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 MarshallDownStructure
  13  *
  14  * Prepare a structure for marshalling/serialization by replacing absolute pointer addresses in its fields by relative offsets.
  15  *
  16  * @param pStructure
  17  * Pointer to the structure to operate on.
  18  *
  19  * @param pParameters
  20  * Array of MARSHALL_DOWN_INFO elements containing information about the fields of the structure as well as how to modify them.
  21  * See the documentation on MARSHALL_DOWN_INFO for more information.
  22  * You have to indicate the end of the array by setting the dwOffset field to MAXDWORD.
  23  *
  24  * @param cbStructureSize
  25  * Apparently, this is the size in bytes of the structure given through pStructure under Windows.
  26  * This parameter is unused in my implementation.
  27  *
  28  * @param bSomeBoolean
  29  * Unknown boolean value
  30  *
  31  * @return
  32  * TRUE if the structure was successfully adjusted, FALSE otherwise.
  33  */
  34 BOOL WINAPI
  35 MarshallDownStructure(PVOID pStructure, PMARSHALL_DOWN_INFO pParameters, DWORD cbStructureSize, BOOL bSomeBoolean)
  36 {
  37     // Sanity checks
  38     if (!pStructure || !pParameters)
  39     {
  40         SetLastError(ERROR_INVALID_PARAMETER);
  41         return FALSE;
  42     }
  43
  44     // Loop until we reach an element with offset set to MAXDWORD.
  45     while (pParameters->dwOffset != MAXDWORD)
  46     {
  47         if (pParameters->bAdjustAddress)
  48         {
  49             // Apply the byte offset on pStructure. There must be a pointer at this position, whose address we're adjusting
  50             // by subtracting the address of pStructure from it.
  51             *((PULONG_PTR)((PBYTE)pStructure + pParameters->dwOffset)) -= (ULONG_PTR)pStructure;
  52         }
  53
  54         // Advance to the next element description.
  55         pParameters++;
  56     }
  57
  58     return TRUE;
  59 }
  60
  61 /**
  62  * @name PackStrings
  63  *
  64  * 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.
  65  * Useful helper for functions that copy an information structure including strings into a given buffer (like PRINTER_INFO_1).
  66  *
  67  * @param pSource
  68  * The array of Unicode strings to copy. Needs to have at least as many elements as the DestOffsets array.
  69  *
  70  * @param pDest
  71  * Pointer to the beginning of the output buffer.
  72  * The caller is responsible for verifying that this buffer is large enough to hold all strings and pointers.
  73  *
  74  * @param DestOffsets
  75  * Array of byte offsets in the output buffer. For each element of DestOffsets, the function will copy the address of the corresponding copied
  76  * 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
  77  * in the output buffer.
  78  * Use macros like FIELD_OFFSET to calculate the offsets for this array.
  79  * The last element of the array must have the value MAXDWORD to let the function detect the end of the array.
  80  *
  81  * @param pEnd
  82  * Pointer to the end of the output buffer. That means the first element outside of the buffer given in pDest.
  83  *
  84  * @return
  85  * Returns a pointer to the beginning of the strings in pDest.
  86  * The strings are copied in reverse order, so this pointer will point to the last copied string of pSource.
  87  */
  88 PBYTE WINAPI
  89 PackStrings(PCWSTR* pSource, PBYTE pDest, PDWORD DestOffsets, PBYTE pEnd)
  90 {
  91     DWORD cbString;
  92     ULONG_PTR StringAddress;
  93
  94     // Loop until we reach an element with offset set to MAXDWORD.
  95     while (*DestOffsets != MAXDWORD)
  96     {
  97         StringAddress = 0;
  98
  99         if (*pSource)
 100         {
 101             // Determine the length of the source string.
 102             cbString = (wcslen(*pSource) + 1) * sizeof(WCHAR);
 103
 104             // Copy it before the last string.
 105             pEnd -= cbString;
 106             StringAddress = (ULONG_PTR)pEnd;
 107             CopyMemory(pEnd, *pSource, cbString);
 108         }
 109
 110         // Copy the address of the copied string to the location given by the offset.
 111         CopyMemory(&pDest[*DestOffsets], &StringAddress, sizeof(ULONG_PTR));
 112
 113         // Advance to the next source string and destination offset.
 114         pSource++;
 115         DestOffsets++;
 116     }
 117
 118     // 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.
 119     return pEnd;
 120 }