在异步模式下使用FtpFindFirstFile unicode版本访问冲突 [英] Access violation using FtpFindFirstFile unicode version in async mode

问题描述

假设我有非常简单的小代码示例，它使用异步WinInet：

  #includestdafx.h
 #includeWinInet.h
 #pragma comment（lib，wininet.lib）
 
 DWORD LatestResult = 0; 
 HANDLE MayContinue = 0; 
 
 VOID CALLBACK 
 CallBack（
 __in HINTERNET hInternet，
 __in DWORD_PTR dwContext，
 __in DWORD dwInternetStatus，
 __in_bcount（dwStatusInformationLength）LPVOID lpvStatusInformation ，
 __in DWORD dwStatusInformationLength 
）
 {
 if（dwInternetStatus == INTERNET_STATUS_REQUEST_COMPLETE）
 {
 LatestResult =（（LPINTERNET_ASYNC_RESULT）lpvStatusInformation） - > dwResult ; 
 SetEvent（MayContinue）; 
} 
} 
 
 int APIENTRY _tWinMain（_In_HINSTANCE hInstance，
 _In_opt_ HINSTANCE hPrevInstance，
 _In_ LPTSTR lpCmdLine，
 _In_ int nCmdShow） 
 {
 MayContinue = :: CreateEvent（NULL，FALSE，FALSE，NULL）; 
 HINTERNET Session = InternetOpen（NULL，INTERNET_OPEN_TYPE_PRECONFIG，NULL，NULL，INTERNET_FLAG_ASYNC）; 
 INTERNET_STATUS_CALLBACK CallbackPointer = InternetSetStatusCallback（Session，（INTERNET_STATUS_CALLBACK）CallBack）; 
 
 MayContinue = :: CreateEvent（NULL，FALSE，FALSE，NULL）; 
 InternetConnect（Session，_T（ftp.secureftp-test.com），INTERNET_INVALID_PORT_NUMBER，_T（test），_T（test），INTERNET_SERVICE_FTP，0,1）; 
 
 WaitForSingleObject（MayContinue，INFINITE）; 
 HINTERNET Internet =（HINTERNET）LatestResult; 
 
 WIN32_FIND_DATA * FindData = new WIN32_FIND_DATA; 
 FtpFindFirstFileW（Internet，_T（*。*），FindData，0，1）; 
 WaitForSingleObject（MayContinue，INFINITE）; 
 delete FindData; 
 return 0; 
} 
  

执行后得到的结果：

WinInetTest.exe中0xBAADF00D处的未处理异常：
0xC0000005：访问冲突执行位置0xBAADF00D。


在最终的WaitForSingleObject和callstack之间发生的事让人困惑。

但如果我改变

  WIN32_FIND_DATA * FindData = new WIN32_FIND_DATA; 
 FtpFindFirstFileW（Internet，_T（*。*），FindData，0，1）; 
  

到

  WIN32_FIND_DATAA * FindData = new WIN32_FIND_DATAA; 
 FtpFindFirstFileA（Internet，*。*，FindData，0，1）; 
  

它执行和工作原理。
所以我的问题是 - 我真的不正确的事情或它只是失败在WinInet端？

我使用Visual Studio 2012 btw在Windows 7上测试。

解决方案

我也有困难FtpFindFirstFileW。当我把我的项目从MBCS转换为Unicode FtpFindFirstFileW导致一个访问冲突，似乎是一个指针解除引用0xbaadf00d在调用后的某个地方，可能是在准备异步结果。我通过在MBCS和Unicode构建中使用FtpFindFirstFileA，InternetFindNextFileA和WIN32_FIND_DATAA结构来解决这个问题。然后我将输出cFileName字段转换为TCHAR字符串。

Let's say I have very simple little code sample which uses async WinInet:

#include "stdafx.h"
#include "WinInet.h"
#pragma comment(lib, "wininet.lib")

DWORD LatestResult = 0;
HANDLE MayContinue = 0;

VOID CALLBACK
  CallBack(
  __in HINTERNET hInternet,
  __in DWORD_PTR dwContext,
  __in DWORD dwInternetStatus,
  __in_bcount(dwStatusInformationLength) LPVOID lpvStatusInformation,
  __in DWORD dwStatusInformationLength
  )
{
  if (dwInternetStatus == INTERNET_STATUS_REQUEST_COMPLETE)
  {
    LatestResult = ((LPINTERNET_ASYNC_RESULT)lpvStatusInformation)->dwResult;
    SetEvent (MayContinue);
  }
}

int APIENTRY _tWinMain(_In_ HINSTANCE hInstance,
                       _In_opt_ HINSTANCE hPrevInstance,
                       _In_ LPTSTR    lpCmdLine,
                       _In_ int       nCmdShow)
{
  MayContinue = ::CreateEvent (NULL, FALSE, FALSE, NULL);
  HINTERNET Session = InternetOpen (NULL, INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, INTERNET_FLAG_ASYNC);
  INTERNET_STATUS_CALLBACK CallbackPointer = InternetSetStatusCallback (Session, (INTERNET_STATUS_CALLBACK) CallBack);

  MayContinue = ::CreateEvent (NULL, FALSE, FALSE, NULL);
  InternetConnect (Session, _T ("ftp.secureftp-test.com"), INTERNET_INVALID_PORT_NUMBER, _T ("test"), _T ("test"), INTERNET_SERVICE_FTP, 0, 1);

  WaitForSingleObject (MayContinue, INFINITE);
  HINTERNET Internet = (HINTERNET) LatestResult;

  WIN32_FIND_DATA *FindData = new WIN32_FIND_DATA;
  FtpFindFirstFileW (Internet, _T ("*.*"), FindData, 0, 1);
  WaitForSingleObject (MayContinue, INFINITE);
  delete FindData;
  return 0;
}

What I've got after execution:

Unhandled exception at 0xBAADF00D in WinInetTest.exe: 
0xC0000005: Access violation     executing location 0xBAADF00D.

It happens somewhere around final WaitForSingleObject and callstack is rather confusing.

But if I change

WIN32_FIND_DATA *FindData = new WIN32_FIND_DATA;
FtpFindFirstFileW (Internet, _T ("*.*"), FindData, 0, 1);

to

WIN32_FIND_DATAA *FindData = new WIN32_FIND_DATAA;
FtpFindFirstFileA (Internet, "*.*", FindData, 0, 1);

It executes and works as it should. So my question is - am I really not doing something correctly or it just failure on WinInet side?

I'm testing it on Windows 7 using Visual Studio 2012 btw.

解决方案

I also had difficulty with FtpFindFirstFileW. When I converted my project from MBCS to Unicode FtpFindFirstFileW resulted in an access violation that appeared to be a pointer dereference of 0xbaadf00d somewhere after the call, possibly when the async result was being prepared. I worked around this by using FtpFindFirstFileA, InternetFindNextFileA and the WIN32_FIND_DATAA struct in both MBCS and Unicode builds. I then convert the output cFileName field to a TCHAR string.

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