Why can't I copy a DLL from C:\\SysWOW64 from the command line?

问题:

I know what I'm doing is weird, please don't worry about that. What is happening, however, is absolutely insane.

If I try to copy a DLL file from C:\SysWOW32\ from the command line using copy on Windows 7 64-bit, I actually end up getting the file that's in C:\System32\. Why is this happening?

OK - dumpbin is able to differentiate the DLL files

C:\Users\user\Desktop>dumpbin /headers C:\Windows\System32\opengl32.dll | grep machine             8664 machine (x64)  C:\Users\user\Desktop>dumpbin /headers C:\Windows\SysWOW64\opengl32.dll | grep machine              14C machine (x86)              32 bit word machine 

NOT OK - Other commands, like md5sum (from GOW) get the wrong bytes!

C:\Users\user\Desktop>md5sum C:\Windows\system32\opengl32.dll \d1bbe227367ed791d5fcf08e132d2956 *C:\\Windows\\system32\\opengl32.dll  C:\Users\user\Desktop>md5sum C:\Windows\SysWow64\opengl32.dll \d1bbe227367ed791d5fcf08e132d2956 *C:\\Windows\\SysWow64\\opengl32.dll 

NOT OK - Copying a 64-bit DLL using the command line

C:\Users\user\Desktop>copy C:\Windows\System32\opengl32.dll .         1 file(s) copied.  C:\Users\user\Desktop>dir opengl32.dll 07/13/2009  06:16 PM           791,552 opengl32.dll  C:\Users\user\Desktop>md5sum opengl32.dll d1bbe227367ed791d5fcf08e132d2956 *opengl32.dll  C:\Users\user\Desktop>dumpbin /headers opengl32.dll | grep machine              14C machine (x86)              32 bit word machine 

Wrong! Why did the 32-bit DLL get copied??

OK - Copying a 32-bit DLL using the command line

C:\Users\user\Desktop>copy C:\Windows\SysWOW64\opengl32.dll . Overwrite .\opengl32.dll? (Yes/No/All): yes         1 file(s) copied.  C:\Users\user\Desktop>dir opengl32.dll 07/13/2009  06:16 PM           791,552 opengl32.dll  C:\Users\user\Desktop>md5sum C:\Windows\System32\opengl32.dll \d1bbe227367ed791d5fcf08e132d2956 *C:\\Windows\\System32\\opengl32.dll  C:\Users\user\Desktop>dumpbin /headers opengl32.dll | grep machine              14C machine (x86)              32 bit word machine 

OK - Copying a 64-bit DLL using Explorer

<control-drag System32\opengl32.dll to desktop>  C:\Users\user\Desktop>dir opengl32.dll 07/13/2009  06:41 PM         1,039,872 opengl32.dll  C:\Users\user\Desktop>md5sum opengl32.dll 585fed4cdb8034b8b58aeb8008255817 *opengl32.dll  C:\Users\user\Desktop>dumpbin /headers opengl32.dll | grep machine             8664 machine (x64) 

OK - Copying a 32-bit DLL using Explorer

<control-drag SysWow64\opengl32.dll to desktop>  C:\Users\user\Desktop>dir opengl32.dll 07/13/2009  06:16 PM           791,552 opengl32.dll  C:\Users\user\Desktop>md5sum opengl32.dll d1bbe227367ed791d5fcf08e132d2956 *opengl32.dll  C:\Users\user\Desktop>dumpbin /headers opengl32.dll | grep machine              14C machine (x86)              32 bit word machine 

Can anyone explain what's happening here?

回答1:

The behavior you see is caused by SysWOW64 File System Redirection

md5sum.exe is a 32-bit binary, so when it requests C:\Windows\System32\opengl32.dll, the file system returns C:\Windows\SysWOW64\opengl32.dll.

Similarly, if you launch a 32-bit prompt (C:\Windows\SysWOW64\cmd.exe), perform a copy operation and inputs the argument C:\Windows\System32\opengl32.dll, C:\Windows\SysWOW64\opengl32.dll is copied

文章来源: Why can't I copy a DLL from C:\\SysWOW64 from the command line?