Delphi TPath.GetTempPath结果被裁剪 [英] Delphi TPath.GetTempPath result is cropped

问题描述

我使用的是Delphi 2010，我的程序想要获得系统的临时路径。我正在使用TPath.GetTempPath，一切都正常工作...至少对我和我的同事。但是在某些客户机器上，此方法返回一个裁剪路径（当然不是）。我发现问题似乎是从底层调用GetLongPathName（）的结果。

完整的代码如下所示：

  [...] 
 var 
 TmpDir：String; 
 Len：整数; 
 begin 
 
 [...调用GetTempPath成功，我们有一个有效的临时目录在var TmpDir ...
 
 Len ：= GetLongPathName（PChar（TmpDir），nil，0）; // Len = 37 
 SetLength（TmpDir，Len-1）; //我们要将TmpDir的len设置为37  -  1. 
 GetLongPathName（PChar（TmpDir），PChar（TmpDir），Len）; //只有32个（而不是36个）字符被复制 - 所以我们有一个裁剪的路径 - 但为什么？ 
 
 end; 
 [...] 
  

这只发生在某些系统上，我不知道为什么。我发现了一个令人讨厌的解决方法，但我想知道这里发生了什么。

有人可以点亮这个吗？

解决方案

在国土安全页面上有关于Windows API函数的注意事项：

的返回缓​​冲区GetLongPathName（）和类似的
函数可能会返回截断的
路径，并导致难以找到的错误。

https://buildsecurityin.us-cert.gov/bsi-rules/home/g1/753-BSI.html

如果你有源代码，您可以检查本文中描述的问题是否存在于Delphi 2010实施中。

I am using Delphi 2010 and my program wants to get the system's temp path. I am using TPath.GetTempPath and everything is working fine... at least for me and my coworkers. But on some customer machines this method returns a cropped path which is (of course) not existing. I found out that the problem seems to be the result from underlying call to GetLongPathName().

The complete code looks like this:

[...]
var
 TmpDir : String;
 Len : Integer;
begin

 [... Call to GetTempPath succeeds and we have a valid temp directory in short "~" notation in var TmpDir ...]

 Len := GetLongPathName(PChar(TmpDir), nil, 0);      // Len = 37
    SetLength(TmpDir, Len - 1);                         // We want to set the len of TmpDir to 37 - 1.
    GetLongPathName(PChar(TmpDir), PChar(TmpDir), Len); // Only 32 (instead of 36) characters are copied - so we have a cropped path - But why?!

end;
[...]

This only happens on some systems and I don't know why. I found a nasty workaround for this, but I would like to know what's going on here.

Can somebody put some light on this?

解决方案

There is a note about this Windows API function on the Homeland Security pages:

"The return buffer for GetLongPathName() and similar functions might return a truncated path and lead to hard-to-find errors."

https://buildsecurityin.us-cert.gov/bsi-rules/home/g1/753-BSI.html

If you have the source code, you could check if the problem described in this article exists in the Delphi 2010 implementation.

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