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+// -*- mode: cpp; mode: fold -*-
+// Description /*{{{*/
+/* ######################################################################
+
+ System - Abstraction for running on different systems.
+
+ Instances of this class can be thought of as factories or meta-classes
+ for a variety of more specialized classes. Together this class and
+ it's specialized offspring completely define the environment and how
+ to access resources for a specific system. There are several sub
+ areas that are all orthogonal - each system has a unique combination of
+ these sub areas:
+ - Versioning. Different systems have different ideas on versions.
+ Within a system all sub classes must follow the same versioning
+ rules.
+ - Local tool locking to prevent multiple tools from accessing the
+ same database.
+ - Candidate Version selection policy - this is probably almost always
+ managed using a standard APT class
+ - Actual Package installation
+ * Indication of what kind of binary formats are supported
+ - Selection of local 'status' indexes that make up the pkgCache.
+
+ It is important to note that the handling of index files is not a
+ function of the system. Index files are handled through a separate
+ abstraction - the only requirement is that the index files have the
+ same idea of versioning as the target system.
+
+ Upon startup each supported system instantiates an instance of the
+ pkgSystem class (using a global constructor) which will make itself
+ available to the main APT init routine. That routine will select the
+ proper system and make it the global default.
+
+ ##################################################################### */
+ /*}}}*/
+#ifndef PKGLIB_PKGSYSTEM_H
+#define PKGLIB_PKGSYSTEM_H
+
+#include <apt-pkg/pkgcache.h>
+
+#include <vector>
+
+
+class pkgDepCache;
+class pkgPackageManager;
+class pkgVersioningSystem;
+class Configuration;
+class pkgIndexFile;
+class OpProgress;
+
+class pkgSystemPrivate;
+class APT_PUBLIC pkgSystem
+{
+ public:
+
+ // Global list of supported systems
+ static pkgSystem **GlobalList;
+ static unsigned long GlobalListLen;
+ static pkgSystem *GetSystem(const char *Label);
+
+ const char * const Label;
+ pkgVersioningSystem * const VS;
+
+ /* Prevent other programs from touching shared data not covered by
+ other locks (cache or state locks) */
+ virtual bool Lock(OpProgress *const Progress = nullptr) = 0;
+ virtual bool UnLock(bool NoErrors = false) = 0;
+
+ /* Various helper classes to interface with specific bits of this
+ environment */
+ virtual pkgPackageManager *CreatePM(pkgDepCache *Cache) const = 0;
+
+ /* Load environment specific configuration and perform any other setup
+ necessary */
+ virtual bool Initialize(Configuration &/*Cnf*/) {return true;};
+
+ /* Type is some kind of Globally Unique way of differentiating
+ archive file types.. */
+ virtual bool ArchiveSupported(const char *Type) = 0;
+
+ // Return a list of system index files..
+ virtual bool AddStatusFiles(std::vector<pkgIndexFile *> &List) = 0;
+
+ virtual bool FindIndex(pkgCache::PkgFileIterator File,
+ pkgIndexFile *&Found) const = 0;
+
+ /* Evaluate how 'right' we are for this system based on the filesystem
+ etc.. */
+ virtual signed Score(Configuration const &/*Cnf*/) {
+ return 0;
+ };
+
+ //FIXME: these methods should be virtual
+ /** does this system has support for MultiArch?
+ *
+ * Systems supporting only single arch (not systems which are single arch)
+ * are considered legacy systems and support for it will likely degrade over
+ * time.
+ *
+ * The default implementation returns always \b true.
+ *
+ * @return \b true if the system supports MultiArch, \b false if not.
+ */
+ virtual bool MultiArchSupported() const = 0;
+ /** architectures supported by this system
+ *
+ * A MultiArch capable system might be configured to use
+ * this capability.
+ *
+ * @return a list of all architectures (native + foreign) configured
+ * for on this system (aka: which can be installed without force)
+ */
+ virtual std::vector<std::string> ArchitecturesSupported() const = 0;
+
+ APT_HIDDEN void SetVersionMapping(map_id_t const in, map_id_t const out);
+ APT_HIDDEN map_id_t GetVersionMapping(map_id_t const in) const;
+
+ pkgSystem(char const * const Label, pkgVersioningSystem * const VS);
+ virtual ~pkgSystem();
+
+
+ /* companions to Lock()/UnLock
+ *
+ * These functions can be called prior to calling dpkg to release an inner
+ * lock without releasing the overall outer lock, so that dpkg can run
+ * correctly but no other APT instance can acquire the system lock.
+ */
+ virtual bool LockInner(OpProgress *const Progress = 0, int timeOutSec = 0) = 0;
+ virtual bool UnLockInner(bool NoErrors = false) = 0;
+ /// checks if the system is currently locked
+ virtual bool IsLocked() = 0;
+ private:
+ pkgSystemPrivate * const d;
+};
+
+// The environment we are operating in.
+APT_PUBLIC extern pkgSystem *_system;
+
+#endif