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 class pkgVersioningSystem;
  83 class pkgCache                                                          /*{{{*/
  84 {
  85    public:
  86    // Cache element predeclarations
  87    struct Header;
  88    struct Group;
  89    struct Package;
  90    struct PackageFile;
  91    struct Version;
  92    struct Description;
  93    struct Provides;
  94    struct Dependency;
  95    struct StringItem;
  96    struct VerFile;
  97    struct DescFile;
  98
  99    // Iterators
 100    template<typename Str, typename Itr> class Iterator;
 101    class GrpIterator;
 102    class PkgIterator;
 103    class VerIterator;
 104    class DescIterator;
 105    class DepIterator;
 106    class PrvIterator;
 107    class PkgFileIterator;
 108    class VerFileIterator;
 109    class DescFileIterator;
 110
 111    class Namespace;
 112
 113    // These are all the constants used in the cache structures
 114
 115    // WARNING - if you change these lists you must also edit
 116    // the stringification in pkgcache.cc and also consider whether
 117    // the cache file will become incompatible.
 118    struct Dep
 119    {
 120       enum DepType {Depends=1,PreDepends=2,Suggests=3,Recommends=4,
 121          Conflicts=5,Replaces=6,Obsoletes=7,DpkgBreaks=8,Enhances=9};
 122       /** \brief available compare operators
 123
 124           The lower 4 bits are used to indicate what operator is being specified and
 125           the upper 4 bits are flags. OR indicates that the next package is
 126           or'd with the current package. */
 127       enum DepCompareOp {Or=0x10,NoOp=0,LessEq=0x1,GreaterEq=0x2,Less=0x3,
 128          Greater=0x4,Equals=0x5,NotEquals=0x6};
 129    };
 130
 131    struct State
 132    {
 133       /** \brief priority of a package version
 134
 135           Zero is used for unparsable or absent Priority fields. */
 136       enum VerPriority {Important=1,Required=2,Standard=3,Optional=4,Extra=5};
 137       enum PkgSelectedState {Unknown=0,Install=1,Hold=2,DeInstall=3,Purge=4};
 138       enum PkgInstState {Ok=0,ReInstReq=1,HoldInst=2,HoldReInstReq=3};
 139       enum PkgCurrentState {NotInstalled=0,UnPacked=1,HalfConfigured=2,
 140            HalfInstalled=4,ConfigFiles=5,Installed=6,
 141            TriggersAwaited=7,TriggersPending=8};
 142    };
 143
 144    struct Flag
 145    {
 146       enum PkgFlags {Auto=(1<<0),Essential=(1<<3),Important=(1<<4)};
 147       enum PkgFFlags {NotSource=(1<<0),NotAutomatic=(1<<1),ButAutomaticUpgrades=(1<<2)};
 148    };
 149
 150    protected:
 151
 152    // Memory mapped cache file
 153    std::string CacheFile;
 154    MMap &Map;
 155
 156    unsigned long sHash(const std::string &S) const;
 157    unsigned long sHash(const char *S) const;
 158
 159    public:
 160
 161    // Pointers to the arrays of items
 162    Header *HeaderP;
 163    Group *GrpP;
 164    Package *PkgP;
 165    VerFile *VerFileP;
 166    DescFile *DescFileP;
 167    PackageFile *PkgFileP;
 168    Version *VerP;
 169    Description *DescP;
 170    Provides *ProvideP;
 171    Dependency *DepP;
 172    StringItem *StringItemP;
 173    char *StrP;
 174
 175    virtual bool ReMap(bool const &Errorchecks = true);
 176    inline bool Sync() {return Map.Sync();};
 177    inline MMap &GetMap() {return Map;};
 178    inline void *DataEnd() {return ((unsigned char *)Map.Data()) + Map.Size();};
 179
 180    // String hashing function (512 range)
 181    inline unsigned long Hash(const std::string &S) const {return sHash(S);};
 182    inline unsigned long Hash(const char *S) const {return sHash(S);};
 183
 184    // Useful transformation things
 185    const char *Priority(unsigned char Priority);
 186
 187    // Accessors
 188    GrpIterator FindGrp(const std::string &Name);
 189    PkgIterator FindPkg(const std::string &Name);
 190    PkgIterator FindPkg(const std::string &Name, const std::string &Arch);
 191
 192    Header &Head() {return *HeaderP;};
 193    inline GrpIterator GrpBegin();
 194    inline GrpIterator GrpEnd();
 195    inline PkgIterator PkgBegin();
 196    inline PkgIterator PkgEnd();
 197    inline PkgFileIterator FileBegin();
 198    inline PkgFileIterator FileEnd();
 199
 200    inline bool MultiArchCache() const { return MultiArchEnabled; };
 201
 202    // Make me a function
 203    pkgVersioningSystem *VS;
 204
 205    // Converters
 206    static const char *CompTypeDeb(unsigned char Comp);
 207    static const char *CompType(unsigned char Comp);
 208    static const char *DepType(unsigned char Dep);
 209
 210    pkgCache(MMap *Map,bool DoMap = true);
 211    virtual ~pkgCache() {};
 212
 213 private:
 214    bool MultiArchEnabled;
 215    PkgIterator SingleArchFindPkg(const std::string &Name);
 216    inline char const * const NativeArch() const;
 217 };
 218                                                                         /*}}}*/
 219 // Header structure                                                     /*{{{*/
 220 struct pkgCache::Header
 221 {
 222    /** \brief Signature information
 223
 224        This must contain the hex value 0x98FE76DC which is designed to
 225        verify that the system loading the image has the same byte order
 226        and byte size as the system saving the image */
 227    unsigned long Signature;
 228    /** These contain the version of the cache file */
 229    short MajorVersion;
 230    short MinorVersion;
 231    /** \brief indicates if the cache should be erased
 232
 233        Dirty is true if the cache file was opened for reading, the client
 234        expects to have written things to it and have not fully synced it.
 235        The file should be erased and rebuilt if it is true. */
 236    bool Dirty;
 237
 238    /** \brief Size of structure values
 239
 240        All *Sz variables contains the sizeof() that particular structure.
 241        It is used as an extra consistency check on the structure of the file.
 242
 243        If any of the size values do not exactly match what the client expects
 244        then the client should refuse the load the file. */
 245    unsigned short HeaderSz;
 246    unsigned short GroupSz;
 247    unsigned short PackageSz;
 248    unsigned short PackageFileSz;
 249    unsigned short VersionSz;
 250    unsigned short DescriptionSz;
 251    unsigned short DependencySz;
 252    unsigned short ProvidesSz;
 253    unsigned short VerFileSz;
 254    unsigned short DescFileSz;
 255
 256    /** \brief Structure counts
 257
 258        These indicate the number of each structure contained in the cache.
 259        PackageCount is especially useful for generating user state structures.
 260        See Package::Id for more info. */
 261    unsigned long GroupCount;
 262    unsigned long PackageCount;
 263    unsigned long VersionCount;
 264    unsigned long DescriptionCount;
 265    unsigned long DependsCount;
 266    unsigned long PackageFileCount;
 267    unsigned long VerFileCount;
 268    unsigned long DescFileCount;
 269    unsigned long ProvidesCount;
 270
 271    /** \brief index of the first PackageFile structure
 272
 273        The PackageFile structures are singly linked lists that represent
 274        all package files that have been merged into the cache. */
 275    map_ptrloc FileList;
 276    /** \brief index of the first StringItem structure
 277
 278        The cache contains a list of all the unique strings (StringItems).
 279        The parser reads this list into memory so it can match strings
 280        against it.*/
 281    map_ptrloc StringList;
 282    /** \brief String representing the version system used */
 283    map_ptrloc VerSysName;
 284    /** \brief Architecture(s) the cache was built against */
 285    map_ptrloc Architecture;
 286    /** \brief The maximum size of a raw entry from the original Package file */
 287    unsigned long MaxVerFileSize;
 288    /** \brief The maximum size of a raw entry from the original Translation file */
 289    unsigned long MaxDescFileSize;
 290
 291    /** \brief The Pool structures manage the allocation pools that the generator uses
 292
 293        Start indicates the first byte of the pool, Count is the number of objects
 294        remaining in the pool and ItemSize is the structure size (alignment factor)
 295        of the pool. An ItemSize of 0 indicates the pool is empty. There should be
 296        the same number of pools as there are structure types. The generator
 297        stores this information so future additions can make use of any unused pool
 298        blocks. */
 299    DynamicMMap::Pool Pools[9];
 300
 301    /** \brief hash tables providing rapid group/package name lookup
 302
 303        Each group/package name is inserted into the hash table using pkgCache::Hash(const &string)
 304        By iterating over each entry in the hash table it is possible to iterate over
 305        the entire list of packages. Hash Collisions are handled with a singly linked
 306        list of packages based at the hash item. The linked list contains only
 307        packages that match the hashing function.
 308        In the PkgHashTable is it possible that multiple packages have the same name -
 309        these packages are stored as a sequence in the list.
 310
 311        Beware: The Hashmethod assumes that the hash table sizes are equal */
 312    map_ptrloc PkgHashTable[2*1048];
 313    map_ptrloc GrpHashTable[2*1048];
 314
 315    /** \brief Size of the complete cache file */
 316    unsigned long  CacheFileSize;
 317
 318    bool CheckSizes(Header &Against) const;
 319    Header();
 320 };
 321                                                                         /*}}}*/
 322 // Group structure                                                      /*{{{*/
 323 /** \brief groups architecture depending packages together
 324
 325     On or more packages with the same name form a group, so we have
 326     a simple way to access a package built for different architectures
 327     Group exists in a singly linked list of group records starting at
 328     the hash index of the name in the pkgCache::Header::GrpHashTable */
 329 struct pkgCache::Group
 330 {
 331    /** \brief Name of the group */
 332    map_ptrloc Name;             // StringItem
 333
 334    // Linked List
 335    /** \brief Link to the first package which belongs to the group */
 336    map_ptrloc FirstPackage;     // Package
 337    /** \brief Link to the last package which belongs to the group */
 338    map_ptrloc LastPackage;      // Package
 339    /** \brief Link to the next Group */
 340    map_ptrloc Next;             // Group
 341    /** \brief unique sequel ID */
 342    unsigned int ID;
 343
 344 };
 345                                                                         /*}}}*/
 346 // Package structure                                                    /*{{{*/
 347 /** \brief contains information for a single unique package
 348
 349     There can be any number of versions of a given package.
 350     Package exists in a singly linked list of package records starting at
 351     the hash index of the name in the pkgCache::Header::PkgHashTable
 352
 353     A package can be created for every architecture so package names are
 354     not unique, but it is garanteed that packages with the same name
 355     are sequencel ordered in the list. Packages with the same name can be
 356     accessed with the Group.
 357 */
 358 struct pkgCache::Package
 359 {
 360    /** \brief Name of the package */
 361    map_ptrloc Name;              // StringItem
 362    /** \brief Architecture of the package */
 363    map_ptrloc Arch;              // StringItem
 364    /** \brief Base of a singly linked list of versions
 365
 366        Each structure represents a unique version of the package.
 367        The version structures contain links into PackageFile and the
 368        original text file as well as detailed information about the size
 369        and dependencies of the specific package. In this way multiple
 370        versions of a package can be cleanly handled by the system.
 371        Furthermore, this linked list is guaranteed to be sorted
 372        from Highest version to lowest version with no duplicate entries. */
 373    map_ptrloc VersionList;       // Version
 374    /** \brief index to the installed version */
 375    map_ptrloc CurrentVer;        // Version
 376    /** \brief indicates the deduced section
 377
 378        Should be the index to the string "Unknown" or to the section
 379        of the last parsed item. */
 380    map_ptrloc Section;           // StringItem
 381    /** \brief index of the group this package belongs to */
 382    map_ptrloc Group;             // Group the Package belongs to
 383
 384    // Linked list
 385    /** \brief Link to the next package in the same bucket */
 386    map_ptrloc NextPackage;       // Package
 387    /** \brief List of all dependencies on this package */
 388    map_ptrloc RevDepends;        // Dependency
 389    /** \brief List of all "packages" this package provide */
 390    map_ptrloc ProvidesList;      // Provides
 391
 392    // Install/Remove/Purge etc
 393    /** \brief state that the user wishes the package to be in */
 394    unsigned char SelectedState;     // What
 395    /** \brief installation state of the package
 396
 397        This should be "ok" but in case the installation failed
 398        it will be different.
 399    */
 400    unsigned char InstState;         // Flags
 401    /** \brief indicates if the package is installed */
 402    unsigned char CurrentState;      // State
 403
 404    /** \brief unique sequel ID
 405
 406        ID is a unique value from 0 to Header->PackageCount assigned by the generator.
 407        This allows clients to create an array of size PackageCount and use it to store
 408        state information for the package map. For instance the status file emitter uses
 409        this to track which packages have been emitted already. */
 410    unsigned int ID;
 411    /** \brief some useful indicators of the package's state */
 412    unsigned long Flags;
 413 };
 414                                                                         /*}}}*/
 415 // Package File structure                                               /*{{{*/
 416 /** \brief stores information about the files used to generate the cache
 417
 418     Package files are referenced by Version structures to be able to know
 419     after the generation still from which Packages file includes this Version
 420     as we need this information later on e.g. for pinning. */
 421 struct pkgCache::PackageFile
 422 {
 423    /** \brief physical disk file that this PackageFile represents */
 424    map_ptrloc FileName;        // StringItem
 425    /** \brief the release information
 426
 427        Please see the files document for a description of what the
 428        release information means. */
 429    map_ptrloc Archive;         // StringItem
 430    map_ptrloc Codename;        // StringItem
 431    map_ptrloc Component;       // StringItem
 432    map_ptrloc Version;         // StringItem
 433    map_ptrloc Origin;          // StringItem
 434    map_ptrloc Label;           // StringItem
 435    map_ptrloc Architecture;    // StringItem
 436    /** \brief The site the index file was fetched from */
 437    map_ptrloc Site;            // StringItem
 438    /** \brief indicates what sort of index file this is
 439
 440        @TODO enumerate at least the possible indexes */
 441    map_ptrloc IndexType;       // StringItem
 442    /** \brief Size of the file
 443
 444        Used together with the modification time as a
 445        simple check to ensure that the Packages
 446        file has not been altered since Cache generation. */
 447    unsigned long Size;
 448    /** \brief Modification time for the file */
 449    time_t mtime;
 450
 451    /* @TODO document PackageFile::Flags */
 452    unsigned long Flags;
 453
 454    // Linked list
 455    /** \brief Link to the next PackageFile in the Cache */
 456    map_ptrloc NextFile;        // PackageFile
 457    /** \brief unique sequel ID */
 458    unsigned int ID;
 459 };
 460                                                                         /*}}}*/
 461 // VerFile structure                                                    /*{{{*/
 462 /** \brief associates a version with a PackageFile
 463
 464     This allows a full description of all Versions in all files
 465     (and hence all sources) under consideration. */
 466 struct pkgCache::VerFile
 467 {
 468    /** \brief index of the package file that this version was found in */
 469    map_ptrloc File;           // PackageFile
 470    /** \brief next step in the linked list */
 471    map_ptrloc NextFile;       // PkgVerFile
 472    /** \brief position in the package file */
 473    map_ptrloc Offset;         // File offset
 474    /* @TODO document pkgCache::VerFile::Size */
 475    unsigned long Size;
 476 };
 477                                                                         /*}}}*/
 478 // DescFile structure                                                   /*{{{*/
 479 /** \brief associates a description with a Translation file */
 480 struct pkgCache::DescFile
 481 {
 482    /** \brief index of the file that this description was found in */
 483    map_ptrloc File;           // PackageFile
 484    /** \brief next step in the linked list */
 485    map_ptrloc NextFile;       // PkgVerFile
 486    /** \brief position in the file */
 487    map_ptrloc Offset;         // File offset
 488    /* @TODO document pkgCache::DescFile::Size */
 489    unsigned long Size;
 490 };
 491                                                                         /*}}}*/
 492 // Version structure                                                    /*{{{*/
 493 /** \brief information for a single version of a package
 494
 495     The version list is always sorted from highest version to lowest
 496     version by the generator. Equal version numbers are either merged
 497     or handled as separate versions based on the Hash value. */
 498 struct pkgCache::Version
 499 {
 500    /** \brief complete version string */
 501    map_ptrloc VerStr;            // StringItem
 502    /** \brief section this version is filled in */
 503    map_ptrloc Section;           // StringItem
 504
 505    /** \brief Multi-Arch capabilities of a package version */
 506    enum VerMultiArch { None = 0, /*!< is the default and doesn't trigger special behaviour */
 507                        All = (1<<0), /*!< will cause that Ver.Arch() will report "all" */
 508                        Foreign = (1<<1), /*!< can satisfy dependencies in another architecture */
 509                        Same = (1<<2), /*!< can be co-installed with itself from other architectures */
 510                        Allowed = (1<<3), /*!< other packages are allowed to depend on thispkg:any */
 511                        AllForeign = All | Foreign,
 512                        AllAllowed = All | Allowed };
 513    /** \brief stores the MultiArch capabilities of this version
 514
 515        Flags used are defined in pkgCache::Version::VerMultiArch
 516    */
 517    unsigned char MultiArch;
 518
 519    /** \brief references all the PackageFile's that this version came from
 520
 521        FileList can be used to determine what distribution(s) the Version
 522        applies to. If FileList is 0 then this is a blank version.
 523        The structure should also have a 0 in all other fields excluding
 524        pkgCache::Version::VerStr and Possibly pkgCache::Version::NextVer. */
 525    map_ptrloc FileList;          // VerFile
 526    /** \brief next (lower or equal) version in the linked list */
 527    map_ptrloc NextVer;           // Version
 528    /** \brief next description in the linked list */
 529    map_ptrloc DescriptionList;   // Description
 530    /** \brief base of the dependency list */
 531    map_ptrloc DependsList;       // Dependency
 532    /** \brief links to the owning package
 533
 534        This allows reverse dependencies to determine the package */
 535    map_ptrloc ParentPkg;         // Package
 536    /** \brief list of pkgCache::Provides */
 537    map_ptrloc ProvidesList;      // Provides
 538
 539    /** \brief archive size for this version
 540
 541        For Debian this is the size of the .deb file. */
 542    unsigned long long Size;      // These are the .deb size
 543    /** \brief uncompressed size for this version */
 544    unsigned long long InstalledSize;
 545    /** \brief characteristic value representing this version
 546
 547        No two packages in existence should have the same VerStr
 548        and Hash with different contents. */
 549    unsigned short Hash;
 550    /** \brief unique sequel ID */
 551    unsigned int ID;
 552    /** \brief parsed priority value */
 553    unsigned char Priority;
 554 };
 555                                                                         /*}}}*/
 556 // Description structure                                                /*{{{*/
 557 /** \brief datamember of a linked list of available description for a version */
 558 struct pkgCache::Description
 559 {
 560    /** \brief Language code of this description (translation)
 561
 562        If the value has a 0 length then this is read using the Package
 563        file else the Translation-CODE file is used. */
 564    map_ptrloc language_code;     // StringItem
 565    /** \brief MD5sum of the original description
 566
 567        Used to map Translations of a description to a version
 568        and to check that the Translation is up-to-date. */
 569    map_ptrloc md5sum;            // StringItem
 570
 571    /* @TODO document pkgCache::Description::FileList */
 572    map_ptrloc FileList;          // DescFile
 573    /** \brief next translation for this description */
 574    map_ptrloc NextDesc;          // Description
 575    /** \brief the text is a description of this package */
 576    map_ptrloc ParentPkg;         // Package
 577
 578    /** \brief unique sequel ID */
 579    unsigned int ID;
 580 };
 581                                                                         /*}}}*/
 582 // Dependency structure                                                 /*{{{*/
 583 /** \brief information for a single dependency record
 584
 585     The records are split up like this to ease processing by the client.
 586     The base of the linked list is pkgCache::Version::DependsList.
 587     All forms of dependencies are recorded here including Depends,
 588     Recommends, Suggests, Enhances, Conflicts, Replaces and Breaks. */
 589 struct pkgCache::Dependency
 590 {
 591    /** \brief string of the version the dependency is applied against */
 592    map_ptrloc Version;         // StringItem
 593    /** \brief index of the package this depends applies to
 594
 595        The generator will - if the package does not already exist -
 596        create a blank (no version records) package. */
 597    map_ptrloc Package;         // Package
 598    /** \brief next dependency of this version */
 599    map_ptrloc NextDepends;     // Dependency
 600    /** \brief next reverse dependency of this package */
 601    map_ptrloc NextRevDepends;  // Dependency
 602    /** \brief version of the package which has the reverse depends */
 603    map_ptrloc ParentVer;       // Version
 604
 605    /** \brief unique sequel ID */
 606    map_ptrloc ID;
 607    /** \brief Dependency type - Depends, Recommends, Conflicts, etc */
 608    unsigned char Type;
 609    /** \brief comparison operator specified on the depends line
 610
 611        If the high bit is set then it is a logical OR with the previous record. */
 612    unsigned char CompareOp;
 613 };
 614                                                                         /*}}}*/
 615 // Provides structure                                                   /*{{{*/
 616 /** \brief handles virtual packages
 617
 618     When a Provides: line is encountered a new provides record is added
 619     associating the package with a virtual package name.
 620     The provides structures are linked off the package structures.
 621     This simplifies the analysis of dependencies and other aspects A provides
 622     refers to a specific version of a specific package, not all versions need to
 623     provide that provides.*/
 624 struct pkgCache::Provides
 625 {
 626    /** \brief index of the package providing this */
 627    map_ptrloc ParentPkg;        // Package
 628    /** \brief index of the version this provide line applies to */
 629    map_ptrloc Version;          // Version
 630    /** \brief version in the provides line (if any)
 631
 632        This version allows dependencies to depend on specific versions of a
 633        Provides, as well as allowing Provides to override existing packages.
 634        This is experimental. Note that Debian doesn't allow versioned provides */
 635    map_ptrloc ProvideVersion;   // StringItem
 636    /** \brief next provides (based of package) */
 637    map_ptrloc NextProvides;     // Provides
 638    /** \brief next provides (based of version) */
 639    map_ptrloc NextPkgProv;      // Provides
 640 };
 641                                                                         /*}}}*/
 642 // StringItem structure                                                 /*{{{*/
 643 /** \brief used for generating single instances of strings
 644
 645     Some things like Section Name are are useful to have as unique tags.
 646     It is part of a linked list based at pkgCache::Header::StringList
 647
 648     All strings are simply inlined any place in the file that is natural
 649     for the writer. The client should make no assumptions about the positioning
 650     of strings. All StringItems should be null-terminated. */
 651 struct pkgCache::StringItem
 652 {
 653    /** \brief string this refers to */
 654    map_ptrloc String;        // StringItem
 655    /** \brief Next link in the chain */
 656    map_ptrloc NextItem;      // StringItem
 657 };
 658                                                                         /*}}}*/
 659
 660
 661 inline char const * const pkgCache::NativeArch() const
 662         { return StrP + HeaderP->Architecture; };
 663
 664 #include <apt-pkg/cacheiterators.h>
 665
 666 inline pkgCache::GrpIterator pkgCache::GrpBegin()
 667        {return GrpIterator(*this);};
 668 inline pkgCache::GrpIterator pkgCache::GrpEnd()
 669        {return GrpIterator(*this,GrpP);};
 670 inline pkgCache::PkgIterator pkgCache::PkgBegin()
 671        {return PkgIterator(*this);};
 672 inline pkgCache::PkgIterator pkgCache::PkgEnd()
 673        {return PkgIterator(*this,PkgP);};
 674 inline pkgCache::PkgFileIterator pkgCache::FileBegin()
 675        {return PkgFileIterator(*this,PkgFileP + HeaderP->FileList);};
 676 inline pkgCache::PkgFileIterator pkgCache::FileEnd()
 677        {return PkgFileIterator(*this,PkgFileP);};
 678
 679 // Oh I wish for Real Name Space Support
 680 class pkgCache::Namespace                                               /*{{{*/
 681 {
 682    public:
 683    typedef pkgCache::GrpIterator GrpIterator;
 684    typedef pkgCache::PkgIterator PkgIterator;
 685    typedef pkgCache::VerIterator VerIterator;
 686    typedef pkgCache::DescIterator DescIterator;
 687    typedef pkgCache::DepIterator DepIterator;
 688    typedef pkgCache::PrvIterator PrvIterator;
 689    typedef pkgCache::PkgFileIterator PkgFileIterator;
 690    typedef pkgCache::VerFileIterator VerFileIterator;
 691    typedef pkgCache::Version Version;
 692    typedef pkgCache::Description Description;
 693    typedef pkgCache::Package Package;
 694    typedef pkgCache::Header Header;
 695    typedef pkgCache::Dep Dep;
 696    typedef pkgCache::Flag Flag;
 697 };
 698                                                                         /*}}}*/
 699 #endif