KernelLand/Modules/IPStack/buffer.c

   1 /*
   2  * Acess2 Networking Stack
   3  * - By John Hodge (thePowersGang)
   4  *
   5  * buffer.c
   6  * - Scatter-gather handling
   7  */
   8 #include "ipstack.h"
   9 #include "include/buffer.h"
  10
  11 // === STRUCTURES ===
  12 struct sIPStackBuffer
  13 {
  14          int    MaxSubBufffers;
  15          int    nSubBuffers;
  16         size_t  TotalLength;
  17         tMutex  lBufferLock;
  18
  19         struct _subbuffer
  20         {
  21                 const void      *Data;
  22                 size_t  PreLength;
  23                 size_t  PostLength;
  24                 tIPStackBufferCb        Cb;
  25                 void    *CbArg;
  26                 // TODO: Callbacks?
  27         } SubBuffers[];
  28 };
  29
  30 // === CODE ===
  31 tIPStackBuffer *IPStack_Buffer_CreateBuffer(int MaxBuffers)
  32 {
  33         tIPStackBuffer *ret;
  34
  35         ret = malloc( sizeof(*ret) + MaxBuffers * sizeof(ret->SubBuffers[0]) );
  36         ASSERTR(ret, NULL);
  37         ret->MaxSubBufffers = MaxBuffers;
  38         ret->nSubBuffers = 0;
  39         ret->TotalLength = 0;
  40         memset(&ret->lBufferLock, 0, sizeof(ret->lBufferLock));
  41         memset(ret->SubBuffers, 0, MaxBuffers * sizeof(ret->SubBuffers[0]));
  42         return ret;
  43 }
  44
  45 void IPStack_Buffer_ClearBuffer(tIPStackBuffer *Buffer)
  46 {
  47         ASSERT(Buffer);
  48         IPStack_Buffer_LockBuffer(Buffer);
  49         for( int i = 0; i < Buffer->nSubBuffers; i ++ )
  50         {
  51                 if( Buffer->SubBuffers[i].Cb == NULL )
  52                         continue ;
  53                 Buffer->SubBuffers[i].Cb(
  54                         Buffer->SubBuffers[i].CbArg,
  55                         Buffer->SubBuffers[i].PreLength,
  56                         Buffer->SubBuffers[i].PostLength,
  57                         Buffer->SubBuffers[i].Data
  58                         );
  59         }
  60         Buffer->nSubBuffers = 0;
  61         IPStack_Buffer_UnlockBuffer(Buffer);
  62 }
  63
  64 void IPStack_Buffer_DestroyBuffer(tIPStackBuffer *Buffer)
  65 {
  66         ASSERT(Buffer);
  67         IPStack_Buffer_ClearBuffer(Buffer);
  68         Buffer->MaxSubBufffers = 0;
  69         free(Buffer);
  70 }
  71
  72 void IPStack_Buffer_LockBuffer(tIPStackBuffer *Buffer)
  73 {
  74         ASSERT(Buffer);
  75         Mutex_Acquire(&Buffer->lBufferLock);
  76 }
  77 void IPStack_Buffer_UnlockBuffer(tIPStackBuffer *Buffer)
  78 {
  79         ASSERT(Buffer);
  80         Mutex_Release(&Buffer->lBufferLock);
  81 }
  82
  83 void IPStack_Buffer_AppendSubBuffer(tIPStackBuffer *Buffer,
  84         size_t HeaderLen, size_t FooterLen, const void *Data,
  85         tIPStackBufferCb Cb, void *Arg
  86         )
  87 {
  88         ASSERT(Buffer);
  89         if( Buffer->nSubBuffers == Buffer->MaxSubBufffers ) {
  90                 // Ah, oops?
  91                 Log_Error("IPStack", "Buffer %p only had %i sub-buffers allocated, which was not enough",
  92                         Buffer, Buffer->MaxSubBufffers);
  93                 return ;
  94         }
  95
  96         int index = Buffer->nSubBuffers++;
  97         Buffer->TotalLength += HeaderLen + FooterLen;
  98
  99         Buffer->SubBuffers[index].Data = Data;
 100         Buffer->SubBuffers[index].PreLength = HeaderLen;
 101         Buffer->SubBuffers[index].PostLength = FooterLen;
 102         Buffer->SubBuffers[index].Cb = Cb;
 103         Buffer->SubBuffers[index].CbArg = Arg;
 104 }
 105
 106 size_t IPStack_Buffer_GetLength(tIPStackBuffer *Buffer)
 107 {
 108         ASSERT(Buffer);
 109         return Buffer->TotalLength;
 110 }
 111
 112 size_t IPStack_Buffer_GetData(tIPStackBuffer *Buffer, void *Dest, size_t MaxBytes)
 113 {
 114         ASSERT(Buffer);
 115         Uint8   *dest = Dest;
 116         size_t  rem_space = MaxBytes;
 117         size_t  len;
 118
 119         for( int i = Buffer->nSubBuffers; i -- && rem_space != 0; )
 120         {
 121                 len = MIN(Buffer->SubBuffers[i].PreLength, rem_space);
 122                 memcpy(dest,
 123                         Buffer->SubBuffers[i].Data,
 124                         len
 125                         );
 126                 dest += len;
 127                 rem_space -= len;
 128         }
 129         for( int i = 0; i < Buffer->nSubBuffers && rem_space; i ++ )
 130         {
 131                 if( Buffer->SubBuffers[i].PostLength == 0  )
 132                         continue ;
 133
 134                 len = MIN(Buffer->SubBuffers[i].PostLength, rem_space);
 135                 memcpy(dest,
 136                         (Uint8*)Buffer->SubBuffers[i].Data + Buffer->SubBuffers[i].PreLength,
 137                         len
 138                         );
 139                 dest += len;
 140                 rem_space -= len;
 141         }
 142
 143         return MaxBytes - rem_space;
 144 }
 145
 146 void *IPStack_Buffer_CompactBuffer(tIPStackBuffer *Buffer, size_t *Length)
 147 {
 148         ASSERT(Buffer);
 149         void    *ret = malloc(Buffer->TotalLength);
 150         if(!ret) {
 151                 *Length = 0;
 152                 return NULL;
 153         }
 154
 155         *Length = Buffer->TotalLength;
 156
 157         IPStack_Buffer_GetData(Buffer, ret, Buffer->TotalLength);
 158
 159         return ret;
 160 }
 161
 162 int IPStack_Buffer_GetBuffer(tIPStackBuffer *Buffer, int Index, size_t *Length, const void **DataPtr)
 163 {
 164         ASSERT(Buffer);
 165         if( Index == -1 )       Index = 0;
 166
 167         if( Index >= Buffer->nSubBuffers*2 ) {
 168                 return -1;
 169         }
 170
 171         if( Index >= Buffer->nSubBuffers )
 172         {
 173                 // Appended buffers
 174                 Index -= Buffer->nSubBuffers;
 175
 176                 // Bit of a hack to avoid multiple calls which return a zero length
 177                 while( !Buffer->SubBuffers[Index].PostLength )
 178                 {
 179                         if( Index++ == Buffer->nSubBuffers )
 180                                 return -1;
 181                 }
 182
 183                 if( DataPtr )
 184                         *DataPtr = (Uint8*)Buffer->SubBuffers[Index].Data + Buffer->SubBuffers[Index].PreLength;
 185                 if( Length )
 186                         *Length = Buffer->SubBuffers[Index].PostLength;
 187
 188                 return (Index + 1) + Buffer->nSubBuffers;
 189         }
 190         else
 191         {
 192                  int    rv = Index + 1;
 193                 Index = Buffer->nSubBuffers - Index - 1;
 194                 // Prepended buffers
 195                 if( DataPtr )
 196                         *DataPtr = Buffer->SubBuffers[Index].Data;
 197                 if( Length )
 198                         *Length = Buffer->SubBuffers[Index].PreLength;
 199                 return rv;
 200         }
 201 }
 202