apt-pkg/pkgcache.h

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 /**\file pkgcache.h
   4    \brief pkgCache - Structure definitions for the cache file
   5
   6    The goal of the cache file is two fold:
   7    Firstly to speed loading and processing of the package file array and
   8    secondly to reduce memory consumption of the package file array.
   9
  10    The implementation is aimed at an environment with many primary package
  11    files, for instance someone that has a Package file for their CD-ROM, a
  12    Package file for the latest version of the distribution on the CD-ROM and a
  13    package file for the development version. Always present is the information
  14    contained in the status file which might be considered a separate package
  15    file.
  16
  17    Please understand, this is designed as a <b>Cache file</b> it is not meant to be
  18    used on any system other than the one it was created for. It is not meant to
  19    be authoritative either, i.e. if a system crash or software failure occurs it
  20    must be perfectly acceptable for the cache file to be in an inconsistent
  21    state. Furthermore at any time the cache file may be erased without losing
  22    any information.
  23
  24    Also the structures and storage layout is optimized for use by the APT
  25    and may not be suitable for all purposes. However it should be possible
  26    to extend it with associate cache files that contain other information.
  27
  28    To keep memory use down the cache file only contains often used fields and
  29    fields that are inexpensive to store, the Package file has a full list of
  30    fields. Also the client may assume that all items are perfectly valid and
  31    need not perform checks against their correctness. Removal of information
  32    from the cache is possible, but blanks will be left in the file, and
  33    unused strings will also be present. The recommended implementation is to
  34    simply rebuild the cache each time any of the data files change. It is
  35    possible to add a new package file to the cache without any negative side
  36    effects.
  37
  38    <b>Note on Pointer access</b>
  39    Clients should always use the CacheIterators classes for access to the
  40    cache and the data in it. They also provide a simple STL-like method for
  41    traversing the links of the datastructure.
  42
  43    Every item in every structure is stored as the index to that structure.
  44    What this means is that once the files is mmaped every data access has to
  45    go through a fix up stage to get a real memory pointer. This is done
  46    by taking the index, multiplying it by the type size and then adding
  47    it to the start address of the memory block. This sounds complex, but
  48    in C it is a single array dereference. Because all items are aligned to
  49    their size and indexes are stored as multiples of the size of the structure
  50    the format is immediately portable to all possible architectures - BUT the
  51    generated files are -NOT-.
  52
  53    This scheme allows code like this to be written:
  54    <example>
  55      void *Map = mmap(...);
  56      Package *PkgList = (Package *)Map;
  57      Header *Head = (Header *)Map;
  58      char *Strings = (char *)Map;
  59      cout << (Strings + PkgList[Head->HashTable[0]]->Name) << endl;
  60    </example>
  61    Notice the lack of casting or multiplication. The net result is to return
  62    the name of the first package in the first hash bucket, without error
  63    checks.
  64
  65    The generator uses allocation pools to group similarly sized structures in
  66    large blocks to eliminate any alignment overhead. The generator also
  67    assures that no structures overlap and all indexes are unique. Although
  68    at first glance it may seem like there is the potential for two structures
  69    to exist at the same point the generator never allows this to happen.
  70    (See the discussion of free space pools)
  71
  72    See \ref pkgcachegen.h for more information about generating cache structures. */
  73                                                                         /*}}}*/
  74 #ifndef PKGLIB_PKGCACHE_H
  75 #define PKGLIB_PKGCACHE_H
  76
  77
  78 #include <string>
  79 #include <time.h>
  80 #include <apt-pkg/mmap.h>
  81
  82 using std::string;
  83
  84 class pkgVersioningSystem;
  85 class pkgCache                                                          /*{{{*/
  86 {
  87    public:
  88    // Cache element predeclarations
  89    struct Header;
  90    struct Group;
  91    struct Package;
  92    struct PackageFile;
  93    struct Version;
  94    struct Description;
  95    struct Provides;
  96    struct Dependency;
  97    struct StringItem;
  98    struct VerFile;
  99    struct DescFile;
 100
 101    // Iterators
 102    template<typename Str, typename Itr> class Iterator;
 103    class GrpIterator;
 104    class PkgIterator;
 105    class VerIterator;
 106    class DescIterator;
 107    class DepIterator;
 108    class PrvIterator;
 109    class PkgFileIterator;
 110    class VerFileIterator;
 111    class DescFileIterator;
 112
 113    class Namespace;
 114
 115    // These are all the constants used in the cache structures
 116
 117    // WARNING - if you change these lists you must also edit
 118    // the stringification in pkgcache.cc and also consider whether
 119    // the cache file will become incompatible.
 120    struct Dep
 121    {
 122       enum DepType {Depends=1,PreDepends=2,Suggests=3,Recommends=4,
 123          Conflicts=5,Replaces=6,Obsoletes=7,DpkgBreaks=8,Enhances=9};
 124       /** \brief available compare operators
 125
 126           The lower 4 bits are used to indicate what operator is being specified and
 127           the upper 4 bits are flags. OR indicates that the next package is
 128           or'd with the current package. */
 129       enum DepCompareOp {Or=0x10,NoOp=0,LessEq=0x1,GreaterEq=0x2,Less=0x3,
 130          Greater=0x4,Equals=0x5,NotEquals=0x6};
 131    };
 132
 133    struct State
 134    {
 135       /** \brief priority of a package version
 136
 137           Zero is used for unparsable or absent Priority fields. */
 138       enum VerPriority {Important=1,Required=2,Standard=3,Optional=4,Extra=5};
 139       enum PkgSelectedState {Unknown=0,Install=1,Hold=2,DeInstall=3,Purge=4};
 140       enum PkgInstState {Ok=0,ReInstReq=1,HoldInst=2,HoldReInstReq=3};
 141       enum PkgCurrentState {NotInstalled=0,UnPacked=1,HalfConfigured=2,
 142            HalfInstalled=4,ConfigFiles=5,Installed=6,
 143            TriggersAwaited=7,TriggersPending=8};
 144    };
 145
 146    struct Flag
 147    {
 148       enum PkgFlags {Auto=(1<<0),Essential=(1<<3),Important=(1<<4)};
 149       enum PkgFFlags {NotSource=(1<<0),NotAutomatic=(1<<1)};
 150    };
 151
 152    protected:
 153
 154    // Memory mapped cache file
 155    string CacheFile;
 156    MMap &Map;
 157
 158    unsigned long sHash(const string &S) const;
 159    unsigned long sHash(const char *S) const;
 160
 161    public:
 162
 163    // Pointers to the arrays of items
 164    Header *HeaderP;
 165    Group *GrpP;
 166    Package *PkgP;
 167    VerFile *VerFileP;
 168    DescFile *DescFileP;
 169    PackageFile *PkgFileP;
 170    Version *VerP;
 171    Description *DescP;
 172    Provides *ProvideP;
 173    Dependency *DepP;
 174    StringItem *StringItemP;
 175    char *StrP;
 176
 177    virtual bool ReMap();
 178    inline bool Sync() {return Map.Sync();};
 179    inline MMap &GetMap() {return Map;};
 180    inline void *DataEnd() {return ((unsigned char *)Map.Data()) + Map.Size();};
 181
 182    // String hashing function (512 range)
 183    inline unsigned long Hash(const string &S) const {return sHash(S);};
 184    inline unsigned long Hash(const char *S) const {return sHash(S);};
 185
 186    // Useful transformation things
 187    const char *Priority(unsigned char Priority);
 188
 189    // Accessors
 190    GrpIterator FindGrp(const string &Name);
 191    PkgIterator FindPkg(const string &Name);
 192    PkgIterator FindPkg(const string &Name, const string &Arch);
 193
 194    Header &Head() {return *HeaderP;};
 195    inline GrpIterator GrpBegin();
 196    inline GrpIterator GrpEnd();
 197    inline PkgIterator PkgBegin();
 198    inline PkgIterator PkgEnd();
 199    inline PkgFileIterator FileBegin();
 200    inline PkgFileIterator FileEnd();
 201
 202    inline bool MultiArchCache() const { return MultiArchEnabled; };
 203
 204    // Make me a function
 205    pkgVersioningSystem *VS;
 206
 207    // Converters
 208    static const char *CompTypeDeb(unsigned char Comp);
 209    static const char *CompType(unsigned char Comp);
 210    static const char *DepType(unsigned char Dep);
 211
 212    pkgCache(MMap *Map,bool DoMap = true);
 213    virtual ~pkgCache() {};
 214
 215 private:
 216    bool MultiArchEnabled;
 217    PkgIterator SingleArchFindPkg(const string &Name);
 218 };
 219                                                                         /*}}}*/
 220 // Header structure                                                     /*{{{*/
 221 struct pkgCache::Header
 222 {
 223    /** \brief Signature information
 224
 225        This must contain the hex value 0x98FE76DC which is designed to
 226        verify that the system loading the image has the same byte order
 227        and byte size as the system saving the image */
 228    unsigned long Signature;
 229    /** These contain the version of the cache file */
 230    short MajorVersion;
 231    short MinorVersion;
 232    /** \brief indicates if the cache should be erased
 233
 234        Dirty is true if the cache file was opened for reading, the client
 235        expects to have written things to it and have not fully synced it.
 236        The file should be erased and rebuilt if it is true. */
 237    bool Dirty;
 238
 239    /** \brief Size of structure values
 240
 241        All *Sz variables contains the sizeof() that particular structure.
 242        It is used as an extra consistency check on the structure of the file.
 243
 244        If any of the size values do not exactly match what the client expects
 245        then the client should refuse the load the file. */
 246    unsigned short HeaderSz;
 247    unsigned short GroupSz;
 248    unsigned short PackageSz;
 249    unsigned short PackageFileSz;
 250    unsigned short VersionSz;
 251    unsigned short DescriptionSz;
 252    unsigned short DependencySz;
 253    unsigned short ProvidesSz;
 254    unsigned short VerFileSz;
 255    unsigned short DescFileSz;
 256
 257    /** \brief Structure counts
 258
 259        These indicate the number of each structure contained in the cache.
 260        PackageCount is especially useful for generating user state structures.
 261        See Package::Id for more info. */
 262    unsigned long GroupCount;
 263    unsigned long PackageCount;
 264    unsigned long VersionCount;
 265    unsigned long DescriptionCount;
 266    unsigned long DependsCount;
 267    unsigned long PackageFileCount;
 268    unsigned long VerFileCount;
 269    unsigned long DescFileCount;
 270    unsigned long ProvidesCount;
 271
 272    /** \brief index of the first PackageFile structure
 273
 274        The PackageFile structures are singly linked lists that represent
 275        all package files that have been merged into the cache. */
 276    map_ptrloc FileList;
 277    /** \brief index of the first StringItem structure
 278
 279        The cache contains a list of all the unique strings (StringItems).
 280        The parser reads this list into memory so it can match strings
 281        against it.*/
 282    map_ptrloc StringList;
 283    /** \brief String representing the version system used */
 284    map_ptrloc VerSysName;
 285    /** \brief Architecture(s) the cache was built against */
 286    map_ptrloc Architecture;
 287    /** \brief The maximum size of a raw entry from the original Package file */
 288    unsigned long MaxVerFileSize;
 289    /** \brief The maximum size of a raw entry from the original Translation file */
 290    unsigned long MaxDescFileSize;
 291
 292    /** \brief The Pool structures manage the allocation pools that the generator uses
 293
 294        Start indicates the first byte of the pool, Count is the number of objects
 295        remaining in the pool and ItemSize is the structure size (alignment factor)
 296        of the pool. An ItemSize of 0 indicates the pool is empty. There should be
 297        the same number of pools as there are structure types. The generator
 298        stores this information so future additions can make use of any unused pool
 299        blocks. */
 300    DynamicMMap::Pool Pools[9];
 301
 302    /** \brief hash tables providing rapid group/package name lookup
 303
 304        Each group/package name is inserted into the hash table using pkgCache::Hash(const &string)
 305        By iterating over each entry in the hash table it is possible to iterate over
 306        the entire list of packages. Hash Collisions are handled with a singly linked
 307        list of packages based at the hash item. The linked list contains only
 308        packages that match the hashing function.
 309        In the PkgHashTable is it possible that multiple packages have the same name -
 310        these packages are stored as a sequence in the list.
 311
 312        Beware: The Hashmethod assumes that the hash table sizes are equal */
 313    map_ptrloc PkgHashTable[2*1048];
 314    map_ptrloc GrpHashTable[2*1048];
 315
 316    bool CheckSizes(Header &Against) const;
 317    Header();
 318 };
 319                                                                         /*}}}*/
 320 // Group structure                                                      /*{{{*/
 321 /** \brief groups architecture depending packages together
 322
 323     On or more packages with the same name form a group, so we have
 324     a simple way to access a package built for different architectures
 325     Group exists in a singly linked list of group records starting at
 326     the hash index of the name in the pkgCache::Header::GrpHashTable */
 327 struct pkgCache::Group
 328 {
 329    /** \brief Name of the group */
 330    map_ptrloc Name;             // StringItem
 331
 332    // Linked List
 333    /** \brief Link to the first package which belongs to the group */
 334    map_ptrloc FirstPackage;     // Package
 335    /** \brief Link to the last package which belongs to the group */
 336    map_ptrloc LastPackage;      // Package
 337    /** \brief Link to the next Group */
 338    map_ptrloc Next;             // Group
 339    /** \brief unique sequel ID */
 340    unsigned int ID;
 341
 342 };
 343                                                                         /*}}}*/
 344 // Package structure                                                    /*{{{*/
 345 /** \brief contains information for a single unique package
 346
 347     There can be any number of versions of a given package.
 348     Package exists in a singly linked list of package records starting at
 349     the hash index of the name in the pkgCache::Header::PkgHashTable
 350
 351     A package can be created for every architecture so package names are
 352     not unique, but it is garanteed that packages with the same name
 353     are sequencel ordered in the list. Packages with the same name can be
 354     accessed with the Group.
 355 */
 356 struct pkgCache::Package
 357 {
 358    /** \brief Name of the package */
 359    map_ptrloc Name;              // StringItem
 360    /** \brief Architecture of the package */
 361    map_ptrloc Arch;              // StringItem
 362    /** \brief Base of a singly linked list of versions
 363
 364        Each structure represents a unique version of the package.
 365        The version structures contain links into PackageFile and the
 366        original text file as well as detailed information about the size
 367        and dependencies of the specific package. In this way multiple
 368        versions of a package can be cleanly handled by the system.
 369        Furthermore, this linked list is guaranteed to be sorted
 370        from Highest version to lowest version with no duplicate entries. */
 371    map_ptrloc VersionList;       // Version
 372    /** \brief index to the installed version */
 373    map_ptrloc CurrentVer;        // Version
 374    /** \brief indicates the deduced section
 375
 376        Should be the index to the string "Unknown" or to the section
 377        of the last parsed item. */
 378    map_ptrloc Section;           // StringItem
 379    /** \brief index of the group this package belongs to */
 380    map_ptrloc Group;             // Group the Package belongs to
 381
 382    // Linked list
 383    /** \brief Link to the next package in the same bucket */
 384    map_ptrloc NextPackage;       // Package
 385    /** \brief List of all dependencies on this package */
 386    map_ptrloc RevDepends;        // Dependency
 387    /** \brief List of all "packages" this package provide */
 388    map_ptrloc ProvidesList;      // Provides
 389
 390    // Install/Remove/Purge etc
 391    /** \brief state that the user wishes the package to be in */
 392    unsigned char SelectedState;     // What
 393    /** \brief installation state of the package
 394
 395        This should be "ok" but in case the installation failed
 396        it will be different.
 397    */
 398    unsigned char InstState;         // Flags
 399    /** \brief indicates if the package is installed */
 400    unsigned char CurrentState;      // State
 401
 402    /** \brief unique sequel ID
 403
 404        ID is a unique value from 0 to Header->PackageCount assigned by the generator.
 405        This allows clients to create an array of size PackageCount and use it to store
 406        state information for the package map. For instance the status file emitter uses
 407        this to track which packages have been emitted already. */
 408    unsigned int ID;
 409    /** \brief some useful indicators of the package's state */
 410    unsigned long Flags;
 411 };
 412                                                                         /*}}}*/
 413 // Package File structure                                               /*{{{*/
 414 /** \brief stores information about the files used to generate the cache
 415
 416     Package files are referenced by Version structures to be able to know
 417     after the generation still from which Packages file includes this Version
 418     as we need this information later on e.g. for pinning. */
 419 struct pkgCache::PackageFile
 420 {
 421    /** \brief physical disk file that this PackageFile represents */
 422    map_ptrloc FileName;        // StringItem
 423    /** \brief the release information
 424
 425        Please see the files document for a description of what the
 426        release information means. */
 427    map_ptrloc Archive;         // StringItem
 428    map_ptrloc Codename;        // StringItem
 429    map_ptrloc Component;       // StringItem
 430    map_ptrloc Version;         // StringItem
 431    map_ptrloc Origin;          // StringItem
 432    map_ptrloc Label;           // StringItem
 433    map_ptrloc Architecture;    // StringItem
 434    /** \brief The site the index file was fetched from */
 435    map_ptrloc Site;            // StringItem
 436    /** \brief indicates what sort of index file this is
 437
 438        @TODO enumerate at least the possible indexes */
 439    map_ptrloc IndexType;       // StringItem
 440    /** \brief Size of the file
 441
 442        Used together with the modification time as a
 443        simple check to ensure that the Packages
 444        file has not been altered since Cache generation. */
 445    unsigned long Size;
 446    /** \brief Modification time for the file */
 447    time_t mtime;
 448
 449    /* @TODO document PackageFile::Flags */
 450    unsigned long Flags;
 451
 452    // Linked list
 453    /** \brief Link to the next PackageFile in the Cache */
 454    map_ptrloc NextFile;        // PackageFile
 455    /** \brief unique sequel ID */
 456    unsigned int ID;
 457 };
 458                                                                         /*}}}*/
 459 // VerFile structure                                                    /*{{{*/
 460 /** \brief associates a version with a PackageFile
 461
 462     This allows a full description of all Versions in all files
 463     (and hence all sources) under consideration. */
 464 struct pkgCache::VerFile
 465 {
 466    /** \brief index of the package file that this version was found in */
 467    map_ptrloc File;           // PackageFile
 468    /** \brief next step in the linked list */
 469    map_ptrloc NextFile;       // PkgVerFile
 470    /** \brief position in the package file */
 471    map_ptrloc Offset;         // File offset
 472    /* @TODO document pkgCache::VerFile::Size */
 473    unsigned long Size;
 474 };
 475                                                                         /*}}}*/
 476 // DescFile structure                                                   /*{{{*/
 477 /** \brief associates a description with a Translation file */
 478 struct pkgCache::DescFile
 479 {
 480    /** \brief index of the file that this description was found in */
 481    map_ptrloc File;           // PackageFile
 482    /** \brief next step in the linked list */
 483    map_ptrloc NextFile;       // PkgVerFile
 484    /** \brief position in the file */
 485    map_ptrloc Offset;         // File offset
 486    /* @TODO document pkgCache::DescFile::Size */
 487    unsigned long Size;
 488 };
 489                                                                         /*}}}*/
 490 // Version structure                                                    /*{{{*/
 491 /** \brief information for a single version of a package
 492
 493     The version list is always sorted from highest version to lowest
 494     version by the generator. Equal version numbers are either merged
 495     or handled as separate versions based on the Hash value. */
 496 struct pkgCache::Version
 497 {
 498    /** \brief complete version string */
 499    map_ptrloc VerStr;            // StringItem
 500    /** \brief section this version is filled in */
 501    map_ptrloc Section;           // StringItem
 502    /** \brief stores the MultiArch capabilities of this version
 503
 504        None is the default and doesn't trigger special behaviour,
 505        Foreign means that this version can fulfill dependencies even
 506        if it is built for another architecture as the requester.
 507        Same indicates that builds for different architectures can
 508        be co-installed on the system and All is the marker for a
 509        version with the Architecture: all. */
 510    enum {None, All, Foreign, Same, Allowed} MultiArch;
 511
 512    /** \brief references all the PackageFile's that this version came from
 513
 514        FileList can be used to determine what distribution(s) the Version
 515        applies to. If FileList is 0 then this is a blank version.
 516        The structure should also have a 0 in all other fields excluding
 517        pkgCache::Version::VerStr and Possibly pkgCache::Version::NextVer. */
 518    map_ptrloc FileList;          // VerFile
 519    /** \brief next (lower or equal) version in the linked list */
 520    map_ptrloc NextVer;           // Version
 521    /** \brief next description in the linked list */
 522    map_ptrloc DescriptionList;   // Description
 523    /** \brief base of the dependency list */
 524    map_ptrloc DependsList;       // Dependency
 525    /** \brief links to the owning package
 526
 527        This allows reverse dependencies to determine the package */
 528    map_ptrloc ParentPkg;         // Package
 529    /** \brief list of pkgCache::Provides */
 530    map_ptrloc ProvidesList;      // Provides
 531
 532    /** \brief archive size for this version
 533
 534        For Debian this is the size of the .deb file. */
 535    map_ptrloc Size;              // These are the .deb size
 536    /** \brief uncompressed size for this version */
 537    map_ptrloc InstalledSize;
 538    /** \brief characteristic value representing this version
 539
 540        No two packages in existence should have the same VerStr
 541        and Hash with different contents. */
 542    unsigned short Hash;
 543    /** \brief unique sequel ID */
 544    unsigned int ID;
 545    /** \brief parsed priority value */
 546    unsigned char Priority;
 547 };
 548                                                                         /*}}}*/
 549 // Description structure                                                /*{{{*/
 550 /** \brief datamember of a linked list of available description for a version */
 551 struct pkgCache::Description
 552 {
 553    /** \brief Language code of this description (translation)
 554
 555        If the value has a 0 length then this is read using the Package
 556        file else the Translation-CODE file is used. */
 557    map_ptrloc language_code;     // StringItem
 558    /** \brief MD5sum of the original description
 559
 560        Used to map Translations of a description to a version
 561        and to check that the Translation is up-to-date. */
 562    map_ptrloc md5sum;            // StringItem
 563
 564    /* @TODO document pkgCache::Description::FileList */
 565    map_ptrloc FileList;          // DescFile
 566    /** \brief next translation for this description */
 567    map_ptrloc NextDesc;          // Description
 568    /** \brief the text is a description of this package */
 569    map_ptrloc ParentPkg;         // Package
 570
 571    /** \brief unique sequel ID */
 572    unsigned int ID;
 573 };
 574                                                                         /*}}}*/
 575 // Dependency structure                                                 /*{{{*/
 576 /** \brief information for a single dependency record
 577
 578     The records are split up like this to ease processing by the client.
 579     The base of the linked list is pkgCache::Version::DependsList.
 580     All forms of dependencies are recorded here including Depends,
 581     Recommends, Suggests, Enhances, Conflicts, Replaces and Breaks. */
 582 struct pkgCache::Dependency
 583 {
 584    /** \brief string of the version the dependency is applied against */
 585    map_ptrloc Version;         // StringItem
 586    /** \brief index of the package this depends applies to
 587
 588        The generator will - if the package does not already exist -
 589        create a blank (no version records) package. */
 590    map_ptrloc Package;         // Package
 591    /** \brief next dependency of this version */
 592    map_ptrloc NextDepends;     // Dependency
 593    /** \brief next reverse dependency of this package */
 594    map_ptrloc NextRevDepends;  // Dependency
 595    /** \brief version of the package which has the reverse depends */
 596    map_ptrloc ParentVer;       // Version
 597
 598    /** \brief unique sequel ID */
 599    map_ptrloc ID;
 600    /** \brief Dependency type - Depends, Recommends, Conflicts, etc */
 601    unsigned char Type;
 602    /** \brief comparison operator specified on the depends line
 603
 604        If the high bit is set then it is a logical OR with the previous record. */
 605    unsigned char CompareOp;
 606 };
 607                                                                         /*}}}*/
 608 // Provides structure                                                   /*{{{*/
 609 /** \brief handles virtual packages
 610
 611     When a Provides: line is encountered a new provides record is added
 612     associating the package with a virtual package name.
 613     The provides structures are linked off the package structures.
 614     This simplifies the analysis of dependencies and other aspects A provides
 615     refers to a specific version of a specific package, not all versions need to
 616     provide that provides.*/
 617 struct pkgCache::Provides
 618 {
 619    /** \brief index of the package providing this */
 620    map_ptrloc ParentPkg;        // Package
 621    /** \brief index of the version this provide line applies to */
 622    map_ptrloc Version;          // Version
 623    /** \brief version in the provides line (if any)
 624
 625        This version allows dependencies to depend on specific versions of a
 626        Provides, as well as allowing Provides to override existing packages.
 627        This is experimental. Note that Debian doesn't allow versioned provides */
 628    map_ptrloc ProvideVersion;   // StringItem
 629    /** \brief next provides (based of package) */
 630    map_ptrloc NextProvides;     // Provides
 631    /** \brief next provides (based of version) */
 632    map_ptrloc NextPkgProv;      // Provides
 633 };
 634                                                                         /*}}}*/
 635 // StringItem structure                                                 /*{{{*/
 636 /** \brief used for generating single instances of strings
 637
 638     Some things like Section Name are are useful to have as unique tags.
 639     It is part of a linked list based at pkgCache::Header::StringList
 640
 641     All strings are simply inlined any place in the file that is natural
 642     for the writer. The client should make no assumptions about the positioning
 643     of strings. All StringItems should be null-terminated. */
 644 struct pkgCache::StringItem
 645 {
 646    /** \brief string this refers to */
 647    map_ptrloc String;        // StringItem
 648    /** \brief Next link in the chain */
 649    map_ptrloc NextItem;      // StringItem
 650 };
 651                                                                         /*}}}*/
 652 #include <apt-pkg/cacheiterators.h>
 653
 654 inline pkgCache::GrpIterator pkgCache::GrpBegin()
 655        {return GrpIterator(*this);};
 656 inline pkgCache::GrpIterator pkgCache::GrpEnd()
 657        {return GrpIterator(*this,GrpP);};
 658 inline pkgCache::PkgIterator pkgCache::PkgBegin()
 659        {return PkgIterator(*this);};
 660 inline pkgCache::PkgIterator pkgCache::PkgEnd()
 661        {return PkgIterator(*this,PkgP);};
 662 inline pkgCache::PkgFileIterator pkgCache::FileBegin()
 663        {return PkgFileIterator(*this,PkgFileP + HeaderP->FileList);};
 664 inline pkgCache::PkgFileIterator pkgCache::FileEnd()
 665        {return PkgFileIterator(*this,PkgFileP);};
 666
 667 // Oh I wish for Real Name Space Support
 668 class pkgCache::Namespace                                               /*{{{*/
 669 {
 670    public:
 671    typedef pkgCache::GrpIterator GrpIterator;
 672    typedef pkgCache::PkgIterator PkgIterator;
 673    typedef pkgCache::VerIterator VerIterator;
 674    typedef pkgCache::DescIterator DescIterator;
 675    typedef pkgCache::DepIterator DepIterator;
 676    typedef pkgCache::PrvIterator PrvIterator;
 677    typedef pkgCache::PkgFileIterator PkgFileIterator;
 678    typedef pkgCache::VerFileIterator VerFileIterator;
 679    typedef pkgCache::Version Version;
 680    typedef pkgCache::Description Description;
 681    typedef pkgCache::Package Package;
 682    typedef pkgCache::Header Header;
 683    typedef pkgCache::Dep Dep;
 684    typedef pkgCache::Flag Flag;
 685 };
 686                                                                         /*}}}*/
 687 #endif