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.
 327         char inside_quote = 0;
 328         vector<char>::iterator it = vec.begin();
 329         vector<char>::iterator const end = vec.end();
 330         for (; it != end; ++it) {
 331                 char const c = *it;
 332                 if (!inside_quote) {
 333                         if (c == ' ')
 334                                 *it = '\0';
 335                         else if (c == '\'' || c == '"') {
 336                                 *it = '\0';
 337                                 inside_quote = c;
 338                         }
 339                 } else if (c == inside_quote) {
 340                         *it = '\0';
 341                         inside_quote = 0;
 342                 }
 343         }
 344
 345         // Build an array of pointers to each word.
 346         it = vec.begin();
 347         vector<char *> argv;
 348         char prev = '\0';
 349         for (; it != end; ++it) {
 350                 if (*it != '\0' && prev == '\0')
 351                         argv.push_back(&*it);
 352                 prev = *it;
 353         }
 354         argv.push_back(0);
 355
 356         // Debug output.
 357         if (lyxerr.debugging(Debug::FILES)) {
 358                 vector<char *>::iterator ait = argv.begin();
 359                 vector<char *>::iterator const aend = argv.end();
 360                 lyxerr << "<command>\n\t" << line
 361                        << "\n\tInterpretted as:\n\n";
 362                 for (; ait != aend; ++ait)
 363                         if (*ait)
 364                                 lyxerr << '\t'<< *ait << '\n';
 365                 lyxerr << "</command>" << endl;
 366         }
 367
 368         pid_t const cpid = ::fork();
 369         if (cpid == 0) {
 370                 // Child
 371                 execvp(argv[0], &*argv.begin());
 372
 373                 // If something goes wrong, we end up here
 374                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 375                        << strerror(errno) << endl;
 376                 _exit(1);
 377         }
 378 #else
 379         // Windows
 380
 381         pid_t cpid = -1;
 382
 383         STARTUPINFO startup;
 384         PROCESS_INFORMATION process;
 385
 386         memset(&startup, 0, sizeof(STARTUPINFO));
 387         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 388
 389         startup.cb = sizeof(STARTUPINFO);
 390
 391         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 392                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 393                 CloseHandle(process.hThread);
 394                 cpid = (pid_t)process.hProcess;
 395         }
 396 #endif
 397
 398         if (cpid < 0) {
 399                 // Error.
 400                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 401         }
 402
 403         return cpid;
 404 }
 405
 406
 407 /////////////////////////////////////////////////////////////////////
 408 //
 409 // ForkedCallQueue
 410 //
 411 /////////////////////////////////////////////////////////////////////
 412
 413 namespace ForkedCallQueue {
 414
 415 /// A process in the queue
 416 typedef pair<string, ForkedCall::SignalTypePtr> Process;
 417 /** Add a process to the queue. Processes are forked sequentially
 418  *  only one is running at a time.
 419  *  Connect to the returned signal and you'll be informed when
 420  *  the process has ended.
 421  */
 422 ForkedCall::SignalTypePtr add(string const & process);
 423
 424 /// in-progress queue
 425 static queue<Process> callQueue_;
 426
 427 /// flag whether queue is running
 428 static bool running_ = 0;
 429
 430 ///
 431 void startCaller();
 432 ///
 433 void stopCaller();
 434 ///
 435 void callback(pid_t, int);
 436
 437 ForkedCall::SignalTypePtr add(string const & process)
 438 {
 439         ForkedCall::SignalTypePtr ptr;
 440         ptr.reset(new ForkedCall::SignalType);
 441         callQueue_.push(Process(process, ptr));
 442         if (!running_)
 443                 startCaller();
 444         return ptr;
 445 }
 446
 447
 448 void callNext()
 449 {
 450         if (callQueue_.empty())
 451                 return;
 452         Process pro = callQueue_.front();
 453         callQueue_.pop();
 454         // Bind our chain caller
 455         pro.second->connect(lyx::bind(&ForkedCallQueue::callback, _1, _2));
 456         ForkedCall call;
 457         //If we fail to fork the process, then emit the signal
 458         //to tell the outside world that it failed.
 459         if (call.startScript(pro.first, pro.second) > 0)
 460                 pro.second->operator()(0,1);
 461 }
 462
 463
 464 void callback(pid_t, int)
 465 {
 466         if (callQueue_.empty())
 467                 stopCaller();
 468         else
 469                 callNext();
 470 }
 471
 472
 473 void startCaller()
 474 {
 475         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 476         running_ = true ;
 477         callNext();
 478 }
 479
 480
 481 void stopCaller()
 482 {
 483         running_ = false ;
 484         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 485 }
 486
 487
 488 bool running()
 489 {
 490         return running_;
 491 }
 492
 493 } // namespace ForkedCallsQueue
 494
 495
 496
 497 /////////////////////////////////////////////////////////////////////
 498 //
 499 // ForkedCallsController
 500 //
 501 /////////////////////////////////////////////////////////////////////
 502
 503 #if defined(_WIN32)
 504 string const getChildErrorMessage()
 505 {
 506         DWORD const error_code = ::GetLastError();
 507
 508         HLOCAL t_message = 0;
 509         bool const ok = ::FormatMessage(
 510                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 511                 FORMAT_MESSAGE_FROM_SYSTEM,
 512                 0, error_code,
 513                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 514                 (LPTSTR) &t_message, 0, 0
 515                 ) != 0;
 516
 517         ostringstream ss;
 518         ss << "LyX: Error waiting for child: " << error_code;
 519
 520         if (ok) {
 521                 ss << ": " << (LPTSTR)t_message;
 522                 ::LocalFree(t_message);
 523         } else
 524                 ss << ": Error unknown.";
 525
 526         return ss.str();
 527 }
 528 #endif
 529
 530
 531 namespace ForkedCallsController {
 532
 533 typedef shared_ptr<ForkedProcess> ForkedProcessPtr;
 534 typedef list<ForkedProcessPtr> ListType;
 535 typedef ListType::iterator iterator;
 536
 537
 538 /// The child processes
 539 static ListType forkedCalls;
 540
 541 iterator find_pid(pid_t pid)
 542 {
 543         return find_if(forkedCalls.begin(), forkedCalls.end(),
 544                             lyx::bind(equal_to<pid_t>(),
 545                             lyx::bind(&ForkedCall::pid, _1),
 546                             pid));
 547 }
 548
 549
 550 void addCall(ForkedProcess const & newcall)
 551 {
 552         forkedCalls.push_back(newcall.clone());
 553 }
 554
 555
 556 // Check the list of dead children and emit any associated signals.
 557 void handleCompletedProcesses()
 558 {
 559         ListType::iterator it  = forkedCalls.begin();
 560         ListType::iterator end = forkedCalls.end();
 561         while (it != end) {
 562                 ForkedProcessPtr actCall = *it;
 563                 bool remove_it = false;
 564
 565 #if defined(_WIN32)
 566                 HANDLE const hProcess = HANDLE(actCall->pid());
 567
 568                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 569
 570                 switch (wait_status) {
 571                 case WAIT_TIMEOUT:
 572                         // Still running
 573                         break;
 574                 case WAIT_OBJECT_0: {
 575                         DWORD exit_code = 0;
 576                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 577                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 578                                        << getChildErrorMessage() << endl;
 579                                 // Child died, so pretend it returned 1
 580                                 actCall->setRetValue(1);
 581                         } else {
 582                                 actCall->setRetValue(exit_code);
 583                         }
 584                         CloseHandle(hProcess);
 585                         remove_it = true;
 586                         break;
 587                 }
 588                 case WAIT_FAILED:
 589                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 590                                << getChildErrorMessage() << endl;
 591                         actCall->setRetValue(1);
 592                         CloseHandle(hProcess);
 593                         remove_it = true;
 594                         break;
 595                 }
 596 #else
 597                 pid_t pid = actCall->pid();
 598                 int stat_loc;
 599                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 600
 601                 if (waitrpid == -1) {
 602                         lyxerr << "LyX: Error waiting for child: "
 603                                << strerror(errno) << endl;
 604
 605                         // Child died, so pretend it returned 1
 606                         actCall->setRetValue(1);
 607                         remove_it = true;
 608
 609                 } else if (waitrpid == 0) {
 610                         // Still running. Move on to the next child.
 611
 612                 } else if (WIFEXITED(stat_loc)) {
 613                         // Ok, the return value goes into retval.
 614                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 615                         remove_it = true;
 616
 617                 } else if (WIFSIGNALED(stat_loc)) {
 618                         // Child died, so pretend it returned 1
 619                         actCall->setRetValue(1);
 620                         remove_it = true;
 621
 622                 } else if (WIFSTOPPED(stat_loc)) {
 623                         lyxerr << "LyX: Child (pid: " << pid
 624                                << ") stopped on signal "
 625                                << WSTOPSIG(stat_loc)
 626                                << ". Waiting for child to finish." << endl;
 627
 628                 } else {
 629                         lyxerr << "LyX: Something rotten happened while "
 630                                 "waiting for child " << pid << endl;
 631
 632                         // Child died, so pretend it returned 1
 633                         actCall->setRetValue(1);
 634                         remove_it = true;
 635                 }
 636 #endif
 637
 638                 if (remove_it) {
 639                         forkedCalls.erase(it);
 640                         actCall->emitSignal();
 641
 642                         /* start all over: emiting the signal can result
 643                          * in changing the list (Ab)
 644                          */
 645                         it = forkedCalls.begin();
 646                 } else {
 647                         ++it;
 648                 }
 649         }
 650 }
 651
 652
 653 // Kill the process prematurely and remove it from the list
 654 // within tolerance secs
 655 void kill(pid_t pid, int tolerance)
 656 {
 657         ListType::iterator it = find_pid(pid);
 658         if (it == forkedCalls.end())
 659                 return;
 660
 661         (*it)->kill(tolerance);
 662         forkedCalls.erase(it);
 663 }
 664
 665 } // namespace ForkedCallsController
 666
 667 } // namespace support
 668 } // namespace lyx