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1 // -*- mode: cpp; mode: fold -*-
2 // Description /*{{{*/
3 /* ######################################################################
4
5 System - Abstraction for running on different systems.
6
7 Instances of this class can be thought of as factories or meta-classes
8 for a variety of more specialized classes. Together this class and
9 it's specialized offspring completely define the environment and how
10 to access resources for a specific system. There are several sub
11 areas that are all orthogonal - each system has a unique combination of
12 these sub areas:
13 - Versioning. Different systems have different ideas on versions.
14 Within a system all sub classes must follow the same versioning
15 rules.
16 - Local tool locking to prevent multiple tools from accessing the
17 same database.
18 - Candidate Version selection policy - this is probably almost always
19 managed using a standard APT class
20 - Actual Package installation
21 * Indication of what kind of binary formats are supported
22 - Selection of local 'status' indexes that make up the pkgCache.
23
24 It is important to note that the handling of index files is not a
25 function of the system. Index files are handled through a separate
26 abstraction - the only requirement is that the index files have the
27 same idea of versioning as the target system.
28
29 Upon startup each supported system instantiates an instance of the
30 pkgSystem class (using a global constructor) which will make itself
31 available to the main APT init routine. That routine will select the
32 proper system and make it the global default.
33
34 ##################################################################### */
35 /*}}}*/
36 #ifndef PKGLIB_PKGSYSTEM_H
37 #define PKGLIB_PKGSYSTEM_H
38
39 #include <apt-pkg/pkgcache.h>
40 #include <apt-pkg/cacheiterators.h>
41
42 #include <vector>
43
44 #ifndef APT_8_CLEANER_HEADERS
45 #include <apt-pkg/depcache.h>
46 #endif
47
48 class pkgDepCache;
49 class pkgPackageManager;
50 class pkgVersioningSystem;
51 class Configuration;
52 class pkgIndexFile;
53
54 class pkgSystemPrivate;
55 class pkgSystem
56 {
57 public:
58
59 // Global list of supported systems
60 static pkgSystem **GlobalList;
61 static unsigned long GlobalListLen;
62 static pkgSystem *GetSystem(const char *Label);
63
64 const char * const Label;
65 pkgVersioningSystem * const VS;
66
67 /* Prevent other programs from touching shared data not covered by
68 other locks (cache or state locks) */
69 virtual bool Lock() = 0;
70 virtual bool UnLock(bool NoErrors = false) = 0;
71
72 /* Various helper classes to interface with specific bits of this
73 environment */
74 virtual pkgPackageManager *CreatePM(pkgDepCache *Cache) const = 0;
75
76 /* Load environment specific configuration and perform any other setup
77 necessary */
78 virtual bool Initialize(Configuration &/*Cnf*/) {return true;};
79
80 /* Type is some kind of Globally Unique way of differentiating
81 archive file types.. */
82 virtual bool ArchiveSupported(const char *Type) = 0;
83
84 // Return a list of system index files..
85 virtual bool AddStatusFiles(std::vector<pkgIndexFile *> &List) = 0;
86
87 virtual bool FindIndex(pkgCache::PkgFileIterator File,
88 pkgIndexFile *&Found) const = 0;
89
90 /* Evauluate how 'right' we are for this system based on the filesystem
91 etc.. */
92 virtual signed Score(Configuration const &/*Cnf*/) {
93 return 0;
94 };
95
96 //FIXME: these methods should be virtual
97 /** does this system has support for MultiArch?
98 *
99 * Systems supporting only single arch (not systems which are single arch)
100 * are considered legacy systems and support for it will likely degrade over
101 * time.
102 *
103 * The default implementation returns always \b true.
104 *
105 * @return \b true if the system supports MultiArch, \b false if not.
106 */
107 bool MultiArchSupported() const;
108 /** architectures supported by this system
109 *
110 * A MultiArch capable system might be configured to use
111 * this capability.
112 *
113 * @return a list of all architectures (native + foreign) configured
114 * for on this system (aka: which can be installed without force)
115 */
116 std::vector<std::string> ArchitecturesSupported() const;
117
118 APT_HIDDEN void SetVersionMapping(map_id_t const in, map_id_t const out);
119 APT_HIDDEN map_id_t GetVersionMapping(map_id_t const in) const;
120
121 pkgSystem(char const * const Label, pkgVersioningSystem * const VS);
122 virtual ~pkgSystem();
123 private:
124 pkgSystemPrivate * const d;
125 };
126
127 // The environment we are operating in.
128 extern pkgSystem *_system;
129
130 #endif