reactos/win32ss/printing/base/spoolss/monitors.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:     Functions related to Print Monitors
   5  * COPYRIGHT:   Copyright 2015 Colin Finck <colin@reactos.org>
   6  */
   7
   8 #include "precomp.h"
   9
  10 BOOL WINAPI
  11 EnumMonitorsW(PWSTR pName, DWORD Level, PBYTE pMonitors, DWORD cbBuf, PDWORD pcbNeeded, PDWORD pcReturned)
  12 {
  13     BOOL bReturnValue;
  14     DWORD cbCallBuffer;
  15     DWORD cbNeeded;
  16     DWORD dwReturned;
  17     PBYTE pCallBuffer;
  18     PSPOOLSS_PRINT_PROVIDER pPrintProvider;
  19     PLIST_ENTRY pEntry;
  20
  21     // Sanity checks.
  22     if ((cbBuf && !pMonitors) || !pcbNeeded || !pcReturned)
  23     {
  24         SetLastError(ERROR_INVALID_PARAMETER);
  25         return FALSE;
  26     }
  27
  28     // Begin counting.
  29     *pcbNeeded = 0;
  30     *pcReturned = 0;
  31
  32     // At the beginning, we have the full buffer available.
  33     cbCallBuffer = cbBuf;
  34     pCallBuffer = pMonitors;
  35
  36     // Loop through all Print Provider.
  37     for (pEntry = PrintProviderList.Flink; pEntry != &PrintProviderList; pEntry = pEntry->Flink)
  38     {
  39         pPrintProvider = CONTAINING_RECORD(pEntry, SPOOLSS_PRINT_PROVIDER, Entry);
  40
  41         // Check if this Print Provider provides an EnumMonitors function.
  42         if (!pPrintProvider->PrintProvider.fpEnumMonitors)
  43             continue;
  44
  45         // Call the EnumMonitors function of this Print Provider.
  46         bReturnValue = pPrintProvider->PrintProvider.fpEnumMonitors(pName, Level, pCallBuffer, cbCallBuffer, &cbNeeded, &dwReturned);
  47
  48         // Add the returned counts to the total values.
  49         *pcbNeeded += cbNeeded;
  50         *pcReturned += dwReturned;
  51
  52         // Reduce the available buffer size for the next call without risking an underflow.
  53         if (cbNeeded < cbCallBuffer)
  54             cbCallBuffer -= cbNeeded;
  55         else
  56             cbCallBuffer = 0;
  57
  58         // Advance the buffer if the caller provided it.
  59         if (pCallBuffer)
  60             pCallBuffer += cbNeeded;
  61
  62         // Check if we shall not ask other Print Providers.
  63         if (bReturnValue == ROUTER_STOP_ROUTING)
  64             break;
  65     }
  66
  67     return bReturnValue;
  68 }