зеркало из https://github.com/github/putty.git
621 строка
17 KiB
C
621 строка
17 KiB
C
/*
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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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* (It's terribly annoying having to spawn a subthread for each
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* direction of each handle. Technically it isn't necessary for
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* serial ports, since we could use overlapped I/O within the main
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* thread and wait directly on the event objects in the OVERLAPPED
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* structures. However, we can't use this trick for some types of
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* file handle at all - for some reason Windows restricts use of
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* OVERLAPPED to files which were opened with the overlapped flag -
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* and so we must use threads for those. This being the case, it's
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* simplest just to use threads for everything rather than trying
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* to keep track of multiple completely separate mechanisms.)
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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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void *privdata; /* for client to remember who they are */
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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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void *privdata; /* for client to remember who they are */
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/*
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* Data set at initialisation and then read-only.
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*/
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int flags;
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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 readerr; /* 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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OVERLAPPED ovl, *povl;
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HANDLE oev;
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int readret, readlen;
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if (ctx->flags & HANDLE_FLAG_OVERLAPPED) {
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povl = &ovl;
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oev = CreateEvent(NULL, TRUE, FALSE, NULL);
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} else {
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povl = NULL;
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}
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if (ctx->flags & HANDLE_FLAG_UNITBUFFER)
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readlen = 1;
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else
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readlen = sizeof(ctx->buffer);
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while (1) {
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if (povl) {
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memset(povl, 0, sizeof(OVERLAPPED));
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povl->hEvent = oev;
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}
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readret = ReadFile(ctx->h, ctx->buffer,readlen, &ctx->len, povl);
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if (!readret)
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ctx->readerr = GetLastError();
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else
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ctx->readerr = 0;
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if (povl && !readret && ctx->readerr == ERROR_IO_PENDING) {
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WaitForSingleObject(povl->hEvent, INFINITE);
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readret = GetOverlappedResult(ctx->h, povl, &ctx->len, FALSE);
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if (!readret)
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ctx->readerr = GetLastError();
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else
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ctx->readerr = 0;
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}
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if (!readret) {
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/*
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* Windows apparently sends ERROR_BROKEN_PIPE when a
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* pipe we're reading from is closed normally from the
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* writing end. This is ludicrous; if that situation
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* isn't a natural EOF, _nothing_ is. So if we get that
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* particular error, we pretend it's EOF.
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*/
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if (ctx->readerr == ERROR_BROKEN_PIPE)
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ctx->readerr = 0;
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ctx->len = 0;
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}
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if (readret && ctx->len == 0 &&
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(ctx->flags & HANDLE_FLAG_IGNOREEOF))
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continue;
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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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if (povl)
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CloseHandle(oev);
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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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if (ctx->defunct)
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return;
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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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void *privdata; /* for client to remember who they are */
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/*
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* Data set at initialisation and then read-only.
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*/
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int flags;
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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 writeerr; /* 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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enum { EOF_NO, EOF_PENDING, EOF_SENT } outgoingeof;
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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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OVERLAPPED ovl, *povl;
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HANDLE oev;
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int writeret;
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if (ctx->flags & HANDLE_FLAG_OVERLAPPED) {
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povl = &ovl;
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oev = CreateEvent(NULL, TRUE, FALSE, NULL);
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} else {
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povl = NULL;
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}
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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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if (povl) {
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memset(povl, 0, sizeof(OVERLAPPED));
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povl->hEvent = oev;
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}
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writeret = WriteFile(ctx->h, ctx->buffer, ctx->len,
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&ctx->lenwritten, povl);
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if (!writeret)
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ctx->writeerr = GetLastError();
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else
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ctx->writeerr = 0;
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if (povl && !writeret && GetLastError() == ERROR_IO_PENDING) {
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writeret = GetOverlappedResult(ctx->h, povl,
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&ctx->lenwritten, TRUE);
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if (!writeret)
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ctx->writeerr = GetLastError();
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else
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ctx->writeerr = 0;
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}
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SetEvent(ctx->ev_to_main);
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if (!writeret)
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break;
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}
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if (povl)
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CloseHandle(oev);
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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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} else if (!ctx->busy && bufchain_size(&ctx->queued_data) == 0 &&
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ctx->outgoingeof == EOF_PENDING) {
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CloseHandle(ctx->h);
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ctx->h = INVALID_HANDLE_VALUE;
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ctx->outgoingeof = EOF_SENT;
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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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void *privdata, int flags)
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{
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struct handle *h = snew(struct handle);
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DWORD in_threadid; /* required for Win9x */
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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.defunct = FALSE;
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h->u.i.moribund = FALSE;
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h->u.i.done = FALSE;
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h->u.i.privdata = privdata;
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h->u.i.flags = flags;
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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, &in_threadid);
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h->u.i.busy = TRUE;
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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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void *privdata, int flags)
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{
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struct handle *h = snew(struct handle);
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DWORD out_threadid; /* required for Win9x */
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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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h->u.o.privdata = privdata;
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bufchain_init(&h->u.o.queued_data);
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h->u.o.outgoingeof = EOF_NO;
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h->u.o.sentdata = sentdata;
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h->u.o.flags = flags;
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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.o, 0, &out_threadid);
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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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assert(h->u.o.outgoingeof == EOF_NO);
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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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void handle_write_eof(struct handle *h)
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{
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/*
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* This function is called when we want to proactively send an
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* end-of-file notification on the handle. We can only do this by
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* actually closing the handle - so never call this on a
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* bidirectional handle if we're still interested in its incoming
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* direction!
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*/
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assert(h->output);
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if (!h->u.o.outgoingeof == EOF_NO) {
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h->u.o.outgoingeof = EOF_PENDING;
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handle_try_output(&h->u.o);
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}
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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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h->u.g.busy = 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);
|
|
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;
|
|
h->u.g.busy = 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.readerr);
|
|
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.writeerr) {
|
|
/*
|
|
* 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, -h->u.o.writeerr);
|
|
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);
|
|
}
|
|
|
|
void *handle_get_privdata(struct handle *h)
|
|
{
|
|
return h->u.g.privdata;
|
|
}
|