295 lines
9.0 KiB
C++
295 lines
9.0 KiB
C++
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/*++
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Copyright (c) 2000-2001 Microsoft Corporation
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Module Name:
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PrinterGetPrtL2.cpp
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Abstract:
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This is a shim that can be applied to those applications who
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assumed false upper-limit on the size of PRINTER_INFO_2 buffer
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GetPrinter returns. What the shim does is that when it detects
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the spooler returned PRINTER_INFO_2 buffer is over a certain
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limit that could break those apps, it truncates the private
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devmode part in PRINTER_INFO_2's pDevMode to retain only the
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public devmode, and returns the truncated PRINTER_INFO_2 buffer.
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History:
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10/29/2001 fengy Created
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--*/
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#include "precomp.h"
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#include <stddef.h>
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IMPLEMENT_SHIM_BEGIN(PrinterGetPrtL2)
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#include "ShimHookMacro.h"
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APIHOOK_ENUM_BEGIN
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APIHOOK_ENUM_ENTRY(GetPrinterA)
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APIHOOK_ENUM_END
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#define ALIGN_PTR_UP(addr) ((ULONG_PTR)((ULONG_PTR)(addr) + (sizeof(ULONG_PTR) - 1)) & ~(sizeof(ULONG_PTR) - 1))
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//
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// The PRINTER_INFO_2 buffer size limit over which this shim
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// will perform the devmode truncation. The default value is
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// set to 8K here. App-specific limit values can be specified
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// as decimal numbers in the XML database as following:
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//
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// <SHIM NAME="PrinterGetPrtL2" COMMAND_LINE="1024"/>
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//
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LONG g_lTruncateLimit = 0x2000;
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//
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// Table of offsets to each string field in PRINTER_INFO_2A
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//
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DWORD g_dwStringOffsets[] = {offsetof(PRINTER_INFO_2A, pServerName),
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offsetof(PRINTER_INFO_2A, pPrinterName),
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offsetof(PRINTER_INFO_2A, pShareName),
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offsetof(PRINTER_INFO_2A, pPortName),
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offsetof(PRINTER_INFO_2A, pDriverName),
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offsetof(PRINTER_INFO_2A, pComment),
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offsetof(PRINTER_INFO_2A, pLocation),
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offsetof(PRINTER_INFO_2A, pSepFile),
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offsetof(PRINTER_INFO_2A, pPrintProcessor),
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offsetof(PRINTER_INFO_2A, pDatatype),
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offsetof(PRINTER_INFO_2A, pParameters),
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0xFFFFFFFF};
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/*++
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This stub function intercepts all level 2 calls to GetPrinterA and detects
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if the spooler returned PRINTER_INFO_2 buffer is over the app limit. If so,
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it will truncate the private devmode of PRINTER_INFO_2's pDevMode.
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--*/
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BOOL
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APIHOOK(GetPrinterA)(
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HANDLE hPrinter,
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DWORD Level,
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LPBYTE pPrinter,
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DWORD cbBuf,
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LPDWORD pcbNeeded
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)
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{
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BOOL bNoTruncation = TRUE;
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BOOL bRet;
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if (Level == 2 && pPrinter != NULL && cbBuf != 0)
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{
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PRINTER_INFO_2A *pInfo2Full = NULL;
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DWORD cbFullNeeded = 0;
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//
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// Call spooler to get the full PRINTER_INFO_2 buffer size
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//
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bRet = ORIGINAL_API(GetPrinterA)(
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hPrinter,
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2,
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NULL,
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0,
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&cbFullNeeded);
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if (!bRet &&
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GetLastError() == ERROR_INSUFFICIENT_BUFFER &&
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cbFullNeeded > (DWORD)g_lTruncateLimit &&
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cbBuf >= cbFullNeeded &&
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(pInfo2Full = (PRINTER_INFO_2A *)malloc(cbFullNeeded)))
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{
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//
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// The full PRINTER_INFO_2 buffer size is over the app limit,
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// so we will first retrieve the full buffer into our internal
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// buffer.
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//
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// The condition "cbBuf >= cbFullNeeded" is here because if
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// that's not true, the original GetPrinterA's behavior is to
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// fail the call. We don't want to change that behavior.
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//
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bRet = ORIGINAL_API(GetPrinterA)(
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hPrinter,
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2,
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(PBYTE)pInfo2Full,
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cbFullNeeded,
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&cbFullNeeded);
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if (bRet)
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{
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PRINTER_INFO_2A *pInfo2In;
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PBYTE pDest;
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INT i;
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//
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// Having the full PRINTER_INFO_2 structure in our internal
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// buffer, now we will copy it into app-allocated output buffer
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// by duplicating every thing except for the pDevMode. For
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// pDevMode we will only copy over the public devmode part,
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// because the bigger size of PRINTER_INFO_2 structure usually
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// are caused by big private devmode.
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//
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pInfo2In = (PRINTER_INFO_2A *)pPrinter;
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pDest = (PBYTE)pInfo2In + sizeof(PRINTER_INFO_2A);
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//
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// First copy over all the strings
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//
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i = 0;
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while (g_dwStringOffsets[i] != (-1))
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{
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PSTR pSrc;
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pSrc = *(PSTR *)((PBYTE)pInfo2Full + g_dwStringOffsets[i]);
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if (pSrc)
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{
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DWORD cbStrSize;
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cbStrSize = strlen(pSrc) + sizeof(CHAR);
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memcpy(pDest, pSrc, cbStrSize);
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*(PSTR *)((PBYTE)pInfo2In + g_dwStringOffsets[i]) = (PSTR)pDest;
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pDest += cbStrSize;
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}
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else
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{
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*(PSTR *)((PBYTE)pInfo2In + g_dwStringOffsets[i]) = NULL;
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}
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i++;
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}
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//
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// Then truncate the private devmode part by only copying over
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// public devmode
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//
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if (pInfo2Full->pDevMode)
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{
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pDest = (PBYTE)ALIGN_PTR_UP(pDest);
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memcpy(pDest, pInfo2Full->pDevMode, pInfo2Full->pDevMode->dmSize);
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pInfo2In->pDevMode = (DEVMODEA *)pDest;
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//
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// Set private devmode size to zero since it was just truncated
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//
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pInfo2In->pDevMode->dmDriverExtra = 0;
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pDest += pInfo2In->pDevMode->dmSize;
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}
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else
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{
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pInfo2In->pDevMode = NULL;
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}
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//
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// Then copy over the security descriptor
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//
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if (pInfo2Full->pSecurityDescriptor &&
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IsValidSecurityDescriptor(pInfo2Full->pSecurityDescriptor))
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{
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DWORD cbSDSize;
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cbSDSize = GetSecurityDescriptorLength(pInfo2Full->pSecurityDescriptor);
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pDest = (PBYTE)ALIGN_PTR_UP(pDest);
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memcpy(pDest, pInfo2Full->pSecurityDescriptor, cbSDSize);
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pInfo2In->pSecurityDescriptor = (PSECURITY_DESCRIPTOR)pDest;
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pDest += cbSDSize;
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}
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else
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{
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pInfo2In->pSecurityDescriptor = NULL;
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}
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//
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// Lastly copy over all the DWORD fields
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//
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pInfo2In->Attributes = pInfo2Full->Attributes;
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pInfo2In->Priority = pInfo2Full->Priority;
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pInfo2In->DefaultPriority = pInfo2Full->DefaultPriority;
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pInfo2In->StartTime = pInfo2Full->StartTime;
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pInfo2In->UntilTime = pInfo2Full->UntilTime;
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pInfo2In->Status = pInfo2Full->Status;
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pInfo2In->cJobs = pInfo2Full->cJobs;
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pInfo2In->AveragePPM = pInfo2Full->AveragePPM;
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//
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// We also need to set the correct return buffer size
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//
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if (pcbNeeded)
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{
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*pcbNeeded = pDest - pPrinter;
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}
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bNoTruncation = FALSE;
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DPFN(eDbgLevelInfo, "GetPrinterA truncated from %X to %X bytes",
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cbBuf, pDest - pPrinter);
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}
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}
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if (pInfo2Full)
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{
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free(pInfo2Full);
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pInfo2Full = NULL;
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}
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}
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if (bNoTruncation)
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{
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//
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// The shim doesn't need to do any truncation, or it has hit
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// an error when it was doing the truncation, so we will
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// just let the original API handle the call.
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//
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bRet = ORIGINAL_API(GetPrinterA)(
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hPrinter,
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Level,
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pPrinter,
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cbBuf,
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pcbNeeded);
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}
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return bRet;
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}
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/*++
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Handle DLL_PROCESS_ATTACH to retrieve command line parameter.
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--*/
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BOOL
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NOTIFY_FUNCTION(
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DWORD fdwReason
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)
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{
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if (fdwReason == DLL_PROCESS_ATTACH)
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{
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LONG lLimit = atol(COMMAND_LINE);
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if (lLimit > 0)
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{
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g_lTruncateLimit = lLimit;
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}
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}
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return TRUE;
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}
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/*++
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Register hooked functions
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--*/
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HOOK_BEGIN
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CALL_NOTIFY_FUNCTION
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APIHOOK_ENTRY(WINSPOOL.DRV, GetPrinterA);
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HOOK_END
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IMPLEMENT_SHIM_END
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