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 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    bool CheckSizes(Header &Against) const;
 316    Header();
 317 };
 318                                                                         /*}}}*/
 319 // Group structure                                                      /*{{{*/
 320 /** \brief groups architecture depending packages together
 321
 322     On or more packages with the same name form a group, so we have
 323     a simple way to access a package built for different architectures
 324     Group exists in a singly linked list of group records starting at
 325     the hash index of the name in the pkgCache::Header::GrpHashTable */
 326 struct pkgCache::Group
 327 {
 328    /** \brief Name of the group */
 329    map_ptrloc Name;             // StringItem
 330
 331    // Linked List
 332    /** Link to the first package which belongs to the group */
 333    map_ptrloc FirstPackage;     // Package
 334    /** Link to the last package which belongs to the group */
 335    map_ptrloc LastPackage;      // Package
 336    /** Link to the next Group */
 337    map_ptrloc Next;             // Group
 338 };
 339                                                                         /*}}}*/
 340 // Package structure                                                    /*{{{*/
 341 /** \brief contains information for a single unique package
 342
 343     There can be any number of versions of a given package.
 344     Package exists in a singly linked list of package records starting at
 345     the hash index of the name in the pkgCache::Header::PkgHashTable
 346
 347     A package can be created for every architecture so package names are
 348     not unique, but it is garanteed that packages with the same name
 349     are sequencel ordered in the list. Packages with the same name can be
 350     accessed with the Group.
 351 */
 352 struct pkgCache::Package
 353 {
 354    /** \brief Name of the package */
 355    map_ptrloc Name;              // StringItem
 356    /** \brief Architecture of the package */
 357    map_ptrloc Arch;              // StringItem
 358    /** \brief Base of a singly linked list of versions
 359
 360        Each structure represents a unique version of the package.
 361        The version structures contain links into PackageFile and the
 362        original text file as well as detailed information about the size
 363        and dependencies of the specific package. In this way multiple
 364        versions of a package can be cleanly handled by the system.
 365        Furthermore, this linked list is guaranteed to be sorted
 366        from Highest version to lowest version with no duplicate entries. */
 367    map_ptrloc VersionList;       // Version
 368    /** \brief index to the installed version */
 369    map_ptrloc CurrentVer;        // Version
 370    /** \brief indicates the deduced section
 371
 372        Should be the index to the string "Unknown" or to the section
 373        of the last parsed item. */
 374    map_ptrloc Section;           // StringItem
 375    /** \brief index of the group this package belongs to */
 376    map_ptrloc Group;             // Group the Package belongs to
 377
 378    // Linked list
 379    /** \brief Link to the next package in the same bucket */
 380    map_ptrloc NextPackage;       // Package
 381    /** \brief List of all dependencies on this package */
 382    map_ptrloc RevDepends;        // Dependency
 383    /** \brief List of all "packages" this package provide */
 384    map_ptrloc ProvidesList;      // Provides
 385
 386    // Install/Remove/Purge etc
 387    /** \brief state that the user wishes the package to be in */
 388    unsigned char SelectedState;     // What
 389    /** \brief installation state of the package
 390
 391        This should be "ok" but in case the installation failed
 392        it will be different.
 393    */
 394    unsigned char InstState;         // Flags
 395    /** \brief indicates if the package is installed */
 396    unsigned char CurrentState;      // State
 397
 398    /** \brief unique sequel ID
 399
 400        ID is a unique value from 0 to Header->PackageCount assigned by the generator.
 401        This allows clients to create an array of size PackageCount and use it to store
 402        state information for the package map. For instance the status file emitter uses
 403        this to track which packages have been emitted already. */
 404    unsigned int ID;
 405    /** \brief some useful indicators of the package's state */
 406    unsigned long Flags;
 407 };
 408                                                                         /*}}}*/
 409 // Package File structure                                               /*{{{*/
 410 /** \brief stores information about the files used to generate the cache
 411
 412     Package files are referenced by Version structures to be able to know
 413     after the generation still from which Packages file includes this Version
 414     as we need this information later on e.g. for pinning. */
 415 struct pkgCache::PackageFile
 416 {
 417    /** \brief physical disk file that this PackageFile represents */
 418    map_ptrloc FileName;        // StringItem
 419    /** \brief the release information
 420
 421        Please see the files document for a description of what the
 422        release information means. */
 423    map_ptrloc Archive;         // StringItem
 424    map_ptrloc Codename;        // StringItem
 425    map_ptrloc Component;       // StringItem
 426    map_ptrloc Version;         // StringItem
 427    map_ptrloc Origin;          // StringItem
 428    map_ptrloc Label;           // StringItem
 429    map_ptrloc Architecture;    // StringItem
 430    /** \brief The site the index file was fetched from */
 431    map_ptrloc Site;            // StringItem
 432    /** \brief indicates what sort of index file this is
 433
 434        @TODO enumerate at least the possible indexes */
 435    map_ptrloc IndexType;       // StringItem
 436    /** \brief Size of the file
 437
 438        Used together with the modification time as a
 439        simple check to ensure that the Packages
 440        file has not been altered since Cache generation. */
 441    unsigned long Size;
 442    /** \brief Modification time for the file */
 443    time_t mtime;
 444
 445    /* @TODO document PackageFile::Flags */
 446    unsigned long Flags;
 447
 448    // Linked list
 449    /** \brief Link to the next PackageFile in the Cache */
 450    map_ptrloc NextFile;        // PackageFile
 451    /** \brief unique sequel ID */
 452    unsigned int ID;
 453 };
 454                                                                         /*}}}*/
 455 // VerFile structure                                                    /*{{{*/
 456 /** \brief associates a version with a PackageFile
 457
 458     This allows a full description of all Versions in all files
 459     (and hence all sources) under consideration. */
 460 struct pkgCache::VerFile
 461 {
 462    /** \brief index of the package file that this version was found in */
 463    map_ptrloc File;           // PackageFile
 464    /** \brief next step in the linked list */
 465    map_ptrloc NextFile;       // PkgVerFile
 466    /** \brief position in the package file */
 467    map_ptrloc Offset;         // File offset
 468    /* @TODO document pkgCache::VerFile::Size */
 469    unsigned long Size;
 470 };
 471                                                                         /*}}}*/
 472 // DescFile structure                                                   /*{{{*/
 473 /** \brief associates a description with a Translation file */
 474 struct pkgCache::DescFile
 475 {
 476    /** \brief index of the file that this description was found in */
 477    map_ptrloc File;           // PackageFile
 478    /** \brief next step in the linked list */
 479    map_ptrloc NextFile;       // PkgVerFile
 480    /** \brief position in the file */
 481    map_ptrloc Offset;         // File offset
 482    /* @TODO document pkgCache::DescFile::Size */
 483    unsigned long Size;
 484 };
 485                                                                         /*}}}*/
 486 // Version structure                                                    /*{{{*/
 487 /** \brief information for a single version of a package
 488
 489     The version list is always sorted from highest version to lowest
 490     version by the generator. Equal version numbers are either merged
 491     or handled as separate versions based on the Hash value. */
 492 struct pkgCache::Version
 493 {
 494    /** \brief complete version string */
 495    map_ptrloc VerStr;            // StringItem
 496    /** \brief section this version is filled in */
 497    map_ptrloc Section;           // StringItem
 498    /** \brief stores the MultiArch capabilities of this version
 499
 500        None is the default and doesn't trigger special behaviour,
 501        Foreign means that this version can fulfill dependencies even
 502        if it is built for another architecture as the requester.
 503        Same indicates that builds for different architectures can
 504        be co-installed on the system and All is the marker for a
 505        version with the Architecture: all. */
 506    enum {None, All, Foreign, Same, Allowed} MultiArch;
 507
 508    /** \brief references all the PackageFile's that this version came from
 509
 510        FileList can be used to determine what distribution(s) the Version
 511        applies to. If FileList is 0 then this is a blank version.
 512        The structure should also have a 0 in all other fields excluding
 513        pkgCache::Version::VerStr and Possibly pkgCache::Version::NextVer. */
 514    map_ptrloc FileList;          // VerFile
 515    /** \brief next (lower or equal) version in the linked list */
 516    map_ptrloc NextVer;           // Version
 517    /** \brief next description in the linked list */
 518    map_ptrloc DescriptionList;   // Description
 519    /** \brief base of the dependency list */
 520    map_ptrloc DependsList;       // Dependency
 521    /** \brief links to the owning package
 522
 523        This allows reverse dependencies to determine the package */
 524    map_ptrloc ParentPkg;         // Package
 525    /** \brief list of pkgCache::Provides */
 526    map_ptrloc ProvidesList;      // Provides
 527
 528    /** \brief archive size for this version
 529
 530        For Debian this is the size of the .deb file. */
 531    map_ptrloc Size;              // These are the .deb size
 532    /** \brief uncompressed size for this version */
 533    map_ptrloc InstalledSize;
 534    /** \brief characteristic value representing this version
 535
 536        No two packages in existence should have the same VerStr
 537        and Hash with different contents. */
 538    unsigned short Hash;
 539    /** \brief unique sequel ID */
 540    unsigned int ID;
 541    /** \brief parsed priority value */
 542    unsigned char Priority;
 543 };
 544                                                                         /*}}}*/
 545 // Description structure                                                /*{{{*/
 546 /** \brief datamember of a linked list of available description for a version */
 547 struct pkgCache::Description
 548 {
 549    /** \brief Language code of this description (translation)
 550
 551        If the value has a 0 length then this is read using the Package
 552        file else the Translation-CODE file is used. */
 553    map_ptrloc language_code;     // StringItem
 554    /** \brief MD5sum of the original description
 555
 556        Used to map Translations of a description to a version
 557        and to check that the Translation is up-to-date. */
 558    map_ptrloc md5sum;            // StringItem
 559
 560    /* @TODO document pkgCache::Description::FileList */
 561    map_ptrloc FileList;          // DescFile
 562    /** \brief next translation for this description */
 563    map_ptrloc NextDesc;          // Description
 564    /** \brief the text is a description of this package */
 565    map_ptrloc ParentPkg;         // Package
 566
 567    /** \brief unique sequel ID */
 568    unsigned int ID;
 569 };
 570                                                                         /*}}}*/
 571 // Dependency structure                                                 /*{{{*/
 572 /** \brief information for a single dependency record
 573
 574     The records are split up like this to ease processing by the client.
 575     The base of the linked list is pkgCache::Version::DependsList.
 576     All forms of dependencies are recorded here including Depends,
 577     Recommends, Suggests, Enhances, Conflicts, Replaces and Breaks. */
 578 struct pkgCache::Dependency
 579 {
 580    /** \brief string of the version the dependency is applied against */
 581    map_ptrloc Version;         // StringItem
 582    /** \brief index of the package this depends applies to
 583
 584        The generator will - if the package does not already exist -
 585        create a blank (no version records) package. */
 586    map_ptrloc Package;         // Package
 587    /** \brief next dependency of this version */
 588    map_ptrloc NextDepends;     // Dependency
 589    /** \brief next reverse dependency of this package */
 590    map_ptrloc NextRevDepends;  // Dependency
 591    /** \brief version of the package which has the reverse depends */
 592    map_ptrloc ParentVer;       // Version
 593
 594    /** \brief unique sequel ID */
 595    map_ptrloc ID;
 596    /** \brief Dependency type - Depends, Recommends, Conflicts, etc */
 597    unsigned char Type;
 598    /** \brief comparison operator specified on the depends line
 599
 600        If the high bit is set then it is a logical OR with the previous record. */
 601    unsigned char CompareOp;
 602 };
 603                                                                         /*}}}*/
 604 // Provides structure                                                   /*{{{*/
 605 /** \brief handles virtual packages
 606
 607     When a Provides: line is encountered a new provides record is added
 608     associating the package with a virtual package name.
 609     The provides structures are linked off the package structures.
 610     This simplifies the analysis of dependencies and other aspects A provides
 611     refers to a specific version of a specific package, not all versions need to
 612     provide that provides.*/
 613 struct pkgCache::Provides
 614 {
 615    /** \brief index of the package providing this */
 616    map_ptrloc ParentPkg;        // Package
 617    /** \brief index of the version this provide line applies to */
 618    map_ptrloc Version;          // Version
 619    /** \brief version in the provides line (if any)
 620
 621        This version allows dependencies to depend on specific versions of a
 622        Provides, as well as allowing Provides to override existing packages.
 623        This is experimental. Note that Debian doesn't allow versioned provides */
 624    map_ptrloc ProvideVersion;   // StringItem
 625    /** \brief next provides (based of package) */
 626    map_ptrloc NextProvides;     // Provides
 627    /** \brief next provides (based of version) */
 628    map_ptrloc NextPkgProv;      // Provides
 629 };
 630                                                                         /*}}}*/
 631 // StringItem structure                                                 /*{{{*/
 632 /** \brief used for generating single instances of strings
 633
 634     Some things like Section Name are are useful to have as unique tags.
 635     It is part of a linked list based at pkgCache::Header::StringList
 636
 637     All strings are simply inlined any place in the file that is natural
 638     for the writer. The client should make no assumptions about the positioning
 639     of strings. All StringItems should be null-terminated. */
 640 struct pkgCache::StringItem
 641 {
 642    /** \brief string this refers to */
 643    map_ptrloc String;        // StringItem
 644    /** \brief Next link in the chain */
 645    map_ptrloc NextItem;      // StringItem
 646 };
 647                                                                         /*}}}*/
 648 #include <apt-pkg/cacheiterators.h>
 649
 650 inline pkgCache::GrpIterator pkgCache::GrpBegin()
 651        {return GrpIterator(*this);};
 652 inline pkgCache::GrpIterator pkgCache::GrpEnd()
 653        {return GrpIterator(*this,GrpP);};
 654 inline pkgCache::PkgIterator pkgCache::PkgBegin()
 655        {return PkgIterator(*this);};
 656 inline pkgCache::PkgIterator pkgCache::PkgEnd()
 657        {return PkgIterator(*this,PkgP);};
 658 inline pkgCache::PkgFileIterator pkgCache::FileBegin()
 659        {return PkgFileIterator(*this,PkgFileP + HeaderP->FileList);};
 660 inline pkgCache::PkgFileIterator pkgCache::FileEnd()
 661        {return PkgFileIterator(*this,PkgFileP);};
 662
 663 // Oh I wish for Real Name Space Support
 664 class pkgCache::Namespace                                               /*{{{*/
 665 {
 666    public:
 667    typedef pkgCache::GrpIterator GrpIterator;
 668    typedef pkgCache::PkgIterator PkgIterator;
 669    typedef pkgCache::VerIterator VerIterator;
 670    typedef pkgCache::DescIterator DescIterator;
 671    typedef pkgCache::DepIterator DepIterator;
 672    typedef pkgCache::PrvIterator PrvIterator;
 673    typedef pkgCache::PkgFileIterator PkgFileIterator;
 674    typedef pkgCache::VerFileIterator VerFileIterator;
 675    typedef pkgCache::Version Version;
 676    typedef pkgCache::Description Description;
 677    typedef pkgCache::Package Package;
 678    typedef pkgCache::Header Header;
 679    typedef pkgCache::Dep Dep;
 680    typedef pkgCache::Flag Flag;
 681 };
 682                                                                         /*}}}*/
 683 #endif