reactos/win32ss/printing/base/spoolss/tools.c

   1 /*
   2  * PROJECT:     ReactOS Spooler Router
   3  * LICENSE:     GNU LGPL v2.1 or any later version as published by the Free Software Foundation
   4  * PURPOSE:     Miscellaneous tool functions
   5  * COPYRIGHT:   Copyright 2015 Colin Finck <colin@reactos.org>
   6  */
   7
   8 #include "precomp.h"
   9
  10
  11 /**
  12  * @name PackStrings
  13  *
  14  * Takes an array of Unicode strings and fills an output buffer with these strings at the end and pointers to each string at specific offsets.
  15  * Useful helper for functions that copy an information structure including strings into a given buffer (like PRINTER_INFO_1).
  16  *
  17  * @param pSource
  18  * The array of Unicode strings to copy. Needs to have at least as many elements as the DestOffsets array.
  19  *
  20  * @param pDest
  21  * Pointer to the beginning of the output buffer.
  22  * The caller is responsible for verifying that this buffer is large enough to hold all strings and pointers.
  23  *
  24  * @param DestOffsets
  25  * Array of byte offsets in the output buffer. For each element of DestOffsets, the function will copy the address of the corresponding copied
  26  * string of pSource to this location in the output buffer. If a string in pSource is NULL, the function will set the pointer address to NULL
  27  * in the output buffer.
  28  * Use macros like FIELD_OFFSET to calculate the offsets for this array.
  29  * The last element of the array must have the value MAXDWORD to let the function detect the end of the array.
  30  *
  31  * @param pEnd
  32  * Pointer to the end of the output buffer. That means the first element outside of the buffer given in pDest.
  33  *
  34  * @return
  35  * Returns a pointer to the beginning of the strings in pDest.
  36  * The strings are copied in reverse order, so this pointer will point to the last copied string of pSource.
  37  */
  38 PBYTE WINAPI
  39 PackStrings(PCWSTR* pSource, PBYTE pDest, PDWORD DestOffsets, PBYTE pEnd)
  40 {
  41     DWORD cbString;
  42     ULONG_PTR StringAddress;
  43
  44     // Loop until we reach an element with offset set to MAXDWORD.
  45     while (*DestOffsets != MAXDWORD)
  46     {
  47         StringAddress = 0;
  48
  49         if (*pSource)
  50         {
  51             // Determine the length of the source string.
  52             cbString = (wcslen(*pSource) + 1) * sizeof(WCHAR);
  53
  54             // Copy it before the last string.
  55             pEnd -= cbString;
  56             StringAddress = (ULONG_PTR)pEnd;
  57             CopyMemory(pEnd, *pSource, cbString);
  58         }
  59
  60         // Copy the address of the copied string to the location given by the offset.
  61         CopyMemory(&pDest[*DestOffsets], &StringAddress, sizeof(ULONG_PTR));
  62
  63         // Advance to the next source string and destination offset.
  64         pSource++;
  65         DestOffsets++;
  66     }
  67
  68     // pEnd is now at the last string we copied. Return this value as a pointer to the beginning of all strings in the output buffer.
  69     return pEnd;
  70 }