	    return back->send(backhandle, data, len);
+	} else {
+	    back->special(backhandle, TS_EOF);
+	    return 0;
+	}
+    } else
+	return 0;
+}
+
+void stdouterr_sent(struct handle *h, int new_backlog)
+{
+    if (new_backlog < 0) {
+	/*
+	 * Special case: report write error.
+	 */
+	fprintf(stderr, "Unable to write to standard %s\n",
+		(h == stdout_handle ? "output" : "error"));
+	cleanup_exit(0);
+    }
+    if (connopen && back->socket(backhandle) != NULL) {
+	back->unthrottle(backhandle, (handle_backlog(stdout_handle) +
+				      handle_backlog(stderr_handle)));
+    }
+}
+
 int main(int argc, char **argv)
 {
-    WSAEVENT stdinevent, stdoutevent, stderrevent;
-    HANDLE handles[4];
-    DWORD in_threadid, out_threadid, err_threadid;
-    struct input_data idata;
-    int reading = FALSE;
     int sending;
     int portnumber = -1;
     SOCKET *sklist;
     int skcount, sksize;
-    int connopen;
     int exitcode;
     int errors;
     int use_subsystem = 0;
@@ -610,13 +560,10 @@ int main(int argc, char **argv)
     }
     connopen = 1;
 
-    stdinevent = CreateEvent(NULL, FALSE, FALSE, NULL);
-    stdoutevent = CreateEvent(NULL, FALSE, FALSE, NULL);
-    stderrevent = CreateEvent(NULL, FALSE, FALSE, NULL);
-
     inhandle = GetStdHandle(STD_INPUT_HANDLE);
     outhandle = GetStdHandle(STD_OUTPUT_HANDLE);
     errhandle = GetStdHandle(STD_ERROR_HANDLE);
+
     /*
      * Turn off ECHO and LINE input modes. We don't care if this
      * call fails, because we know we aren't necessarily running in
@@ -625,69 +572,29 @@ int main(int argc, char **argv)
     GetConsoleMode(inhandle, &orig_console_mode);
     SetConsoleMode(inhandle, ENABLE_PROCESSED_INPUT);
 
+    /*
+     * Pass the output handles to the handle-handling subsystem.
+     * (The input one we leave until we're through the
+     * authentication process.)
+     */
+    stdout_handle = handle_output_new(outhandle, stdouterr_sent);
+    stderr_handle = handle_output_new(errhandle, stdouterr_sent);
+
     main_thread_id = GetCurrentThreadId();
 
-    handles[0] = netevent;
-    handles[1] = stdinevent;
-    handles[2] = stdoutevent;
-    handles[3] = stderrevent;
     sending = FALSE;
 
-    /*
-     * Create spare threads to write to stdout and stderr, so we
-     * can arrange asynchronous writes.
-     */
-    odata.event = stdoutevent;
-    odata.eventback = CreateEvent(NULL, FALSE, FALSE, NULL);
-    odata.is_stderr = 0;
-    odata.busy = odata.done = 0;
-    if (!CreateThread(NULL, 0, stdout_write_thread,
-		      &odata, 0, &out_threadid)) {
-	fprintf(stderr, "Unable to create output thread\n");
-	cleanup_exit(1);
-    }
-    edata.event = stderrevent;
-    edata.eventback = CreateEvent(NULL, FALSE, FALSE, NULL);
-    edata.is_stderr = 1;
-    edata.busy = edata.done = 0;
-    if (!CreateThread(NULL, 0, stdout_write_thread,
-		      &edata, 0, &err_threadid)) {
-	fprintf(stderr, "Unable to create error output thread\n");
-	cleanup_exit(1);
-    }
-
     now = GETTICKCOUNT();
 
     while (1) {
+	int nhandles;
+	HANDLE *handles;	
 	int n;
 	DWORD ticks;
 
 	if (!sending && back->sendok(backhandle)) {
-	    /*
+	    stdin_handle = handle_input_new(inhandle, stdin_gotdata);
-	     * Create a separate thread to read from stdin. This is
-	     * a total pain, but I can't find another way to do it:
-	     *
-	     *  - an overlapped ReadFile or ReadFileEx just doesn't
-	     *    happen; we get failure from ReadFileEx, and
-	     *    ReadFile blocks despite being given an OVERLAPPED
-	     *    structure. Perhaps we can't do overlapped reads
-	     *    on consoles. WHY THE HELL NOT?
-	     * 
-	     *  - WaitForMultipleObjects(netevent, console) doesn't
-	     *    work, because it signals the console when
-	     *    _anything_ happens, including mouse motions and
-	     *    other things that don't cause data to be readable
-	     *    - so we're back to ReadFile blocking.
-	     */
-	    idata.event = stdinevent;
-	    idata.eventback = CreateEvent(NULL, FALSE, FALSE, NULL);
-	    if (!CreateThread(NULL, 0, stdin_read_thread,
-			      &idata, 0, &in_threadid)) {
-		fprintf(stderr, "Unable to create input thread\n");
-		cleanup_exit(1);
-	    }
 	    sending = TRUE;
-	    reading = TRUE;
 	}
 
 	if (run_timers(now, &next)) {
@@ -697,9 +604,14 @@ int main(int argc, char **argv)
 	    ticks = INFINITE;
 	}
 
-	n = MsgWaitForMultipleObjects(4, handles, FALSE, ticks,
+	handles = handle_get_events(&nhandles);
+	handles = sresize(handles, nhandles+1, HANDLE);
+	handles[nhandles] = netevent;
+	n = MsgWaitForMultipleObjects(nhandles+1, handles, FALSE, ticks,
 				      QS_POSTMESSAGE);
-	if (n == WAIT_OBJECT_0 + 0) {
+	if ((unsigned)(n - WAIT_OBJECT_0) < (unsigned)nhandles) {
+	    handle_got_event(handles[n - WAIT_OBJECT_0]);
+	} else if (n == WAIT_OBJECT_0 + nhandles) {
 	    WSANETWORKEVENTS things;
 	    SOCKET socket;
 	    extern SOCKET first_socket(int *), next_socket(int *);
@@ -760,43 +672,7 @@ int main(int argc, char **argv)
                         }
 		}
 	    }
-	} else if (n == WAIT_OBJECT_0 + 1) {
+	} else if (n == WAIT_OBJECT_0 + nhandles + 1) {
-	    reading = 0;
-	    noise_ultralight(idata.len);
-	    if (connopen && back->socket(backhandle) != NULL) {
-		if (idata.len > 0) {
-		    back->send(backhandle, idata.buffer, idata.len);
-		} else {
-		    back->special(backhandle, TS_EOF);
-		}
-	    }
-	} else if (n == WAIT_OBJECT_0 + 2) {
-	    odata.busy = 0;
-	    if (!odata.writeret) {
-		fprintf(stderr, "Unable to write to standard output\n");
-		cleanup_exit(0);
-	    }
-	    bufchain_consume(&stdout_data, odata.lenwritten);
-	    if (bufchain_size(&stdout_data) > 0)
-		try_output(0);
-	    if (connopen && back->socket(backhandle) != NULL) {
-		back->unthrottle(backhandle, bufchain_size(&stdout_data) +
-				 bufchain_size(&stderr_data));
-	    }
-	} else if (n == WAIT_OBJECT_0 + 3) {
-	    edata.busy = 0;
-	    if (!edata.writeret) {
-		fprintf(stderr, "Unable to write to standard output\n");
-		cleanup_exit(0);
-	    }
-	    bufchain_consume(&stderr_data, edata.lenwritten);
-	    if (bufchain_size(&stderr_data) > 0)
-		try_output(1);
-	    if (connopen && back->socket(backhandle) != NULL) {
-		back->unthrottle(backhandle, bufchain_size(&stdout_data) +
-				 bufchain_size(&stderr_data));
-	    }
-	} else if (n == WAIT_OBJECT_0 + 4) {
 	    MSG msg;
 	    while (PeekMessage(&msg, INVALID_HANDLE_VALUE,
 			       WM_AGENT_CALLBACK, WM_AGENT_CALLBACK,
@@ -813,13 +689,13 @@ int main(int argc, char **argv)
 	    now = GETTICKCOUNT();
 	}
 
-	if (!reading && back->sendbuffer(backhandle) < MAX_STDIN_BACKLOG) {
+	sfree(handles);
-	    SetEvent(idata.eventback);
+
-	    reading = 1;
+	if (sending)
-	}
+	    handle_unthrottle(stdin_handle, back->sendbuffer(backhandle));
+
 	if ((!connopen || back->socket(backhandle) == NULL) &&
-	    bufchain_size(&stdout_data) == 0 &&
+	    handle_backlog(stdout_handle) + handle_backlog(stderr_handle) == 0)
-	    bufchain_size(&stderr_data) == 0)
 	    break;		       /* we closed the connection */
     }
     exitcode = back->exitcode(backhandle);

windows/winsftp.c

@@ -463,9 +463,9 @@ extern int select_result(WPARAM, LPARAM);
 
 int do_eventsel_loop(HANDLE other_event)
 {
-    int n;
+    int n, nhandles, nallhandles;
     long next, ticks;
-    HANDLE handles[2];
+    HANDLE *handles;
     SOCKET *sklist;
     int skcount;
     long now = GETTICKCOUNT();
@@ -474,8 +474,13 @@ int do_eventsel_loop(HANDLE other_event)
 	return -1;		       /* doom */
     }
 
-    handles[0] = netevent;
+    handles = handle_get_events(&nhandles);
-    handles[1] = other_event;
+    handles = sresize(handles, nhandles+2, HANDLE);
+    nallhandles = nhandles;
+
+    handles[nallhandles++] = netevent;
+    if (other_event)
+	handles[nallhandles++] = other_event;
 
     if (run_timers(now, &next)) {
 	ticks = next - GETTICKCOUNT();
@@ -484,10 +489,12 @@ int do_eventsel_loop(HANDLE other_event)
 	ticks = INFINITE;
     }
 
-    n = MsgWaitForMultipleObjects(other_event ? 2 : 1, handles, FALSE, ticks,
+    n = MsgWaitForMultipleObjects(nallhandles, handles, FALSE, ticks,
 				  QS_POSTMESSAGE);
 
-    if (n == WAIT_OBJECT_0 + 0) {
+    if ((unsigned)(n - WAIT_OBJECT_0) < (unsigned)nhandles) {
+	handle_got_event(handles[n - WAIT_OBJECT_0]);
+    } else if (n == WAIT_OBJECT_0 + nhandles) {
 	WSANETWORKEVENTS things;
 	SOCKET socket;
 	extern SOCKET first_socket(int *), next_socket(int *);
@@ -549,13 +556,15 @@ int do_eventsel_loop(HANDLE other_event)
 	sfree(sklist);
     }
 
+    sfree(handles);
+
     if (n == WAIT_TIMEOUT) {
 	now = next;
     } else {
 	now = GETTICKCOUNT();
     }
 
-    if (other_event && n == WAIT_OBJECT_0 + 1)
+    if (other_event && n == WAIT_OBJECT_0 + nhandles + 1)
 	return 1;
 
     return 0;

windows/winstuff.h

@@ -405,6 +405,21 @@ void EnableSizeTip(int bEnable);
 struct unicode_data;
 void init_ucs(Config *, struct unicode_data *);
 
+/*
+ * Exports from winhandl.c.
+ */
+struct handle;
+typedef int (*handle_inputfn_t)(struct handle *h, void *data, int len);
+typedef void (*handle_outputfn_t)(struct handle *h, int new_backlog);
+struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata);
+struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata);
+int handle_write(struct handle *h, const void *data, int len);
+HANDLE *handle_get_events(int *nevents);
+void handle_free(struct handle *h);
+void handle_got_event(HANDLE event);
+void handle_unthrottle(struct handle *h, int backlog);
+int handle_backlog(struct handle *h);
+
 /*
  * pageantc.c needs to schedule callbacks for asynchronous agent
  * requests. This has to be done differently in GUI and console, so