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