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 namespace lyx {
  51 namespace support {
  52
  53 namespace {
  54
  55 /////////////////////////////////////////////////////////////////////
  56 //
  57 // Murder
  58 //
  59 /////////////////////////////////////////////////////////////////////
  60
  61 class Murder {
  62 public:
  63         //
  64         static void killItDead(int secs, pid_t pid)
  65         {
  66                 if (secs > 0)
  67                         new Murder(secs, pid);
  68                 else if (pid != 0)
  69                         support::kill(pid, SIGKILL);
  70         }
  71
  72         //
  73         void kill()
  74         {
  75                 if (pid_ != 0)
  76                         support::kill(pid_, SIGKILL);
  77                 lyxerr << "Killed " << pid_ << endl;
  78                 delete this;
  79         }
  80
  81 private:
  82         //
  83         Murder(int secs, pid_t pid)
  84                 : timeout_(1000*secs, Timeout::ONETIME), pid_(pid)
  85         {
  86                 // Connection is closed with this.
  87                 timeout_.timeout.connect([this](){ kill(); });
  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_) {
 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, string const & lpath)
 274         : cmd_prefix_(to_filesystem8bit(from_utf8(latexEnvCmdPrefix(path, lpath))))
 275 {}
 276
 277
 278 int ForkedCall::startScript(Starttype wait, string const & what)
 279 {
 280         if (wait != Wait) {
 281                 retval_ = startScript(what, sigPtr());
 282                 return retval_;
 283         }
 284
 285         command_ = commandPrep(trim(what));
 286         signal_.reset();
 287         return run(Wait);
 288 }
 289
 290
 291 int ForkedCall::startScript(string const & what, sigPtr signal)
 292 {
 293         command_ = commandPrep(trim(what));
 294         signal_  = signal;
 295
 296         return run(DontWait);
 297 }
 298
 299
 300 // generate child in background
 301 int ForkedCall::generateChild()
 302 {
 303         if (command_.empty())
 304                 return 1;
 305
 306         // Make sure that a V2 python is run, if available.
 307         string const line = cmd_prefix_ +
 308                 (prefixIs(command_, "python -tt")
 309                  ? os::python() + command_.substr(10) : command_);
 310
 311 #if !defined (_WIN32)
 312         // POSIX
 313
 314         // Split the input command up into an array of words stored
 315         // in a contiguous block of memory. The array contains pointers
 316         // to each word.
 317         // Don't forget the terminating `\0' character.
 318         char const * const c_str = line.c_str();
 319         vector<char> vec(c_str, c_str + line.size() + 1);
 320
 321         // Splitting the command up into an array of words means replacing
 322         // the whitespace between words with '\0'. Life is complicated
 323         // however, because words protected by quotes can contain whitespace.
 324         //
 325         // The strategy we adopt is:
 326         // 1. If we're not inside quotes, then replace white space with '\0'.
 327         // 2. If we are inside quotes, then don't replace the white space
 328         //    but do remove the quotes themselves. We do this naively by
 329         //    replacing the quote with '\0' which is fine if quotes
 330         //    delimit the entire word. However, if quotes do not delimit the
 331         //    entire word (i.e., open quote is inside word), simply discard
 332         //    them such as not to break the current word.
 333         char inside_quote = 0;
 334         char c_before_open_quote = ' ';
 335         vector<char>::iterator it = vec.begin();
 336         vector<char>::iterator itc = vec.begin();
 337         vector<char>::iterator const end = vec.end();
 338         for (; it != end; ++it, ++itc) {
 339                 char const c = *it;
 340                 if (!inside_quote) {
 341                         if (c == '\'' || c == '"') {
 342                                 if (c_before_open_quote == ' ')
 343                                         *itc = '\0';
 344                                 else
 345                                         --itc;
 346                                 inside_quote = c;
 347                         } else {
 348                                 if (c == ' ')
 349                                         *itc = '\0';
 350                                 else
 351                                         *itc = c;
 352                                 c_before_open_quote = c;
 353                         }
 354                 } else if (c == inside_quote) {
 355                         if (c_before_open_quote == ' ')
 356                                 *itc = '\0';
 357                         else
 358                                 --itc;
 359                         inside_quote = 0;
 360                 } else
 361                         *itc = c;
 362         }
 363
 364         // Clear what remains.
 365         for (; itc != end; ++itc)
 366                 *itc = '\0';
 367
 368         // Build an array of pointers to each word.
 369         it = vec.begin();
 370         vector<char *> argv;
 371         char prev = '\0';
 372         for (; it != end; ++it) {
 373                 if (*it != '\0' && prev == '\0')
 374                         argv.push_back(&*it);
 375                 prev = *it;
 376         }
 377         argv.push_back(0);
 378
 379         // Debug output.
 380         if (lyxerr.debugging(Debug::FILES)) {
 381                 vector<char *>::iterator ait = argv.begin();
 382                 vector<char *>::iterator const aend = argv.end();
 383                 lyxerr << "<command>\n\t" << line
 384                        << "\n\tInterpreted as:\n\n";
 385                 for (; ait != aend; ++ait)
 386                         if (*ait)
 387                                 lyxerr << '\t'<< *ait << '\n';
 388                 lyxerr << "</command>" << endl;
 389         }
 390
 391         pid_t const cpid = ::fork();
 392         if (cpid == 0) {
 393                 // Child
 394                 execvp(argv[0], &*argv.begin());
 395
 396                 // If something goes wrong, we end up here
 397                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 398                        << strerror(errno) << endl;
 399                 _exit(1);
 400         }
 401 #else
 402         // Windows
 403
 404         pid_t cpid = -1;
 405
 406         STARTUPINFO startup;
 407         PROCESS_INFORMATION process;
 408
 409         memset(&startup, 0, sizeof(STARTUPINFO));
 410         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 411
 412         startup.cb = sizeof(STARTUPINFO);
 413
 414         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 415                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 416                 CloseHandle(process.hThread);
 417                 cpid = (pid_t)process.hProcess;
 418         }
 419 #endif
 420
 421         if (cpid < 0) {
 422                 // Error.
 423                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 424         }
 425
 426         return cpid;
 427 }
 428
 429
 430 /////////////////////////////////////////////////////////////////////
 431 //
 432 // ForkedCallQueue
 433 //
 434 /////////////////////////////////////////////////////////////////////
 435
 436 namespace ForkedCallQueue {
 437
 438 /// A process in the queue
 439 typedef pair<string, ForkedCall::sigPtr> Process;
 440 /** Add a process to the queue. Processes are forked sequentially
 441  *  only one is running at a time.
 442  *  Connect to the returned signal and you'll be informed when
 443  *  the process has ended.
 444  */
 445 ForkedCall::sigPtr add(string const & process);
 446
 447 /// in-progress queue
 448 static queue<Process> callQueue_;
 449
 450 /// flag whether queue is running
 451 static bool running_ = 0;
 452
 453 ///
 454 void startCaller();
 455 ///
 456 void stopCaller();
 457 ///
 458 void callback(pid_t, int);
 459
 460 ForkedCall::sigPtr add(string const & process)
 461 {
 462         ForkedCall::sigPtr ptr;
 463         ptr.reset(new ForkedCall::sig);
 464         callQueue_.push(Process(process, ptr));
 465         if (!running_)
 466                 startCaller();
 467         return ptr;
 468 }
 469
 470
 471 void callNext()
 472 {
 473         if (callQueue_.empty())
 474                 return;
 475         Process pro = callQueue_.front();
 476         callQueue_.pop();
 477         // Bind our chain caller
 478         pro.second->connect(callback);
 479         ForkedCall call;
 480         //If we fail to fork the process, then emit the signal
 481         //to tell the outside world that it failed.
 482         if (call.startScript(pro.first, pro.second) > 0)
 483                 pro.second->operator()(0,1);
 484 }
 485
 486
 487 void callback(pid_t, int)
 488 {
 489         if (callQueue_.empty())
 490                 stopCaller();
 491         else
 492                 callNext();
 493 }
 494
 495
 496 void startCaller()
 497 {
 498         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 499         running_ = true ;
 500         callNext();
 501 }
 502
 503
 504 void stopCaller()
 505 {
 506         running_ = false ;
 507         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 508 }
 509
 510
 511 bool running()
 512 {
 513         return running_;
 514 }
 515
 516 } // namespace ForkedCallsQueue
 517
 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: emiting 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