apt-pkg/contrib/mmap.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: mmap.cc,v 1.1 1998/07/02 02:58:13 jgg Exp $
   4 /* ######################################################################
   5
   6    MMap Class - Provides 'real' mmap or a faked mmap using read().
   7
   8    MMap cover class.
   9
  10    Some broken versions of glibc2 (libc6) have a broken definition
  11    of mmap that accepts a char * -- all other systems (and libc5) use
  12    void *. We can't safely do anything here that would be portable, so
  13    libc6 generates warnings -- which should be errors, g++ isn't properly
  14    strict.
  15
  16    The configure test notes that some OS's have broken private mmap's
  17    so on those OS's we can't use mmap. This means we have to use
  18    configure to test mmap and can't rely on the POSIX
  19    _POSIX_MAPPED_FILES test.
  20
  21    ##################################################################### */
  22                                                                         /*}}}*/
  23 // Include Files                                                        /*{{{*/
  24 #define _BSD_SOURCE
  25 #include <pkglib/mmap.h>
  26 #include <pkglib/error.h>
  27
  28 #include <sys/mman.h>
  29 #include <sys/stat.h>
  30 #include <sys/user.h>
  31 #include <unistd.h>
  32 #include <fcntl.h>
  33                                                                         /*}}}*/
  34
  35 // MMap::MMap - Constructor                                             /*{{{*/
  36 // ---------------------------------------------------------------------
  37 /* */
  38 MMap::MMap(File &F,unsigned long Flags) : Fd(F), Flags(Flags), iSize(0),
  39                      Base(0)
  40 {
  41    if ((Flags & NoImmMap) != NoImmMap)
  42       Map();
  43 }
  44                                                                         /*}}}*/
  45 // MMap::~MMap - Destructor                                             /*{{{*/
  46 // ---------------------------------------------------------------------
  47 /* */
  48 MMap::~MMap()
  49 {
  50    Close(true);
  51 }
  52                                                                         /*}}}*/
  53 // MMap::Map - Perform the mapping                                      /*{{{*/
  54 // ---------------------------------------------------------------------
  55 /* */
  56 bool MMap::Map()
  57 {
  58    iSize = Fd.Size();
  59
  60    // Set the permissions.
  61    int Prot = PROT_READ;
  62    int Map = MAP_SHARED;
  63    if ((Flags & ReadOnly) != ReadOnly)
  64       Prot |= PROT_WRITE;
  65    if ((Flags & Public) != Public)
  66       Map = MAP_PRIVATE;
  67
  68    // Map it.
  69    Base = mmap(0,iSize,Prot,Map,Fd.Fd(),0);
  70    if (Base == (void *)-1)
  71       return _error->Errno("mmap","Couldn't make mmap of %u bytes",iSize);
  72
  73    return true;
  74 }
  75                                                                         /*}}}*/
  76 // MMap::Close - Close the map                                          /*{{{*/
  77 // ---------------------------------------------------------------------
  78 /* */
  79 bool MMap::Close(bool DoClose)
  80 {
  81    if (Fd.IsOpen() == false)
  82       return true;
  83
  84    Sync();
  85
  86    if (munmap((char *)Base,iSize) != 0)
  87       _error->Warning("Unable to munmap");
  88
  89    iSize = 0;
  90    if (DoClose == true)
  91       Fd.Close();
  92    return true;
  93 }
  94                                                                         /*}}}*/
  95 // MMap::Sync - Syncronize the map with the disk                        /*{{{*/
  96 // ---------------------------------------------------------------------
  97 /* */
  98 bool MMap::Sync()
  99 {
 100    if ((Flags & ReadOnly) == ReadOnly)
 101       if (msync((char *)Base,iSize,MS_SYNC) != 0)
 102          return _error->Error("msync","Unable to write mmap");
 103    return true;
 104 }
 105                                                                         /*}}}*/
 106 // MMap::Sync - Syncronize a section of the file to disk                /*{{{*/
 107 // ---------------------------------------------------------------------
 108 /* */
 109 bool MMap::Sync(unsigned long Start,unsigned long Stop)
 110 {
 111    if ((Flags & ReadOnly) == ReadOnly)
 112       if (msync((char *)Base+(int)(Start/PAGE_SIZE)*PAGE_SIZE,Stop - Start,MS_SYNC) != 0)
 113          return _error->Error("msync","Unable to write mmap");
 114    return true;
 115 }
 116                                                                         /*}}}*/
 117
 118 // DynamicMMap::DynamicMMap - Constructor                               /*{{{*/
 119 // ---------------------------------------------------------------------
 120 /* */
 121 DynamicMMap::DynamicMMap(File &F,unsigned long Flags,unsigned long WorkSpace) :
 122              MMap(F,Flags | NoImmMap), WorkSpace(WorkSpace)
 123 {
 124    unsigned long EndOfFile = Fd.Size();
 125    Fd.Seek(WorkSpace);
 126    char C = 0;
 127    Fd.Write(&C,sizeof(C));
 128    Map();
 129    iSize = EndOfFile;
 130 }
 131                                                                         /*}}}*/
 132 // DynamicMMap::~DynamicMMap - Destructor                               /*{{{*/
 133 // ---------------------------------------------------------------------
 134 /* We truncate the file to the size of the memory data set */
 135 DynamicMMap::~DynamicMMap()
 136 {
 137    unsigned long EndOfFile = iSize;
 138    Close(false);
 139    ftruncate(Fd.Fd(),EndOfFile);
 140    Fd.Close();
 141 }
 142                                                                         /*}}}*/
 143 // DynamicMMap::RawAllocate - Allocate a raw chunk of unaligned space   /*{{{*/
 144 // ---------------------------------------------------------------------
 145 /* */
 146 unsigned long DynamicMMap::RawAllocate(unsigned long Size)
 147 {
 148    unsigned long Result = iSize;
 149    iSize += Size;
 150
 151    // Just in case error check
 152    if (Result > WorkSpace)
 153    {
 154       _error->Error("Dynamic MMap ran out of room");
 155       return 0;
 156    }
 157
 158    return Result;
 159 }
 160                                                                         /*}}}*/
 161 // DynamicMMap::Allocate - Pooled aligned allocation                    /*{{{*/
 162 // ---------------------------------------------------------------------
 163 /* This allocates an Item of size ItemSize so that it is aligned to its
 164    size in the file. */
 165 unsigned long DynamicMMap::Allocate(unsigned long ItemSize)
 166 {
 167    // Look for a matching pool entry
 168    Pool *I;
 169    Pool *Empty = 0;
 170    for (I = Pools; I != Pools + PoolCount; I++)
 171    {
 172       if (I->ItemSize == 0)
 173          Empty = I;
 174       if (I->ItemSize == ItemSize)
 175          break;
 176    }
 177
 178    // No pool is allocated, use an unallocated one
 179    if (I == Pools + PoolCount)
 180    {
 181       // Woops, we ran out, the calling code should allocate more.
 182       if (Empty == 0)
 183       {
 184          _error->Error("Ran out of allocation pools");
 185          return 0;
 186       }
 187
 188       I = Empty;
 189       I->ItemSize = ItemSize;
 190       I->Count = 0;
 191    }
 192
 193    // Out of space, allocate some more
 194    if (I->Count == 0)
 195    {
 196       I->Count = 20*1024/ItemSize;
 197       I->Start = RawAllocate(I->Count*ItemSize);
 198    }
 199
 200    I->Count--;
 201    unsigned long Result = I->Start;
 202    I->Start += ItemSize;
 203    return Result/ItemSize;
 204 }
 205                                                                         /*}}}*/
 206 // DynamicMMap::WriteString - Write a string to the file                /*{{{*/
 207 // ---------------------------------------------------------------------
 208 /* Strings are not aligned to anything */
 209 unsigned long DynamicMMap::WriteString(const char *String,
 210                                        unsigned long Len)
 211 {
 212    unsigned long Result = iSize;
 213    // Just in case error check
 214    if (Result > WorkSpace)
 215    {
 216       _error->Error("Dynamic MMap ran out of room");
 217       return 0;
 218    }
 219
 220    if (Len == 0)
 221       Len = strlen(String);
 222    iSize += Len + 1;
 223    memcpy((char *)Base + Result,String,Len);
 224    ((char *)Base)[Result + Len] = 0;
 225    return Result;
 226 }
 227                                                                         /*}}}*/