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_) {
 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_ = trim(what);
 286         signal_.reset();
 287         return run(Wait);
 288 }
 289
 290
 291 int ForkedCall::startScript(string const & what, SignalTypePtr signal)
 292 {
 293         command_ = 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         string const line = cmd_prefix_ + command_;
 307
 308 #if !defined (_WIN32)
 309         // POSIX
 310
 311         // Split the input command up into an array of words stored
 312         // in a contiguous block of memory. The array contains pointers
 313         // to each word.
 314         // Don't forget the terminating `\0' character.
 315         char const * const c_str = line.c_str();
 316         vector<char> vec(c_str, c_str + line.size() + 1);
 317
 318         // Splitting the command up into an array of words means replacing
 319         // the whitespace between words with '\0'. Life is complicated
 320         // however, because words protected by quotes can contain whitespace.
 321         //
 322         // The strategy we adopt is:
 323         // 1. If we're not inside quotes, then replace white space with '\0'.
 324         // 2. If we are inside quotes, then don't replace the white space
 325         //    but do remove the quotes themselves. We do this naively by
 326         //    replacing the quote with '\0' which is fine if quotes
 327         //    delimit the entire word. However, if quotes do not delimit the
 328         //    entire word (i.e., open quote is inside word), simply discard
 329         //    them such as not to break the current word.
 330         char inside_quote = 0;
 331         char c_before_open_quote = ' ';
 332         vector<char>::iterator it = vec.begin();
 333         vector<char>::iterator itc = vec.begin();
 334         vector<char>::iterator const end = vec.end();
 335         for (; it != end; ++it, ++itc) {
 336                 char const c = *it;
 337                 if (!inside_quote) {
 338                         if (c == '\'' || c == '"') {
 339                                 if (c_before_open_quote == ' ')
 340                                         *itc = '\0';
 341                                 else
 342                                         --itc;
 343                                 inside_quote = c;
 344                         } else {
 345                                 if (c == ' ')
 346                                         *itc = '\0';
 347                                 else
 348                                         *itc = c;
 349                                 c_before_open_quote = c;
 350                         }
 351                 } else if (c == inside_quote) {
 352                         if (c_before_open_quote == ' ')
 353                                 *itc = '\0';
 354                         else
 355                                 --itc;
 356                         inside_quote = 0;
 357                 } else
 358                         *itc = c;
 359         }
 360
 361         // Clear what remains.
 362         for (; itc != end; ++itc)
 363                 *itc = '\0';
 364
 365         // Build an array of pointers to each word.
 366         it = vec.begin();
 367         vector<char *> argv;
 368         char prev = '\0';
 369         for (; it != end; ++it) {
 370                 if (*it != '\0' && prev == '\0')
 371                         argv.push_back(&*it);
 372                 prev = *it;
 373         }
 374         argv.push_back(0);
 375
 376         // Debug output.
 377         if (lyxerr.debugging(Debug::FILES)) {
 378                 vector<char *>::iterator ait = argv.begin();
 379                 vector<char *>::iterator const aend = argv.end();
 380                 lyxerr << "<command>\n\t" << line
 381                        << "\n\tInterpretted as:\n\n";
 382                 for (; ait != aend; ++ait)
 383                         if (*ait)
 384                                 lyxerr << '\t'<< *ait << '\n';
 385                 lyxerr << "</command>" << endl;
 386         }
 387
 388         pid_t const cpid = ::fork();
 389         if (cpid == 0) {
 390                 // Child
 391                 execvp(argv[0], &*argv.begin());
 392
 393                 // If something goes wrong, we end up here
 394                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 395                        << strerror(errno) << endl;
 396                 _exit(1);
 397         }
 398 #else
 399         // Windows
 400
 401         pid_t cpid = -1;
 402
 403         STARTUPINFO startup;
 404         PROCESS_INFORMATION process;
 405
 406         memset(&startup, 0, sizeof(STARTUPINFO));
 407         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 408
 409         startup.cb = sizeof(STARTUPINFO);
 410
 411         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 412                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 413                 CloseHandle(process.hThread);
 414                 cpid = (pid_t)process.hProcess;
 415         }
 416 #endif
 417
 418         if (cpid < 0) {
 419                 // Error.
 420                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 421         }
 422
 423         return cpid;
 424 }
 425
 426
 427 /////////////////////////////////////////////////////////////////////
 428 //
 429 // ForkedCallQueue
 430 //
 431 /////////////////////////////////////////////////////////////////////
 432
 433 namespace ForkedCallQueue {
 434
 435 /// A process in the queue
 436 typedef pair<string, ForkedCall::SignalTypePtr> Process;
 437 /** Add a process to the queue. Processes are forked sequentially
 438  *  only one is running at a time.
 439  *  Connect to the returned signal and you'll be informed when
 440  *  the process has ended.
 441  */
 442 ForkedCall::SignalTypePtr add(string const & process);
 443
 444 /// in-progress queue
 445 static queue<Process> callQueue_;
 446
 447 /// flag whether queue is running
 448 static bool running_ = 0;
 449
 450 ///
 451 void startCaller();
 452 ///
 453 void stopCaller();
 454 ///
 455 void callback(pid_t, int);
 456
 457 ForkedCall::SignalTypePtr add(string const & process)
 458 {
 459         ForkedCall::SignalTypePtr ptr;
 460         ptr.reset(new ForkedCall::SignalType);
 461         callQueue_.push(Process(process, ptr));
 462         if (!running_)
 463                 startCaller();
 464         return ptr;
 465 }
 466
 467
 468 void callNext()
 469 {
 470         if (callQueue_.empty())
 471                 return;
 472         Process pro = callQueue_.front();
 473         callQueue_.pop();
 474         // Bind our chain caller
 475         pro.second->connect(lyx::bind(&ForkedCallQueue::callback, _1, _2));
 476         ForkedCall call;
 477         //If we fail to fork the process, then emit the signal
 478         //to tell the outside world that it failed.
 479         if (call.startScript(pro.first, pro.second) > 0)
 480                 pro.second->operator()(0,1);
 481 }
 482
 483
 484 void callback(pid_t, int)
 485 {
 486         if (callQueue_.empty())
 487                 stopCaller();
 488         else
 489                 callNext();
 490 }
 491
 492
 493 void startCaller()
 494 {
 495         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 496         running_ = true ;
 497         callNext();
 498 }
 499
 500
 501 void stopCaller()
 502 {
 503         running_ = false ;
 504         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 505 }
 506
 507
 508 bool running()
 509 {
 510         return running_;
 511 }
 512
 513 } // namespace ForkedCallsQueue
 514
 515
 516
 517 /////////////////////////////////////////////////////////////////////
 518 //
 519 // ForkedCallsController
 520 //
 521 /////////////////////////////////////////////////////////////////////
 522
 523 #if defined(_WIN32)
 524 string const getChildErrorMessage()
 525 {
 526         DWORD const error_code = ::GetLastError();
 527
 528         HLOCAL t_message = 0;
 529         bool const ok = ::FormatMessage(
 530                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 531                 FORMAT_MESSAGE_FROM_SYSTEM,
 532                 0, error_code,
 533                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 534                 (LPTSTR) &t_message, 0, 0
 535                 ) != 0;
 536
 537         ostringstream ss;
 538         ss << "LyX: Error waiting for child: " << error_code;
 539
 540         if (ok) {
 541                 ss << ": " << (LPTSTR)t_message;
 542                 ::LocalFree(t_message);
 543         } else
 544                 ss << ": Error unknown.";
 545
 546         return ss.str();
 547 }
 548 #endif
 549
 550
 551 namespace ForkedCallsController {
 552
 553 typedef shared_ptr<ForkedProcess> ForkedProcessPtr;
 554 typedef list<ForkedProcessPtr> ListType;
 555 typedef ListType::iterator iterator;
 556
 557
 558 /// The child processes
 559 static ListType forkedCalls;
 560
 561 iterator find_pid(pid_t pid)
 562 {
 563         return find_if(forkedCalls.begin(), forkedCalls.end(),
 564                             lyx::bind(equal_to<pid_t>(),
 565                             lyx::bind(&ForkedCall::pid, _1),
 566                             pid));
 567 }
 568
 569
 570 void addCall(ForkedProcess const & newcall)
 571 {
 572         forkedCalls.push_back(newcall.clone());
 573 }
 574
 575
 576 // Check the list of dead children and emit any associated signals.
 577 void handleCompletedProcesses()
 578 {
 579         ListType::iterator it  = forkedCalls.begin();
 580         ListType::iterator end = forkedCalls.end();
 581         while (it != end) {
 582                 ForkedProcessPtr actCall = *it;
 583                 bool remove_it = false;
 584
 585 #if defined(_WIN32)
 586                 HANDLE const hProcess = HANDLE(actCall->pid());
 587
 588                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 589
 590                 switch (wait_status) {
 591                 case WAIT_TIMEOUT:
 592                         // Still running
 593                         break;
 594                 case WAIT_OBJECT_0: {
 595                         DWORD exit_code = 0;
 596                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 597                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 598                                        << getChildErrorMessage() << endl;
 599                                 // Child died, so pretend it returned 1
 600                                 actCall->setRetValue(1);
 601                         } else {
 602                                 actCall->setRetValue(exit_code);
 603                         }
 604                         CloseHandle(hProcess);
 605                         remove_it = true;
 606                         break;
 607                 }
 608                 case WAIT_FAILED:
 609                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 610                                << getChildErrorMessage() << endl;
 611                         actCall->setRetValue(1);
 612                         CloseHandle(hProcess);
 613                         remove_it = true;
 614                         break;
 615                 }
 616 #else
 617                 pid_t pid = actCall->pid();
 618                 int stat_loc;
 619                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 620
 621                 if (waitrpid == -1) {
 622                         lyxerr << "LyX: Error waiting for child: "
 623                                << strerror(errno) << endl;
 624
 625                         // Child died, so pretend it returned 1
 626                         actCall->setRetValue(1);
 627                         remove_it = true;
 628
 629                 } else if (waitrpid == 0) {
 630                         // Still running. Move on to the next child.
 631
 632                 } else if (WIFEXITED(stat_loc)) {
 633                         // Ok, the return value goes into retval.
 634                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 635                         remove_it = true;
 636
 637                 } else if (WIFSIGNALED(stat_loc)) {
 638                         // Child died, so pretend it returned 1
 639                         actCall->setRetValue(1);
 640                         remove_it = true;
 641
 642                 } else if (WIFSTOPPED(stat_loc)) {
 643                         lyxerr << "LyX: Child (pid: " << pid
 644                                << ") stopped on signal "
 645                                << WSTOPSIG(stat_loc)
 646                                << ". Waiting for child to finish." << endl;
 647
 648                 } else {
 649                         lyxerr << "LyX: Something rotten happened while "
 650                                 "waiting for child " << pid << endl;
 651
 652                         // Child died, so pretend it returned 1
 653                         actCall->setRetValue(1);
 654                         remove_it = true;
 655                 }
 656 #endif
 657
 658                 if (remove_it) {
 659                         forkedCalls.erase(it);
 660                         actCall->emitSignal();
 661
 662                         /* start all over: emiting the signal can result
 663                          * in changing the list (Ab)
 664                          */
 665                         it = forkedCalls.begin();
 666                 } else {
 667                         ++it;
 668                 }
 669         }
 670 }
 671
 672
 673 // Kill the process prematurely and remove it from the list
 674 // within tolerance secs
 675 void kill(pid_t pid, int tolerance)
 676 {
 677         ListType::iterator it = find_pid(pid);
 678         if (it == forkedCalls.end())
 679                 return;
 680
 681         (*it)->kill(tolerance);
 682         forkedCalls.erase(it);
 683 }
 684
 685 } // namespace ForkedCallsController
 686
 687 } // namespace support
 688 } // namespace lyx