lib/dnslib/flatbuf.c

   1 /*
   2  * COPYRIGHT:   See COPYING in the top level directory
   3  * PROJECT:     ReactOS DNS Shared Library
   4  * FILE:        lib/dnslib/flatbuf.c
   5  * PURPOSE:     Functions for managing the Flat Buffer Implementation (FLATBUF)
   6  */
   7
   8 /* INCLUDES ******************************************************************/
   9 #include "precomp.h"
  10
  11 /* DATA **********************************************************************/
  12
  13 /* FUNCTIONS *****************************************************************/
  14
  15 VOID
  16 WINAPI
  17 FlatBuf_Init(IN PFLATBUFF FlatBuffer,
  18              IN PVOID Buffer,
  19              IN SIZE_T Size)
  20 {
  21     /* Set up the Flat Buffer start, current and ending position */
  22     FlatBuffer->Buffer = Buffer;
  23     FlatBuffer->BufferPos = (ULONG_PTR)Buffer;
  24     FlatBuffer->BufferEnd = (PVOID)(FlatBuffer->BufferPos + Size);
  25
  26     /* Setup the current size and the available size */
  27     FlatBuffer->BufferSize = FlatBuffer->BufferFreeSize = Size;
  28 }
  29
  30 PVOID
  31 WINAPI
  32 FlatBuf_Arg_Reserve(IN OUT PULONG_PTR Position,
  33                     IN OUT PSIZE_T FreeSize,
  34                     IN SIZE_T Size,
  35                     IN ULONG Align)
  36 {
  37     ULONG_PTR NewPosition, OldPosition = *Position;
  38     SIZE_T NewFreeSize = *FreeSize;
  39
  40     /* Start by aligning our position */
  41     if (Align) OldPosition += (Align - 1) & ~Align;
  42
  43     /* Update it */
  44     NewPosition = OldPosition + Size;
  45
  46     /* Update Free Size */
  47     NewFreeSize += (OldPosition - NewPosition);
  48
  49     /* Save new values */
  50     *Position = NewPosition;
  51     *FreeSize = NewFreeSize;
  52
  53     /* Check if we're out of space or not */
  54     if (NewFreeSize > 0) return (PVOID)OldPosition;
  55     return NULL;
  56 }
  57
  58 PVOID
  59 WINAPI
  60 FlatBuf_Arg_CopyMemory(IN OUT PULONG_PTR Position,
  61                        IN OUT PSIZE_T FreeSize,
  62                        IN PVOID Buffer,
  63                        IN SIZE_T Size,
  64                        IN ULONG Align)
  65 {
  66     PVOID Destination;
  67
  68     /* First reserve the memory */
  69     Destination = FlatBuf_Arg_Reserve(Position, FreeSize, Size, Align);
  70     if (Destination)
  71     {
  72         /* We have space, do the copy */
  73         RtlCopyMemory(Destination, Buffer, Size);
  74     }
  75
  76     /* Return the pointer to the data */
  77     return Destination;
  78 }
  79
  80 PVOID
  81 WINAPI
  82 FlatBuf_Arg_WriteString(IN OUT PULONG_PTR Position,
  83                         IN OUT PSIZE_T FreeSize,
  84                         IN PVOID String,
  85                         IN BOOLEAN IsUnicode)
  86 {
  87     PVOID Destination;
  88     SIZE_T StringLength;
  89     ULONG Align;
  90
  91     /* Calculate the string length */
  92     if (IsUnicode)
  93     {
  94         /* Get the length in bytes and use WCHAR alignment */
  95         StringLength = (wcslen((LPWSTR)String) + 1) * sizeof(WCHAR);
  96         Align = sizeof(WCHAR);
  97     }
  98     else
  99     {
 100         /* Get the length in bytes and use CHAR alignment */
 101         StringLength = strlen((LPSTR)String) + 1;
 102         Align = sizeof(CHAR);
 103     }
 104
 105     /* Now reserve the memory */
 106     Destination = FlatBuf_Arg_Reserve(Position, FreeSize, StringLength, Align);
 107     if (Destination)
 108     {
 109         /* We have space, do the copy */
 110         RtlCopyMemory(Destination, String, StringLength);
 111     }
 112
 113     /* Return the pointer to the data */
 114     return Destination;
 115 }
 116