apt-inst/extract.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: extract.cc,v 1.6.2.1 2004/01/16 18:58:50 mdz Exp $
   4 /* ######################################################################
   5
   6    Archive Extraction Directory Stream
   7
   8    Extraction for each file is a bit of an involved process. Each object
   9    undergoes an atomic backup, overwrite, erase sequence. First the
  10    object is unpacked to '.dpkg.new' then the original is hardlinked to
  11    '.dpkg.tmp' and finally the new object is renamed to overwrite the old
  12    one. From an external perspective the file never ceased to exist.
  13    After the archive has been successfully unpacked the .dpkg.tmp files
  14    are erased. A failure causes all the .dpkg.tmp files to be restored.
  15
  16    Decisions about unpacking go like this:
  17       - Store the original filename in the file listing
  18       - Resolve any diversions that would effect this file, all checks
  19         below apply to the diverted name, not the real one.
  20       - Resolve any symlinked configuration files.
  21       - If the existing file does not exist then .dpkg-tmp is checked for.
  22         [Note, this is reduced to only check if a file was expected to be
  23          there]
  24       - If the existing link/file is not a directory then it is replaced
  25         regardless
  26       - If the existing link/directory is being replaced by a directory then
  27         absolutely nothing happens.
  28       - If the existing link/directory is being replaced by a link then
  29         absolutely nothing happens.
  30       - If the existing link/directory is being replaced by a non-directory
  31         then this will abort if the package is not the sole owner of the
  32         directory. [Note, this is changed to not happen if the directory
  33         non-empty - that is, it only includes files that are part of this
  34         package - prevents removing user files accidentally.]
  35       - If the non-directory exists in the listing database and it
  36         does not belong to the current package then an overwrite condition
  37         is invoked.
  38
  39    As we unpack we record the file list differences in the FL cache. If
  40    we need to unroll the the FL cache knows which files have been unpacked
  41    and can undo. When we need to erase then it knows which files have not
  42    been unpacked.
  43
  44    ##################################################################### */
  45                                                                         /*}}}*/
  46 // Include Files                                                        /*{{{*/
  47 #include<config.h>
  48
  49 #include <apt-pkg/extract.h>
  50 #include <apt-pkg/error.h>
  51 #include <apt-pkg/debversion.h>
  52 #include <apt-pkg/fileutl.h>
  53 #include <apt-pkg/dirstream.h>
  54 #include <apt-pkg/filelist.h>
  55 #include <apt-pkg/mmap.h>
  56 #include <apt-pkg/pkgcache.h>
  57 #include <apt-pkg/cacheiterators.h>
  58
  59 #include <string.h>
  60 #include <string>
  61 #include <sys/stat.h>
  62 #include <stdio.h>
  63 #include <errno.h>
  64 #include <dirent.h>
  65 #include <iostream>
  66
  67 #include <apti18n.h>
  68                                                                         /*}}}*/
  69 using namespace std;
  70
  71 static const char *TempExt = "dpkg-tmp";
  72 //static const char *NewExt = "dpkg-new";
  73
  74 // Extract::pkgExtract - Constructor                                    /*{{{*/
  75 // ---------------------------------------------------------------------
  76 /* */
  77 pkgExtract::pkgExtract(pkgFLCache &FLCache,pkgCache::VerIterator Ver) :
  78                        FLCache(FLCache), Ver(Ver)
  79 {
  80    FLPkg = FLCache.GetPkg(Ver.ParentPkg().Name(),true);
  81    if (FLPkg.end() == true)
  82       return;
  83    Debug = true;
  84 }
  85                                                                         /*}}}*/
  86 // Extract::DoItem - Handle a single item from the stream               /*{{{*/
  87 // ---------------------------------------------------------------------
  88 /* This performs the setup for the extraction.. */
  89 bool pkgExtract::DoItem(Item &Itm, int &/*Fd*/)
  90 {
  91    /* Strip any leading/trailing /s from the filename, then copy it to the
  92       temp buffer and re-apply the leading / We use a class variable
  93       to store the new filename for use by the three extraction funcs */
  94    char *End = FileName+1;
  95    const char *I = Itm.Name;
  96    for (; *I != 0 && *I == '/'; I++);
  97    *FileName = '/';
  98    for (; *I != 0 && End < FileName + sizeof(FileName); I++, End++)
  99       *End = *I;
 100    if (End + 20 >= FileName + sizeof(FileName))
 101       return _error->Error(_("The path %s is too long"),Itm.Name);
 102    for (; End > FileName && End[-1] == '/'; End--);
 103    *End = 0;
 104    Itm.Name = FileName;
 105
 106    /* Lookup the file. Nde is the file [group] we are going to write to and
 107       RealNde is the actual node we are manipulating. Due to diversions
 108       they may be entirely different. */
 109    pkgFLCache::NodeIterator Nde = FLCache.GetNode(Itm.Name,End,0,false,false);
 110    pkgFLCache::NodeIterator RealNde = Nde;
 111
 112    // See if the file is already in the file listing
 113    unsigned long FileGroup = RealNde->File;
 114    for (; RealNde.end() == false && FileGroup == RealNde->File; RealNde++)
 115       if (RealNde.RealPackage() == FLPkg)
 116          break;
 117
 118    // Nope, create an entry
 119    if (RealNde.end() == true)
 120    {
 121       RealNde = FLCache.GetNode(Itm.Name,End,FLPkg.Offset(),true,false);
 122       if (RealNde.end() == true)
 123          return false;
 124       RealNde->Flags |= pkgFLCache::Node::NewFile;
 125    }
 126
 127    /* Check if this entry already was unpacked. The only time this should
 128       ever happen is if someone has hacked tar to support capabilities, in
 129       which case this needs to be modified anyhow.. */
 130    if ((RealNde->Flags & pkgFLCache::Node::Unpacked) ==
 131        pkgFLCache::Node::Unpacked)
 132       return _error->Error(_("Unpacking %s more than once"),Itm.Name);
 133
 134    if (Nde.end() == true)
 135       Nde = RealNde;
 136
 137    /* Consider a diverted file - We are not permitted to divert directories,
 138       but everything else is fair game (including conf files!) */
 139    if ((Nde->Flags & pkgFLCache::Node::Diversion) != 0)
 140    {
 141       if (Itm.Type == Item::Directory)
 142          return _error->Error(_("The directory %s is diverted"),Itm.Name);
 143
 144       /* A package overwriting a diversion target is just the same as
 145          overwriting a normally owned file and is checked for below in
 146          the overwrites mechanism */
 147
 148       /* If this package is trying to overwrite the target of a diversion,
 149          that is never, ever permitted */
 150       pkgFLCache::DiverIterator Div = Nde.Diversion();
 151       if (Div.DivertTo() == Nde)
 152          return _error->Error(_("The package is trying to write to the "
 153                               "diversion target %s/%s"),Nde.DirN(),Nde.File());
 154
 155       // See if it is us and we are following it in the right direction
 156       if (Div->OwnerPkg != FLPkg.Offset() && Div.DivertFrom() == Nde)
 157       {
 158          Nde = Div.DivertTo();
 159          End = FileName + snprintf(FileName,sizeof(FileName)-20,"%s/%s",
 160                                    Nde.DirN(),Nde.File());
 161          if (End <= FileName)
 162             return _error->Error(_("The diversion path is too long"));
 163       }
 164    }
 165
 166    // Deal with symlinks and conf files
 167    if ((RealNde->Flags & pkgFLCache::Node::NewConfFile) ==
 168        pkgFLCache::Node::NewConfFile)
 169    {
 170       string Res = flNoLink(Itm.Name);
 171       if (Res.length() > sizeof(FileName))
 172          return _error->Error(_("The path %s is too long"),Res.c_str());
 173       if (Debug == true)
 174          clog << "Followed conf file from " << FileName << " to " << Res << endl;
 175       Itm.Name = strcpy(FileName,Res.c_str());
 176    }
 177
 178    /* Get information about the existing file, and attempt to restore
 179       a backup if it does not exist */
 180    struct stat LExisting;
 181    bool EValid = false;
 182    if (lstat(Itm.Name,&LExisting) != 0)
 183    {
 184       // This is bad news.
 185       if (errno != ENOENT)
 186          return _error->Errno("stat",_("Failed to stat %s"),Itm.Name);
 187
 188       // See if we can recover the backup file
 189       if (Nde.end() == false)
 190       {
 191          char Temp[sizeof(FileName)];
 192          snprintf(Temp,sizeof(Temp),"%s.%s",Itm.Name,TempExt);
 193          if (rename(Temp,Itm.Name) != 0 && errno != ENOENT)
 194             return _error->Errno("rename",_("Failed to rename %s to %s"),
 195                                  Temp,Itm.Name);
 196          if (stat(Itm.Name,&LExisting) != 0)
 197          {
 198             if (errno != ENOENT)
 199                return _error->Errno("stat",_("Failed to stat %s"),Itm.Name);
 200          }
 201          else
 202             EValid = true;
 203       }
 204    }
 205    else
 206       EValid = true;
 207
 208    /* If the file is a link we need to stat its destination, get the
 209       existing file modes */
 210    struct stat Existing = LExisting;
 211    if (EValid == true && S_ISLNK(Existing.st_mode))
 212    {
 213       if (stat(Itm.Name,&Existing) != 0)
 214       {
 215          if (errno != ENOENT)
 216             return _error->Errno("stat",_("Failed to stat %s"),Itm.Name);
 217          Existing = LExisting;
 218       }
 219    }
 220
 221    // We pretend a non-existing file looks like it is a normal file
 222    if (EValid == false)
 223       Existing.st_mode = S_IFREG;
 224
 225    /* Okay, at this point 'Existing' is the stat information for the
 226       real non-link file */
 227
 228    /* The only way this can be a no-op is if a directory is being
 229       replaced by a directory or by a link */
 230    if (S_ISDIR(Existing.st_mode) != 0 &&
 231        (Itm.Type == Item::Directory || Itm.Type == Item::SymbolicLink))
 232       return true;
 233
 234    /* Non-Directory being replaced by non-directory. We check for over
 235       writes here. */
 236    if (Nde.end() == false)
 237    {
 238       if (HandleOverwrites(Nde) == false)
 239          return false;
 240    }
 241
 242    /* Directory being replaced by a non-directory - this needs to see if
 243       the package is the owner and then see if the directory would be
 244       empty after the package is removed [ie no user files will be
 245       erased] */
 246    if (S_ISDIR(Existing.st_mode) != 0)
 247    {
 248       if (CheckDirReplace(Itm.Name) == false)
 249          return _error->Error(_("The directory %s is being replaced by a non-directory"),Itm.Name);
 250    }
 251
 252    if (Debug == true)
 253       clog << "Extract " << string(Itm.Name,End) << endl;
 254 /*   if (Count != 0)
 255       return _error->Error(_("Done"));*/
 256
 257    return true;
 258 }
 259                                                                         /*}}}*/
 260 // Extract::Finished - Sequence finished, erase the temp files          /*{{{*/
 261 // ---------------------------------------------------------------------
 262 /* */
 263 APT_CONST bool pkgExtract::Finished()
 264 {
 265    return true;
 266 }
 267                                                                         /*}}}*/
 268 // Extract::Aborted - Sequence aborted, undo all our unpacking          /*{{{*/
 269 // ---------------------------------------------------------------------
 270 /* This undoes everything that was done by all calls to the DoItem method
 271    and restores the File Listing cache to its original form. It bases its
 272    actions on the flags value for each node in the cache. */
 273 bool pkgExtract::Aborted()
 274 {
 275    if (Debug == true)
 276       clog << "Aborted, backing out" << endl;
 277
 278    pkgFLCache::NodeIterator Files = FLPkg.Files();
 279    map_ptrloc *Last = &FLPkg->Files;
 280
 281    /* Loop over all files, restore those that have been unpacked from their
 282       dpkg-tmp entires */
 283    while (Files.end() == false)
 284    {
 285       // Locate the hash bucket for the node and locate its group head
 286       pkgFLCache::NodeIterator Nde(FLCache,FLCache.HashNode(Files));
 287       for (; Nde.end() == false && Files->File != Nde->File; Nde++);
 288       if (Nde.end() == true)
 289          return _error->Error(_("Failed to locate node in its hash bucket"));
 290
 291       if (snprintf(FileName,sizeof(FileName)-20,"%s/%s",
 292                    Nde.DirN(),Nde.File()) <= 0)
 293          return _error->Error(_("The path is too long"));
 294
 295       // Deal with diversions
 296       if ((Nde->Flags & pkgFLCache::Node::Diversion) != 0)
 297       {
 298          pkgFLCache::DiverIterator Div = Nde.Diversion();
 299
 300          // See if it is us and we are following it in the right direction
 301          if (Div->OwnerPkg != FLPkg.Offset() && Div.DivertFrom() == Nde)
 302          {
 303             Nde = Div.DivertTo();
 304             if (snprintf(FileName,sizeof(FileName)-20,"%s/%s",
 305                          Nde.DirN(),Nde.File()) <= 0)
 306                return _error->Error(_("The diversion path is too long"));
 307          }
 308       }
 309
 310       // Deal with overwrites+replaces
 311       for (; Nde.end() == false && Files->File == Nde->File; Nde++)
 312       {
 313          if ((Nde->Flags & pkgFLCache::Node::Replaced) ==
 314              pkgFLCache::Node::Replaced)
 315          {
 316             if (Debug == true)
 317                clog << "De-replaced " << FileName << " from " << Nde.RealPackage()->Name << endl;
 318             Nde->Flags &= ~pkgFLCache::Node::Replaced;
 319          }
 320       }
 321
 322       // Undo the change in the filesystem
 323       if (Debug == true)
 324          clog << "Backing out " << FileName;
 325
 326       // Remove a new node
 327       if ((Files->Flags & pkgFLCache::Node::NewFile) ==
 328          pkgFLCache::Node::NewFile)
 329       {
 330          if (Debug == true)
 331             clog << " [new node]" << endl;
 332          pkgFLCache::Node *Tmp = Files;
 333          Files++;
 334          *Last = Tmp->NextPkg;
 335          Tmp->NextPkg = 0;
 336
 337          FLCache.DropNode(Tmp - FLCache.NodeP);
 338       }
 339       else
 340       {
 341          if (Debug == true)
 342             clog << endl;
 343
 344          Last = &Files->NextPkg;
 345          Files++;
 346       }
 347    }
 348
 349    return true;
 350 }
 351                                                                         /*}}}*/
 352 // Extract::Fail - Extraction of a file Failed                          /*{{{*/
 353 // ---------------------------------------------------------------------
 354 /* */
 355 bool pkgExtract::Fail(Item &Itm,int Fd)
 356 {
 357    return pkgDirStream::Fail(Itm,Fd);
 358 }
 359                                                                         /*}}}*/
 360 // Extract::FinishedFile - Finished a file                              /*{{{*/
 361 // ---------------------------------------------------------------------
 362 /* */
 363 bool pkgExtract::FinishedFile(Item &Itm,int Fd)
 364 {
 365    return pkgDirStream::FinishedFile(Itm,Fd);
 366 }
 367                                                                         /*}}}*/
 368 // Extract::HandleOverwrites - See if a replaces covers this overwrite  /*{{{*/
 369 // ---------------------------------------------------------------------
 370 /* Check if the file is in a package that is being replaced by this
 371    package or if the file is being overwritten. Note that if the file
 372    is really a directory but it has been erased from the filesystem
 373    this will fail with an overwrite message. This is a limitation of the
 374    dpkg file information format.
 375
 376    XX If a new package installs and another package replaces files in this
 377    package what should we do? */
 378 bool pkgExtract::HandleOverwrites(pkgFLCache::NodeIterator Nde,
 379                                   bool DiverCheck)
 380 {
 381    pkgFLCache::NodeIterator TmpNde = Nde;
 382    unsigned long DiverOwner = 0;
 383    unsigned long FileGroup = Nde->File;
 384    for (; Nde.end() == false && FileGroup == Nde->File; Nde++)
 385    {
 386       if ((Nde->Flags & pkgFLCache::Node::Diversion) != 0)
 387       {
 388          /* Store the diversion owner if this is the forward direction
 389             of the diversion */
 390          if (DiverCheck == true)
 391             DiverOwner = Nde.Diversion()->OwnerPkg;
 392          continue;
 393       }
 394
 395       pkgFLCache::PkgIterator FPkg(FLCache,Nde.RealPackage());
 396       if (FPkg.end() == true || FPkg == FLPkg)
 397          continue;
 398
 399       /* This tests trips when we are checking a diversion to see
 400          if something has already been diverted by this diversion */
 401       if (FPkg.Offset() == DiverOwner)
 402          continue;
 403
 404       // Now see if this package matches one in a replace depends
 405       pkgCache::DepIterator Dep = Ver.DependsList();
 406       bool Ok = false;
 407       for (; Dep.end() == false; Dep++)
 408       {
 409          if (Dep->Type != pkgCache::Dep::Replaces)
 410             continue;
 411
 412          // Does the replaces apply to this package?
 413          if (strcmp(Dep.TargetPkg().Name(),FPkg.Name()) != 0)
 414              continue;
 415
 416          /* Check the version for match. I do not think CurrentVer can be
 417             0 if we are here.. */
 418          pkgCache::PkgIterator Pkg = Dep.TargetPkg();
 419          if (Pkg->CurrentVer == 0)
 420          {
 421             _error->Warning(_("Overwrite package match with no version for %s"),Pkg.Name());
 422             continue;
 423          }
 424
 425          // Replaces is met
 426          if (debVS.CheckDep(Pkg.CurrentVer().VerStr(),Dep->CompareOp,Dep.TargetVer()) == true)
 427          {
 428             if (Debug == true)
 429                clog << "Replaced file " << Nde.DirN() << '/' << Nde.File() << " from " << Pkg.Name() << endl;
 430             Nde->Flags |= pkgFLCache::Node::Replaced;
 431             Ok = true;
 432             break;
 433          }
 434       }
 435
 436       // Negative Hit
 437       if (Ok == false)
 438          return _error->Error(_("File %s/%s overwrites the one in the package %s"),
 439                               Nde.DirN(),Nde.File(),FPkg.Name());
 440    }
 441
 442    /* If this is a diversion we might have to recurse to process
 443       the other side of it */
 444    if ((TmpNde->Flags & pkgFLCache::Node::Diversion) != 0)
 445    {
 446       pkgFLCache::DiverIterator Div = TmpNde.Diversion();
 447       if (Div.DivertTo() == TmpNde)
 448          return HandleOverwrites(Div.DivertFrom(),true);
 449    }
 450
 451    return true;
 452 }
 453                                                                         /*}}}*/
 454 // Extract::CheckDirReplace - See if this directory can be erased       /*{{{*/
 455 // ---------------------------------------------------------------------
 456 /* If this directory is owned by a single package and that package is
 457    replacing it with something non-directoryish then dpkg allows this.
 458    We increase the requirement to be that the directory is non-empty after
 459    the package is removed */
 460 bool pkgExtract::CheckDirReplace(string Dir,unsigned int Depth)
 461 {
 462    // Looping?
 463    if (Depth > 40)
 464       return false;
 465
 466    if (Dir[Dir.size() - 1] != '/')
 467       Dir += '/';
 468
 469    DIR *D = opendir(Dir.c_str());
 470    if (D == 0)
 471       return _error->Errno("opendir",_("Unable to read %s"),Dir.c_str());
 472
 473    string File;
 474    for (struct dirent *Dent = readdir(D); Dent != 0; Dent = readdir(D))
 475    {
 476       // Skip some files
 477       if (strcmp(Dent->d_name,".") == 0 ||
 478           strcmp(Dent->d_name,"..") == 0)
 479          continue;
 480
 481       // Look up the node
 482       File = Dir + Dent->d_name;
 483       pkgFLCache::NodeIterator Nde = FLCache.GetNode(File.c_str(),
 484                                                      File.c_str() + File.length(),0,false,false);
 485
 486       // The file is not owned by this package
 487       if (Nde.end() != false || Nde.RealPackage() != FLPkg)
 488       {
 489          closedir(D);
 490          return false;
 491       }
 492
 493       // See if it is a directory
 494       struct stat St;
 495       if (lstat(File.c_str(),&St) != 0)
 496       {
 497          closedir(D);
 498          return _error->Errno("lstat",_("Unable to stat %s"),File.c_str());
 499       }
 500
 501       // Recurse down directories
 502       if (S_ISDIR(St.st_mode) != 0)
 503       {
 504          if (CheckDirReplace(File,Depth + 1) == false)
 505          {
 506             closedir(D);
 507             return false;
 508          }
 509       }
 510    }
 511
 512    // No conflicts
 513    closedir(D);
 514    return true;
 515 }
 516                                                                         /*}}}*/