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 <cstring>
  28 #include <list>
  29 #include <queue>
  30 #include <sstream>
  31 #include <utility>
  32 #include <vector>
  33
  34 #ifdef _WIN32
  35 # define SIGHUP 1
  36 # define SIGKILL 9
  37 # include <windows.h>
  38 # include <process.h>
  39 # undef max
  40 #else
  41 # include <csignal>
  42 # include <cstdlib>
  43 # ifdef HAVE_UNISTD_H
  44 #  include <unistd.h>
  45 # endif
  46 # include <sys/wait.h>
  47 #endif
  48
  49 using namespace std;
  50
  51
  52 namespace lyx {
  53 namespace support {
  54
  55 namespace {
  56
  57 /////////////////////////////////////////////////////////////////////
  58 //
  59 // Murder
  60 //
  61 /////////////////////////////////////////////////////////////////////
  62
  63 class Murder {
  64 public:
  65         //
  66         static void killItDead(int secs, pid_t pid)
  67         {
  68                 if (secs > 0)
  69                         new Murder(secs, pid);
  70                 else if (pid != 0)
  71                         support::kill(pid, SIGKILL);
  72         }
  73
  74         //
  75         void kill()
  76         {
  77                 if (pid_ != 0)
  78                         support::kill(pid_, SIGKILL);
  79                 lyxerr << "Killed " << pid_ << endl;
  80                 delete this;
  81         }
  82
  83 private:
  84         //
  85         Murder(int secs, pid_t pid)
  86                 : timeout_(1000*secs, Timeout::ONETIME), pid_(pid)
  87         {
  88                 // Connection is closed with this.
  89                 timeout_.timeout.connect([this](){ kill(); });
  90                 timeout_.start();
  91         }
  92
  93         //
  94         Timeout timeout_;
  95         //
  96         pid_t pid_;
  97 };
  98
  99 } // namespace
 100
 101
 102 /////////////////////////////////////////////////////////////////////
 103 //
 104 // ForkedProcess
 105 //
 106 /////////////////////////////////////////////////////////////////////
 107
 108 ForkedProcess::ForkedProcess()
 109         : pid_(0), retval_(0)
 110 {}
 111
 112
 113 bool ForkedProcess::IAmAChild = false;
 114
 115
 116 void ForkedProcess::emitSignal()
 117 {
 118         if (signal_) {
 119                 signal_->operator()(pid_, retval_);
 120         }
 121 }
 122
 123
 124 // Spawn the child process
 125 int ForkedProcess::run(Starttype type)
 126 {
 127         retval_ = 0;
 128         pid_ = generateChild();
 129         if (pid_ <= 0) { // child or fork failed.
 130                 retval_ = 1;
 131                 if (pid_ == 0)
 132                         //we also do this in fork(), too, but maybe someone will try
 133                         //to bypass that
 134                         IAmAChild = true;
 135                 return retval_;
 136         }
 137
 138         switch (type) {
 139         case Wait:
 140                 retval_ = waitForChild();
 141                 break;
 142         case DontWait: {
 143                 // Integrate into the Controller
 144                 ForkedCallsController::addCall(*this);
 145                 break;
 146         }
 147         }
 148
 149         return retval_;
 150 }
 151
 152
 153 bool ForkedProcess::running() const
 154 {
 155         if (pid() <= 0)
 156                 return false;
 157
 158 #if !defined (_WIN32)
 159         // Un-UNIX like, but we don't have much use for
 160         // knowing if a zombie exists, so just reap it first.
 161         int waitstatus;
 162         waitpid(pid(), &waitstatus, WNOHANG);
 163 #endif
 164
 165         // Racy of course, but it will do.
 166         if (support::kill(pid(), 0) && errno == ESRCH)
 167                 return false;
 168         return true;
 169 }
 170
 171
 172 void ForkedProcess::kill(int tol)
 173 {
 174         lyxerr << "ForkedProcess::kill(" << tol << ')' << endl;
 175         if (pid() <= 0) {
 176                 lyxerr << "Can't kill non-existent process!" << endl;
 177                 return;
 178         }
 179
 180         int const tolerance = max(0, tol);
 181         if (tolerance == 0) {
 182                 // Kill it dead NOW!
 183                 Murder::killItDead(0, pid());
 184         } else {
 185                 int ret = support::kill(pid(), SIGHUP);
 186
 187                 // The process is already dead if wait_for_death is false
 188                 bool const wait_for_death = (ret == 0 && errno != ESRCH);
 189
 190                 if (wait_for_death)
 191                         Murder::killItDead(tolerance, pid());
 192         }
 193 }
 194
 195
 196 pid_t ForkedProcess::fork() {
 197 #if !defined (HAVE_FORK)
 198         return -1;
 199 #else
 200         pid_t pid = ::fork();
 201         if (pid == 0)
 202                 IAmAChild = true;
 203         return pid;
 204 #endif
 205 }
 206
 207
 208 // Wait for child process to finish. Returns returncode from child.
 209 int ForkedProcess::waitForChild()
 210 {
 211         // We'll pretend that the child returns 1 on all error conditions.
 212         retval_ = 1;
 213
 214 #if defined (_WIN32)
 215         HANDLE const hProcess = HANDLE(pid_);
 216
 217         DWORD const wait_status = ::WaitForSingleObject(hProcess, INFINITE);
 218
 219         switch (wait_status) {
 220         case WAIT_OBJECT_0: {
 221                 DWORD exit_code = 0;
 222                 if (!GetExitCodeProcess(hProcess, &exit_code)) {
 223                         lyxerr << "GetExitCodeProcess failed waiting for child\n"
 224                                << getChildErrorMessage() << endl;
 225                 } else
 226                         retval_ = exit_code;
 227                 break;
 228         }
 229         case WAIT_FAILED:
 230                 lyxerr << "WaitForSingleObject failed waiting for child\n"
 231                        << getChildErrorMessage() << endl;
 232                 break;
 233         }
 234
 235 #else
 236         int status;
 237         bool wait = true;
 238         while (wait) {
 239                 pid_t waitrpid = waitpid(pid_, &status, WUNTRACED);
 240                 if (waitrpid == -1) {
 241                         lyxerr << "LyX: Error waiting for child:"
 242                                << strerror(errno) << endl;
 243                         wait = false;
 244                 } else if (WIFEXITED(status)) {
 245                         // Child exited normally. Update return value.
 246                         retval_ = WEXITSTATUS(status);
 247                         wait = false;
 248                 } else if (WIFSIGNALED(status)) {
 249                         lyxerr << "LyX: Child didn't catch signal "
 250                                << WTERMSIG(status)
 251                                << "and died. Too bad." << endl;
 252                         wait = false;
 253                 } else if (WIFSTOPPED(status)) {
 254                         lyxerr << "LyX: Child (pid: " << pid_
 255                                << ") stopped on signal "
 256                                << WSTOPSIG(status)
 257                                << ". Waiting for child to finish." << endl;
 258                 } else {
 259                         lyxerr << "LyX: Something rotten happened while "
 260                                 "waiting for child " << pid_ << endl;
 261                         wait = false;
 262                 }
 263         }
 264 #endif
 265         return retval_;
 266 }
 267
 268
 269 /////////////////////////////////////////////////////////////////////
 270 //
 271 // ForkedCall
 272 //
 273 /////////////////////////////////////////////////////////////////////
 274
 275 ForkedCall::ForkedCall(string const & path, string const & lpath)
 276         : cmd_prefix_(to_filesystem8bit(from_utf8(latexEnvCmdPrefix(path, lpath))))
 277 {}
 278
 279
 280 int ForkedCall::startScript(Starttype wait, string const & what)
 281 {
 282         if (wait != Wait) {
 283                 retval_ = startScript(what, sigPtr());
 284                 return retval_;
 285         }
 286
 287         command_ = commandPrep(trim(what));
 288         signal_.reset();
 289         return run(Wait);
 290 }
 291
 292
 293 int ForkedCall::startScript(string const & what, sigPtr signal)
 294 {
 295         command_ = commandPrep(trim(what));
 296         signal_  = signal;
 297
 298         return run(DontWait);
 299 }
 300
 301
 302 // generate child in background
 303 int ForkedCall::generateChild()
 304 {
 305         if (command_.empty())
 306                 return 1;
 307
 308         // Make sure that a V2 python is run, if available.
 309         string const line = cmd_prefix_ +
 310                 (prefixIs(command_, "python -tt")
 311                  ? os::python() + command_.substr(10) : command_);
 312
 313 #if !defined (_WIN32)
 314         // POSIX
 315
 316         // Split the input command up into an array of words stored
 317         // in a contiguous block of memory. The array contains pointers
 318         // to each word.
 319         // Don't forget the terminating `\0' character.
 320         char const * const c_str = line.c_str();
 321         vector<char> vec(c_str, c_str + line.size() + 1);
 322
 323         // Splitting the command up into an array of words means replacing
 324         // the whitespace between words with '\0'. Life is complicated
 325         // however, because words protected by quotes can contain whitespace.
 326         //
 327         // The strategy we adopt is:
 328         // 1. If we're not inside quotes, then replace white space with '\0'.
 329         // 2. If we are inside quotes, then don't replace the white space
 330         //    but do remove the quotes themselves. We do this naively by
 331         //    replacing the quote with '\0' which is fine if quotes
 332         //    delimit the entire word. However, if quotes do not delimit the
 333         //    entire word (i.e., open quote is inside word), simply discard
 334         //    them such as not to break the current word.
 335         char inside_quote = 0;
 336         char c_before_open_quote = ' ';
 337         vector<char>::iterator it = vec.begin();
 338         vector<char>::iterator itc = vec.begin();
 339         vector<char>::iterator const end = vec.end();
 340         for (; it != end; ++it, ++itc) {
 341                 char const c = *it;
 342                 if (!inside_quote) {
 343                         if (c == '\'' || c == '"') {
 344                                 if (c_before_open_quote == ' ')
 345                                         *itc = '\0';
 346                                 else
 347                                         --itc;
 348                                 inside_quote = c;
 349                         } else {
 350                                 if (c == ' ')
 351                                         *itc = '\0';
 352                                 else
 353                                         *itc = c;
 354                                 c_before_open_quote = c;
 355                         }
 356                 } else if (c == inside_quote) {
 357                         if (c_before_open_quote == ' ')
 358                                 *itc = '\0';
 359                         else
 360                                 --itc;
 361                         inside_quote = 0;
 362                 } else
 363                         *itc = c;
 364         }
 365
 366         // Clear what remains.
 367         for (; itc != end; ++itc)
 368                 *itc = '\0';
 369
 370         // Build an array of pointers to each word.
 371         it = vec.begin();
 372         vector<char *> argv;
 373         char prev = '\0';
 374         for (; it != end; ++it) {
 375                 if (*it != '\0' && prev == '\0')
 376                         argv.push_back(&*it);
 377                 prev = *it;
 378         }
 379         argv.push_back(nullptr);
 380
 381         // Debug output.
 382         if (lyxerr.debugging(Debug::FILES)) {
 383                 vector<char *>::iterator ait = argv.begin();
 384                 vector<char *>::iterator const aend = argv.end();
 385                 lyxerr << "<command>\n\t" << line
 386                        << "\n\tInterpreted as:\n\n";
 387                 for (; ait != aend; ++ait)
 388                         if (*ait)
 389                                 lyxerr << '\t'<< *ait << '\n';
 390                 lyxerr << "</command>" << endl;
 391         }
 392
 393         pid_t const cpid = ::fork();
 394         if (cpid == 0) {
 395                 // Child
 396                 execvp(argv[0], &*argv.begin());
 397
 398                 // If something goes wrong, we end up here
 399                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 400                        << strerror(errno) << endl;
 401                 _exit(1);
 402         }
 403 #else
 404         // Windows
 405
 406         pid_t cpid = -1;
 407
 408         STARTUPINFO startup;
 409         PROCESS_INFORMATION process;
 410
 411         memset(&startup, 0, sizeof(STARTUPINFO));
 412         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 413
 414         startup.cb = sizeof(STARTUPINFO);
 415
 416         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 417                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 418                 CloseHandle(process.hThread);
 419                 cpid = (pid_t)process.hProcess;
 420         }
 421 #endif
 422
 423         if (cpid < 0) {
 424                 // Error.
 425                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 426         }
 427
 428         return cpid;
 429 }
 430
 431
 432 /////////////////////////////////////////////////////////////////////
 433 //
 434 // ForkedCallQueue
 435 //
 436 /////////////////////////////////////////////////////////////////////
 437
 438 namespace ForkedCallQueue {
 439
 440 /// A process in the queue
 441 typedef pair<string, ForkedCall::sigPtr> Process;
 442
 443 /// in-progress queue
 444 static queue<Process> callQueue_;
 445
 446 /// flag whether queue is running
 447 static bool running_ = false;
 448
 449 ///
 450 void startCaller();
 451 ///
 452 void stopCaller();
 453 ///
 454 void callback(pid_t, int);
 455
 456 /** Add a process to the queue. Processes are forked sequentially
 457  *  only one is running at a time.
 458  *  Connect to the returned signal and you'll be informed when
 459  *  the process has ended.
 460  */
 461 ForkedCall::sigPtr add(string const & process)
 462 {
 463         ForkedCall::sigPtr ptr;
 464         ptr.reset(new ForkedCall::sig);
 465         callQueue_.push(Process(process, ptr));
 466         if (!running_)
 467                 startCaller();
 468         return ptr;
 469 }
 470
 471
 472 void callNext()
 473 {
 474         if (callQueue_.empty())
 475                 return;
 476         Process pro = callQueue_.front();
 477         callQueue_.pop();
 478         // Bind our chain caller
 479         pro.second->connect(callback);
 480         ForkedCall call;
 481         //If we fail to fork the process, then emit the signal
 482         //to tell the outside world that it failed.
 483         if (call.startScript(pro.first, pro.second) > 0)
 484                 pro.second->operator()(0,1);
 485 }
 486
 487
 488 void callback(pid_t, int)
 489 {
 490         if (callQueue_.empty())
 491                 stopCaller();
 492         else
 493                 callNext();
 494 }
 495
 496
 497 void startCaller()
 498 {
 499         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 500         running_ = true ;
 501         callNext();
 502 }
 503
 504
 505 void stopCaller()
 506 {
 507         running_ = false ;
 508         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 509 }
 510
 511
 512 bool running()
 513 {
 514         return running_;
 515 }
 516
 517 } // namespace ForkedCallQueue
 518
 519
 520 /////////////////////////////////////////////////////////////////////
 521 //
 522 // ForkedCallsController
 523 //
 524 /////////////////////////////////////////////////////////////////////
 525
 526 #if defined(_WIN32)
 527 string const getChildErrorMessage()
 528 {
 529         DWORD const error_code = ::GetLastError();
 530
 531         HLOCAL t_message = 0;
 532         bool const ok = ::FormatMessage(
 533                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 534                 FORMAT_MESSAGE_FROM_SYSTEM,
 535                 0, error_code,
 536                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 537                 (LPTSTR) &t_message, 0, 0
 538                 ) != 0;
 539
 540         ostringstream ss;
 541         ss << "LyX: Error waiting for child: " << error_code;
 542
 543         if (ok) {
 544                 ss << ": " << (LPTSTR)t_message;
 545                 ::LocalFree(t_message);
 546         } else
 547                 ss << ": Error unknown.";
 548
 549         return ss.str();
 550 }
 551 #endif
 552
 553
 554 namespace ForkedCallsController {
 555
 556 typedef shared_ptr<ForkedProcess> ForkedProcessPtr;
 557 typedef list<ForkedProcessPtr> ListType;
 558 typedef ListType::iterator iterator;
 559
 560
 561 /// The child processes
 562 static ListType forkedCalls;
 563
 564 iterator find_pid(pid_t pid)
 565 {
 566         return find_if(forkedCalls.begin(), forkedCalls.end(),
 567                             lyx::bind(equal_to<pid_t>(),
 568                             lyx::bind(&ForkedCall::pid, _1),
 569                             pid));
 570 }
 571
 572
 573 void addCall(ForkedProcess const & newcall)
 574 {
 575         forkedCalls.push_back(newcall.clone());
 576 }
 577
 578
 579 // Check the list of dead children and emit any associated signals.
 580 void handleCompletedProcesses()
 581 {
 582         ListType::iterator it  = forkedCalls.begin();
 583         ListType::iterator end = forkedCalls.end();
 584         while (it != end) {
 585                 ForkedProcessPtr actCall = *it;
 586                 bool remove_it = false;
 587
 588 #if defined(_WIN32)
 589                 HANDLE const hProcess = HANDLE(actCall->pid());
 590
 591                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 592
 593                 switch (wait_status) {
 594                 case WAIT_TIMEOUT:
 595                         // Still running
 596                         break;
 597                 case WAIT_OBJECT_0: {
 598                         DWORD exit_code = 0;
 599                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 600                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 601                                        << getChildErrorMessage() << endl;
 602                                 // Child died, so pretend it returned 1
 603                                 actCall->setRetValue(1);
 604                         } else {
 605                                 actCall->setRetValue(exit_code);
 606                         }
 607                         CloseHandle(hProcess);
 608                         remove_it = true;
 609                         break;
 610                 }
 611                 case WAIT_FAILED:
 612                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 613                                << getChildErrorMessage() << endl;
 614                         actCall->setRetValue(1);
 615                         CloseHandle(hProcess);
 616                         remove_it = true;
 617                         break;
 618                 }
 619 #else
 620                 pid_t pid = actCall->pid();
 621                 int stat_loc;
 622                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 623
 624                 if (waitrpid == -1) {
 625                         lyxerr << "LyX: Error waiting for child: "
 626                                << strerror(errno) << endl;
 627
 628                         // Child died, so pretend it returned 1
 629                         actCall->setRetValue(1);
 630                         remove_it = true;
 631
 632                 } else if (waitrpid == 0) {
 633                         // Still running. Move on to the next child.
 634
 635                 } else if (WIFEXITED(stat_loc)) {
 636                         // Ok, the return value goes into retval.
 637                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 638                         remove_it = true;
 639
 640                 } else if (WIFSIGNALED(stat_loc)) {
 641                         // Child died, so pretend it returned 1
 642                         actCall->setRetValue(1);
 643                         remove_it = true;
 644
 645                 } else if (WIFSTOPPED(stat_loc)) {
 646                         lyxerr << "LyX: Child (pid: " << pid
 647                                << ") stopped on signal "
 648                                << WSTOPSIG(stat_loc)
 649                                << ". Waiting for child to finish." << endl;
 650
 651                 } else {
 652                         lyxerr << "LyX: Something rotten happened while "
 653                                 "waiting for child " << pid << endl;
 654
 655                         // Child died, so pretend it returned 1
 656                         actCall->setRetValue(1);
 657                         remove_it = true;
 658                 }
 659 #endif
 660
 661                 if (remove_it) {
 662                         forkedCalls.erase(it);
 663                         actCall->emitSignal();
 664
 665                         /* start all over: emitting the signal can result
 666                          * in changing the list (Ab)
 667                          */
 668                         it = forkedCalls.begin();
 669                 } else {
 670                         ++it;
 671                 }
 672         }
 673 }
 674
 675
 676 // Kill the process prematurely and remove it from the list
 677 // within tolerance secs
 678 void kill(pid_t pid, int tolerance)
 679 {
 680         ListType::iterator it = find_pid(pid);
 681         if (it == forkedCalls.end())
 682                 return;
 683
 684         (*it)->kill(tolerance);
 685         forkedCalls.erase(it);
 686 }
 687
 688 } // namespace ForkedCallsController
 689
 690 } // namespace support
 691 } // namespace lyx