// -*- 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
{
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};
struct Flag
{
enum PkgFlags {Auto=(1<<0),Essential=(1<<3),Important=(1<<4)};
- enum PkgFFlags {NotSource=(1<<0),NotAutomatic=(1<<1)};
+ enum PkgFFlags {NotSource=(1<<0),NotAutomatic=(1<<1),ButAutomaticUpgrades=(1<<2)};
};
protected:
StringItem *StringItemP;
char *StrP;
- virtual bool ReMap();
+ virtual bool ReMap(bool const &Errorchecks = true);
inline bool Sync() {return Map.Sync();};
inline MMap &GetMap() {return Map;};
inline void *DataEnd() {return ((unsigned char *)Map.Data()) + Map.Size();};
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, string Arch);
+ PkgIterator FindPkg(const string &Name, const string &Arch);
Header &Head() {return *HeaderP;};
inline GrpIterator GrpBegin();
inline PkgFileIterator FileBegin();
inline PkgFileIterator FileEnd();
+ inline bool MultiArchCache() const { return MultiArchEnabled; };
+
// Make me a function
pkgVersioningSystem *VS;
pkgCache(MMap *Map,bool DoMap = true);
virtual ~pkgCache() {};
+
+private:
+ bool MultiArchEnabled;
+ PkgIterator SingleArchFindPkg(const string &Name);
+ inline char const * const NativeArch() const;
};
/*}}}*/
// 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;
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 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 */
+ /** \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 and group name lookup
- // Notice: Increase only both table sizes as the
- // hashmethod assume the size of the Pkg one
+ /** \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];
Header();
};
/*}}}*/
-struct pkgCache::Group { /*{{{*/
- map_ptrloc Name; // Stringtable
+// 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;
- // Linked List
- map_ptrloc FirstPackage;// Package
- map_ptrloc LastPackage; // Package
- map_ptrloc Next; // Group
};
/*}}}*/
-struct pkgCache::Package /*{{{*/
+// 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
- map_ptrloc Arch; // StringTable (StringItem)
+ /** \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)
+ /** \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
+
+ // 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
+ /* @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
+ /* @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)
- enum {None, All, Foreign, Same, Allowed} MultiArch;
+ /** \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 */
+ /* FIXME: A bitflag would be better with the next abibreak… */
+ enum {None, All, Foreign, Same, Allowed, AllForeign, AllAllowed} MultiArch;
- // Lists
+ /** \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
-
- map_ptrloc Size; // These are the .deb size
- map_ptrloc InstalledSize;
+
+ /** \brief archive size for this version
+
+ For Debian this is the size of the .deb file. */
+ unsigned long long Size; // These are the .deb size
+ /** \brief uncompressed size for this version */
+ unsigned long long 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
};
/*}}}*/
+
+
+inline char const * const pkgCache::NativeArch() const
+ { return StrP + HeaderP->Architecture; };
+
#include <apt-pkg/cacheiterators.h>
inline pkgCache::GrpIterator pkgCache::GrpBegin()
projects / apt.git / blobdiff