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
 274 int ForkedCall::startScript(Starttype wait, string const & what)
 275 {
 276         if (wait != Wait) {
 277                 retval_ = startScript(what, SignalTypePtr());
 278                 return retval_;
 279         }
 280
 281         command_ = what;
 282         signal_.reset();
 283         return run(Wait);
 284 }
 285
 286
 287 int ForkedCall::startScript(string const & what, SignalTypePtr signal)
 288 {
 289         command_ = what;
 290         signal_  = signal;
 291
 292         return run(DontWait);
 293 }
 294
 295
 296 // generate child in background
 297 int ForkedCall::generateChild()
 298 {
 299         string line = trim(command_);
 300         if (line.empty())
 301                 return 1;
 302
 303 #if !defined (_WIN32)
 304         // POSIX
 305
 306         // Split the input command up into an array of words stored
 307         // in a contiguous block of memory. The array contains pointers
 308         // to each word.
 309         // Don't forget the terminating `\0' character.
 310         char const * const c_str = line.c_str();
 311         vector<char> vec(c_str, c_str + line.size() + 1);
 312
 313         // Splitting the command up into an array of words means replacing
 314         // the whitespace between words with '\0'. Life is complicated
 315         // however, because words protected by quotes can contain whitespace.
 316         //
 317         // The strategy we adopt is:
 318         // 1. If we're not inside quotes, then replace white space with '\0'.
 319         // 2. If we are inside quotes, then don't replace the white space
 320         //    but do remove the quotes themselves. We do this naively by
 321         //    replacing the quote with '\0' which is fine if quotes
 322         //    delimit the entire word.
 323         char inside_quote = 0;
 324         vector<char>::iterator it = vec.begin();
 325         vector<char>::iterator const end = vec.end();
 326         for (; it != end; ++it) {
 327                 char const c = *it;
 328                 if (!inside_quote) {
 329                         if (c == ' ')
 330                                 *it = '\0';
 331                         else if (c == '\'' || c == '"') {
 332                                 *it = '\0';
 333                                 inside_quote = c;
 334                         }
 335                 } else if (c == inside_quote) {
 336                         *it = '\0';
 337                         inside_quote = 0;
 338                 }
 339         }
 340
 341         // Build an array of pointers to each word.
 342         it = vec.begin();
 343         vector<char *> argv;
 344         char prev = '\0';
 345         for (; it != end; ++it) {
 346                 if (*it != '\0' && prev == '\0')
 347                         argv.push_back(&*it);
 348                 prev = *it;
 349         }
 350         argv.push_back(0);
 351
 352         // Debug output.
 353         if (lyxerr.debugging(Debug::FILES)) {
 354                 vector<char *>::iterator ait = argv.begin();
 355                 vector<char *>::iterator const aend = argv.end();
 356                 lyxerr << "<command>\n\t" << line
 357                        << "\n\tInterpretted as:\n\n";
 358                 for (; ait != aend; ++ait)
 359                         if (*ait)
 360                                 lyxerr << '\t'<< *ait << '\n';
 361                 lyxerr << "</command>" << endl;
 362         }
 363
 364         pid_t const cpid = ::fork();
 365         if (cpid == 0) {
 366                 // Child
 367                 execvp(argv[0], &*argv.begin());
 368
 369                 // If something goes wrong, we end up here
 370                 lyxerr << "execvp of \"" << command_ << "\" failed: "
 371                        << strerror(errno) << endl;
 372                 _exit(1);
 373         }
 374 #else
 375         // Windows
 376
 377         pid_t cpid = -1;
 378
 379         STARTUPINFO startup;
 380         PROCESS_INFORMATION process;
 381
 382         memset(&startup, 0, sizeof(STARTUPINFO));
 383         memset(&process, 0, sizeof(PROCESS_INFORMATION));
 384
 385         startup.cb = sizeof(STARTUPINFO);
 386
 387         if (CreateProcess(0, (LPSTR)line.c_str(), 0, 0, FALSE,
 388                 CREATE_NO_WINDOW, 0, 0, &startup, &process)) {
 389                 CloseHandle(process.hThread);
 390                 cpid = (pid_t)process.hProcess;
 391         }
 392 #endif
 393
 394         if (cpid < 0) {
 395                 // Error.
 396                 lyxerr << "Could not fork: " << strerror(errno) << endl;
 397         }
 398
 399         return cpid;
 400 }
 401
 402
 403 /////////////////////////////////////////////////////////////////////
 404 //
 405 // ForkedCallQueue
 406 //
 407 /////////////////////////////////////////////////////////////////////
 408
 409 namespace ForkedCallQueue {
 410
 411 /// A process in the queue
 412 typedef pair<string, ForkedCall::SignalTypePtr> Process;
 413 /** Add a process to the queue. Processes are forked sequentially
 414  *  only one is running at a time.
 415  *  Connect to the returned signal and you'll be informed when
 416  *  the process has ended.
 417  */
 418 ForkedCall::SignalTypePtr add(string const & process);
 419
 420 /// in-progress queue
 421 static queue<Process> callQueue_;
 422
 423 /// flag whether queue is running
 424 static bool running_ = 0;
 425
 426 ///
 427 void startCaller();
 428 ///
 429 void stopCaller();
 430 ///
 431 void callback(pid_t, int);
 432
 433 ForkedCall::SignalTypePtr add(string const & process)
 434 {
 435         ForkedCall::SignalTypePtr ptr;
 436         ptr.reset(new ForkedCall::SignalType);
 437         callQueue_.push(Process(process, ptr));
 438         if (!running_)
 439                 startCaller();
 440         return ptr;
 441 }
 442
 443
 444 void callNext()
 445 {
 446         if (callQueue_.empty())
 447                 return;
 448         Process pro = callQueue_.front();
 449         callQueue_.pop();
 450         // Bind our chain caller
 451         pro.second->connect(lyx::bind(&ForkedCallQueue::callback, _1, _2));
 452         ForkedCall call;
 453         //If we fail to fork the process, then emit the signal
 454         //to tell the outside world that it failed.
 455         if (call.startScript(pro.first, pro.second) > 0)
 456                 pro.second->operator()(0,1);
 457 }
 458
 459
 460 void callback(pid_t, int)
 461 {
 462         if (callQueue_.empty())
 463                 stopCaller();
 464         else
 465                 callNext();
 466 }
 467
 468
 469 void startCaller()
 470 {
 471         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: waking up");
 472         running_ = true ;
 473         callNext();
 474 }
 475
 476
 477 void stopCaller()
 478 {
 479         running_ = false ;
 480         LYXERR(Debug::GRAPHICS, "ForkedCallQueue: I'm going to sleep");
 481 }
 482
 483
 484 bool running()
 485 {
 486         return running_;
 487 }
 488
 489 } // namespace ForkedCallsQueue
 490
 491
 492
 493 /////////////////////////////////////////////////////////////////////
 494 //
 495 // ForkedCallsController
 496 //
 497 /////////////////////////////////////////////////////////////////////
 498
 499 #if defined(_WIN32)
 500 string const getChildErrorMessage()
 501 {
 502         DWORD const error_code = ::GetLastError();
 503
 504         HLOCAL t_message = 0;
 505         bool const ok = ::FormatMessage(
 506                 FORMAT_MESSAGE_ALLOCATE_BUFFER |
 507                 FORMAT_MESSAGE_FROM_SYSTEM,
 508                 0, error_code,
 509                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 510                 (LPTSTR) &t_message, 0, 0
 511                 ) != 0;
 512
 513         ostringstream ss;
 514         ss << "LyX: Error waiting for child: " << error_code;
 515
 516         if (ok) {
 517                 ss << ": " << (LPTSTR)t_message;
 518                 ::LocalFree(t_message);
 519         } else
 520                 ss << ": Error unknown.";
 521
 522         return ss.str();
 523 }
 524 #endif
 525
 526
 527 namespace ForkedCallsController {
 528
 529 typedef shared_ptr<ForkedProcess> ForkedProcessPtr;
 530 typedef list<ForkedProcessPtr> ListType;
 531 typedef ListType::iterator iterator;
 532
 533
 534 /// The child processes
 535 static ListType forkedCalls;
 536
 537 iterator find_pid(pid_t pid)
 538 {
 539         return find_if(forkedCalls.begin(), forkedCalls.end(),
 540                             lyx::bind(equal_to<pid_t>(),
 541                             lyx::bind(&ForkedCall::pid, _1),
 542                             pid));
 543 }
 544
 545
 546 void addCall(ForkedProcess const & newcall)
 547 {
 548         forkedCalls.push_back(newcall.clone());
 549 }
 550
 551
 552 // Check the list of dead children and emit any associated signals.
 553 void handleCompletedProcesses()
 554 {
 555         ListType::iterator it  = forkedCalls.begin();
 556         ListType::iterator end = forkedCalls.end();
 557         while (it != end) {
 558                 ForkedProcessPtr actCall = *it;
 559                 bool remove_it = false;
 560
 561 #if defined(_WIN32)
 562                 HANDLE const hProcess = HANDLE(actCall->pid());
 563
 564                 DWORD const wait_status = ::WaitForSingleObject(hProcess, 0);
 565
 566                 switch (wait_status) {
 567                 case WAIT_TIMEOUT:
 568                         // Still running
 569                         break;
 570                 case WAIT_OBJECT_0: {
 571                         DWORD exit_code = 0;
 572                         if (!GetExitCodeProcess(hProcess, &exit_code)) {
 573                                 lyxerr << "GetExitCodeProcess failed waiting for child\n"
 574                                        << getChildErrorMessage() << endl;
 575                                 // Child died, so pretend it returned 1
 576                                 actCall->setRetValue(1);
 577                         } else {
 578                                 actCall->setRetValue(exit_code);
 579                         }
 580                         CloseHandle(hProcess);
 581                         remove_it = true;
 582                         break;
 583                 }
 584                 case WAIT_FAILED:
 585                         lyxerr << "WaitForSingleObject failed waiting for child\n"
 586                                << getChildErrorMessage() << endl;
 587                         actCall->setRetValue(1);
 588                         CloseHandle(hProcess);
 589                         remove_it = true;
 590                         break;
 591                 }
 592 #else
 593                 pid_t pid = actCall->pid();
 594                 int stat_loc;
 595                 pid_t const waitrpid = waitpid(pid, &stat_loc, WNOHANG);
 596
 597                 if (waitrpid == -1) {
 598                         lyxerr << "LyX: Error waiting for child: "
 599                                << strerror(errno) << endl;
 600
 601                         // Child died, so pretend it returned 1
 602                         actCall->setRetValue(1);
 603                         remove_it = true;
 604
 605                 } else if (waitrpid == 0) {
 606                         // Still running. Move on to the next child.
 607
 608                 } else if (WIFEXITED(stat_loc)) {
 609                         // Ok, the return value goes into retval.
 610                         actCall->setRetValue(WEXITSTATUS(stat_loc));
 611                         remove_it = true;
 612
 613                 } else if (WIFSIGNALED(stat_loc)) {
 614                         // Child died, so pretend it returned 1
 615                         actCall->setRetValue(1);
 616                         remove_it = true;
 617
 618                 } else if (WIFSTOPPED(stat_loc)) {
 619                         lyxerr << "LyX: Child (pid: " << pid
 620                                << ") stopped on signal "
 621                                << WSTOPSIG(stat_loc)
 622                                << ". Waiting for child to finish." << endl;
 623
 624                 } else {
 625                         lyxerr << "LyX: Something rotten happened while "
 626                                 "waiting for child " << pid << endl;
 627
 628                         // Child died, so pretend it returned 1
 629                         actCall->setRetValue(1);
 630                         remove_it = true;
 631                 }
 632 #endif
 633
 634                 if (remove_it) {
 635                         forkedCalls.erase(it);
 636                         actCall->emitSignal();
 637
 638                         /* start all over: emiting the signal can result
 639                          * in changing the list (Ab)
 640                          */
 641                         it = forkedCalls.begin();
 642                 } else {
 643                         ++it;
 644                 }
 645         }
 646 }
 647
 648
 649 // Kill the process prematurely and remove it from the list
 650 // within tolerance secs
 651 void kill(pid_t pid, int tolerance)
 652 {
 653         ListType::iterator it = find_pid(pid);
 654         if (it == forkedCalls.end())
 655                 return;
 656
 657         (*it)->kill(tolerance);
 658         forkedCalls.erase(it);
 659 }
 660
 661 } // namespace ForkedCallsController
 662
 663 } // namespace support
 664 } // namespace lyx