CODEWITHSUNDEEP
delphiwindows-7delphi-2007
SevenEleven
SevenEleven

Reputation: 2474

FileExists() returns false, even if file exists

I want to check if a dll in System32 directory (Windows 7) exists. But even if it exists, FileExists() returns false. LoadLibrary returns a valid handle. In this case, I only want to check, if the files exists and visualize this information. Do you have a any tips to solve this?

Upvotes: 8

Views: 12090

Answers (4)

Magnus
Magnus

Reputation: 18810

This is the most ridiculous reason, but if it can help just one person...

Make sure you didn't accidentally name the file something.dll.dll.

I just had a situation where I installed an application on a clients computer, and then the application couldn't find config.txt located in the same directory. This had been working fine on other computers, so of course I was stumped.

Turns out the "show file extensions" setting was turned off on this clients computer, and the file had actually been named config.txt.txt... in my defence, I spend 90% of the time on OSx, and 9.99% on my own Windows system, with "show file extensions" enabled since ages ago.

Upvotes: 1

David Heffernan
David Heffernan

Reputation: 613511

Most likely this is down to file redirection. You have a 64 bit machine but from the 32 Delphi process, Windows\system32 actually redirects to Windows\Syswow64. So when you think you are asking for the existence of a file in Windows\system32, the system is actually reporting the existance (or otherwise) of a file in Windows\Syswow64.

If you really do need to see into the true 64 bit system32 then you need to disable file redirection. You can do this with the Wow64DisableWow64FsRedirection() function. Don't forget to switch it back on with Wow64RevertWow64FsRedirection(). Beware that disabling the redirector has wide reaching effects and can result in very strange behaviour so do so with care.

Upvotes: 21

Larry Lustig
Larry Lustig

Reputation: 50998

You are almost certainly not specifying the full or valid relative path of the file in your FileExists call. LoadLibrary will search certain locations (those where dlls are expected to reside) for you, but FileExists will not. Supply the complete and correct path and FileExists will work correctly.

Upvotes: 2

Paul Hunt
Paul Hunt

Reputation: 3575

Not much information to go on, the code you are using might help, but could this be a 64 bit issue and that the dll is actually in the SysWOW64 folder? See here for a good description of the how this works.

Upvotes: 10

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