apt-pkg/contrib/mmap.h

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: mmap.h,v 1.12 2001/05/14 05:16:43 jgg Exp $
   4 /* ######################################################################
   5
   6    MMap Class - Provides 'real' mmap or a faked mmap using read().
   7
   8    The purpose of this code is to provide a generic way for clients to
   9    access the mmap function. In environments that do not support mmap
  10    from file fd's this function will use read and normal allocated
  11    memory.
  12
  13    Writing to a public mmap will always fully comit all changes when the
  14    class is deleted. Ie it will rewrite the file, unless it is readonly
  15
  16    The DynamicMMap class is used to help the on-disk data structure
  17    generators. It provides a large allocated workspace and members
  18    to allocate space from the workspace in an efficient fashion.
  19
  20    This source is placed in the Public Domain, do with it what you will
  21    It was originally written by Jason Gunthorpe.
  22
  23    ##################################################################### */
  24                                                                         /*}}}*/
  25 #ifndef PKGLIB_MMAP_H
  26 #define PKGLIB_MMAP_H
  27
  28
  29 #include <string>
  30
  31 #ifndef APT_8_CLEANER_HEADERS
  32 #include <apt-pkg/fileutl.h>
  33 using std::string;
  34 #endif
  35
  36 class FileFd;
  37
  38 /* This should be a 32 bit type, larger tyes use too much ram and smaller
  39    types are too small. Where ever possible 'unsigned long' should be used
  40    instead of this internal type */
  41 typedef unsigned int map_ptrloc;
  42
  43 class MMap
  44 {
  45    protected:
  46
  47    unsigned long Flags;
  48    unsigned long long iSize;
  49    void *Base;
  50
  51    // In case mmap can not be used, we keep a dup of the file
  52    // descriptor that should have been mmaped so that we can write to
  53    // the file in Sync().
  54    FileFd *SyncToFd;
  55
  56    bool Map(FileFd &Fd);
  57    bool Close(bool DoSync = true);
  58
  59    public:
  60
  61    enum OpenFlags {Public = (1<<1),ReadOnly = (1<<2),
  62                    UnMapped = (1<<3), Moveable = (1<<4), Fallback = (1 << 5)};
  63
  64    // Simple accessors
  65    inline operator void *() {return Base;};
  66    inline void *Data() {return Base;};
  67    inline unsigned long long Size() {return iSize;};
  68    inline void AddSize(unsigned long long const size) {iSize += size;};
  69    inline bool validData() const { return Base != (void *)-1 && Base != 0; };
  70
  71    // File manipulators
  72    bool Sync();
  73    bool Sync(unsigned long Start,unsigned long Stop);
  74
  75    MMap(FileFd &F,unsigned long Flags);
  76    MMap(unsigned long Flags);
  77    virtual ~MMap();
  78 };
  79
  80 class DynamicMMap : public MMap
  81 {
  82    public:
  83
  84    // This is the allocation pool structure
  85    struct Pool
  86    {
  87       unsigned long ItemSize;
  88       unsigned long Start;
  89       unsigned long Count;
  90    };
  91
  92    protected:
  93
  94    FileFd *Fd;
  95    unsigned long WorkSpace;
  96    unsigned long const GrowFactor;
  97    unsigned long const Limit;
  98    Pool *Pools;
  99    unsigned int PoolCount;
 100
 101    bool Grow();
 102
 103    public:
 104
 105    // Allocation
 106    unsigned long RawAllocate(unsigned long long Size,unsigned long Aln = 0);
 107    unsigned long Allocate(unsigned long ItemSize);
 108    unsigned long WriteString(const char *String,unsigned long Len = (unsigned long)-1);
 109    inline unsigned long WriteString(const std::string &S) {return WriteString(S.c_str(),S.length());};
 110    void UsePools(Pool &P,unsigned int Count) {Pools = &P; PoolCount = Count;};
 111
 112    DynamicMMap(FileFd &F,unsigned long Flags,unsigned long const &WorkSpace = 2*1024*1024,
 113                unsigned long const &Grow = 1024*1024, unsigned long const &Limit = 0);
 114    DynamicMMap(unsigned long Flags,unsigned long const &WorkSpace = 2*1024*1024,
 115                unsigned long const &Grow = 1024*1024, unsigned long const &Limit = 0);
 116    virtual ~DynamicMMap();
 117 };
 118
 119 #endif