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 "support/bind.h"
  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
  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(lyx::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 bool ForkedProcess::IAmAChild = false;
 112
 113
 114 void ForkedProcess::emitSignal()
 115 {
 116         if (signal_.get()) {
 117                 signal_->operator()(pid_, retval_);
 118         }
 119 }
 120
 121
 122 // Spawn the child process
 123 int ForkedProcess::run(Starttype type)
 124 {
 125         retval_ = 0;
 126         pid_ = generateChild();
 127         if (pid_ <= 0) { // child or fork failed.
 128                 retval_ = 1;
 129                 if (pid_ == 0)
 130                         //we also do this in fork(), too, but maybe someone will try
 131                         //to bypass that
 132                         IAmAChild = true;
 133                 return retval_;
 134         }
 135
 136         switch (type) {
 137         case Wait:
 138                 retval_ = waitForChild();
 139                 break;
 140         case DontWait: {
 141                 // Integrate into the Controller
 142                 ForkedCallsController::addCall(*this);
 143                 break;
 144         }
 145         }
 146
 147         return retval_;
 148 }
 149
 150
 151 bool ForkedProcess::running() const
 152 {
 153         if (pid() <= 0)
 154                 return false;
 155
 156 #if !defined (_WIN32)
 157         // Un-UNIX like, but we don't have much use for
 158         // knowing if a zombie exists, so just reap it first.
 159         int waitstatus;
 160         waitpid(pid(), &waitstatus, WNOHANG);
 161 #endif
 162
 163         // Racy of course, but it will do.
 164         if (support::kill(pid(), 0) && errno == ESRCH)
 165                 return false;
 166         return true;
 167 }
 168
 169
 170 void ForkedProcess::kill(int tol)
 171 {
 172         lyxerr << "ForkedProcess::kill(" << tol << ')' << endl;
 173         if (pid() <= 0) {
 174                 lyxerr << "Can't kill non-existent process!" << endl;
 175                 return;
 176         }
 177
 178         int const tolerance = max(0, tol);
 179         if (tolerance == 0) {
 180                 // Kill it dead NOW!
 181                 Murder::killItDead(0, pid());
 182         } else {
 183                 int ret = support::kill(pid(), SIGHUP);
 184
 185                 // The process is already dead if wait_for_death is false
 186                 bool const wait_for_death = (ret == 0 && errno != ESRCH);
 187
 188                 if (wait_for_death)
 189                         Murder::killItDead(tolerance, pid());
 190         }
 191 }
 192
 193
 194 pid_t ForkedProcess::fork() {
 195 #if !defined (HAVE_FORK)
 196         return -1;
 197 #else
 198         pid_t pid = ::fork();
 199         if (pid == 0)
 200                 IAmAChild = true;
 201         return pid;
 202 #endif
 203 }
 204
 205
 206 // Wait for child process to finish. Returns returncode from child.
 207 int ForkedProcess::waitForChild()
 208 {
 209         // We'll pretend that the child returns 1 on all error conditions.
 210         retval_ = 1;
 211
 212 #if defined (_WIN32)
 213         HANDLE const hProcess = HANDLE(pid_);
 214
 215         DWORD const wait_status = ::WaitForSingleObject(hProcess, INFINITE);
 216
 217         switch (wait_status) {
 218         case WAIT_OBJECT_0: {
 219                 DWORD exit_code = 0;
 220                 if (!GetExitCodeProcess(hProcess, &exit_code)) {
 221                         lyxerr << "GetExitCodeProcess failed waiting for child\n"
 222                                << getChildErrorMessage() << endl;
 223                 } else
 224                         retval_ = exit_code;
 225                 break;
 226         }
 227         case WAIT_FAILED:
 228                 lyxerr << "WaitForSingleObject failed waiting for child\n"
 229                        << getChildErrorMessage() << endl;
 230                 break;
 231         }
 232
 233 #else
 234         int status;
 235         bool wait = true;
 236         while (wait) {
 237                 pid_t waitrpid = waitpid(pid_, &status, WUNTRACED);
 238                 if (waitrpid == -1) {
 239                         lyxerr << "LyX: Error waiting for child:"
 240                                << strerror(errno) << endl;
 241                         wait = false;
 242                 } else if (WIFEXITED(status)) {
 243                         // Child exited normally. Update return value.
 244                         retval_ = WEXITSTATUS(status);
 245                         wait = false;
 246                 } else if (WIFSIGNALED(status)) {
 247                         lyxerr << "LyX: Child didn't catch signal "
 248                                << WTERMSIG(status)
 249                                << "and died. Too bad." << endl;
 250                         wait = false;
 251                 } else if (WIFSTOPPED(status)) {
 252                         lyxerr << "LyX: Child (pid: " << pid_
 253                                << ") stopped on signal "
 254                                << WSTOPSIG(status)
 255                                << ". Waiting for child to finish." << endl;
 256                 } else {
 257                         lyxerr << "LyX: Something rotten happened while "
 258                                 "waiting for child " << pid_ << endl;
 259                         wait = false;
 260                 }
 261         }
 262 #endif
 263         return retval_;
 264 }
 265
 266
 267 /////////////////////////////////////////////////////////////////////
 268 //
 269 // ForkedCall
 270 //
 271 /////////////////////////////////////////////////////////////////////
 272
 273 ForkedCall::ForkedCall(string const & path)
 274         : cmd_prefix_(to_filesystem8bit(from_utf8(latexEnvCmdPrefix(path))))
 275 {}
 276
 277
 278 int ForkedCall::startScript(Starttype wait, string const & what)
 279 {
 280         if (wait != Wait) {
 281                 retval_ = startScript(what, SignalTypePtr());
 282                 return retval_;
 283         }
 284
 285         command_ = what;
 286         signal_.reset();
 287         return run(Wait);
 288 }
 289
 290
 291 int ForkedCall::startScript(string const & what, SignalTypePtr signal)
 292 {
 293         command_ = what;
 294         signal_  = signal;
 295
 296         return run(DontWait);
 297 }
 298
 299
 300 // generate child in background
 301 int ForkedCall::generateChild()
 302 {
 303         string const line = trim(cmd_prefix_ + command_);
 304         if (line.empty())
 305                 return 1;
 306
 307 #if !defined (_WIN32)
 308         // POSIX
 309
 310         // Split the input command up into an array of words stored
 311         // in a contiguous block of memory. The array contains pointers
 312         // to each word.
 313         // Don't forget the terminating `\0' character.
 314         char const * const c_str = line.c_str();
 315         vector<char> vec(c_str, c_str + line.size() + 1);
 316
 317         // Splitting the command up into an array of words means replacing
 318         // the whitespace between words with '\0'. Life is complicated
 319         // however, because words protected by quotes can contain whitespace.
 320         //
 321         // The strategy we adopt is:
 322         // 1. If we're not inside quotes, then replace white space with '\0'.
 323         // 2. If we are inside quotes, then don't replace the white space
 324         //    but do remove the quotes themselves. We do this naively by
 325         //    replacing the quote with '\0' which is fine if quotes
 326         //    delimit the entire word. However, if quotes do not delimit the
 327         //    entire word (i.e., open quote is inside word), leave them alone.
 328         char inside_quote = 0;
 329         char c_before_open_quote = ' ';
 330         vector<char>::iterator it = vec.begin();
 331         vector<char>::iterator const end = vec.end();
 332         for (; it != end; ++it) {
 333                 char const c = *it;
 334                 if (!inside_quote) {
 335                         if (c == '\'' || c == '"') {
 336                                 if (c_before_open_quote == ' ')
 337                                         *it = '\0';
 338                                 inside_quote = c;
 339                         } else {
 340                                 if (c == ' ')
 341                                         *it = '\0';
 342                                 c_before_open_quote = c;
 343                         }
 344                 } else if (c == inside_quote) {
 345                         if (c_before_open_quote = ' ')
 346                                 *it = '\0';
 347                         inside_quote = 0;
 348                 }
 349         }
 350
 351         // Build an array of pointers to each word.
 352         it = vec.begin();
 353         vector<char *> argv;
 354         char prev = '\0';
 355         for (; it != end; ++it) {
 356                 if (*it != '\0' && prev == '\0')
 357                         argv.push_back(&*it);
 358                 prev = *it;
 359         }
 360         argv.push_back(0);
 361
 362         // Debug output.
 363         if (lyxerr.debugging(Debug::FILES)) {
 364                 vector<char *>::iterator ait = argv.begin();
 365                 vector<char *>::iterator const aend = argv.end();
 366                 lyxerr << "<command>\n\t" << line
 367                        << "\n\tInterpretted as:\n\n";
 368                 for (; ait != aend; ++ait)
 369                         if (*ait)
 370                                 lyxerr << '\t'<< *ait << '\n';
 371                 lyxerr << "</command>" << endl;
 372         }
 373
 374         pid_t const cpid = ::fork();
 375         if (cpid == 0) {
 376                 // Child
 377                 execvp(argv[0], &*argv.begin());
 378
 379                 // If something goes wrong, we end up here
 380                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 381                        << strerror(errno) << endl;
 382                 _exit(1);
 383         }
 384 #else
 385         // Windows
 386
 387         pid_t cpid = -1;
 388
 389         STARTUPINFO startup;
 390         PROCESS_INFORMATION process;
 391
 392         memset(&startup, 0, sizeof(STARTUPINFO));
 393         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 394
 395         startup.cb = sizeof(STARTUPINFO);
 396
 397         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 398                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 399                 CloseHandle(process.hThread);
 400                 cpid = (pid_t)process.hProcess;
 401         }
 402 #endif
 403
 404         if (cpid < 0) {
 405                 // Error.
 406                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 407         }
 408
 409         return cpid;
 410 }
 411
 412
 413 /////////////////////////////////////////////////////////////////////
 414 //
 415 // ForkedCallQueue
 416 //
 417 /////////////////////////////////////////////////////////////////////
 418
 419 namespace ForkedCallQueue {
 420
 421 /// A process in the queue
 422 typedef pair<string, ForkedCall::SignalTypePtr> Process;
 423 /** Add a process to the queue. Processes are forked sequentially
 424  *  only one is running at a time.
 425  *  Connect to the returned signal and you'll be informed when
 426  *  the process has ended.
 427  */
 428 ForkedCall::SignalTypePtr add(string const & process);
 429
 430 /// in-progress queue
 431 static queue<Process> callQueue_;
 432
 433 /// flag whether queue is running
 434 static bool running_ = 0;
 435
 436 ///
 437 void startCaller();
 438 ///
 439 void stopCaller();
 440 ///
 441 void callback(pid_t, int);
 442
 443 ForkedCall::SignalTypePtr add(string const & process)
 444 {
 445         ForkedCall::SignalTypePtr ptr;
 446         ptr.reset(new ForkedCall::SignalType);
 447         callQueue_.push(Process(process, ptr));
 448         if (!running_)
 449                 startCaller();
 450         return ptr;
 451 }
 452
 453
 454 void callNext()
 455 {
 456         if (callQueue_.empty())
 457                 return;
 458         Process pro = callQueue_.front();
 459         callQueue_.pop();
 460         // Bind our chain caller
 461         pro.second->connect(lyx::bind(&ForkedCallQueue::callback, _1, _2));
 462         ForkedCall call;
 463         //If we fail to fork the process, then emit the signal
 464         //to tell the outside world that it failed.
 465         if (call.startScript(pro.first, pro.second) > 0)
 466                 pro.second->operator()(0,1);
 467 }
 468
 469
 470 void callback(pid_t, int)
 471 {
 472         if (callQueue_.empty())
 473                 stopCaller();
 474         else
 475                 callNext();
 476 }
 477
 478
 479 void startCaller()
 480 {
 481         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 482         running_ = true ;
 483         callNext();
 484 }
 485
 486
 487 void stopCaller()
 488 {
 489         running_ = false ;
 490         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 491 }
 492
 493
 494 bool running()
 495 {
 496         return running_;
 497 }
 498
 499 } // namespace ForkedCallsQueue
 500
 501
 502
 503 /////////////////////////////////////////////////////////////////////
 504 //
 505 // ForkedCallsController
 506 //
 507 /////////////////////////////////////////////////////////////////////
 508
 509 #if defined(_WIN32)
 510 string const getChildErrorMessage()
 511 {
 512         DWORD const error_code = ::GetLastError();
 513
 514         HLOCAL t_message = 0;
 515         bool const ok = ::FormatMessage(
 516                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 517                 FORMAT_MESSAGE_FROM_SYSTEM,
 518                 0, error_code,
 519                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 520                 (LPTSTR) &t_message, 0, 0
 521                 ) != 0;
 522
 523         ostringstream ss;
 524         ss << "LyX: Error waiting for child: " << error_code;
 525
 526         if (ok) {
 527                 ss << ": " << (LPTSTR)t_message;
 528                 ::LocalFree(t_message);
 529         } else
 530                 ss << ": Error unknown.";
 531
 532         return ss.str();
 533 }
 534 #endif
 535
 536
 537 namespace ForkedCallsController {
 538
 539 typedef shared_ptr<ForkedProcess> ForkedProcessPtr;
 540 typedef list<ForkedProcessPtr> ListType;
 541 typedef ListType::iterator iterator;
 542
 543
 544 /// The child processes
 545 static ListType forkedCalls;
 546
 547 iterator find_pid(pid_t pid)
 548 {
 549         return find_if(forkedCalls.begin(), forkedCalls.end(),
 550                             lyx::bind(equal_to<pid_t>(),
 551                             lyx::bind(&ForkedCall::pid, _1),
 552                             pid));
 553 }
 554
 555
 556 void addCall(ForkedProcess const & newcall)
 557 {
 558         forkedCalls.push_back(newcall.clone());
 559 }
 560
 561
 562 // Check the list of dead children and emit any associated signals.
 563 void handleCompletedProcesses()
 564 {
 565         ListType::iterator it  = forkedCalls.begin();
 566         ListType::iterator end = forkedCalls.end();
 567         while (it != end) {
 568                 ForkedProcessPtr actCall = *it;
 569                 bool remove_it = false;
 570
 571 #if defined(_WIN32)
 572                 HANDLE const hProcess = HANDLE(actCall->pid());
 573
 574                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 575
 576                 switch (wait_status) {
 577                 case WAIT_TIMEOUT:
 578                         // Still running
 579                         break;
 580                 case WAIT_OBJECT_0: {
 581                         DWORD exit_code = 0;
 582                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 583                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 584                                        << getChildErrorMessage() << endl;
 585                                 // Child died, so pretend it returned 1
 586                                 actCall->setRetValue(1);
 587                         } else {
 588                                 actCall->setRetValue(exit_code);
 589                         }
 590                         CloseHandle(hProcess);
 591                         remove_it = true;
 592                         break;
 593                 }
 594                 case WAIT_FAILED:
 595                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 596                                << getChildErrorMessage() << endl;
 597                         actCall->setRetValue(1);
 598                         CloseHandle(hProcess);
 599                         remove_it = true;
 600                         break;
 601                 }
 602 #else
 603                 pid_t pid = actCall->pid();
 604                 int stat_loc;
 605                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 606
 607                 if (waitrpid == -1) {
 608                         lyxerr << "LyX: Error waiting for child: "
 609                                << strerror(errno) << endl;
 610
 611                         // Child died, so pretend it returned 1
 612                         actCall->setRetValue(1);
 613                         remove_it = true;
 614
 615                 } else if (waitrpid == 0) {
 616                         // Still running. Move on to the next child.
 617
 618                 } else if (WIFEXITED(stat_loc)) {
 619                         // Ok, the return value goes into retval.
 620                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 621                         remove_it = true;
 622
 623                 } else if (WIFSIGNALED(stat_loc)) {
 624                         // Child died, so pretend it returned 1
 625                         actCall->setRetValue(1);
 626                         remove_it = true;
 627
 628                 } else if (WIFSTOPPED(stat_loc)) {
 629                         lyxerr << "LyX: Child (pid: " << pid
 630                                << ") stopped on signal "
 631                                << WSTOPSIG(stat_loc)
 632                                << ". Waiting for child to finish." << endl;
 633
 634                 } else {
 635                         lyxerr << "LyX: Something rotten happened while "
 636                                 "waiting for child " << pid << endl;
 637
 638                         // Child died, so pretend it returned 1
 639                         actCall->setRetValue(1);
 640                         remove_it = true;
 641                 }
 642 #endif
 643
 644                 if (remove_it) {
 645                         forkedCalls.erase(it);
 646                         actCall->emitSignal();
 647
 648                         /* start all over: emiting the signal can result
 649                          * in changing the list (Ab)
 650                          */
 651                         it = forkedCalls.begin();
 652                 } else {
 653                         ++it;
 654                 }
 655         }
 656 }
 657
 658
 659 // Kill the process prematurely and remove it from the list
 660 // within tolerance secs
 661 void kill(pid_t pid, int tolerance)
 662 {
 663         ListType::iterator it = find_pid(pid);
 664         if (it == forkedCalls.end())
 665                 return;
 666
 667         (*it)->kill(tolerance);
 668         forkedCalls.erase(it);
 669 }
 670
 671 } // namespace ForkedCallsController
 672
 673 } // namespace support
 674 } // namespace lyx