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 : public boost::signals2::trackable {
  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                 timeout_.timeout.connect(lyx::bind(&Murder::kill, this));
  87                 timeout_.start();
  88         }
  89
  90         //
  91         Timeout timeout_;
  92         //
  93         pid_t pid_;
  94 };
  95
  96 } // namespace anon
  97
  98
  99 /////////////////////////////////////////////////////////////////////
 100 //
 101 // ForkedProcess
 102 //
 103 /////////////////////////////////////////////////////////////////////
 104
 105 ForkedProcess::ForkedProcess()
 106         : pid_(0), retval_(0)
 107 {}
 108
 109
 110 bool ForkedProcess::IAmAChild = false;
 111
 112
 113 void ForkedProcess::emitSignal()
 114 {
 115         if (signal_) {
 116                 signal_->operator()(pid_, retval_);
 117         }
 118 }
 119
 120
 121 // Spawn the child process
 122 int ForkedProcess::run(Starttype type)
 123 {
 124         retval_ = 0;
 125         pid_ = generateChild();
 126         if (pid_ <= 0) { // child or fork failed.
 127                 retval_ = 1;
 128                 if (pid_ == 0)
 129                         //we also do this in fork(), too, but maybe someone will try
 130                         //to bypass that
 131                         IAmAChild = true;
 132                 return retval_;
 133         }
 134
 135         switch (type) {
 136         case Wait:
 137                 retval_ = waitForChild();
 138                 break;
 139         case DontWait: {
 140                 // Integrate into the Controller
 141                 ForkedCallsController::addCall(*this);
 142                 break;
 143         }
 144         }
 145
 146         return retval_;
 147 }
 148
 149
 150 bool ForkedProcess::running() const
 151 {
 152         if (pid() <= 0)
 153                 return false;
 154
 155 #if !defined (_WIN32)
 156         // Un-UNIX like, but we don't have much use for
 157         // knowing if a zombie exists, so just reap it first.
 158         int waitstatus;
 159         waitpid(pid(), &waitstatus, WNOHANG);
 160 #endif
 161
 162         // Racy of course, but it will do.
 163         if (support::kill(pid(), 0) && errno == ESRCH)
 164                 return false;
 165         return true;
 166 }
 167
 168
 169 void ForkedProcess::kill(int tol)
 170 {
 171         lyxerr << "ForkedProcess::kill(" << tol << ')' << endl;
 172         if (pid() <= 0) {
 173                 lyxerr << "Can't kill non-existent process!" << endl;
 174                 return;
 175         }
 176
 177         int const tolerance = max(0, tol);
 178         if (tolerance == 0) {
 179                 // Kill it dead NOW!
 180                 Murder::killItDead(0, pid());
 181         } else {
 182                 int ret = support::kill(pid(), SIGHUP);
 183
 184                 // The process is already dead if wait_for_death is false
 185                 bool const wait_for_death = (ret == 0 && errno != ESRCH);
 186
 187                 if (wait_for_death)
 188                         Murder::killItDead(tolerance, pid());
 189         }
 190 }
 191
 192
 193 pid_t ForkedProcess::fork() {
 194 #if !defined (HAVE_FORK)
 195         return -1;
 196 #else
 197         pid_t pid = ::fork();
 198         if (pid == 0)
 199                 IAmAChild = true;
 200         return pid;
 201 #endif
 202 }
 203
 204
 205 // Wait for child process to finish. Returns returncode from child.
 206 int ForkedProcess::waitForChild()
 207 {
 208         // We'll pretend that the child returns 1 on all error conditions.
 209         retval_ = 1;
 210
 211 #if defined (_WIN32)
 212         HANDLE const hProcess = HANDLE(pid_);
 213
 214         DWORD const wait_status = ::WaitForSingleObject(hProcess, INFINITE);
 215
 216         switch (wait_status) {
 217         case WAIT_OBJECT_0: {
 218                 DWORD exit_code = 0;
 219                 if (!GetExitCodeProcess(hProcess, &exit_code)) {
 220                         lyxerr << "GetExitCodeProcess failed waiting for child\n"
 221                                << getChildErrorMessage() << endl;
 222                 } else
 223                         retval_ = exit_code;
 224                 break;
 225         }
 226         case WAIT_FAILED:
 227                 lyxerr << "WaitForSingleObject failed waiting for child\n"
 228                        << getChildErrorMessage() << endl;
 229                 break;
 230         }
 231
 232 #else
 233         int status;
 234         bool wait = true;
 235         while (wait) {
 236                 pid_t waitrpid = waitpid(pid_, &status, WUNTRACED);
 237                 if (waitrpid == -1) {
 238                         lyxerr << "LyX: Error waiting for child:"
 239                                << strerror(errno) << endl;
 240                         wait = false;
 241                 } else if (WIFEXITED(status)) {
 242                         // Child exited normally. Update return value.
 243                         retval_ = WEXITSTATUS(status);
 244                         wait = false;
 245                 } else if (WIFSIGNALED(status)) {
 246                         lyxerr << "LyX: Child didn't catch signal "
 247                                << WTERMSIG(status)
 248                                << "and died. Too bad." << endl;
 249                         wait = false;
 250                 } else if (WIFSTOPPED(status)) {
 251                         lyxerr << "LyX: Child (pid: " << pid_
 252                                << ") stopped on signal "
 253                                << WSTOPSIG(status)
 254                                << ". Waiting for child to finish." << endl;
 255                 } else {
 256                         lyxerr << "LyX: Something rotten happened while "
 257                                 "waiting for child " << pid_ << endl;
 258                         wait = false;
 259                 }
 260         }
 261 #endif
 262         return retval_;
 263 }
 264
 265
 266 /////////////////////////////////////////////////////////////////////
 267 //
 268 // ForkedCall
 269 //
 270 /////////////////////////////////////////////////////////////////////
 271
 272 ForkedCall::ForkedCall(string const & path, string const & lpath)
 273         : cmd_prefix_(to_filesystem8bit(from_utf8(latexEnvCmdPrefix(path, lpath))))
 274 {}
 275
 276
 277 int ForkedCall::startScript(Starttype wait, string const & what)
 278 {
 279         if (wait != Wait) {
 280                 retval_ = startScript(what, SignalTypePtr());
 281                 return retval_;
 282         }
 283
 284         command_ = commandPrep(trim(what));
 285         signal_.reset();
 286         return run(Wait);
 287 }
 288
 289
 290 int ForkedCall::startScript(string const & what, SignalTypePtr signal)
 291 {
 292         command_ = commandPrep(trim(what));
 293         signal_  = signal;
 294
 295         return run(DontWait);
 296 }
 297
 298
 299 // generate child in background
 300 int ForkedCall::generateChild()
 301 {
 302         if (command_.empty())
 303                 return 1;
 304
 305         // Make sure that a V2 python is run, if available.
 306         string const line = cmd_prefix_ +
 307                 (prefixIs(command_, "python -tt")
 308                  ? os::python() + command_.substr(10) : command_);
 309
 310 #if !defined (_WIN32)
 311         // POSIX
 312
 313         // Split the input command up into an array of words stored
 314         // in a contiguous block of memory. The array contains pointers
 315         // to each word.
 316         // Don't forget the terminating `\0' character.
 317         char const * const c_str = line.c_str();
 318         vector<char> vec(c_str, c_str + line.size() + 1);
 319
 320         // Splitting the command up into an array of words means replacing
 321         // the whitespace between words with '\0'. Life is complicated
 322         // however, because words protected by quotes can contain whitespace.
 323         //
 324         // The strategy we adopt is:
 325         // 1. If we're not inside quotes, then replace white space with '\0'.
 326         // 2. If we are inside quotes, then don't replace the white space
 327         //    but do remove the quotes themselves. We do this naively by
 328         //    replacing the quote with '\0' which is fine if quotes
 329         //    delimit the entire word. However, if quotes do not delimit the
 330         //    entire word (i.e., open quote is inside word), simply discard
 331         //    them such as not to break the current word.
 332         char inside_quote = 0;
 333         char c_before_open_quote = ' ';
 334         vector<char>::iterator it = vec.begin();
 335         vector<char>::iterator itc = vec.begin();
 336         vector<char>::iterator const end = vec.end();
 337         for (; it != end; ++it, ++itc) {
 338                 char const c = *it;
 339                 if (!inside_quote) {
 340                         if (c == '\'' || c == '"') {
 341                                 if (c_before_open_quote == ' ')
 342                                         *itc = '\0';
 343                                 else
 344                                         --itc;
 345                                 inside_quote = c;
 346                         } else {
 347                                 if (c == ' ')
 348                                         *itc = '\0';
 349                                 else
 350                                         *itc = c;
 351                                 c_before_open_quote = c;
 352                         }
 353                 } else if (c == inside_quote) {
 354                         if (c_before_open_quote == ' ')
 355                                 *itc = '\0';
 356                         else
 357                                 --itc;
 358                         inside_quote = 0;
 359                 } else
 360                         *itc = c;
 361         }
 362
 363         // Clear what remains.
 364         for (; itc != end; ++itc)
 365                 *itc = '\0';
 366
 367         // Build an array of pointers to each word.
 368         it = vec.begin();
 369         vector<char *> argv;
 370         char prev = '\0';
 371         for (; it != end; ++it) {
 372                 if (*it != '\0' && prev == '\0')
 373                         argv.push_back(&*it);
 374                 prev = *it;
 375         }
 376         argv.push_back(0);
 377
 378         // Debug output.
 379         if (lyxerr.debugging(Debug::FILES)) {
 380                 vector<char *>::iterator ait = argv.begin();
 381                 vector<char *>::iterator const aend = argv.end();
 382                 lyxerr << "<command>\n\t" << line
 383                        << "\n\tInterpreted as:\n\n";
 384                 for (; ait != aend; ++ait)
 385                         if (*ait)
 386                                 lyxerr << '\t'<< *ait << '\n';
 387                 lyxerr << "</command>" << endl;
 388         }
 389
 390         pid_t const cpid = ::fork();
 391         if (cpid == 0) {
 392                 // Child
 393                 execvp(argv[0], &*argv.begin());
 394
 395                 // If something goes wrong, we end up here
 396                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 397                        << strerror(errno) << endl;
 398                 _exit(1);
 399         }
 400 #else
 401         // Windows
 402
 403         pid_t cpid = -1;
 404
 405         STARTUPINFO startup;
 406         PROCESS_INFORMATION process;
 407
 408         memset(&startup, 0, sizeof(STARTUPINFO));
 409         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 410
 411         startup.cb = sizeof(STARTUPINFO);
 412
 413         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 414                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 415                 CloseHandle(process.hThread);
 416                 cpid = (pid_t)process.hProcess;
 417         }
 418 #endif
 419
 420         if (cpid < 0) {
 421                 // Error.
 422                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 423         }
 424
 425         return cpid;
 426 }
 427
 428
 429 /////////////////////////////////////////////////////////////////////
 430 //
 431 // ForkedCallQueue
 432 //
 433 /////////////////////////////////////////////////////////////////////
 434
 435 namespace ForkedCallQueue {
 436
 437 /// A process in the queue
 438 typedef pair<string, ForkedCall::SignalTypePtr> Process;
 439 /** Add a process to the queue. Processes are forked sequentially
 440  *  only one is running at a time.
 441  *  Connect to the returned signal and you'll be informed when
 442  *  the process has ended.
 443  */
 444 ForkedCall::SignalTypePtr add(string const & process);
 445
 446 /// in-progress queue
 447 static queue<Process> callQueue_;
 448
 449 /// flag whether queue is running
 450 static bool running_ = 0;
 451
 452 ///
 453 void startCaller();
 454 ///
 455 void stopCaller();
 456 ///
 457 void callback(pid_t, int);
 458
 459 ForkedCall::SignalTypePtr add(string const & process)
 460 {
 461         ForkedCall::SignalTypePtr ptr;
 462         ptr.reset(new ForkedCall::SignalType);
 463         callQueue_.push(Process(process, ptr));
 464         if (!running_)
 465                 startCaller();
 466         return ptr;
 467 }
 468
 469
 470 void callNext()
 471 {
 472         if (callQueue_.empty())
 473                 return;
 474         Process pro = callQueue_.front();
 475         callQueue_.pop();
 476         // Bind our chain caller
 477         pro.second->connect(callback);
 478         ForkedCall call;
 479         //If we fail to fork the process, then emit the signal
 480         //to tell the outside world that it failed.
 481         if (call.startScript(pro.first, pro.second) > 0)
 482                 pro.second->operator()(0,1);
 483 }
 484
 485
 486 void callback(pid_t, int)
 487 {
 488         if (callQueue_.empty())
 489                 stopCaller();
 490         else
 491                 callNext();
 492 }
 493
 494
 495 void startCaller()
 496 {
 497         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 498         running_ = true ;
 499         callNext();
 500 }
 501
 502
 503 void stopCaller()
 504 {
 505         running_ = false ;
 506         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 507 }
 508
 509
 510 bool running()
 511 {
 512         return running_;
 513 }
 514
 515 } // namespace ForkedCallsQueue
 516
 517
 518
 519 /////////////////////////////////////////////////////////////////////
 520 //
 521 // ForkedCallsController
 522 //
 523 /////////////////////////////////////////////////////////////////////
 524
 525 #if defined(_WIN32)
 526 string const getChildErrorMessage()
 527 {
 528         DWORD const error_code = ::GetLastError();
 529
 530         HLOCAL t_message = 0;
 531         bool const ok = ::FormatMessage(
 532                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 533                 FORMAT_MESSAGE_FROM_SYSTEM,
 534                 0, error_code,
 535                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 536                 (LPTSTR) &t_message, 0, 0
 537                 ) != 0;
 538
 539         ostringstream ss;
 540         ss << "LyX: Error waiting for child: " << error_code;
 541
 542         if (ok) {
 543                 ss << ": " << (LPTSTR)t_message;
 544                 ::LocalFree(t_message);
 545         } else
 546                 ss << ": Error unknown.";
 547
 548         return ss.str();
 549 }
 550 #endif
 551
 552
 553 namespace ForkedCallsController {
 554
 555 typedef shared_ptr<ForkedProcess> ForkedProcessPtr;
 556 typedef list<ForkedProcessPtr> ListType;
 557 typedef ListType::iterator iterator;
 558
 559
 560 /// The child processes
 561 static ListType forkedCalls;
 562
 563 iterator find_pid(pid_t pid)
 564 {
 565         return find_if(forkedCalls.begin(), forkedCalls.end(),
 566                             lyx::bind(equal_to<pid_t>(),
 567                             lyx::bind(&ForkedCall::pid, _1),
 568                             pid));
 569 }
 570
 571
 572 void addCall(ForkedProcess const & newcall)
 573 {
 574         forkedCalls.push_back(newcall.clone());
 575 }
 576
 577
 578 // Check the list of dead children and emit any associated signals.
 579 void handleCompletedProcesses()
 580 {
 581         ListType::iterator it  = forkedCalls.begin();
 582         ListType::iterator end = forkedCalls.end();
 583         while (it != end) {
 584                 ForkedProcessPtr actCall = *it;
 585                 bool remove_it = false;
 586
 587 #if defined(_WIN32)
 588                 HANDLE const hProcess = HANDLE(actCall->pid());
 589
 590                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 591
 592                 switch (wait_status) {
 593                 case WAIT_TIMEOUT:
 594                         // Still running
 595                         break;
 596                 case WAIT_OBJECT_0: {
 597                         DWORD exit_code = 0;
 598                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 599                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 600                                        << getChildErrorMessage() << endl;
 601                                 // Child died, so pretend it returned 1
 602                                 actCall->setRetValue(1);
 603                         } else {
 604                                 actCall->setRetValue(exit_code);
 605                         }
 606                         CloseHandle(hProcess);
 607                         remove_it = true;
 608                         break;
 609                 }
 610                 case WAIT_FAILED:
 611                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 612                                << getChildErrorMessage() << endl;
 613                         actCall->setRetValue(1);
 614                         CloseHandle(hProcess);
 615                         remove_it = true;
 616                         break;
 617                 }
 618 #else
 619                 pid_t pid = actCall->pid();
 620                 int stat_loc;
 621                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 622
 623                 if (waitrpid == -1) {
 624                         lyxerr << "LyX: Error waiting for child: "
 625                                << strerror(errno) << endl;
 626
 627                         // Child died, so pretend it returned 1
 628                         actCall->setRetValue(1);
 629                         remove_it = true;
 630
 631                 } else if (waitrpid == 0) {
 632                         // Still running. Move on to the next child.
 633
 634                 } else if (WIFEXITED(stat_loc)) {
 635                         // Ok, the return value goes into retval.
 636                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 637                         remove_it = true;
 638
 639                 } else if (WIFSIGNALED(stat_loc)) {
 640                         // Child died, so pretend it returned 1
 641                         actCall->setRetValue(1);
 642                         remove_it = true;
 643
 644                 } else if (WIFSTOPPED(stat_loc)) {
 645                         lyxerr << "LyX: Child (pid: " << pid
 646                                << ") stopped on signal "
 647                                << WSTOPSIG(stat_loc)
 648                                << ". Waiting for child to finish." << endl;
 649
 650                 } else {
 651                         lyxerr << "LyX: Something rotten happened while "
 652                                 "waiting for child " << pid << endl;
 653
 654                         // Child died, so pretend it returned 1
 655                         actCall->setRetValue(1);
 656                         remove_it = true;
 657                 }
 658 #endif
 659
 660                 if (remove_it) {
 661                         forkedCalls.erase(it);
 662                         actCall->emitSignal();
 663
 664                         /* start all over: emiting the signal can result
 665                          * in changing the list (Ab)
 666                          */
 667                         it = forkedCalls.begin();
 668                 } else {
 669                         ++it;
 670                 }
 671         }
 672 }
 673
 674
 675 // Kill the process prematurely and remove it from the list
 676 // within tolerance secs
 677 void kill(pid_t pid, int tolerance)
 678 {
 679         ListType::iterator it = find_pid(pid);
 680         if (it == forkedCalls.end())
 681                 return;
 682
 683         (*it)->kill(tolerance);
 684         forkedCalls.erase(it);
 685 }
 686
 687 } // namespace ForkedCallsController
 688
 689 } // namespace support
 690 } // namespace lyx