src/support/ForkedCalls.cpp

   1 /**
   2  * \file ForkedCalls.cpp
   3  * This file is part of LyX, the document processor.
   4  * Licence details can be found in the file COPYING.
   5  *
   6  * \author Asger Alstrup
   7  * \author Angus Leeming
   8  * \author Alfredo Braunstein
   9  *
  10  * Full author contact details are available in file CREDITS.
  11  */
  12
  13 #include <config.h>
  14
  15 #include "support/ForkedCalls.h"
  16
  17 #include "support/debug.h"
  18 #include "support/filetools.h"
  19 #include "support/lstrings.h"
  20 #include "support/lyxlib.h"
  21 #include "support/os.h"
  22 #include "support/Timeout.h"
  23
  24 #include <boost/bind.hpp>
  25
  26 #include <cerrno>
  27 #include <queue>
  28 #include <sstream>
  29 #include <utility>
  30 #include <vector>
  31
  32 #ifdef _WIN32
  33 # define SIGHUP 1
  34 # define SIGKILL 9
  35 # include <windows.h>
  36 # include <process.h>
  37 # undef max
  38 #else
  39 # include <csignal>
  40 # include <cstdlib>
  41 # ifdef HAVE_UNISTD_H
  42 #  include <unistd.h>
  43 # endif
  44 # include <sys/wait.h>
  45 #endif
  46
  47 using namespace std;
  48
  49 using boost::bind;
  50
  51 namespace lyx {
  52 namespace support {
  53
  54 namespace {
  55
  56 /////////////////////////////////////////////////////////////////////
  57 //
  58 // Murder
  59 //
  60 /////////////////////////////////////////////////////////////////////
  61
  62 class Murder : public boost::signals::trackable {
  63 public:
  64         //
  65         static void killItDead(int secs, pid_t pid)
  66         {
  67                 if (secs > 0)
  68                         new Murder(secs, pid);
  69                 else if (pid != 0)
  70                         support::kill(pid, SIGKILL);
  71         }
  72
  73         //
  74         void kill()
  75         {
  76                 if (pid_ != 0)
  77                         support::kill(pid_, SIGKILL);
  78                 lyxerr << "Killed " << pid_ << endl;
  79                 delete this;
  80         }
  81
  82 private:
  83         //
  84         Murder(int secs, pid_t pid)
  85                 : timeout_(1000*secs, Timeout::ONETIME), pid_(pid)
  86         {
  87                 timeout_.timeout.connect(boost::bind(&Murder::kill, this));
  88                 timeout_.start();
  89         }
  90
  91         //
  92         Timeout timeout_;
  93         //
  94         pid_t pid_;
  95 };
  96
  97 } // namespace anon
  98
  99
 100 /////////////////////////////////////////////////////////////////////
 101 //
 102 // ForkedProcess
 103 //
 104 /////////////////////////////////////////////////////////////////////
 105
 106 ForkedProcess::ForkedProcess()
 107         : pid_(0), retval_(0)
 108 {}
 109
 110
 111 void ForkedProcess::emitSignal()
 112 {
 113         if (signal_.get()) {
 114                 signal_->operator()(pid_, retval_);
 115         }
 116 }
 117
 118
 119 // Spawn the child process
 120 int ForkedProcess::run(Starttype type)
 121 {
 122         retval_ = 0;
 123         pid_ = generateChild();
 124         if (pid_ <= 0) { // child or fork failed.
 125                 retval_ = 1;
 126                 return retval_;
 127         }
 128
 129         switch (type) {
 130         case Wait:
 131                 retval_ = waitForChild();
 132                 break;
 133         case DontWait: {
 134                 // Integrate into the Controller
 135                 ForkedCallsController::addCall(*this);
 136                 break;
 137         }
 138         }
 139
 140         return retval_;
 141 }
 142
 143
 144 bool ForkedProcess::running() const
 145 {
 146         if (!pid())
 147                 return false;
 148
 149 #if !defined (_WIN32)
 150         // Un-UNIX like, but we don't have much use for
 151         // knowing if a zombie exists, so just reap it first.
 152         int waitstatus;
 153         waitpid(pid(), &waitstatus, WNOHANG);
 154 #endif
 155
 156         // Racy of course, but it will do.
 157         if (support::kill(pid(), 0) && errno == ESRCH)
 158                 return false;
 159         return true;
 160 }
 161
 162
 163 void ForkedProcess::kill(int tol)
 164 {
 165         lyxerr << "ForkedProcess::kill(" << tol << ')' << endl;
 166         if (pid() == 0) {
 167                 lyxerr << "Can't kill non-existent process!" << endl;
 168                 return;
 169         }
 170
 171         int const tolerance = max(0, tol);
 172         if (tolerance == 0) {
 173                 // Kill it dead NOW!
 174                 Murder::killItDead(0, pid());
 175         } else {
 176                 int ret = support::kill(pid(), SIGHUP);
 177
 178                 // The process is already dead if wait_for_death is false
 179                 bool const wait_for_death = (ret == 0 && errno != ESRCH);
 180
 181                 if (wait_for_death)
 182                         Murder::killItDead(tolerance, pid());
 183         }
 184 }
 185
 186
 187 // Wait for child process to finish. Returns returncode from child.
 188 int ForkedProcess::waitForChild()
 189 {
 190         // We'll pretend that the child returns 1 on all error conditions.
 191         retval_ = 1;
 192
 193 #if defined (_WIN32)
 194         HANDLE const hProcess = HANDLE(pid_);
 195
 196         DWORD const wait_status = ::WaitForSingleObject(hProcess, INFINITE);
 197
 198         switch (wait_status) {
 199         case WAIT_OBJECT_0: {
 200                 DWORD exit_code = 0;
 201                 if (!GetExitCodeProcess(hProcess, &exit_code)) {
 202                         lyxerr << "GetExitCodeProcess failed waiting for child\n"
 203                                << getChildErrorMessage() << endl;
 204                 } else
 205                         retval_ = exit_code;
 206                 break;
 207         }
 208         case WAIT_FAILED:
 209                 lyxerr << "WaitForSingleObject failed waiting for child\n"
 210                        << getChildErrorMessage() << endl;
 211                 break;
 212         }
 213
 214 #else
 215         int status;
 216         bool wait = true;
 217         while (wait) {
 218                 pid_t waitrpid = waitpid(pid_, &status, WUNTRACED);
 219                 if (waitrpid == -1) {
 220                         lyxerr << "LyX: Error waiting for child:"
 221                                << strerror(errno) << endl;
 222                         wait = false;
 223                 } else if (WIFEXITED(status)) {
 224                         // Child exited normally. Update return value.
 225                         retval_ = WEXITSTATUS(status);
 226                         wait = false;
 227                 } else if (WIFSIGNALED(status)) {
 228                         lyxerr << "LyX: Child didn't catch signal "
 229                                << WTERMSIG(status)
 230                                << "and died. Too bad." << endl;
 231                         wait = false;
 232                 } else if (WIFSTOPPED(status)) {
 233                         lyxerr << "LyX: Child (pid: " << pid_
 234                                << ") stopped on signal "
 235                                << WSTOPSIG(status)
 236                                << ". Waiting for child to finish." << endl;
 237                 } else {
 238                         lyxerr << "LyX: Something rotten happened while "
 239                                 "waiting for child " << pid_ << endl;
 240                         wait = false;
 241                 }
 242         }
 243 #endif
 244         return retval_;
 245 }
 246
 247
 248 /////////////////////////////////////////////////////////////////////
 249 //
 250 // ForkedCall
 251 //
 252 /////////////////////////////////////////////////////////////////////
 253
 254
 255 int ForkedCall::startScript(Starttype wait, string const & what)
 256 {
 257         if (wait != Wait) {
 258                 retval_ = startScript(what, SignalTypePtr());
 259                 return retval_;
 260         }
 261
 262         command_ = what;
 263         signal_.reset();
 264         return run(Wait);
 265 }
 266
 267
 268 int ForkedCall::startScript(string const & what, SignalTypePtr signal)
 269 {
 270         command_ = what;
 271         signal_  = signal;
 272
 273         return run(DontWait);
 274 }
 275
 276
 277 // generate child in background
 278 int ForkedCall::generateChild()
 279 {
 280         string line = trim(command_);
 281         if (line.empty())
 282                 return 1;
 283
 284         // Split the input command up into an array of words stored
 285         // in a contiguous block of memory. The array contains pointers
 286         // to each word.
 287         // Don't forget the terminating `\0' character.
 288         char const * const c_str = line.c_str();
 289         vector<char> vec(c_str, c_str + line.size() + 1);
 290
 291         // Splitting the command up into an array of words means replacing
 292         // the whitespace between words with '\0'. Life is complicated
 293         // however, because words protected by quotes can contain whitespace.
 294         //
 295         // The strategy we adopt is:
 296         // 1. If we're not inside quotes, then replace white space with '\0'.
 297         // 2. If we are inside quotes, then don't replace the white space
 298         //    but do remove the quotes themselves. We do this naively by
 299         //    replacing the quote with '\0' which is fine if quotes
 300         //    delimit the entire word.
 301         char inside_quote = 0;
 302         vector<char>::iterator it = vec.begin();
 303         vector<char>::iterator const end = vec.end();
 304         for (; it != end; ++it) {
 305                 char const c = *it;
 306                 if (!inside_quote) {
 307                         if (c == ' ')
 308                                 *it = '\0';
 309                         else if (c == '\'' || c == '"') {
 310 #if defined (_WIN32)
 311                                 // How perverse!
 312                                 // spawnvp *requires* the quotes or it will
 313                                 // split the arg at the internal whitespace!
 314                                 // Make shure the quote is a DOS-style one.
 315                                 *it = '"';
 316 #else
 317                                 *it = '\0';
 318 #endif
 319                                 inside_quote = c;
 320                         }
 321                 } else if (c == inside_quote) {
 322 #if defined (_WIN32)
 323                         *it = '"';
 324 #else
 325                         *it = '\0';
 326 #endif
 327                         inside_quote = 0;
 328                 }
 329         }
 330
 331         // Build an array of pointers to each word.
 332         it = vec.begin();
 333         vector<char *> argv;
 334         char prev = '\0';
 335         for (; it != end; ++it) {
 336                 if (*it != '\0' && prev == '\0')
 337                         argv.push_back(&*it);
 338                 prev = *it;
 339         }
 340         argv.push_back(0);
 341
 342         // Debug output.
 343         if (lyxerr.debugging(Debug::FILES)) {
 344                 vector<char *>::iterator ait = argv.begin();
 345                 vector<char *>::iterator const aend = argv.end();
 346                 lyxerr << "<command>\n\t" << line
 347                        << "\n\tInterpretted as:\n\n";
 348                 for (; ait != aend; ++ait)
 349                         if (*ait)
 350                                 lyxerr << '\t'<< *ait << '\n';
 351                 lyxerr << "</command>" << endl;
 352         }
 353
 354 #ifdef _WIN32
 355         pid_t const cpid = spawnvp(_P_NOWAIT, argv[0], &*argv.begin());
 356 #else // POSIX
 357         pid_t const cpid = ::fork();
 358         if (cpid == 0) {
 359                 // Child
 360                 execvp(argv[0], &*argv.begin());
 361
 362                 // If something goes wrong, we end up here
 363                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 364                        << strerror(errno) << endl;
 365                 _exit(1);
 366         }
 367 #endif
 368
 369         if (cpid < 0) {
 370                 // Error.
 371                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 372         }
 373
 374         return cpid;
 375 }
 376
 377
 378 /////////////////////////////////////////////////////////////////////
 379 //
 380 // ForkedCallQueue
 381 //
 382 /////////////////////////////////////////////////////////////////////
 383
 384 namespace ForkedCallQueue {
 385
 386 /// A process in the queue
 387 typedef pair<string, ForkedCall::SignalTypePtr> Process;
 388 /** Add a process to the queue. Processes are forked sequentially
 389  *  only one is running at a time.
 390  *  Connect to the returned signal and you'll be informed when
 391  *  the process has ended.
 392  */
 393 ForkedCall::SignalTypePtr add(string const & process);
 394
 395 /// in-progress queue
 396 static queue<Process> callQueue_;
 397
 398 /// flag whether queue is running
 399 static bool running_ = 0;
 400
 401 ///
 402 void startCaller();
 403 ///
 404 void stopCaller();
 405 ///
 406 void callback(pid_t, int);
 407
 408 ForkedCall::SignalTypePtr add(string const & process)
 409 {
 410         ForkedCall::SignalTypePtr ptr;
 411         ptr.reset(new ForkedCall::SignalType);
 412         callQueue_.push(Process(process, ptr));
 413         if (!running_)
 414                 startCaller();
 415         return ptr;
 416 }
 417
 418
 419 void callNext()
 420 {
 421         if (callQueue_.empty())
 422                 return;
 423         Process pro = callQueue_.front();
 424         callQueue_.pop();
 425         // Bind our chain caller
 426         pro.second->connect(boost::bind(&ForkedCallQueue::callback, _1, _2));
 427         ForkedCall call;
 428         // If we fail to fork the process, then emit the signal
 429         // to tell the outside world that it failed.
 430         if (call.startScript(pro.first, pro.second) > 0)
 431                 pro.second->operator()(0,1);
 432 }
 433
 434
 435 void callback(pid_t, int)
 436 {
 437         if (callQueue_.empty())
 438                 stopCaller();
 439         else
 440                 callNext();
 441 }
 442
 443
 444 void startCaller()
 445 {
 446         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 447         running_ = true ;
 448         callNext();
 449 }
 450
 451
 452 void stopCaller()
 453 {
 454         running_ = false ;
 455         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 456 }
 457
 458
 459 bool running()
 460 {
 461         return running_;
 462 }
 463
 464 } // namespace ForkedCallsQueue
 465
 466
 467
 468 /////////////////////////////////////////////////////////////////////
 469 //
 470 // ForkedCallsController
 471 //
 472 /////////////////////////////////////////////////////////////////////
 473
 474 #if defined(_WIN32)
 475 string const getChildErrorMessage()
 476 {
 477         DWORD const error_code = ::GetLastError();
 478
 479         HLOCAL t_message = 0;
 480         bool const ok = ::FormatMessage(
 481                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 482                 FORMAT_MESSAGE_FROM_SYSTEM,
 483                 0, error_code,
 484                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 485                 (LPTSTR) &t_message, 0, 0
 486                 ) != 0;
 487
 488         ostringstream ss;
 489         ss << "LyX: Error waiting for child: " << error_code;
 490
 491         if (ok) {
 492                 ss << ": " << (LPTSTR)t_message;
 493                 ::LocalFree(t_message);
 494         } else
 495                 ss << ": Error unknown.";
 496
 497         return ss.str();
 498 }
 499 #endif
 500
 501
 502 namespace ForkedCallsController {
 503
 504 typedef boost::shared_ptr<ForkedProcess> ForkedProcessPtr;
 505 typedef list<ForkedProcessPtr> ListType;
 506 typedef ListType::iterator iterator;
 507
 508
 509 /// The child processes
 510 static ListType forkedCalls;
 511
 512 iterator find_pid(pid_t pid)
 513 {
 514         return find_if(forkedCalls.begin(), forkedCalls.end(),
 515                        bind(equal_to<pid_t>(),
 516                             bind(&ForkedCall::pid, _1),
 517                             pid));
 518 }
 519
 520
 521 void addCall(ForkedProcess const & newcall)
 522 {
 523         forkedCalls.push_back(newcall.clone());
 524 }
 525
 526
 527 // Check the list of dead children and emit any associated signals.
 528 void handleCompletedProcesses()
 529 {
 530         ListType::iterator it  = forkedCalls.begin();
 531         ListType::iterator end = forkedCalls.end();
 532         while (it != end) {
 533                 ForkedProcessPtr actCall = *it;
 534                 bool remove_it = false;
 535
 536 #if defined(_WIN32)
 537                 HANDLE const hProcess = HANDLE(actCall->pid());
 538
 539                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 540
 541                 switch (wait_status) {
 542                 case WAIT_TIMEOUT:
 543                         // Still running
 544                         break;
 545                 case WAIT_OBJECT_0: {
 546                         DWORD exit_code = 0;
 547                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 548                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 549                                        << getChildErrorMessage() << endl;
 550                                 // Child died, so pretend it returned 1
 551                                 actCall->setRetValue(1);
 552                         } else {
 553                                 actCall->setRetValue(exit_code);
 554                         }
 555                         remove_it = true;
 556                         break;
 557                 }
 558                 case WAIT_FAILED:
 559                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 560                                << getChildErrorMessage() << endl;
 561                         actCall->setRetValue(1);
 562                         remove_it = true;
 563                         break;
 564                 }
 565 #else
 566                 pid_t pid = actCall->pid();
 567                 int stat_loc;
 568                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 569
 570                 if (waitrpid == -1) {
 571                         lyxerr << "LyX: Error waiting for child: "
 572                                << strerror(errno) << endl;
 573
 574                         // Child died, so pretend it returned 1
 575                         actCall->setRetValue(1);
 576                         remove_it = true;
 577
 578                 } else if (waitrpid == 0) {
 579                         // Still running. Move on to the next child.
 580
 581                 } else if (WIFEXITED(stat_loc)) {
 582                         // Ok, the return value goes into retval.
 583                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 584                         remove_it = true;
 585
 586                 } else if (WIFSIGNALED(stat_loc)) {
 587                         // Child died, so pretend it returned 1
 588                         actCall->setRetValue(1);
 589                         remove_it = true;
 590
 591                 } else if (WIFSTOPPED(stat_loc)) {
 592                         lyxerr << "LyX: Child (pid: " << pid
 593                                << ") stopped on signal "
 594                                << WSTOPSIG(stat_loc)
 595                                << ". Waiting for child to finish." << endl;
 596
 597                 } else {
 598                         lyxerr << "LyX: Something rotten happened while "
 599                                 "waiting for child " << pid << endl;
 600
 601                         // Child died, so pretend it returned 1
 602                         actCall->setRetValue(1);
 603                         remove_it = true;
 604                 }
 605 #endif
 606
 607                 if (remove_it) {
 608                         forkedCalls.erase(it);
 609                         actCall->emitSignal();
 610
 611                         /* start all over: emiting the signal can result
 612                          * in changing the list (Ab)
 613                          */
 614                         it = forkedCalls.begin();
 615                 } else {
 616                         ++it;
 617                 }
 618         }
 619 }
 620
 621
 622 // Kill the process prematurely and remove it from the list
 623 // within tolerance secs
 624 void kill(pid_t pid, int tolerance)
 625 {
 626         ListType::iterator it = find_pid(pid);
 627         if (it == forkedCalls.end())
 628                 return;
 629
 630         (*it)->kill(tolerance);
 631         forkedCalls.erase(it);
 632 }
 633
 634 } // namespace ForkedCallsController
 635
 636 } // namespace support
 637 } // namespace lyx