Why is FindNextFile failing on Windows 7 - windows

Question

This code works on Windows XP at home but fails at work on 64bit Windows 7. The loop isn't entered even once although there are more than 50 files in the supplied folder. Not only it doesn't enter, it also returns ERROR_NO_MORE_FILES for GetLastError. Why?
string dir = "d:\\validfolder";
WIN32_FIND_DATA ffd;
HANDLE h = FindFirstFile(dir.c_str(), &ffd);
while(FindNextFile(h, &ffd))
{
// some operation
}
DWORD dw = GetLastError();// returns ERROR_NO_MORE_FILES
I tried Wow64DisableWow64FsRedirection but that has no effect.

Answer 1

You need to add a file wildcard to your dir:
string dir = "d:\\validfolder\\*";
For it to list the files in a directory. Otherwise you are only asking for information about the directory itself.
At least that's how I read the documentation for FindFirstFile
To examine a directory that is not a root directory, use the path to
that directory, without a trailing backslash. For example, an argument
of "C:\Windows" returns information about the directory "C:\Windows",
not about a directory or file in "C:\Windows". To examine the files
and directories in "C:\Windows", use an lpFileName of "C:\Windows*".
I don't know why it's working for you on XP

Answer 2

This code is incorrect in a number of ways.
You must check the return value of FindFirstFile. If the call to FindFirstFile succeeds then you already have the first file in ffd. As your code stands, you throw away the first file. So you need to re-jig your loop logic to account for that. Naturally, if GetLastError returns ERROR_NO_MORE_FILES then that means the search has exhausted all files.
So, what is probably happening is you ask for the first file matching the search string "d:\\validfolder". This is returned in ffd after the call to FindFirstFile. You then ignore that information and ask for the next match. But there is no subsequent match since there is only one object matching "d:\\validfolder" since you included no wildcards in your search pattern.
This code will behave exactly the same on XP as it does on Windows 7 and I suspect that you are not running the same code on both systems.
If you want to enumerate the contents of the folder then you need to search for "d:\\validfolder\\*". Something like this:
string dir = "d:\\validfolder\\*";
WIN32_FIND_DATA ffd;
HANDLE h = FindFirstFile(dir.c_str(), &ffd);
BOOL success = h<>INVALID_HANDLE_VALUE;
while(success)
{
// do something with ffd
success = FindNextFile(h, &ffd));
}