mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-07-02 03:52:49 -05:00
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]
This commit is contained in:
Simon Tatham
486
windows/winhandl.c
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486
windows/winhandl.c
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@ -0,0 +1,486 @@
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/*
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* winhandl.c: Module to give Windows front ends the general
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* ability to deal with consoles, pipes, serial ports, or any other
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* type of data stream accessed through a Windows API HANDLE rather
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* than a WinSock SOCKET.
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*
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* We do this by spawning a subthread to continuously try to read
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* from the handle. Every time a read successfully returns some
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* data, the subthread sets an event object which is picked up by
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* the main thread, and the main thread then sets an event in
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* return to instruct the subthread to resume reading.
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*
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* Output works precisely the other way round, in a second
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* subthread. The output subthread should not be attempting to
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* write all the time, because it hasn't always got data _to_
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* write; so the output thread waits for an event object notifying
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* it to _attempt_ a write, and then it sets an event in return
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* when one completes.
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*/
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/*
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* TODO:
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*
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* - could do with some sort of private-data field in each handle
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* structure.
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*/
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#include <assert.h>
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#include "putty.h"
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/* ----------------------------------------------------------------------
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* Generic definitions.
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*/
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/*
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* Maximum amount of backlog we will allow to build up on an input
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* handle before we stop reading from it.
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*/
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#define MAX_BACKLOG 32768
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struct handle_generic {
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/*
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* Initial fields common to both handle_input and handle_output
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* structures.
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*
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* The three HANDLEs are set up at initialisation time and are
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* thereafter read-only to both main thread and subthread.
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* `moribund' is only used by the main thread; `done' is
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* written by the main thread before signalling to the
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* subthread. `defunct' and `busy' are used only by the main
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* thread.
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*/
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HANDLE h; /* the handle itself */
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HANDLE ev_to_main; /* event used to signal main thread */
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HANDLE ev_from_main; /* event used to signal back to us */
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int moribund; /* are we going to kill this soon? */
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int done; /* request subthread to terminate */
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int defunct; /* has the subthread already gone? */
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int busy; /* operation currently in progress? */
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};
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/* ----------------------------------------------------------------------
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* Input threads.
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*/
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/*
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* Data required by an input thread.
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*/
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struct handle_input {
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/*
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* Copy of the handle_generic structure.
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*/
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HANDLE h; /* the handle itself */
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HANDLE ev_to_main; /* event used to signal main thread */
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HANDLE ev_from_main; /* event used to signal back to us */
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int moribund; /* are we going to kill this soon? */
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int done; /* request subthread to terminate */
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int defunct; /* has the subthread already gone? */
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int busy; /* operation currently in progress? */
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/*
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* Data set by the input thread before signalling ev_to_main,
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* and read by the main thread after receiving that signal.
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*/
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char buffer[4096]; /* the data read from the handle */
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DWORD len; /* how much data that was */
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int readret; /* lets us know about read errors */
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/*
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* Callback function called by this module when data arrives on
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* an input handle.
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*/
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handle_inputfn_t gotdata;
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};
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/*
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* The actual thread procedure for an input thread.
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*/
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static DWORD WINAPI handle_input_threadfunc(void *param)
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{
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struct handle_input *ctx = (struct handle_input *) param;
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while (1) {
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ctx->readret = ReadFile(ctx->h, ctx->buffer, sizeof(ctx->buffer),
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&ctx->len, NULL);
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if (!ctx->readret)
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ctx->len = 0;
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SetEvent(ctx->ev_to_main);
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if (!ctx->len)
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break;
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WaitForSingleObject(ctx->ev_from_main, INFINITE);
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if (ctx->done)
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break; /* main thread told us to shut down */
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}
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return 0;
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}
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/*
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* This is called after a succcessful read, or from the
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* `unthrottle' function. It decides whether or not to begin a new
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* read operation.
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*/
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static void handle_throttle(struct handle_input *ctx, int backlog)
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{
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assert(!ctx->defunct);
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/*
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* If there's a read operation already in progress, do nothing:
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* when that completes, we'll come back here and be in a
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* position to make a better decision.
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*/
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if (ctx->busy)
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return;
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/*
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* Otherwise, we must decide whether to start a new read based
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* on the size of the backlog.
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*/
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if (backlog < MAX_BACKLOG) {
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SetEvent(ctx->ev_from_main);
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ctx->busy = TRUE;
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}
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}
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/* ----------------------------------------------------------------------
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* Output threads.
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*/
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/*
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* Data required by an output thread.
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*/
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struct handle_output {
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/*
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* Copy of the handle_generic structure.
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*/
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HANDLE h; /* the handle itself */
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HANDLE ev_to_main; /* event used to signal main thread */
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HANDLE ev_from_main; /* event used to signal back to us */
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int moribund; /* are we going to kill this soon? */
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int done; /* request subthread to terminate */
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int defunct; /* has the subthread already gone? */
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int busy; /* operation currently in progress? */
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/*
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* Data set by the main thread before signalling ev_from_main,
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* and read by the input thread after receiving that signal.
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*/
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char *buffer; /* the data to write */
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DWORD len; /* how much data there is */
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/*
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* Data set by the input thread before signalling ev_to_main,
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* and read by the main thread after receiving that signal.
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*/
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DWORD lenwritten; /* how much data we actually wrote */
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int writeret; /* return value from WriteFile */
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/*
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* Data only ever read or written by the main thread.
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*/
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bufchain queued_data; /* data still waiting to be written */
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/*
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* Callback function called when the backlog in the bufchain
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* drops.
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*/
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handle_outputfn_t sentdata;
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};
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static DWORD WINAPI handle_output_threadfunc(void *param)
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{
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struct handle_output *ctx = (struct handle_output *) param;
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while (1) {
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WaitForSingleObject(ctx->ev_from_main, INFINITE);
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if (ctx->done) {
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SetEvent(ctx->ev_to_main);
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break;
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}
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ctx->writeret = WriteFile(ctx->h, ctx->buffer, ctx->len,
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&ctx->lenwritten, NULL);
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SetEvent(ctx->ev_to_main);
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if (!ctx->writeret)
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break;
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}
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return 0;
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}
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static void handle_try_output(struct handle_output *ctx)
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{
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void *senddata;
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int sendlen;
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if (!ctx->busy && bufchain_size(&ctx->queued_data)) {
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bufchain_prefix(&ctx->queued_data, &senddata, &sendlen);
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ctx->buffer = senddata;
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ctx->len = sendlen;
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SetEvent(ctx->ev_from_main);
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ctx->busy = TRUE;
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}
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}
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/* ----------------------------------------------------------------------
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* Unified code handling both input and output threads.
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*/
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struct handle {
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int output;
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union {
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struct handle_generic g;
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struct handle_input i;
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struct handle_output o;
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} u;
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};
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static tree234 *handles_by_evtomain;
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static int handle_cmp_evtomain(void *av, void *bv)
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{
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struct handle *a = (struct handle *)av;
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struct handle *b = (struct handle *)bv;
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if ((unsigned)a->u.g.ev_to_main < (unsigned)b->u.g.ev_to_main)
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return -1;
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else if ((unsigned)a->u.g.ev_to_main > (unsigned)b->u.g.ev_to_main)
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return +1;
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else
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return 0;
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}
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static int handle_find_evtomain(void *av, void *bv)
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{
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HANDLE *a = (HANDLE *)av;
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struct handle *b = (struct handle *)bv;
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if ((unsigned)*a < (unsigned)b->u.g.ev_to_main)
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return -1;
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else if ((unsigned)*a > (unsigned)b->u.g.ev_to_main)
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return +1;
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else
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return 0;
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}
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struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata)
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{
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struct handle *h = snew(struct handle);
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h->output = FALSE;
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h->u.i.h = handle;
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h->u.i.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL);
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h->u.i.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL);
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h->u.i.gotdata = gotdata;
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h->u.i.busy = FALSE;
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h->u.i.defunct = FALSE;
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h->u.i.moribund = FALSE;
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h->u.i.done = FALSE;
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if (!handles_by_evtomain)
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handles_by_evtomain = newtree234(handle_cmp_evtomain);
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add234(handles_by_evtomain, h);
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CreateThread(NULL, 0, handle_input_threadfunc,
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&h->u.i, 0, NULL);
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handle_throttle(&h->u.i, 0); /* start first read operation */
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return h;
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}
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struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata)
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{
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struct handle *h = snew(struct handle);
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h->output = TRUE;
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h->u.o.h = handle;
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h->u.o.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL);
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h->u.o.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL);
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h->u.o.busy = FALSE;
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h->u.o.defunct = FALSE;
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h->u.o.moribund = FALSE;
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h->u.o.done = FALSE;
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bufchain_init(&h->u.o.queued_data);
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h->u.o.sentdata = sentdata;
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if (!handles_by_evtomain)
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handles_by_evtomain = newtree234(handle_cmp_evtomain);
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add234(handles_by_evtomain, h);
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CreateThread(NULL, 0, handle_output_threadfunc,
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&h->u.i, 0, NULL);
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return h;
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}
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int handle_write(struct handle *h, const void *data, int len)
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{
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assert(h->output);
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bufchain_add(&h->u.o.queued_data, data, len);
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handle_try_output(&h->u.o);
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return bufchain_size(&h->u.o.queued_data);
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}
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HANDLE *handle_get_events(int *nevents)
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{
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HANDLE *ret;
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struct handle *h;
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int i, n, size;
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/*
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* Go through our tree counting the handle objects currently
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* engaged in useful activity.
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*/
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ret = NULL;
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n = size = 0;
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if (handles_by_evtomain) {
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for (i = 0; (h = index234(handles_by_evtomain, i)) != NULL; i++) {
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if (h->u.g.busy) {
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if (n >= size) {
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size += 32;
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ret = sresize(ret, size, HANDLE);
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}
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ret[n++] = h->u.g.ev_to_main;
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}
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}
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}
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*nevents = n;
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return ret;
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}
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static void handle_destroy(struct handle *h)
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{
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if (h->output)
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bufchain_clear(&h->u.o.queued_data);
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CloseHandle(h->u.g.ev_from_main);
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CloseHandle(h->u.g.ev_to_main);
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del234(handles_by_evtomain, h);
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sfree(h);
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}
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void handle_free(struct handle *h)
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{
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/*
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* If the handle is currently busy, we cannot immediately free
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* it. Instead we must wait until it's finished its current
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* operation, because otherwise the subthread will write to
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* invalid memory after we free its context from under it.
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*/
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assert(h && !h->u.g.moribund);
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if (h->u.g.busy) {
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/*
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* Just set the moribund flag, which will be noticed next
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* time an operation completes.
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*/
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h->u.g.moribund = TRUE;
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} else if (h->u.g.defunct) {
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/*
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* There isn't even a subthread; we can go straight to
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* handle_destroy.
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*/
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handle_destroy(h);
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} else {
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/*
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* The subthread is alive but not busy, so we now signal it
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* to die. Set the moribund flag to indicate that it will
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* want destroying after that.
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*/
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h->u.g.moribund = TRUE;
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h->u.g.done = TRUE;
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SetEvent(h->u.g.ev_from_main);
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}
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}
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void handle_got_event(HANDLE event)
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{
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struct handle *h;
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assert(handles_by_evtomain);
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h = find234(handles_by_evtomain, &event, handle_find_evtomain);
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if (!h) {
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/*
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* This isn't an error condition. If two or more event
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* objects were signalled during the same select operation,
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* and processing of the first caused the second handle to
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* be closed, then it will sometimes happen that we receive
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* an event notification here for a handle which is already
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* deceased. In that situation we simply do nothing.
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*/
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return;
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}
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if (h->u.g.moribund) {
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/*
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* A moribund handle is already treated as dead from the
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* external user's point of view, so do nothing with the
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* actual event. Just signal the thread to die if
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* necessary, or destroy the handle if not.
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*/
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if (h->u.g.done) {
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handle_destroy(h);
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} else {
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h->u.g.done = TRUE;
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SetEvent(h->u.g.ev_from_main);
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}
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return;
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}
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if (!h->output) {
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int backlog;
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h->u.i.busy = FALSE;
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/*
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* A signal on an input handle means data has arrived.
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*/
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if (h->u.i.len == 0) {
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/*
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* EOF, or (nearly equivalently) read error.
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*/
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h->u.i.gotdata(h, NULL, (h->u.i.readret ? 0 : -1));
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h->u.i.defunct = TRUE;
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} else {
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backlog = h->u.i.gotdata(h, h->u.i.buffer, h->u.i.len);
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handle_throttle(&h->u.i, backlog);
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}
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} else {
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h->u.o.busy = FALSE;
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/*
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* A signal on an output handle means we have completed a
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* write. Call the callback to indicate that the output
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* buffer size has decreased, or to indicate an error.
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*/
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if (!h->u.o.writeret) {
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/*
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* Write error. Send a negative value to the callback,
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* and mark the thread as defunct (because the output
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* thread is terminating by now).
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*/
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h->u.o.sentdata(h, -1);
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h->u.o.defunct = TRUE;
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} else {
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bufchain_consume(&h->u.o.queued_data, h->u.o.lenwritten);
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h->u.o.sentdata(h, bufchain_size(&h->u.o.queued_data));
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handle_try_output(&h->u.o);
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}
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}
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}
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void handle_unthrottle(struct handle *h, int backlog)
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{
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assert(!h->output);
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handle_throttle(&h->u.i, backlog);
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}
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int handle_backlog(struct handle *h)
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{
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assert(h->output);
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return bufchain_size(&h->u.o.queued_data);
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}
|
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