| 1 | /* |
| 2 | * winhandl.c: Module to give Windows front ends the general |
| 3 | * ability to deal with consoles, pipes, serial ports, or any other |
| 4 | * type of data stream accessed through a Windows API HANDLE rather |
| 5 | * than a WinSock SOCKET. |
| 6 | * |
| 7 | * We do this by spawning a subthread to continuously try to read |
| 8 | * from the handle. Every time a read successfully returns some |
| 9 | * data, the subthread sets an event object which is picked up by |
| 10 | * the main thread, and the main thread then sets an event in |
| 11 | * return to instruct the subthread to resume reading. |
| 12 | * |
| 13 | * Output works precisely the other way round, in a second |
| 14 | * subthread. The output subthread should not be attempting to |
| 15 | * write all the time, because it hasn't always got data _to_ |
| 16 | * write; so the output thread waits for an event object notifying |
| 17 | * it to _attempt_ a write, and then it sets an event in return |
| 18 | * when one completes. |
| 19 | * |
| 20 | * (It's terribly annoying having to spawn a subthread for each |
| 21 | * direction of each handle. Technically it isn't necessary for |
| 22 | * serial ports, since we could use overlapped I/O within the main |
| 23 | * thread and wait directly on the event objects in the OVERLAPPED |
| 24 | * structures. However, we can't use this trick for some types of |
| 25 | * file handle at all - for some reason Windows restricts use of |
| 26 | * OVERLAPPED to files which were opened with the overlapped flag - |
| 27 | * and so we must use threads for those. This being the case, it's |
| 28 | * simplest just to use threads for everything rather than trying |
| 29 | * to keep track of multiple completely separate mechanisms.) |
| 30 | */ |
| 31 | |
| 32 | #include <assert.h> |
| 33 | |
| 34 | #include "putty.h" |
| 35 | |
| 36 | /* ---------------------------------------------------------------------- |
| 37 | * Generic definitions. |
| 38 | */ |
| 39 | |
| 40 | /* |
| 41 | * Maximum amount of backlog we will allow to build up on an input |
| 42 | * handle before we stop reading from it. |
| 43 | */ |
| 44 | #define MAX_BACKLOG 32768 |
| 45 | |
| 46 | struct handle_generic { |
| 47 | /* |
| 48 | * Initial fields common to both handle_input and handle_output |
| 49 | * structures. |
| 50 | * |
| 51 | * The three HANDLEs are set up at initialisation time and are |
| 52 | * thereafter read-only to both main thread and subthread. |
| 53 | * `moribund' is only used by the main thread; `done' is |
| 54 | * written by the main thread before signalling to the |
| 55 | * subthread. `defunct' and `busy' are used only by the main |
| 56 | * thread. |
| 57 | */ |
| 58 | HANDLE h; /* the handle itself */ |
| 59 | HANDLE ev_to_main; /* event used to signal main thread */ |
| 60 | HANDLE ev_from_main; /* event used to signal back to us */ |
| 61 | int moribund; /* are we going to kill this soon? */ |
| 62 | int done; /* request subthread to terminate */ |
| 63 | int defunct; /* has the subthread already gone? */ |
| 64 | int busy; /* operation currently in progress? */ |
| 65 | void *privdata; /* for client to remember who they are */ |
| 66 | }; |
| 67 | |
| 68 | /* ---------------------------------------------------------------------- |
| 69 | * Input threads. |
| 70 | */ |
| 71 | |
| 72 | /* |
| 73 | * Data required by an input thread. |
| 74 | */ |
| 75 | struct handle_input { |
| 76 | /* |
| 77 | * Copy of the handle_generic structure. |
| 78 | */ |
| 79 | HANDLE h; /* the handle itself */ |
| 80 | HANDLE ev_to_main; /* event used to signal main thread */ |
| 81 | HANDLE ev_from_main; /* event used to signal back to us */ |
| 82 | int moribund; /* are we going to kill this soon? */ |
| 83 | int done; /* request subthread to terminate */ |
| 84 | int defunct; /* has the subthread already gone? */ |
| 85 | int busy; /* operation currently in progress? */ |
| 86 | void *privdata; /* for client to remember who they are */ |
| 87 | |
| 88 | /* |
| 89 | * Data set at initialisation and then read-only. |
| 90 | */ |
| 91 | int flags; |
| 92 | |
| 93 | /* |
| 94 | * Data set by the input thread before signalling ev_to_main, |
| 95 | * and read by the main thread after receiving that signal. |
| 96 | */ |
| 97 | char buffer[4096]; /* the data read from the handle */ |
| 98 | DWORD len; /* how much data that was */ |
| 99 | int readerr; /* lets us know about read errors */ |
| 100 | |
| 101 | /* |
| 102 | * Callback function called by this module when data arrives on |
| 103 | * an input handle. |
| 104 | */ |
| 105 | handle_inputfn_t gotdata; |
| 106 | }; |
| 107 | |
| 108 | /* |
| 109 | * The actual thread procedure for an input thread. |
| 110 | */ |
| 111 | static DWORD WINAPI handle_input_threadfunc(void *param) |
| 112 | { |
| 113 | struct handle_input *ctx = (struct handle_input *) param; |
| 114 | OVERLAPPED ovl, *povl; |
| 115 | HANDLE oev; |
| 116 | int readret, readlen; |
| 117 | |
| 118 | if (ctx->flags & HANDLE_FLAG_OVERLAPPED) { |
| 119 | povl = &ovl; |
| 120 | oev = CreateEvent(NULL, TRUE, FALSE, NULL); |
| 121 | } else { |
| 122 | povl = NULL; |
| 123 | } |
| 124 | |
| 125 | if (ctx->flags & HANDLE_FLAG_UNITBUFFER) |
| 126 | readlen = 1; |
| 127 | else |
| 128 | readlen = sizeof(ctx->buffer); |
| 129 | |
| 130 | while (1) { |
| 131 | if (povl) { |
| 132 | memset(povl, 0, sizeof(OVERLAPPED)); |
| 133 | povl->hEvent = oev; |
| 134 | } |
| 135 | readret = ReadFile(ctx->h, ctx->buffer,readlen, &ctx->len, povl); |
| 136 | if (!readret) |
| 137 | ctx->readerr = GetLastError(); |
| 138 | else |
| 139 | ctx->readerr = 0; |
| 140 | if (povl && !readret && ctx->readerr == ERROR_IO_PENDING) { |
| 141 | WaitForSingleObject(povl->hEvent, INFINITE); |
| 142 | readret = GetOverlappedResult(ctx->h, povl, &ctx->len, FALSE); |
| 143 | if (!readret) |
| 144 | ctx->readerr = GetLastError(); |
| 145 | else |
| 146 | ctx->readerr = 0; |
| 147 | } |
| 148 | |
| 149 | if (!readret) { |
| 150 | /* |
| 151 | * Windows apparently sends ERROR_BROKEN_PIPE when a |
| 152 | * pipe we're reading from is closed normally from the |
| 153 | * writing end. This is ludicrous; if that situation |
| 154 | * isn't a natural EOF, _nothing_ is. So if we get that |
| 155 | * particular error, we pretend it's EOF. |
| 156 | */ |
| 157 | if (ctx->readerr == ERROR_BROKEN_PIPE) |
| 158 | ctx->readerr = 0; |
| 159 | ctx->len = 0; |
| 160 | } |
| 161 | |
| 162 | if (readret && ctx->len == 0 && |
| 163 | (ctx->flags & HANDLE_FLAG_IGNOREEOF)) |
| 164 | continue; |
| 165 | |
| 166 | SetEvent(ctx->ev_to_main); |
| 167 | |
| 168 | if (!ctx->len) |
| 169 | break; |
| 170 | |
| 171 | WaitForSingleObject(ctx->ev_from_main, INFINITE); |
| 172 | if (ctx->done) |
| 173 | break; /* main thread told us to shut down */ |
| 174 | } |
| 175 | |
| 176 | if (povl) |
| 177 | CloseHandle(oev); |
| 178 | |
| 179 | return 0; |
| 180 | } |
| 181 | |
| 182 | /* |
| 183 | * This is called after a succcessful read, or from the |
| 184 | * `unthrottle' function. It decides whether or not to begin a new |
| 185 | * read operation. |
| 186 | */ |
| 187 | static void handle_throttle(struct handle_input *ctx, int backlog) |
| 188 | { |
| 189 | if (ctx->defunct) |
| 190 | return; |
| 191 | |
| 192 | /* |
| 193 | * If there's a read operation already in progress, do nothing: |
| 194 | * when that completes, we'll come back here and be in a |
| 195 | * position to make a better decision. |
| 196 | */ |
| 197 | if (ctx->busy) |
| 198 | return; |
| 199 | |
| 200 | /* |
| 201 | * Otherwise, we must decide whether to start a new read based |
| 202 | * on the size of the backlog. |
| 203 | */ |
| 204 | if (backlog < MAX_BACKLOG) { |
| 205 | SetEvent(ctx->ev_from_main); |
| 206 | ctx->busy = TRUE; |
| 207 | } |
| 208 | } |
| 209 | |
| 210 | /* ---------------------------------------------------------------------- |
| 211 | * Output threads. |
| 212 | */ |
| 213 | |
| 214 | /* |
| 215 | * Data required by an output thread. |
| 216 | */ |
| 217 | struct handle_output { |
| 218 | /* |
| 219 | * Copy of the handle_generic structure. |
| 220 | */ |
| 221 | HANDLE h; /* the handle itself */ |
| 222 | HANDLE ev_to_main; /* event used to signal main thread */ |
| 223 | HANDLE ev_from_main; /* event used to signal back to us */ |
| 224 | int moribund; /* are we going to kill this soon? */ |
| 225 | int done; /* request subthread to terminate */ |
| 226 | int defunct; /* has the subthread already gone? */ |
| 227 | int busy; /* operation currently in progress? */ |
| 228 | void *privdata; /* for client to remember who they are */ |
| 229 | |
| 230 | /* |
| 231 | * Data set at initialisation and then read-only. |
| 232 | */ |
| 233 | int flags; |
| 234 | |
| 235 | /* |
| 236 | * Data set by the main thread before signalling ev_from_main, |
| 237 | * and read by the input thread after receiving that signal. |
| 238 | */ |
| 239 | char *buffer; /* the data to write */ |
| 240 | DWORD len; /* how much data there is */ |
| 241 | |
| 242 | /* |
| 243 | * Data set by the input thread before signalling ev_to_main, |
| 244 | * and read by the main thread after receiving that signal. |
| 245 | */ |
| 246 | DWORD lenwritten; /* how much data we actually wrote */ |
| 247 | int writeerr; /* return value from WriteFile */ |
| 248 | |
| 249 | /* |
| 250 | * Data only ever read or written by the main thread. |
| 251 | */ |
| 252 | bufchain queued_data; /* data still waiting to be written */ |
| 253 | |
| 254 | /* |
| 255 | * Callback function called when the backlog in the bufchain |
| 256 | * drops. |
| 257 | */ |
| 258 | handle_outputfn_t sentdata; |
| 259 | }; |
| 260 | |
| 261 | static DWORD WINAPI handle_output_threadfunc(void *param) |
| 262 | { |
| 263 | struct handle_output *ctx = (struct handle_output *) param; |
| 264 | OVERLAPPED ovl, *povl; |
| 265 | HANDLE oev; |
| 266 | int writeret; |
| 267 | |
| 268 | if (ctx->flags & HANDLE_FLAG_OVERLAPPED) { |
| 269 | povl = &ovl; |
| 270 | oev = CreateEvent(NULL, TRUE, FALSE, NULL); |
| 271 | } else { |
| 272 | povl = NULL; |
| 273 | } |
| 274 | |
| 275 | while (1) { |
| 276 | WaitForSingleObject(ctx->ev_from_main, INFINITE); |
| 277 | if (ctx->done) { |
| 278 | SetEvent(ctx->ev_to_main); |
| 279 | break; |
| 280 | } |
| 281 | if (povl) { |
| 282 | memset(povl, 0, sizeof(OVERLAPPED)); |
| 283 | povl->hEvent = oev; |
| 284 | } |
| 285 | |
| 286 | writeret = WriteFile(ctx->h, ctx->buffer, ctx->len, |
| 287 | &ctx->lenwritten, povl); |
| 288 | if (!writeret) |
| 289 | ctx->writeerr = GetLastError(); |
| 290 | else |
| 291 | ctx->writeerr = 0; |
| 292 | if (povl && !writeret && GetLastError() == ERROR_IO_PENDING) { |
| 293 | writeret = GetOverlappedResult(ctx->h, povl, |
| 294 | &ctx->lenwritten, TRUE); |
| 295 | if (!writeret) |
| 296 | ctx->writeerr = GetLastError(); |
| 297 | else |
| 298 | ctx->writeerr = 0; |
| 299 | } |
| 300 | |
| 301 | SetEvent(ctx->ev_to_main); |
| 302 | if (!writeret) |
| 303 | break; |
| 304 | } |
| 305 | |
| 306 | if (povl) |
| 307 | CloseHandle(oev); |
| 308 | |
| 309 | return 0; |
| 310 | } |
| 311 | |
| 312 | static void handle_try_output(struct handle_output *ctx) |
| 313 | { |
| 314 | void *senddata; |
| 315 | int sendlen; |
| 316 | |
| 317 | if (!ctx->busy && bufchain_size(&ctx->queued_data)) { |
| 318 | bufchain_prefix(&ctx->queued_data, &senddata, &sendlen); |
| 319 | ctx->buffer = senddata; |
| 320 | ctx->len = sendlen; |
| 321 | SetEvent(ctx->ev_from_main); |
| 322 | ctx->busy = TRUE; |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | /* ---------------------------------------------------------------------- |
| 327 | * Unified code handling both input and output threads. |
| 328 | */ |
| 329 | |
| 330 | struct handle { |
| 331 | int output; |
| 332 | union { |
| 333 | struct handle_generic g; |
| 334 | struct handle_input i; |
| 335 | struct handle_output o; |
| 336 | } u; |
| 337 | }; |
| 338 | |
| 339 | static tree234 *handles_by_evtomain; |
| 340 | |
| 341 | static int handle_cmp_evtomain(void *av, void *bv) |
| 342 | { |
| 343 | struct handle *a = (struct handle *)av; |
| 344 | struct handle *b = (struct handle *)bv; |
| 345 | |
| 346 | if ((unsigned)a->u.g.ev_to_main < (unsigned)b->u.g.ev_to_main) |
| 347 | return -1; |
| 348 | else if ((unsigned)a->u.g.ev_to_main > (unsigned)b->u.g.ev_to_main) |
| 349 | return +1; |
| 350 | else |
| 351 | return 0; |
| 352 | } |
| 353 | |
| 354 | static int handle_find_evtomain(void *av, void *bv) |
| 355 | { |
| 356 | HANDLE *a = (HANDLE *)av; |
| 357 | struct handle *b = (struct handle *)bv; |
| 358 | |
| 359 | if ((unsigned)*a < (unsigned)b->u.g.ev_to_main) |
| 360 | return -1; |
| 361 | else if ((unsigned)*a > (unsigned)b->u.g.ev_to_main) |
| 362 | return +1; |
| 363 | else |
| 364 | return 0; |
| 365 | } |
| 366 | |
| 367 | struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata, |
| 368 | void *privdata, int flags) |
| 369 | { |
| 370 | struct handle *h = snew(struct handle); |
| 371 | DWORD in_threadid; /* required for Win9x */ |
| 372 | |
| 373 | h->output = FALSE; |
| 374 | h->u.i.h = handle; |
| 375 | h->u.i.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
| 376 | h->u.i.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
| 377 | h->u.i.gotdata = gotdata; |
| 378 | h->u.i.defunct = FALSE; |
| 379 | h->u.i.moribund = FALSE; |
| 380 | h->u.i.done = FALSE; |
| 381 | h->u.i.privdata = privdata; |
| 382 | h->u.i.flags = flags; |
| 383 | |
| 384 | if (!handles_by_evtomain) |
| 385 | handles_by_evtomain = newtree234(handle_cmp_evtomain); |
| 386 | add234(handles_by_evtomain, h); |
| 387 | |
| 388 | CreateThread(NULL, 0, handle_input_threadfunc, |
| 389 | &h->u.i, 0, &in_threadid); |
| 390 | h->u.i.busy = TRUE; |
| 391 | |
| 392 | return h; |
| 393 | } |
| 394 | |
| 395 | struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata, |
| 396 | void *privdata, int flags) |
| 397 | { |
| 398 | struct handle *h = snew(struct handle); |
| 399 | DWORD out_threadid; /* required for Win9x */ |
| 400 | |
| 401 | h->output = TRUE; |
| 402 | h->u.o.h = handle; |
| 403 | h->u.o.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
| 404 | h->u.o.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
| 405 | h->u.o.busy = FALSE; |
| 406 | h->u.o.defunct = FALSE; |
| 407 | h->u.o.moribund = FALSE; |
| 408 | h->u.o.done = FALSE; |
| 409 | h->u.o.privdata = privdata; |
| 410 | bufchain_init(&h->u.o.queued_data); |
| 411 | h->u.o.sentdata = sentdata; |
| 412 | h->u.o.flags = flags; |
| 413 | |
| 414 | if (!handles_by_evtomain) |
| 415 | handles_by_evtomain = newtree234(handle_cmp_evtomain); |
| 416 | add234(handles_by_evtomain, h); |
| 417 | |
| 418 | CreateThread(NULL, 0, handle_output_threadfunc, |
| 419 | &h->u.o, 0, &out_threadid); |
| 420 | |
| 421 | return h; |
| 422 | } |
| 423 | |
| 424 | int handle_write(struct handle *h, const void *data, int len) |
| 425 | { |
| 426 | assert(h->output); |
| 427 | bufchain_add(&h->u.o.queued_data, data, len); |
| 428 | handle_try_output(&h->u.o); |
| 429 | return bufchain_size(&h->u.o.queued_data); |
| 430 | } |
| 431 | |
| 432 | HANDLE *handle_get_events(int *nevents) |
| 433 | { |
| 434 | HANDLE *ret; |
| 435 | struct handle *h; |
| 436 | int i, n, size; |
| 437 | |
| 438 | /* |
| 439 | * Go through our tree counting the handle objects currently |
| 440 | * engaged in useful activity. |
| 441 | */ |
| 442 | ret = NULL; |
| 443 | n = size = 0; |
| 444 | if (handles_by_evtomain) { |
| 445 | for (i = 0; (h = index234(handles_by_evtomain, i)) != NULL; i++) { |
| 446 | if (h->u.g.busy) { |
| 447 | if (n >= size) { |
| 448 | size += 32; |
| 449 | ret = sresize(ret, size, HANDLE); |
| 450 | } |
| 451 | ret[n++] = h->u.g.ev_to_main; |
| 452 | } |
| 453 | } |
| 454 | } |
| 455 | |
| 456 | *nevents = n; |
| 457 | return ret; |
| 458 | } |
| 459 | |
| 460 | static void handle_destroy(struct handle *h) |
| 461 | { |
| 462 | if (h->output) |
| 463 | bufchain_clear(&h->u.o.queued_data); |
| 464 | CloseHandle(h->u.g.ev_from_main); |
| 465 | CloseHandle(h->u.g.ev_to_main); |
| 466 | del234(handles_by_evtomain, h); |
| 467 | sfree(h); |
| 468 | } |
| 469 | |
| 470 | void handle_free(struct handle *h) |
| 471 | { |
| 472 | /* |
| 473 | * If the handle is currently busy, we cannot immediately free |
| 474 | * it. Instead we must wait until it's finished its current |
| 475 | * operation, because otherwise the subthread will write to |
| 476 | * invalid memory after we free its context from under it. |
| 477 | */ |
| 478 | assert(h && !h->u.g.moribund); |
| 479 | if (h->u.g.busy) { |
| 480 | /* |
| 481 | * Just set the moribund flag, which will be noticed next |
| 482 | * time an operation completes. |
| 483 | */ |
| 484 | h->u.g.moribund = TRUE; |
| 485 | } else if (h->u.g.defunct) { |
| 486 | /* |
| 487 | * There isn't even a subthread; we can go straight to |
| 488 | * handle_destroy. |
| 489 | */ |
| 490 | handle_destroy(h); |
| 491 | } else { |
| 492 | /* |
| 493 | * The subthread is alive but not busy, so we now signal it |
| 494 | * to die. Set the moribund flag to indicate that it will |
| 495 | * want destroying after that. |
| 496 | */ |
| 497 | h->u.g.moribund = TRUE; |
| 498 | h->u.g.done = TRUE; |
| 499 | h->u.g.busy = TRUE; |
| 500 | SetEvent(h->u.g.ev_from_main); |
| 501 | } |
| 502 | } |
| 503 | |
| 504 | void handle_got_event(HANDLE event) |
| 505 | { |
| 506 | struct handle *h; |
| 507 | |
| 508 | assert(handles_by_evtomain); |
| 509 | h = find234(handles_by_evtomain, &event, handle_find_evtomain); |
| 510 | if (!h) { |
| 511 | /* |
| 512 | * This isn't an error condition. If two or more event |
| 513 | * objects were signalled during the same select operation, |
| 514 | * and processing of the first caused the second handle to |
| 515 | * be closed, then it will sometimes happen that we receive |
| 516 | * an event notification here for a handle which is already |
| 517 | * deceased. In that situation we simply do nothing. |
| 518 | */ |
| 519 | return; |
| 520 | } |
| 521 | |
| 522 | if (h->u.g.moribund) { |
| 523 | /* |
| 524 | * A moribund handle is already treated as dead from the |
| 525 | * external user's point of view, so do nothing with the |
| 526 | * actual event. Just signal the thread to die if |
| 527 | * necessary, or destroy the handle if not. |
| 528 | */ |
| 529 | if (h->u.g.done) { |
| 530 | handle_destroy(h); |
| 531 | } else { |
| 532 | h->u.g.done = TRUE; |
| 533 | h->u.g.busy = TRUE; |
| 534 | SetEvent(h->u.g.ev_from_main); |
| 535 | } |
| 536 | return; |
| 537 | } |
| 538 | |
| 539 | if (!h->output) { |
| 540 | int backlog; |
| 541 | |
| 542 | h->u.i.busy = FALSE; |
| 543 | |
| 544 | /* |
| 545 | * A signal on an input handle means data has arrived. |
| 546 | */ |
| 547 | if (h->u.i.len == 0) { |
| 548 | /* |
| 549 | * EOF, or (nearly equivalently) read error. |
| 550 | */ |
| 551 | h->u.i.gotdata(h, NULL, -h->u.i.readerr); |
| 552 | h->u.i.defunct = TRUE; |
| 553 | } else { |
| 554 | backlog = h->u.i.gotdata(h, h->u.i.buffer, h->u.i.len); |
| 555 | handle_throttle(&h->u.i, backlog); |
| 556 | } |
| 557 | } else { |
| 558 | h->u.o.busy = FALSE; |
| 559 | |
| 560 | /* |
| 561 | * A signal on an output handle means we have completed a |
| 562 | * write. Call the callback to indicate that the output |
| 563 | * buffer size has decreased, or to indicate an error. |
| 564 | */ |
| 565 | if (h->u.o.writeerr) { |
| 566 | /* |
| 567 | * Write error. Send a negative value to the callback, |
| 568 | * and mark the thread as defunct (because the output |
| 569 | * thread is terminating by now). |
| 570 | */ |
| 571 | h->u.o.sentdata(h, -h->u.o.writeerr); |
| 572 | h->u.o.defunct = TRUE; |
| 573 | } else { |
| 574 | bufchain_consume(&h->u.o.queued_data, h->u.o.lenwritten); |
| 575 | h->u.o.sentdata(h, bufchain_size(&h->u.o.queued_data)); |
| 576 | handle_try_output(&h->u.o); |
| 577 | } |
| 578 | } |
| 579 | } |
| 580 | |
| 581 | void handle_unthrottle(struct handle *h, int backlog) |
| 582 | { |
| 583 | assert(!h->output); |
| 584 | handle_throttle(&h->u.i, backlog); |
| 585 | } |
| 586 | |
| 587 | int handle_backlog(struct handle *h) |
| 588 | { |
| 589 | assert(h->output); |
| 590 | return bufchain_size(&h->u.o.queued_data); |
| 591 | } |
| 592 | |
| 593 | void *handle_get_privdata(struct handle *h) |
| 594 | { |
| 595 | return h->u.g.privdata; |
| 596 | } |