diff options
Diffstat (limited to 'apt-pkg/pkgcache.h')
| -rw-r--r-- | apt-pkg/pkgcache.h | 511 |
1 files changed, 421 insertions, 90 deletions
diff --git a/apt-pkg/pkgcache.h b/apt-pkg/pkgcache.h index 38733713f..643f240b0 100644 --- a/apt-pkg/pkgcache.h +++ b/apt-pkg/pkgcache.h @@ -1,20 +1,75 @@ // -*- mode: cpp; mode: fold -*- // Description /*{{{*/ -// $Id: pkgcache.h,v 1.25 2001/07/01 22:28:24 jgg Exp $ -/* ###################################################################### - - Cache - Structure definitions for the cache file - - Please see doc/apt-pkg/cache.sgml for a more detailed description of - this format. Also be sure to keep that file up-to-date!! - +/**\file pkgcache.h + \brief pkgCache - Structure definitions for the cache file + + The goal of the cache file is two fold: + Firstly to speed loading and processing of the package file array and + secondly to reduce memory consumption of the package file array. + + The implementation is aimed at an environment with many primary package + files, for instance someone that has a Package file for their CD-ROM, a + Package file for the latest version of the distribution on the CD-ROM and a + package file for the development version. Always present is the information + contained in the status file which might be considered a separate package + file. + + Please understand, this is designed as a <b>Cache file</b> it is not meant to be + used on any system other than the one it was created for. It is not meant to + be authoritative either, i.e. if a system crash or software failure occurs it + must be perfectly acceptable for the cache file to be in an inconsistent + state. Furthermore at any time the cache file may be erased without losing + any information. + + Also the structures and storage layout is optimized for use by the APT + and may not be suitable for all purposes. However it should be possible + to extend it with associate cache files that contain other information. + + To keep memory use down the cache file only contains often used fields and + fields that are inexpensive to store, the Package file has a full list of + fields. Also the client may assume that all items are perfectly valid and + need not perform checks against their correctness. Removal of information + from the cache is possible, but blanks will be left in the file, and + unused strings will also be present. The recommended implementation is to + simply rebuild the cache each time any of the data files change. It is + possible to add a new package file to the cache without any negative side + effects. + + <b>Note on Pointer access</b> Clients should always use the CacheIterators classes for access to the - cache. They provide a simple STL-like method for traversing the links - of the datastructure. - - See pkgcachegen.h for information about generating cache structures. - - ##################################################################### */ + cache and the data in it. They also provide a simple STL-like method for + traversing the links of the datastructure. + + Every item in every structure is stored as the index to that structure. + What this means is that once the files is mmaped every data access has to + go through a fix up stage to get a real memory pointer. This is done + by taking the index, multiplying it by the type size and then adding + it to the start address of the memory block. This sounds complex, but + in C it is a single array dereference. Because all items are aligned to + their size and indexes are stored as multiples of the size of the structure + the format is immediately portable to all possible architectures - BUT the + generated files are -NOT-. + + This scheme allows code like this to be written: + <example> + void *Map = mmap(...); + Package *PkgList = (Package *)Map; + Header *Head = (Header *)Map; + char *Strings = (char *)Map; + cout << (Strings + PkgList[Head->HashTable[0]]->Name) << endl; + </example> + Notice the lack of casting or multiplication. The net result is to return + the name of the first package in the first hash bucket, without error + checks. + + The generator uses allocation pools to group similarly sized structures in + large blocks to eliminate any alignment overhead. The generator also + assures that no structures overlap and all indexes are unique. Although + at first glance it may seem like there is the potential for two structures + to exist at the same point the generator never allows this to happen. + (See the discussion of free space pools) + + See \ref pkgcachegen.h for more information about generating cache structures. */ /*}}}*/ #ifndef PKGLIB_PKGCACHE_H #define PKGLIB_PKGCACHE_H @@ -32,6 +87,7 @@ class pkgCache /*{{{*/ public: // Cache element predeclarations struct Header; + struct Group; struct Package; struct PackageFile; struct Version; @@ -43,6 +99,8 @@ class pkgCache /*{{{*/ struct DescFile; // Iterators + template<typename Str, typename Itr> class Iterator; + class GrpIterator; class PkgIterator; class VerIterator; class DescIterator; @@ -51,14 +109,6 @@ class pkgCache /*{{{*/ class PkgFileIterator; class VerFileIterator; class DescFileIterator; - friend class PkgIterator; - friend class VerIterator; - friend class DescInterator; - friend class DepIterator; - friend class PrvIterator; - friend class PkgFileIterator; - friend class VerFileIterator; - friend class DescFileIterator; class Namespace; @@ -71,12 +121,20 @@ class pkgCache /*{{{*/ { enum DepType {Depends=1,PreDepends=2,Suggests=3,Recommends=4, Conflicts=5,Replaces=6,Obsoletes=7,DpkgBreaks=8,Enhances=9}; + /** \brief available compare operators + + The lower 4 bits are used to indicate what operator is being specified and + the upper 4 bits are flags. OR indicates that the next package is + or'd with the current package. */ enum DepCompareOp {Or=0x10,NoOp=0,LessEq=0x1,GreaterEq=0x2,Less=0x3, Greater=0x4,Equals=0x5,NotEquals=0x6}; }; struct State { + /** \brief priority of a package version + + Zero is used for unparsable or absent Priority fields. */ enum VerPriority {Important=1,Required=2,Standard=3,Optional=4,Extra=5}; enum PkgSelectedState {Unknown=0,Install=1,Hold=2,DeInstall=3,Purge=4}; enum PkgInstState {Ok=0,ReInstReq=1,HoldInst=2,HoldReInstReq=3}; @@ -104,6 +162,7 @@ class pkgCache /*{{{*/ // Pointers to the arrays of items Header *HeaderP; + Group *GrpP; Package *PkgP; VerFile *VerFileP; DescFile *DescFileP; @@ -124,17 +183,24 @@ class pkgCache /*{{{*/ inline unsigned long Hash(const string &S) const {return sHash(S);}; inline unsigned long Hash(const char *S) const {return sHash(S);}; - // Usefull transformation things + // Useful transformation things const char *Priority(unsigned char Priority); // Accessors + GrpIterator FindGrp(const string &Name); PkgIterator FindPkg(const string &Name); + PkgIterator FindPkg(const string &Name, const string &Arch); + Header &Head() {return *HeaderP;}; + inline GrpIterator GrpBegin(); + inline GrpIterator GrpEnd(); inline PkgIterator PkgBegin(); inline PkgIterator PkgEnd(); inline PkgFileIterator FileBegin(); inline PkgFileIterator FileEnd(); + inline bool MultiArchCache() const { return MultiArchEnabled; }; + // Make me a function pkgVersioningSystem *VS; @@ -145,19 +211,40 @@ class pkgCache /*{{{*/ pkgCache(MMap *Map,bool DoMap = true); virtual ~pkgCache() {}; + +private: + bool MultiArchEnabled; + PkgIterator SingleArchFindPkg(const string &Name); }; /*}}}*/ // Header structure /*{{{*/ struct pkgCache::Header { - // Signature information + /** \brief Signature information + + This must contain the hex value 0x98FE76DC which is designed to + verify that the system loading the image has the same byte order + and byte size as the system saving the image */ unsigned long Signature; + /** These contain the version of the cache file */ short MajorVersion; short MinorVersion; + /** \brief indicates if the cache should be erased + + Dirty is true if the cache file was opened for reading, the client + expects to have written things to it and have not fully synced it. + The file should be erased and rebuilt if it is true. */ bool Dirty; - - // Size of structure values + + /** \brief Size of structure values + + All *Sz variables contains the sizeof() that particular structure. + It is used as an extra consistency check on the structure of the file. + + If any of the size values do not exactly match what the client expects + then the client should refuse the load the file. */ unsigned short HeaderSz; + unsigned short GroupSz; unsigned short PackageSz; unsigned short PackageFileSz; unsigned short VersionSz; @@ -166,8 +253,13 @@ struct pkgCache::Header unsigned short ProvidesSz; unsigned short VerFileSz; unsigned short DescFileSz; - - // Structure counts + + /** \brief Structure counts + + These indicate the number of each structure contained in the cache. + PackageCount is especially useful for generating user state structures. + See Package::Id for more info. */ + unsigned long GroupCount; unsigned long PackageCount; unsigned long VersionCount; unsigned long DescriptionCount; @@ -176,154 +268,393 @@ struct pkgCache::Header unsigned long VerFileCount; unsigned long DescFileCount; unsigned long ProvidesCount; - - // Offsets - map_ptrloc FileList; // struct PackageFile - map_ptrloc StringList; // struct StringItem - map_ptrloc VerSysName; // StringTable - map_ptrloc Architecture; // StringTable + + /** \brief index of the first PackageFile structure + + The PackageFile structures are singly linked lists that represent + all package files that have been merged into the cache. */ + map_ptrloc FileList; + /** \brief index of the first StringItem structure + + The cache contains a list of all the unique strings (StringItems). + The parser reads this list into memory so it can match strings + against it.*/ + map_ptrloc StringList; + /** \brief String representing the version system used */ + map_ptrloc VerSysName; + /** \brief Architecture(s) the cache was built against */ + map_ptrloc Architecture; + /** \brief The maximum size of a raw entry from the original Package file */ unsigned long MaxVerFileSize; + /** \brief The maximum size of a raw entry from the original Translation file */ unsigned long MaxDescFileSize; - /* Allocation pools, there should be one of these for each structure - excluding the header */ - DynamicMMap::Pool Pools[8]; + /** \brief The Pool structures manage the allocation pools that the generator uses + + Start indicates the first byte of the pool, Count is the number of objects + remaining in the pool and ItemSize is the structure size (alignment factor) + of the pool. An ItemSize of 0 indicates the pool is empty. There should be + the same number of pools as there are structure types. The generator + stores this information so future additions can make use of any unused pool + blocks. */ + DynamicMMap::Pool Pools[9]; - // Rapid package name lookup - map_ptrloc HashTable[2*1048]; + /** \brief hash tables providing rapid group/package name lookup + + Each group/package name is inserted into the hash table using pkgCache::Hash(const &string) + By iterating over each entry in the hash table it is possible to iterate over + the entire list of packages. Hash Collisions are handled with a singly linked + list of packages based at the hash item. The linked list contains only + packages that match the hashing function. + In the PkgHashTable is it possible that multiple packages have the same name - + these packages are stored as a sequence in the list. + + Beware: The Hashmethod assumes that the hash table sizes are equal */ + map_ptrloc PkgHashTable[2*1048]; + map_ptrloc GrpHashTable[2*1048]; bool CheckSizes(Header &Against) const; Header(); }; /*}}}*/ -struct pkgCache::Package /*{{{*/ +// Group structure /*{{{*/ +/** \brief groups architecture depending packages together + + On or more packages with the same name form a group, so we have + a simple way to access a package built for different architectures + Group exists in a singly linked list of group records starting at + the hash index of the name in the pkgCache::Header::GrpHashTable */ +struct pkgCache::Group +{ + /** \brief Name of the group */ + map_ptrloc Name; // StringItem + + // Linked List + /** \brief Link to the first package which belongs to the group */ + map_ptrloc FirstPackage; // Package + /** \brief Link to the last package which belongs to the group */ + map_ptrloc LastPackage; // Package + /** \brief Link to the next Group */ + map_ptrloc Next; // Group + /** \brief unique sequel ID */ + unsigned int ID; + +}; + /*}}}*/ +// Package structure /*{{{*/ +/** \brief contains information for a single unique package + + There can be any number of versions of a given package. + Package exists in a singly linked list of package records starting at + the hash index of the name in the pkgCache::Header::PkgHashTable + + A package can be created for every architecture so package names are + not unique, but it is garanteed that packages with the same name + are sequencel ordered in the list. Packages with the same name can be + accessed with the Group. +*/ +struct pkgCache::Package { - // Pointers - map_ptrloc Name; // Stringtable + /** \brief Name of the package */ + map_ptrloc Name; // StringItem + /** \brief Architecture of the package */ + map_ptrloc Arch; // StringItem + /** \brief Base of a singly linked list of versions + + Each structure represents a unique version of the package. + The version structures contain links into PackageFile and the + original text file as well as detailed information about the size + and dependencies of the specific package. In this way multiple + versions of a package can be cleanly handled by the system. + Furthermore, this linked list is guaranteed to be sorted + from Highest version to lowest version with no duplicate entries. */ map_ptrloc VersionList; // Version + /** \brief index to the installed version */ map_ptrloc CurrentVer; // Version - map_ptrloc Section; // StringTable (StringItem) - - // Linked list + /** \brief indicates the deduced section + + Should be the index to the string "Unknown" or to the section + of the last parsed item. */ + map_ptrloc Section; // StringItem + /** \brief index of the group this package belongs to */ + map_ptrloc Group; // Group the Package belongs to + + // Linked list + /** \brief Link to the next package in the same bucket */ map_ptrloc NextPackage; // Package + /** \brief List of all dependencies on this package */ map_ptrloc RevDepends; // Dependency + /** \brief List of all "packages" this package provide */ map_ptrloc ProvidesList; // Provides // Install/Remove/Purge etc + /** \brief state that the user wishes the package to be in */ unsigned char SelectedState; // What + /** \brief installation state of the package + + This should be "ok" but in case the installation failed + it will be different. + */ unsigned char InstState; // Flags + /** \brief indicates if the package is installed */ unsigned char CurrentState; // State - + + /** \brief unique sequel ID + + ID is a unique value from 0 to Header->PackageCount assigned by the generator. + This allows clients to create an array of size PackageCount and use it to store + state information for the package map. For instance the status file emitter uses + this to track which packages have been emitted already. */ unsigned int ID; + /** \brief some useful indicators of the package's state */ unsigned long Flags; }; /*}}}*/ -struct pkgCache::PackageFile /*{{{*/ +// Package File structure /*{{{*/ +/** \brief stores information about the files used to generate the cache + + Package files are referenced by Version structures to be able to know + after the generation still from which Packages file includes this Version + as we need this information later on e.g. for pinning. */ +struct pkgCache::PackageFile { - // Names - map_ptrloc FileName; // Stringtable - map_ptrloc Archive; // Stringtable - map_ptrloc Codename; // Stringtable - map_ptrloc Component; // Stringtable - map_ptrloc Version; // Stringtable - map_ptrloc Origin; // Stringtable - map_ptrloc Label; // Stringtable - map_ptrloc Architecture; // Stringtable - map_ptrloc Site; // Stringtable - map_ptrloc IndexType; // Stringtable - unsigned long Size; + /** \brief physical disk file that this PackageFile represents */ + map_ptrloc FileName; // StringItem + /** \brief the release information + + Please see the files document for a description of what the + release information means. */ + map_ptrloc Archive; // StringItem + map_ptrloc Codename; // StringItem + map_ptrloc Component; // StringItem + map_ptrloc Version; // StringItem + map_ptrloc Origin; // StringItem + map_ptrloc Label; // StringItem + map_ptrloc Architecture; // StringItem + /** \brief The site the index file was fetched from */ + map_ptrloc Site; // StringItem + /** \brief indicates what sort of index file this is + + @TODO enumerate at least the possible indexes */ + map_ptrloc IndexType; // StringItem + /** \brief Size of the file + + Used together with the modification time as a + simple check to ensure that the Packages + file has not been altered since Cache generation. */ + unsigned long Size; + /** \brief Modification time for the file */ + time_t mtime; + + /* @TODO document PackageFile::Flags */ unsigned long Flags; - + // Linked list + /** \brief Link to the next PackageFile in the Cache */ map_ptrloc NextFile; // PackageFile + /** \brief unique sequel ID */ unsigned int ID; - time_t mtime; // Modification time for the file }; /*}}}*/ -struct pkgCache::VerFile /*{{{*/ +// VerFile structure /*{{{*/ +/** \brief associates a version with a PackageFile + + This allows a full description of all Versions in all files + (and hence all sources) under consideration. */ +struct pkgCache::VerFile { + /** \brief index of the package file that this version was found in */ map_ptrloc File; // PackageFile + /** \brief next step in the linked list */ map_ptrloc NextFile; // PkgVerFile + /** \brief position in the package file */ map_ptrloc Offset; // File offset - unsigned short Size; + /* @TODO document pkgCache::VerFile::Size */ + unsigned long Size; }; /*}}}*/ -struct pkgCache::DescFile /*{{{*/ +// DescFile structure /*{{{*/ +/** \brief associates a description with a Translation file */ +struct pkgCache::DescFile { + /** \brief index of the file that this description was found in */ map_ptrloc File; // PackageFile + /** \brief next step in the linked list */ map_ptrloc NextFile; // PkgVerFile + /** \brief position in the file */ map_ptrloc Offset; // File offset - unsigned short Size; + /* @TODO document pkgCache::DescFile::Size */ + unsigned long Size; }; /*}}}*/ -struct pkgCache::Version /*{{{*/ +// Version structure /*{{{*/ +/** \brief information for a single version of a package + + The version list is always sorted from highest version to lowest + version by the generator. Equal version numbers are either merged + or handled as separate versions based on the Hash value. */ +struct pkgCache::Version { - map_ptrloc VerStr; // Stringtable - map_ptrloc Section; // StringTable (StringItem) - map_ptrloc Arch; // StringTable - - // Lists + /** \brief complete version string */ + map_ptrloc VerStr; // StringItem + /** \brief section this version is filled in */ + map_ptrloc Section; // StringItem + /** \brief stores the MultiArch capabilities of this version + + None is the default and doesn't trigger special behaviour, + Foreign means that this version can fulfill dependencies even + if it is built for another architecture as the requester. + Same indicates that builds for different architectures can + be co-installed on the system and All is the marker for a + version with the Architecture: all. */ + enum {None, All, Foreign, Same, Allowed} MultiArch; + + /** \brief references all the PackageFile's that this version came from + + FileList can be used to determine what distribution(s) the Version + applies to. If FileList is 0 then this is a blank version. + The structure should also have a 0 in all other fields excluding + pkgCache::Version::VerStr and Possibly pkgCache::Version::NextVer. */ map_ptrloc FileList; // VerFile + /** \brief next (lower or equal) version in the linked list */ map_ptrloc NextVer; // Version + /** \brief next description in the linked list */ map_ptrloc DescriptionList; // Description + /** \brief base of the dependency list */ map_ptrloc DependsList; // Dependency + /** \brief links to the owning package + + This allows reverse dependencies to determine the package */ map_ptrloc ParentPkg; // Package + /** \brief list of pkgCache::Provides */ map_ptrloc ProvidesList; // Provides - + + /** \brief archive size for this version + + For Debian this is the size of the .deb file. */ map_ptrloc Size; // These are the .deb size + /** \brief uncompressed size for this version */ map_ptrloc InstalledSize; + /** \brief characteristic value representing this version + + No two packages in existence should have the same VerStr + and Hash with different contents. */ unsigned short Hash; + /** \brief unique sequel ID */ unsigned int ID; + /** \brief parsed priority value */ unsigned char Priority; }; /*}}}*/ -struct pkgCache::Description /*{{{*/ +// Description structure /*{{{*/ +/** \brief datamember of a linked list of available description for a version */ +struct pkgCache::Description { - // Language Code store the description translation language code. If - // the value has a 0 lenght then this is readed using the Package - // file else the Translation-CODE are used. - map_ptrloc language_code; // StringTable - map_ptrloc md5sum; // StringTable + /** \brief Language code of this description (translation) + + If the value has a 0 length then this is read using the Package + file else the Translation-CODE file is used. */ + map_ptrloc language_code; // StringItem + /** \brief MD5sum of the original description + + Used to map Translations of a description to a version + and to check that the Translation is up-to-date. */ + map_ptrloc md5sum; // StringItem - // Linked list + /* @TODO document pkgCache::Description::FileList */ map_ptrloc FileList; // DescFile + /** \brief next translation for this description */ map_ptrloc NextDesc; // Description + /** \brief the text is a description of this package */ map_ptrloc ParentPkg; // Package + /** \brief unique sequel ID */ unsigned int ID; }; /*}}}*/ -struct pkgCache::Dependency /*{{{*/ +// Dependency structure /*{{{*/ +/** \brief information for a single dependency record + + The records are split up like this to ease processing by the client. + The base of the linked list is pkgCache::Version::DependsList. + All forms of dependencies are recorded here including Depends, + Recommends, Suggests, Enhances, Conflicts, Replaces and Breaks. */ +struct pkgCache::Dependency { - map_ptrloc Version; // Stringtable + /** \brief string of the version the dependency is applied against */ + map_ptrloc Version; // StringItem + /** \brief index of the package this depends applies to + + The generator will - if the package does not already exist - + create a blank (no version records) package. */ map_ptrloc Package; // Package + /** \brief next dependency of this version */ map_ptrloc NextDepends; // Dependency + /** \brief next reverse dependency of this package */ map_ptrloc NextRevDepends; // Dependency + /** \brief version of the package which has the reverse depends */ map_ptrloc ParentVer; // Version - - // Specific types of depends - map_ptrloc ID; + + /** \brief unique sequel ID */ + map_ptrloc ID; + /** \brief Dependency type - Depends, Recommends, Conflicts, etc */ unsigned char Type; + /** \brief comparison operator specified on the depends line + + If the high bit is set then it is a logical OR with the previous record. */ unsigned char CompareOp; }; /*}}}*/ -struct pkgCache::Provides /*{{{*/ +// Provides structure /*{{{*/ +/** \brief handles virtual packages + + When a Provides: line is encountered a new provides record is added + associating the package with a virtual package name. + The provides structures are linked off the package structures. + This simplifies the analysis of dependencies and other aspects A provides + refers to a specific version of a specific package, not all versions need to + provide that provides.*/ +struct pkgCache::Provides { - map_ptrloc ParentPkg; // Pacakge + /** \brief index of the package providing this */ + map_ptrloc ParentPkg; // Package + /** \brief index of the version this provide line applies to */ map_ptrloc Version; // Version - map_ptrloc ProvideVersion; // Stringtable + /** \brief version in the provides line (if any) + + This version allows dependencies to depend on specific versions of a + Provides, as well as allowing Provides to override existing packages. + This is experimental. Note that Debian doesn't allow versioned provides */ + map_ptrloc ProvideVersion; // StringItem + /** \brief next provides (based of package) */ map_ptrloc NextProvides; // Provides + /** \brief next provides (based of version) */ map_ptrloc NextPkgProv; // Provides }; /*}}}*/ -struct pkgCache::StringItem /*{{{*/ +// StringItem structure /*{{{*/ +/** \brief used for generating single instances of strings + + Some things like Section Name are are useful to have as unique tags. + It is part of a linked list based at pkgCache::Header::StringList + + All strings are simply inlined any place in the file that is natural + for the writer. The client should make no assumptions about the positioning + of strings. All StringItems should be null-terminated. */ +struct pkgCache::StringItem { - map_ptrloc String; // Stringtable + /** \brief string this refers to */ + map_ptrloc String; // StringItem + /** \brief Next link in the chain */ map_ptrloc NextItem; // StringItem }; /*}}}*/ #include <apt-pkg/cacheiterators.h> +inline pkgCache::GrpIterator pkgCache::GrpBegin() + {return GrpIterator(*this);}; +inline pkgCache::GrpIterator pkgCache::GrpEnd() + {return GrpIterator(*this,GrpP);}; inline pkgCache::PkgIterator pkgCache::PkgBegin() {return PkgIterator(*this);}; inline pkgCache::PkgIterator pkgCache::PkgEnd() @@ -337,7 +668,7 @@ inline pkgCache::PkgFileIterator pkgCache::FileEnd() class pkgCache::Namespace /*{{{*/ { public: - + typedef pkgCache::GrpIterator GrpIterator; typedef pkgCache::PkgIterator PkgIterator; typedef pkgCache::VerIterator VerIterator; typedef pkgCache::DescIterator DescIterator; |