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/environment.h"
  19 #include "support/filetools.h"
  20 #include "support/lstrings.h"
  21 #include "support/lyxlib.h"
  22 #include "support/os.h"
  23 #include "support/Timeout.h"
  24
  25 #include "support/bind.h"
  26
  27 #include "LyXRC.h"
  28
  29 #include <cerrno>
  30 #include <queue>
  31 #include <sstream>
  32 #include <utility>
  33 #include <vector>
  34
  35 #ifdef _WIN32
  36 # define SIGHUP 1
  37 # define SIGKILL 9
  38 # include <windows.h>
  39 # include <process.h>
  40 # undef max
  41 #else
  42 # include <csignal>
  43 # include <cstdlib>
  44 # ifdef HAVE_UNISTD_H
  45 #  include <unistd.h>
  46 # endif
  47 # include <sys/wait.h>
  48 #endif
  49
  50 using namespace std;
  51
  52
  53
  54 namespace lyx {
  55 namespace support {
  56
  57 namespace {
  58
  59 /////////////////////////////////////////////////////////////////////
  60 //
  61 // Murder
  62 //
  63 /////////////////////////////////////////////////////////////////////
  64
  65 class Murder : public boost::signals::trackable {
  66 public:
  67         //
  68         static void killItDead(int secs, pid_t pid)
  69         {
  70                 if (secs > 0)
  71                         new Murder(secs, pid);
  72                 else if (pid != 0)
  73                         support::kill(pid, SIGKILL);
  74         }
  75
  76         //
  77         void kill()
  78         {
  79                 if (pid_ != 0)
  80                         support::kill(pid_, SIGKILL);
  81                 lyxerr << "Killed " << pid_ << endl;
  82                 delete this;
  83         }
  84
  85 private:
  86         //
  87         Murder(int secs, pid_t pid)
  88                 : timeout_(1000*secs, Timeout::ONETIME), pid_(pid)
  89         {
  90                 timeout_.timeout.connect(lyx::bind(&Murder::kill, this));
  91                 timeout_.start();
  92         }
  93
  94         //
  95         Timeout timeout_;
  96         //
  97         pid_t pid_;
  98 };
  99
 100 } // namespace anon
 101
 102
 103 /////////////////////////////////////////////////////////////////////
 104 //
 105 // ForkedProcess
 106 //
 107 /////////////////////////////////////////////////////////////////////
 108
 109 ForkedProcess::ForkedProcess()
 110         : pid_(0), retval_(0)
 111 {}
 112
 113
 114 bool ForkedProcess::IAmAChild = false;
 115
 116
 117 void ForkedProcess::emitSignal()
 118 {
 119         if (signal_.get()) {
 120                 signal_->operator()(pid_, retval_);
 121         }
 122 }
 123
 124
 125 // Spawn the child process
 126 int ForkedProcess::run(Starttype type)
 127 {
 128         retval_ = 0;
 129         pid_ = generateChild();
 130         if (pid_ <= 0) { // child or fork failed.
 131                 retval_ = 1;
 132                 if (pid_ == 0)
 133                         //we also do this in fork(), too, but maybe someone will try
 134                         //to bypass that
 135                         IAmAChild = true;
 136                 return retval_;
 137         }
 138
 139         switch (type) {
 140         case Wait:
 141                 retval_ = waitForChild();
 142                 break;
 143         case DontWait: {
 144                 // Integrate into the Controller
 145                 ForkedCallsController::addCall(*this);
 146                 break;
 147         }
 148         }
 149
 150         return retval_;
 151 }
 152
 153
 154 bool ForkedProcess::running() const
 155 {
 156         if (pid() <= 0)
 157                 return false;
 158
 159 #if !defined (_WIN32)
 160         // Un-UNIX like, but we don't have much use for
 161         // knowing if a zombie exists, so just reap it first.
 162         int waitstatus;
 163         waitpid(pid(), &waitstatus, WNOHANG);
 164 #endif
 165
 166         // Racy of course, but it will do.
 167         if (support::kill(pid(), 0) && errno == ESRCH)
 168                 return false;
 169         return true;
 170 }
 171
 172
 173 void ForkedProcess::kill(int tol)
 174 {
 175         lyxerr << "ForkedProcess::kill(" << tol << ')' << endl;
 176         if (pid() <= 0) {
 177                 lyxerr << "Can't kill non-existent process!" << endl;
 178                 return;
 179         }
 180
 181         int const tolerance = max(0, tol);
 182         if (tolerance == 0) {
 183                 // Kill it dead NOW!
 184                 Murder::killItDead(0, pid());
 185         } else {
 186                 int ret = support::kill(pid(), SIGHUP);
 187
 188                 // The process is already dead if wait_for_death is false
 189                 bool const wait_for_death = (ret == 0 && errno != ESRCH);
 190
 191                 if (wait_for_death)
 192                         Murder::killItDead(tolerance, pid());
 193         }
 194 }
 195
 196
 197 pid_t ForkedProcess::fork() {
 198 #if !defined (HAVE_FORK)
 199         return -1;
 200 #else
 201         pid_t pid = ::fork();
 202         if (pid == 0)
 203                 IAmAChild = true;
 204         return pid;
 205 #endif
 206 }
 207
 208
 209 // Wait for child process to finish. Returns returncode from child.
 210 int ForkedProcess::waitForChild()
 211 {
 212         // We'll pretend that the child returns 1 on all error conditions.
 213         retval_ = 1;
 214
 215 #if defined (_WIN32)
 216         HANDLE const hProcess = HANDLE(pid_);
 217
 218         DWORD const wait_status = ::WaitForSingleObject(hProcess, INFINITE);
 219
 220         switch (wait_status) {
 221         case WAIT_OBJECT_0: {
 222                 DWORD exit_code = 0;
 223                 if (!GetExitCodeProcess(hProcess, &exit_code)) {
 224                         lyxerr << "GetExitCodeProcess failed waiting for child\n"
 225                                << getChildErrorMessage() << endl;
 226                 } else
 227                         retval_ = exit_code;
 228                 break;
 229         }
 230         case WAIT_FAILED:
 231                 lyxerr << "WaitForSingleObject failed waiting for child\n"
 232                        << getChildErrorMessage() << endl;
 233                 break;
 234         }
 235
 236 #else
 237         int status;
 238         bool wait = true;
 239         while (wait) {
 240                 pid_t waitrpid = waitpid(pid_, &status, WUNTRACED);
 241                 if (waitrpid == -1) {
 242                         lyxerr << "LyX: Error waiting for child:"
 243                                << strerror(errno) << endl;
 244                         wait = false;
 245                 } else if (WIFEXITED(status)) {
 246                         // Child exited normally. Update return value.
 247                         retval_ = WEXITSTATUS(status);
 248                         wait = false;
 249                 } else if (WIFSIGNALED(status)) {
 250                         lyxerr << "LyX: Child didn't catch signal "
 251                                << WTERMSIG(status)
 252                                << "and died. Too bad." << endl;
 253                         wait = false;
 254                 } else if (WIFSTOPPED(status)) {
 255                         lyxerr << "LyX: Child (pid: " << pid_
 256                                << ") stopped on signal "
 257                                << WSTOPSIG(status)
 258                                << ". Waiting for child to finish." << endl;
 259                 } else {
 260                         lyxerr << "LyX: Something rotten happened while "
 261                                 "waiting for child " << pid_ << endl;
 262                         wait = false;
 263                 }
 264         }
 265 #endif
 266         return retval_;
 267 }
 268
 269
 270 /////////////////////////////////////////////////////////////////////
 271 //
 272 // ForkedCall
 273 //
 274 /////////////////////////////////////////////////////////////////////
 275
 276 ForkedCall::ForkedCall(string const & path)
 277         : cmd_prefix_(empty_string())
 278 {
 279         if (path.empty() || lyxrc.texinputs_prefix.empty())
 280                 return;
 281
 282         string const texinputs = os::latex_path_list(
 283                         replaceCurdirPath(path, lyxrc.texinputs_prefix));
 284         string const sep = string(1, os::path_separator(os::TEXENGINE));
 285         string const env = getEnv("TEXINPUTS");
 286
 287         if (os::shell() == os::UNIX)
 288                 cmd_prefix_ = "env 'TEXINPUTS=." + sep + texinputs
 289                                                  + sep + env + "' ";
 290         else
 291                 cmd_prefix_ = "cmd /p /c set TEXINPUTS=." + sep + texinputs
 292                                                           + sep + env + " & ";
 293 }
 294
 295
 296 int ForkedCall::startScript(Starttype wait, string const & what)
 297 {
 298         if (wait != Wait) {
 299                 retval_ = startScript(what, SignalTypePtr());
 300                 return retval_;
 301         }
 302
 303         command_ = what;
 304         signal_.reset();
 305         return run(Wait);
 306 }
 307
 308
 309 int ForkedCall::startScript(string const & what, SignalTypePtr signal)
 310 {
 311         command_ = what;
 312         signal_  = signal;
 313
 314         return run(DontWait);
 315 }
 316
 317
 318 // generate child in background
 319 int ForkedCall::generateChild()
 320 {
 321         string const line = trim(cmd_prefix_ + command_);
 322         if (line.empty())
 323                 return 1;
 324
 325 #if !defined (_WIN32)
 326         // POSIX
 327
 328         // Split the input command up into an array of words stored
 329         // in a contiguous block of memory. The array contains pointers
 330         // to each word.
 331         // Don't forget the terminating `\0' character.
 332         char const * const c_str = line.c_str();
 333         vector<char> vec(c_str, c_str + line.size() + 1);
 334
 335         // Splitting the command up into an array of words means replacing
 336         // the whitespace between words with '\0'. Life is complicated
 337         // however, because words protected by quotes can contain whitespace.
 338         //
 339         // The strategy we adopt is:
 340         // 1. If we're not inside quotes, then replace white space with '\0'.
 341         // 2. If we are inside quotes, then don't replace the white space
 342         //    but do remove the quotes themselves. We do this naively by
 343         //    replacing the quote with '\0' which is fine if quotes
 344         //    delimit the entire word.
 345         char inside_quote = 0;
 346         vector<char>::iterator it = vec.begin();
 347         vector<char>::iterator const end = vec.end();
 348         for (; it != end; ++it) {
 349                 char const c = *it;
 350                 if (!inside_quote) {
 351                         if (c == ' ')
 352                                 *it = '\0';
 353                         else if (c == '\'' || c == '"') {
 354                                 *it = '\0';
 355                                 inside_quote = c;
 356                         }
 357                 } else if (c == inside_quote) {
 358                         *it = '\0';
 359                         inside_quote = 0;
 360                 }
 361         }
 362
 363         // Build an array of pointers to each word.
 364         it = vec.begin();
 365         vector<char *> argv;
 366         char prev = '\0';
 367         for (; it != end; ++it) {
 368                 if (*it != '\0' && prev == '\0')
 369                         argv.push_back(&*it);
 370                 prev = *it;
 371         }
 372         argv.push_back(0);
 373
 374         // Debug output.
 375         if (lyxerr.debugging(Debug::FILES)) {
 376                 vector<char *>::iterator ait = argv.begin();
 377                 vector<char *>::iterator const aend = argv.end();
 378                 lyxerr << "<command>\n\t" << line
 379                        << "\n\tInterpretted as:\n\n";
 380                 for (; ait != aend; ++ait)
 381                         if (*ait)
 382                                 lyxerr << '\t'<< *ait << '\n';
 383                 lyxerr << "</command>" << endl;
 384         }
 385
 386         pid_t const cpid = ::fork();
 387         if (cpid == 0) {
 388                 // Child
 389                 execvp(argv[0], &*argv.begin());
 390
 391                 // If something goes wrong, we end up here
 392                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 393                        << strerror(errno) << endl;
 394                 _exit(1);
 395         }
 396 #else
 397         // Windows
 398
 399         pid_t cpid = -1;
 400
 401         STARTUPINFO startup;
 402         PROCESS_INFORMATION process;
 403
 404         memset(&startup, 0, sizeof(STARTUPINFO));
 405         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 406
 407         startup.cb = sizeof(STARTUPINFO);
 408
 409         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 410                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 411                 CloseHandle(process.hThread);
 412                 cpid = (pid_t)process.hProcess;
 413         }
 414 #endif
 415
 416         if (cpid < 0) {
 417                 // Error.
 418                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 419         }
 420
 421         return cpid;
 422 }
 423
 424
 425 /////////////////////////////////////////////////////////////////////
 426 //
 427 // ForkedCallQueue
 428 //
 429 /////////////////////////////////////////////////////////////////////
 430
 431 namespace ForkedCallQueue {
 432
 433 /// A process in the queue
 434 typedef pair<string, ForkedCall::SignalTypePtr> Process;
 435 /** Add a process to the queue. Processes are forked sequentially
 436  *  only one is running at a time.
 437  *  Connect to the returned signal and you'll be informed when
 438  *  the process has ended.
 439  */
 440 ForkedCall::SignalTypePtr add(string const & process);
 441
 442 /// in-progress queue
 443 static queue<Process> callQueue_;
 444
 445 /// flag whether queue is running
 446 static bool running_ = 0;
 447
 448 ///
 449 void startCaller();
 450 ///
 451 void stopCaller();
 452 ///
 453 void callback(pid_t, int);
 454
 455 ForkedCall::SignalTypePtr add(string const & process)
 456 {
 457         ForkedCall::SignalTypePtr ptr;
 458         ptr.reset(new ForkedCall::SignalType);
 459         callQueue_.push(Process(process, ptr));
 460         if (!running_)
 461                 startCaller();
 462         return ptr;
 463 }
 464
 465
 466 void callNext()
 467 {
 468         if (callQueue_.empty())
 469                 return;
 470         Process pro = callQueue_.front();
 471         callQueue_.pop();
 472         // Bind our chain caller
 473         pro.second->connect(lyx::bind(&ForkedCallQueue::callback, _1, _2));
 474         ForkedCall call;
 475         //If we fail to fork the process, then emit the signal
 476         //to tell the outside world that it failed.
 477         if (call.startScript(pro.first, pro.second) > 0)
 478                 pro.second->operator()(0,1);
 479 }
 480
 481
 482 void callback(pid_t, int)
 483 {
 484         if (callQueue_.empty())
 485                 stopCaller();
 486         else
 487                 callNext();
 488 }
 489
 490
 491 void startCaller()
 492 {
 493         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 494         running_ = true ;
 495         callNext();
 496 }
 497
 498
 499 void stopCaller()
 500 {
 501         running_ = false ;
 502         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 503 }
 504
 505
 506 bool running()
 507 {
 508         return running_;
 509 }
 510
 511 } // namespace ForkedCallsQueue
 512
 513
 514
 515 /////////////////////////////////////////////////////////////////////
 516 //
 517 // ForkedCallsController
 518 //
 519 /////////////////////////////////////////////////////////////////////
 520
 521 #if defined(_WIN32)
 522 string const getChildErrorMessage()
 523 {
 524         DWORD const error_code = ::GetLastError();
 525
 526         HLOCAL t_message = 0;
 527         bool const ok = ::FormatMessage(
 528                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 529                 FORMAT_MESSAGE_FROM_SYSTEM,
 530                 0, error_code,
 531                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 532                 (LPTSTR) &t_message, 0, 0
 533                 ) != 0;
 534
 535         ostringstream ss;
 536         ss << "LyX: Error waiting for child: " << error_code;
 537
 538         if (ok) {
 539                 ss << ": " << (LPTSTR)t_message;
 540                 ::LocalFree(t_message);
 541         } else
 542                 ss << ": Error unknown.";
 543
 544         return ss.str();
 545 }
 546 #endif
 547
 548
 549 namespace ForkedCallsController {
 550
 551 typedef shared_ptr<ForkedProcess> ForkedProcessPtr;
 552 typedef list<ForkedProcessPtr> ListType;
 553 typedef ListType::iterator iterator;
 554
 555
 556 /// The child processes
 557 static ListType forkedCalls;
 558
 559 iterator find_pid(pid_t pid)
 560 {
 561         return find_if(forkedCalls.begin(), forkedCalls.end(),
 562                             lyx::bind(equal_to<pid_t>(),
 563                             lyx::bind(&ForkedCall::pid, _1),
 564                             pid));
 565 }
 566
 567
 568 void addCall(ForkedProcess const & newcall)
 569 {
 570         forkedCalls.push_back(newcall.clone());
 571 }
 572
 573
 574 // Check the list of dead children and emit any associated signals.
 575 void handleCompletedProcesses()
 576 {
 577         ListType::iterator it  = forkedCalls.begin();
 578         ListType::iterator end = forkedCalls.end();
 579         while (it != end) {
 580                 ForkedProcessPtr actCall = *it;
 581                 bool remove_it = false;
 582
 583 #if defined(_WIN32)
 584                 HANDLE const hProcess = HANDLE(actCall->pid());
 585
 586                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 587
 588                 switch (wait_status) {
 589                 case WAIT_TIMEOUT:
 590                         // Still running
 591                         break;
 592                 case WAIT_OBJECT_0: {
 593                         DWORD exit_code = 0;
 594                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 595                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 596                                        << getChildErrorMessage() << endl;
 597                                 // Child died, so pretend it returned 1
 598                                 actCall->setRetValue(1);
 599                         } else {
 600                                 actCall->setRetValue(exit_code);
 601                         }
 602                         CloseHandle(hProcess);
 603                         remove_it = true;
 604                         break;
 605                 }
 606                 case WAIT_FAILED:
 607                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 608                                << getChildErrorMessage() << endl;
 609                         actCall->setRetValue(1);
 610                         CloseHandle(hProcess);
 611                         remove_it = true;
 612                         break;
 613                 }
 614 #else
 615                 pid_t pid = actCall->pid();
 616                 int stat_loc;
 617                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 618
 619                 if (waitrpid == -1) {
 620                         lyxerr << "LyX: Error waiting for child: "
 621                                << strerror(errno) << endl;
 622
 623                         // Child died, so pretend it returned 1
 624                         actCall->setRetValue(1);
 625                         remove_it = true;
 626
 627                 } else if (waitrpid == 0) {
 628                         // Still running. Move on to the next child.
 629
 630                 } else if (WIFEXITED(stat_loc)) {
 631                         // Ok, the return value goes into retval.
 632                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 633                         remove_it = true;
 634
 635                 } else if (WIFSIGNALED(stat_loc)) {
 636                         // Child died, so pretend it returned 1
 637                         actCall->setRetValue(1);
 638                         remove_it = true;
 639
 640                 } else if (WIFSTOPPED(stat_loc)) {
 641                         lyxerr << "LyX: Child (pid: " << pid
 642                                << ") stopped on signal "
 643                                << WSTOPSIG(stat_loc)
 644                                << ". Waiting for child to finish." << endl;
 645
 646                 } else {
 647                         lyxerr << "LyX: Something rotten happened while "
 648                                 "waiting for child " << pid << endl;
 649
 650                         // Child died, so pretend it returned 1
 651                         actCall->setRetValue(1);
 652                         remove_it = true;
 653                 }
 654 #endif
 655
 656                 if (remove_it) {
 657                         forkedCalls.erase(it);
 658                         actCall->emitSignal();
 659
 660                         /* start all over: emiting the signal can result
 661                          * in changing the list (Ab)
 662                          */
 663                         it = forkedCalls.begin();
 664                 } else {
 665                         ++it;
 666                 }
 667         }
 668 }
 669
 670
 671 // Kill the process prematurely and remove it from the list
 672 // within tolerance secs
 673 void kill(pid_t pid, int tolerance)
 674 {
 675         ListType::iterator it = find_pid(pid);
 676         if (it == forkedCalls.end())
 677                 return;
 678
 679         (*it)->kill(tolerance);
 680         forkedCalls.erase(it);
 681 }
 682
 683 } // namespace ForkedCallsController
 684
 685 } // namespace support
 686 } // namespace lyx