apt-pkg/contrib/mmap.h

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: mmap.h,v 1.7 1998/11/12 03:14:40 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 enviroments 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 effecient 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 // Header section: pkglib
  26 #ifndef PKGLIB_MMAP_H
  27 #define PKGLIB_MMAP_H
  28
  29 #ifdef __GNUG__
  30 #pragma interface "apt-pkg/mmap.h"
  31 #endif
  32
  33 #include <string>
  34 #include <apt-pkg/fileutl.h>
  35
  36 class MMap
  37 {
  38    protected:
  39
  40    FileFd &Fd;
  41    unsigned long Flags;
  42    unsigned long iSize;
  43    void *Base;
  44
  45    bool Map();
  46    bool Close(bool DoClose = true,bool DoSync = true);
  47
  48    public:
  49
  50    enum OpenFlags {NoImmMap = (1<<0),Public = (1<<1),ReadOnly = (1<<2)};
  51
  52    // Simple accessors
  53    inline operator void *() {return Base;};
  54    inline void *Data() {return Base;};
  55    inline unsigned long Size() {return iSize;};
  56
  57    // File manipulators
  58    bool Sync();
  59    bool Sync(unsigned long Start,unsigned long Stop);
  60
  61    MMap(FileFd &F,unsigned long Flags);
  62    virtual ~MMap();
  63 };
  64
  65 class DynamicMMap : public MMap
  66 {
  67    public:
  68
  69    // This is the allocation pool structure
  70    struct Pool
  71    {
  72       unsigned long ItemSize;
  73       unsigned long Start;
  74       unsigned long Count;
  75    };
  76
  77    protected:
  78
  79    unsigned long WorkSpace;
  80    Pool *Pools;
  81    unsigned int PoolCount;
  82
  83    public:
  84
  85    // Allocation
  86    unsigned long RawAllocate(unsigned long Size,unsigned long Aln = 0);
  87    unsigned long Allocate(unsigned long ItemSize);
  88    unsigned long WriteString(const char *String,unsigned long Len = 0);
  89    inline unsigned long WriteString(string S) {return WriteString(S.begin(),S.size());};
  90    void UsePools(Pool &P,unsigned int Count) {Pools = &P; PoolCount = Count;};
  91
  92    DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace = 2*1024*1024);
  93    virtual ~DynamicMMap();
  94 };
  95
  96 #endif