apt-pkg/acquire-worker.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: acquire-worker.cc,v 1.34 2001/05/22 04:42:54 jgg Exp $
   4 /* ######################################################################
   5
   6    Acquire Worker
   7
   8    The worker process can startup either as a Configuration prober
   9    or as a queue runner. As a configuration prober it only reads the
  10    configuration message and
  11
  12    ##################################################################### */
  13                                                                         /*}}}*/
  14 // Include Files                                                        /*{{{*/
  15 #include <config.h>
  16
  17 #include <apt-pkg/acquire.h>
  18 #include <apt-pkg/acquire-worker.h>
  19 #include <apt-pkg/acquire-item.h>
  20 #include <apt-pkg/configuration.h>
  21 #include <apt-pkg/error.h>
  22 #include <apt-pkg/fileutl.h>
  23 #include <apt-pkg/strutl.h>
  24 #include <apt-pkg/hashes.h>
  25
  26 #include <algorithm>
  27 #include <string>
  28 #include <vector>
  29 #include <iostream>
  30
  31 #include <sys/stat.h>
  32 #include <stdlib.h>
  33 #include <unistd.h>
  34 #include <signal.h>
  35 #include <stdio.h>
  36 #include <errno.h>
  37 #include <sstream>
  38
  39 #include <apti18n.h>
  40                                                                         /*}}}*/
  41
  42 using namespace std;
  43
  44 // Worker::Worker - Constructor for Queue startup                       /*{{{*/
  45 pkgAcquire::Worker::Worker(Queue *Q, MethodConfig *Cnf, pkgAcquireStatus *log) :
  46    d(NULL), OwnerQ(Q), Log(log), Config(Cnf), Access(Cnf->Access),
  47    CurrentItem(nullptr), CurrentSize(0), TotalSize(0)
  48 {
  49    Construct();
  50 }
  51                                                                         /*}}}*/
  52 // Worker::Worker - Constructor for method config startup               /*{{{*/
  53 pkgAcquire::Worker::Worker(MethodConfig *Cnf) : Worker(nullptr, Cnf, nullptr)
  54 {
  55 }
  56                                                                         /*}}}*/
  57 // Worker::Construct - Constructor helper                               /*{{{*/
  58 // ---------------------------------------------------------------------
  59 /* */
  60 void pkgAcquire::Worker::Construct()
  61 {
  62    NextQueue = 0;
  63    NextAcquire = 0;
  64    Process = -1;
  65    InFd = -1;
  66    OutFd = -1;
  67    OutReady = false;
  68    InReady = false;
  69    Debug = _config->FindB("Debug::pkgAcquire::Worker",false);
  70 }
  71                                                                         /*}}}*/
  72 // Worker::~Worker - Destructor                                         /*{{{*/
  73 // ---------------------------------------------------------------------
  74 /* */
  75 pkgAcquire::Worker::~Worker()
  76 {
  77    close(InFd);
  78    close(OutFd);
  79
  80    if (Process > 0)
  81    {
  82       /* Closing of stdin is the signal to exit and die when the process
  83          indicates it needs cleanup */
  84       if (Config->NeedsCleanup == false)
  85          kill(Process,SIGINT);
  86       ExecWait(Process,Access.c_str(),true);
  87    }
  88 }
  89                                                                         /*}}}*/
  90 // Worker::Start - Start the worker process                             /*{{{*/
  91 // ---------------------------------------------------------------------
  92 /* This forks the method and inits the communication channel */
  93 bool pkgAcquire::Worker::Start()
  94 {
  95    // Get the method path
  96    string Method = _config->FindDir("Dir::Bin::Methods") + Access;
  97    if (FileExists(Method) == false)
  98    {
  99       _error->Error(_("The method driver %s could not be found."),Method.c_str());
 100       if (Access == "https")
 101          _error->Notice(_("Is the package %s installed?"), "apt-transport-https");
 102       return false;
 103    }
 104
 105    if (Debug == true)
 106       clog << "Starting method '" << Method << '\'' << endl;
 107
 108    // Create the pipes
 109    int Pipes[4] = {-1,-1,-1,-1};
 110    if (pipe(Pipes) != 0 || pipe(Pipes+2) != 0)
 111    {
 112       _error->Errno("pipe","Failed to create IPC pipe to subprocess");
 113       for (int I = 0; I != 4; I++)
 114          close(Pipes[I]);
 115       return false;
 116    }
 117    for (int I = 0; I != 4; I++)
 118       SetCloseExec(Pipes[I],true);
 119
 120    // Fork off the process
 121    Process = ExecFork();
 122    if (Process == 0)
 123    {
 124       // Setup the FDs
 125       dup2(Pipes[1],STDOUT_FILENO);
 126       dup2(Pipes[2],STDIN_FILENO);
 127       SetCloseExec(STDOUT_FILENO,false);
 128       SetCloseExec(STDIN_FILENO,false);
 129       SetCloseExec(STDERR_FILENO,false);
 130
 131       const char *Args[2];
 132       Args[0] = Method.c_str();
 133       Args[1] = 0;
 134       execv(Args[0],(char **)Args);
 135       cerr << "Failed to exec method " << Args[0] << endl;
 136       _exit(100);
 137    }
 138
 139    // Fix up our FDs
 140    InFd = Pipes[0];
 141    OutFd = Pipes[3];
 142    SetNonBlock(Pipes[0],true);
 143    SetNonBlock(Pipes[3],true);
 144    close(Pipes[1]);
 145    close(Pipes[2]);
 146    OutReady = false;
 147    InReady = true;
 148
 149    // Read the configuration data
 150    if (WaitFd(InFd) == false ||
 151        ReadMessages() == false)
 152       return _error->Error(_("Method %s did not start correctly"),Method.c_str());
 153
 154    RunMessages();
 155    if (OwnerQ != 0)
 156       SendConfiguration();
 157
 158    return true;
 159 }
 160                                                                         /*}}}*/
 161 // Worker::ReadMessages - Read all pending messages into the list       /*{{{*/
 162 // ---------------------------------------------------------------------
 163 /* */
 164 bool pkgAcquire::Worker::ReadMessages()
 165 {
 166    if (::ReadMessages(InFd,MessageQueue) == false)
 167       return MethodFailure();
 168    return true;
 169 }
 170                                                                         /*}}}*/
 171 // Worker::RunMessage - Empty the message queue                         /*{{{*/
 172 // ---------------------------------------------------------------------
 173 /* This takes the messages from the message queue and runs them through
 174    the parsers in order. */
 175 enum class APT_HIDDEN MessageType {
 176    CAPABILITIES = 100,
 177    LOG = 101,
 178    STATUS = 102,
 179    REDIRECT = 103,
 180    WARNING = 104,
 181    URI_START = 200,
 182    URI_DONE = 201,
 183    URI_FAILURE = 400,
 184    GENERAL_FAILURE = 401,
 185    MEDIA_CHANGE = 403
 186 };
 187 static bool isDoomedItem(pkgAcquire::Item const * const Itm)
 188 {
 189    auto const TransItm = dynamic_cast<pkgAcqTransactionItem const * const>(Itm);
 190    if (TransItm == nullptr)
 191       return false;
 192    return TransItm->TransactionManager->State != pkgAcqTransactionItem::TransactionStarted;
 193 }
 194 bool pkgAcquire::Worker::RunMessages()
 195 {
 196    while (MessageQueue.empty() == false)
 197    {
 198       string Message = MessageQueue.front();
 199       MessageQueue.erase(MessageQueue.begin());
 200
 201       if (Debug == true)
 202          clog << " <- " << Access << ':' << QuoteString(Message,"\n") << endl;
 203
 204       // Fetch the message number
 205       char *End;
 206       MessageType const Number = static_cast<MessageType>(strtoul(Message.c_str(),&End,10));
 207       if (End == Message.c_str())
 208          return _error->Error("Invalid message from method %s: %s",Access.c_str(),Message.c_str());
 209
 210       string URI = LookupTag(Message,"URI");
 211       pkgAcquire::Queue::QItem *Itm = NULL;
 212       if (URI.empty() == false)
 213          Itm = OwnerQ->FindItem(URI,this);
 214
 215       if (Itm != NULL)
 216       {
 217          // update used mirror
 218          string UsedMirror = LookupTag(Message,"UsedMirror", "");
 219          if (UsedMirror.empty() == false)
 220          {
 221             for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
 222                (*O)->UsedMirror = UsedMirror;
 223
 224             if (Itm->Description.find(" ") != string::npos)
 225                Itm->Description.replace(0, Itm->Description.find(" "), UsedMirror);
 226          }
 227       }
 228
 229       // Determine the message number and dispatch
 230       switch (Number)
 231       {
 232          case MessageType::CAPABILITIES:
 233          if (Capabilities(Message) == false)
 234             return _error->Error("Unable to process Capabilities message from %s",Access.c_str());
 235          break;
 236
 237          case MessageType::LOG:
 238          if (Debug == true)
 239             clog << " <- (log) " << LookupTag(Message,"Message") << endl;
 240          break;
 241
 242          case MessageType::STATUS:
 243          Status = LookupTag(Message,"Message");
 244          break;
 245
 246          case MessageType::REDIRECT:
 247          {
 248             if (Itm == nullptr)
 249             {
 250                _error->Error("Method gave invalid 103 Redirect message");
 251                break;
 252             }
 253
 254             std::string const NewURI = LookupTag(Message,"New-URI",URI.c_str());
 255             Itm->URI = NewURI;
 256
 257             ItemDone();
 258
 259             // Change the status so that it can be dequeued
 260             for (auto const &O: Itm->Owners)
 261                O->Status = pkgAcquire::Item::StatIdle;
 262             // Mark the item as done (taking care of all queues)
 263             // and then put it in the main queue again
 264             std::vector<Item*> const ItmOwners = Itm->Owners;
 265             OwnerQ->ItemDone(Itm);
 266             Itm = nullptr;
 267             for (auto const &Owner: ItmOwners)
 268             {
 269                pkgAcquire::ItemDesc &desc = Owner->GetItemDesc();
 270                if (Log != nullptr)
 271                   Log->Done(desc);
 272
 273                // if we change site, treat it as a mirror change
 274                if (URI::SiteOnly(NewURI) != URI::SiteOnly(desc.URI))
 275                {
 276                   std::string const OldSite = desc.Description.substr(0, desc.Description.find(" "));
 277                   if (likely(APT::String::Startswith(desc.URI, OldSite)))
 278                   {
 279                      std::string const OldExtra = desc.URI.substr(OldSite.length() + 1);
 280                      if (likely(APT::String::Endswith(NewURI, OldExtra)))
 281                      {
 282                         std::string const NewSite = NewURI.substr(0, NewURI.length() - OldExtra.length());
 283                         Owner->UsedMirror = URI::ArchiveOnly(NewSite);
 284                         if (desc.Description.find(" ") != string::npos)
 285                            desc.Description.replace(0, desc.Description.find(" "), Owner->UsedMirror);
 286                      }
 287                   }
 288                }
 289                desc.URI = NewURI;
 290                if (isDoomedItem(Owner) == false)
 291                   OwnerQ->Owner->Enqueue(desc);
 292             }
 293             break;
 294          }
 295
 296          case MessageType::WARNING:
 297             _error->Warning("%s: %s", Itm->Owner->DescURI().c_str(), LookupTag(Message,"Message").c_str());
 298             break;
 299
 300          case MessageType::URI_START:
 301          {
 302             if (Itm == nullptr)
 303             {
 304                _error->Error("Method gave invalid 200 URI Start message");
 305                break;
 306             }
 307
 308             CurrentItem = Itm;
 309             CurrentSize = 0;
 310             TotalSize = strtoull(LookupTag(Message,"Size","0").c_str(), NULL, 10);
 311             ResumePoint = strtoull(LookupTag(Message,"Resume-Point","0").c_str(), NULL, 10);
 312             for (auto const Owner: Itm->Owners)
 313             {
 314                Owner->Start(Message, TotalSize);
 315                // Display update before completion
 316                if (Log != nullptr)
 317                {
 318                   if (Log->MorePulses == true)
 319                      Log->Pulse(Owner->GetOwner());
 320                   Log->Fetch(Owner->GetItemDesc());
 321                }
 322             }
 323
 324             break;
 325          }
 326
 327          case MessageType::URI_DONE:
 328          {
 329             if (Itm == nullptr)
 330             {
 331                _error->Error("Method gave invalid 201 URI Done message");
 332                break;
 333             }
 334
 335             PrepareFiles("201::URIDone", Itm);
 336
 337             // Display update before completion
 338             if (Log != 0 && Log->MorePulses == true)
 339                for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
 340                   Log->Pulse((*O)->GetOwner());
 341
 342             HashStringList ReceivedHashes;
 343             {
 344                std::string const givenfilename = LookupTag(Message, "Filename");
 345                std::string const filename = givenfilename.empty() ? Itm->Owner->DestFile : givenfilename;
 346                // see if we got hashes to verify
 347                for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
 348                {
 349                   std::string const tagname = std::string(*type) + "-Hash";
 350                   std::string const hashsum = LookupTag(Message, tagname.c_str());
 351                   if (hashsum.empty() == false)
 352                      ReceivedHashes.push_back(HashString(*type, hashsum));
 353                }
 354                // not all methods always sent Hashes our way
 355                if (ReceivedHashes.usable() == false)
 356                {
 357                   HashStringList const ExpectedHashes = Itm->GetExpectedHashes();
 358                   if (ExpectedHashes.usable() == true && RealFileExists(filename))
 359                   {
 360                      Hashes calc(ExpectedHashes);
 361                      FileFd file(filename, FileFd::ReadOnly, FileFd::None);
 362                      calc.AddFD(file);
 363                      ReceivedHashes = calc.GetHashStringList();
 364                   }
 365                }
 366
 367                // only local files can refer other filenames and counting them as fetched would be unfair
 368                if (Log != NULL && Itm->Owner->Complete == false && Itm->Owner->Local == false && givenfilename == filename)
 369                   Log->Fetched(ReceivedHashes.FileSize(),atoi(LookupTag(Message,"Resume-Point","0").c_str()));
 370             }
 371
 372             std::vector<Item*> const ItmOwners = Itm->Owners;
 373             OwnerQ->ItemDone(Itm);
 374             Itm = NULL;
 375
 376             bool const isIMSHit = StringToBool(LookupTag(Message,"IMS-Hit"),false) ||
 377                StringToBool(LookupTag(Message,"Alt-IMS-Hit"),false);
 378             for (auto const Owner: ItmOwners)
 379             {
 380                HashStringList const ExpectedHashes = Owner->GetExpectedHashes();
 381                if(_config->FindB("Debug::pkgAcquire::Auth", false) == true)
 382                {
 383                   std::clog << "201 URI Done: " << Owner->DescURI() << endl
 384                      << "ReceivedHash:" << endl;
 385                   for (HashStringList::const_iterator hs = ReceivedHashes.begin(); hs != ReceivedHashes.end(); ++hs)
 386                      std::clog <<  "\t- " << hs->toStr() << std::endl;
 387                   std::clog << "ExpectedHash:" << endl;
 388                   for (HashStringList::const_iterator hs = ExpectedHashes.begin(); hs != ExpectedHashes.end(); ++hs)
 389                      std::clog <<  "\t- " << hs->toStr() << std::endl;
 390                   std::clog << endl;
 391                }
 392
 393                // decide if what we got is what we expected
 394                bool consideredOkay = false;
 395                if (ExpectedHashes.usable())
 396                {
 397                   if (ReceivedHashes.usable() == false)
 398                   {
 399                      /* IMS-Hits can't be checked here as we will have uncompressed file,
 400                         but the hashes for the compressed file. What we have was good through
 401                         so all we have to ensure later is that we are not stalled. */
 402                      consideredOkay = isIMSHit;
 403                   }
 404                   else if (ReceivedHashes == ExpectedHashes)
 405                      consideredOkay = true;
 406                   else
 407                      consideredOkay = false;
 408
 409                }
 410                else if (Owner->HashesRequired() == true)
 411                   consideredOkay = false;
 412                else
 413                {
 414                   consideredOkay = true;
 415                   // even if the hashes aren't usable to declare something secure
 416                   // we can at least use them to declare it an integrity failure
 417                   if (ExpectedHashes.empty() == false && ReceivedHashes != ExpectedHashes && _config->Find("Acquire::ForceHash").empty())
 418                      consideredOkay = false;
 419                }
 420
 421                if (consideredOkay == true)
 422                   consideredOkay = Owner->VerifyDone(Message, Config);
 423                else // hashsum mismatch
 424                   Owner->Status = pkgAcquire::Item::StatAuthError;
 425
 426
 427                if (consideredOkay == true)
 428                {
 429                   if (isDoomedItem(Owner) == false)
 430                      Owner->Done(Message, ReceivedHashes, Config);
 431                   if (Log != nullptr)
 432                   {
 433                      if (isIMSHit)
 434                         Log->IMSHit(Owner->GetItemDesc());
 435                      else
 436                         Log->Done(Owner->GetItemDesc());
 437                   }
 438                }
 439                else
 440                {
 441                   if (isDoomedItem(Owner) == false)
 442                      Owner->Failed(Message,Config);
 443                   if (Log != nullptr)
 444                      Log->Fail(Owner->GetItemDesc());
 445                }
 446             }
 447             ItemDone();
 448             break;
 449          }
 450
 451          case MessageType::URI_FAILURE:
 452          {
 453             if (Itm == nullptr)
 454             {
 455                std::string const msg = LookupTag(Message,"Message");
 456                _error->Error("Method gave invalid 400 URI Failure message: %s", msg.c_str());
 457                break;
 458             }
 459
 460             PrepareFiles("400::URIFailure", Itm);
 461
 462             // Display update before completion
 463             if (Log != nullptr && Log->MorePulses == true)
 464                for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
 465                   Log->Pulse((*O)->GetOwner());
 466
 467             std::vector<Item*> const ItmOwners = Itm->Owners;
 468             OwnerQ->ItemDone(Itm);
 469             Itm = nullptr;
 470
 471             bool errTransient;
 472             {
 473                std::string const failReason = LookupTag(Message, "FailReason");
 474                std::string const reasons[] = { "Timeout", "ConnectionRefused",
 475                   "ConnectionTimedOut", "ResolveFailure", "TmpResolveFailure" };
 476                errTransient = std::find(std::begin(reasons), std::end(reasons), failReason) != std::end(reasons);
 477             }
 478
 479             for (auto const Owner: ItmOwners)
 480             {
 481                if (errTransient)
 482                   Owner->Status = pkgAcquire::Item::StatTransientNetworkError;
 483                if (isDoomedItem(Owner) == false)
 484                   Owner->Failed(Message,Config);
 485                if (Log != nullptr)
 486                   Log->Fail(Owner->GetItemDesc());
 487             }
 488             ItemDone();
 489
 490             break;
 491          }
 492
 493          case MessageType::GENERAL_FAILURE:
 494          _error->Error("Method %s General failure: %s",Access.c_str(),LookupTag(Message,"Message").c_str());
 495          break;
 496
 497          case MessageType::MEDIA_CHANGE:
 498          MediaChange(Message);
 499          break;
 500       }
 501    }
 502    return true;
 503 }
 504                                                                         /*}}}*/
 505 // Worker::Capabilities - 100 Capabilities handler                      /*{{{*/
 506 // ---------------------------------------------------------------------
 507 /* This parses the capabilities message and dumps it into the configuration
 508    structure. */
 509 bool pkgAcquire::Worker::Capabilities(string Message)
 510 {
 511    if (Config == 0)
 512       return true;
 513
 514    Config->Version = LookupTag(Message,"Version");
 515    Config->SingleInstance = StringToBool(LookupTag(Message,"Single-Instance"),false);
 516    Config->Pipeline = StringToBool(LookupTag(Message,"Pipeline"),false);
 517    Config->SendConfig = StringToBool(LookupTag(Message,"Send-Config"),false);
 518    Config->LocalOnly = StringToBool(LookupTag(Message,"Local-Only"),false);
 519    Config->NeedsCleanup = StringToBool(LookupTag(Message,"Needs-Cleanup"),false);
 520    Config->Removable = StringToBool(LookupTag(Message,"Removable"),false);
 521
 522    // Some debug text
 523    if (Debug == true)
 524    {
 525       clog << "Configured access method " << Config->Access << endl;
 526       clog << "Version:" << Config->Version <<
 527               " SingleInstance:" << Config->SingleInstance <<
 528               " Pipeline:" << Config->Pipeline <<
 529               " SendConfig:" << Config->SendConfig <<
 530               " LocalOnly: " << Config->LocalOnly <<
 531               " NeedsCleanup: " << Config->NeedsCleanup <<
 532               " Removable: " << Config->Removable << endl;
 533    }
 534
 535    return true;
 536 }
 537                                                                         /*}}}*/
 538 // Worker::MediaChange - Request a media change                         /*{{{*/
 539 // ---------------------------------------------------------------------
 540 /* */
 541 bool pkgAcquire::Worker::MediaChange(string Message)
 542 {
 543    int status_fd = _config->FindI("APT::Status-Fd",-1);
 544    if(status_fd > 0)
 545    {
 546       string Media = LookupTag(Message,"Media");
 547       string Drive = LookupTag(Message,"Drive");
 548       ostringstream msg,status;
 549       ioprintf(msg,_("Please insert the disc labeled: "
 550                      "'%s' "
 551                      "in the drive '%s' and press [Enter]."),
 552                Media.c_str(),Drive.c_str());
 553       status << "media-change: "  // message
 554              << Media  << ":"     // media
 555              << Drive  << ":"     // drive
 556              << msg.str()         // l10n message
 557              << endl;
 558
 559       std::string const dlstatus = status.str();
 560       FileFd::Write(status_fd, dlstatus.c_str(), dlstatus.size());
 561    }
 562
 563    if (Log == 0 || Log->MediaChange(LookupTag(Message,"Media"),
 564                                     LookupTag(Message,"Drive")) == false)
 565    {
 566       char S[300];
 567       snprintf(S,sizeof(S),"603 Media Changed\nFailed: true\n\n");
 568       if (Debug == true)
 569          clog << " -> " << Access << ':' << QuoteString(S,"\n") << endl;
 570       OutQueue += S;
 571       OutReady = true;
 572       return true;
 573    }
 574
 575    char S[300];
 576    snprintf(S,sizeof(S),"603 Media Changed\n\n");
 577    if (Debug == true)
 578       clog << " -> " << Access << ':' << QuoteString(S,"\n") << endl;
 579    OutQueue += S;
 580    OutReady = true;
 581    return true;
 582 }
 583                                                                         /*}}}*/
 584 // Worker::SendConfiguration - Send the config to the method            /*{{{*/
 585 // ---------------------------------------------------------------------
 586 /* */
 587 bool pkgAcquire::Worker::SendConfiguration()
 588 {
 589    if (Config->SendConfig == false)
 590       return true;
 591
 592    if (OutFd == -1)
 593       return false;
 594
 595    /* Write out all of the configuration directives by walking the
 596       configuration tree */
 597    std::ostringstream Message;
 598    Message << "601 Configuration\n";
 599    _config->Dump(Message, NULL, "Config-Item: %F=%V\n", false);
 600    Message << '\n';
 601
 602    if (Debug == true)
 603       clog << " -> " << Access << ':' << QuoteString(Message.str(),"\n") << endl;
 604    OutQueue += Message.str();
 605    OutReady = true;
 606
 607    return true;
 608 }
 609                                                                         /*}}}*/
 610 // Worker::QueueItem - Add an item to the outbound queue                /*{{{*/
 611 // ---------------------------------------------------------------------
 612 /* Send a URI Acquire message to the method */
 613 bool pkgAcquire::Worker::QueueItem(pkgAcquire::Queue::QItem *Item)
 614 {
 615    if (OutFd == -1)
 616       return false;
 617
 618    string Message = "600 URI Acquire\n";
 619    Message.reserve(300);
 620    Message += "URI: " + Item->URI;
 621    Message += "\nFilename: " + Item->Owner->DestFile;
 622
 623    HashStringList const hsl = Item->GetExpectedHashes();
 624    for (HashStringList::const_iterator hs = hsl.begin(); hs != hsl.end(); ++hs)
 625       Message += "\nExpected-" + hs->HashType() + ": " + hs->HashValue();
 626
 627    if (hsl.FileSize() == 0)
 628    {
 629       unsigned long long FileSize = Item->GetMaximumSize();
 630       if(FileSize > 0)
 631       {
 632          string MaximumSize;
 633          strprintf(MaximumSize, "%llu", FileSize);
 634          Message += "\nMaximum-Size: " + MaximumSize;
 635       }
 636    }
 637
 638    Item->SyncDestinationFiles();
 639    Message += Item->Custom600Headers();
 640    Message += "\n\n";
 641
 642    if (RealFileExists(Item->Owner->DestFile))
 643    {
 644       std::string const SandboxUser = _config->Find("APT::Sandbox::User");
 645       ChangeOwnerAndPermissionOfFile("Item::QueueURI", Item->Owner->DestFile.c_str(),
 646                                      SandboxUser.c_str(), "root", 0600);
 647    }
 648
 649    if (Debug == true)
 650       clog << " -> " << Access << ':' << QuoteString(Message,"\n") << endl;
 651    OutQueue += Message;
 652    OutReady = true;
 653
 654    return true;
 655 }
 656                                                                         /*}}}*/
 657 // Worker::OutFdRead - Out bound FD is ready                            /*{{{*/
 658 // ---------------------------------------------------------------------
 659 /* */
 660 bool pkgAcquire::Worker::OutFdReady()
 661 {
 662    int Res;
 663    do
 664    {
 665       Res = write(OutFd,OutQueue.c_str(),OutQueue.length());
 666    }
 667    while (Res < 0 && errno == EINTR);
 668
 669    if (Res <= 0)
 670       return MethodFailure();
 671
 672    OutQueue.erase(0,Res);
 673    if (OutQueue.empty() == true)
 674       OutReady = false;
 675
 676    return true;
 677 }
 678                                                                         /*}}}*/
 679 // Worker::InFdRead - In bound FD is ready                              /*{{{*/
 680 // ---------------------------------------------------------------------
 681 /* */
 682 bool pkgAcquire::Worker::InFdReady()
 683 {
 684    if (ReadMessages() == false)
 685       return false;
 686    RunMessages();
 687    return true;
 688 }
 689                                                                         /*}}}*/
 690 // Worker::MethodFailure - Called when the method fails                 /*{{{*/
 691 // ---------------------------------------------------------------------
 692 /* This is called when the method is believed to have failed, probably because
 693    read returned -1. */
 694 bool pkgAcquire::Worker::MethodFailure()
 695 {
 696    _error->Error("Method %s has died unexpectedly!",Access.c_str());
 697
 698    // do not reap the child here to show meaningfull error to the user
 699    ExecWait(Process,Access.c_str(),false);
 700    Process = -1;
 701    close(InFd);
 702    close(OutFd);
 703    InFd = -1;
 704    OutFd = -1;
 705    OutReady = false;
 706    InReady = false;
 707    OutQueue = string();
 708    MessageQueue.erase(MessageQueue.begin(),MessageQueue.end());
 709
 710    return false;
 711 }
 712                                                                         /*}}}*/
 713 // Worker::Pulse - Called periodically                                  /*{{{*/
 714 // ---------------------------------------------------------------------
 715 /* */
 716 void pkgAcquire::Worker::Pulse()
 717 {
 718    if (CurrentItem == 0)
 719       return;
 720
 721    struct stat Buf;
 722    if (stat(CurrentItem->Owner->DestFile.c_str(),&Buf) != 0)
 723       return;
 724    CurrentSize = Buf.st_size;
 725 }
 726                                                                         /*}}}*/
 727 // Worker::ItemDone - Called when the current item is finished          /*{{{*/
 728 // ---------------------------------------------------------------------
 729 /* */
 730 void pkgAcquire::Worker::ItemDone()
 731 {
 732    CurrentItem = 0;
 733    CurrentSize = 0;
 734    TotalSize = 0;
 735    Status = string();
 736 }
 737                                                                         /*}}}*/
 738 void pkgAcquire::Worker::PrepareFiles(char const * const caller, pkgAcquire::Queue::QItem const * const Itm)/*{{{*/
 739 {
 740    if (RealFileExists(Itm->Owner->DestFile))
 741    {
 742       ChangeOwnerAndPermissionOfFile(caller, Itm->Owner->DestFile.c_str(), "root", "root", 0644);
 743       std::string const filename = Itm->Owner->DestFile;
 744       for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
 745       {
 746          pkgAcquire::Item const * const Owner = *O;
 747          if (Owner->DestFile == filename || filename == "/dev/null")
 748             continue;
 749          RemoveFile("PrepareFiles", Owner->DestFile);
 750          if (link(filename.c_str(), Owner->DestFile.c_str()) != 0)
 751          {
 752             // different mounts can't happen for us as we download to lists/ by default,
 753             // but if the system is reused by others the locations can potentially be on
 754             // different disks, so use symlink as poor-men replacement.
 755             // FIXME: Real copying as last fallback, but that is costly, so offload to a method preferable
 756             if (symlink(filename.c_str(), Owner->DestFile.c_str()) != 0)
 757                _error->Error("Can't create (sym)link of file %s to %s", filename.c_str(), Owner->DestFile.c_str());
 758          }
 759       }
 760    }
 761    else
 762    {
 763       for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
 764          RemoveFile("PrepareFiles", (*O)->DestFile);
 765    }
 766 }
 767                                                                         /*}}}*/