[boost] Windows invalid chars in file names

From: Yitzhak Sapir (yitzhak.sapir_at_[hidden])
Date: 2006-08-20 05:34:28

The following MSDN article treats the issue of invalid characters 
in filenames: 

http://support.microsoft.com/kb/177506/EN-US/

Another article has a similar text (but misses the asterisk in the list):
http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/w2000Msgs/2993.mspx

A simple cpp program also throws on this simple issue.  For example, 
with a question mark:

#include "windows.h"

int main(int argc, char* argv[])
{
        HANDLE hf = ::CreateFile("c:\\hi?.c", GENERIC_WRITE, 0, NULL, OPEN_ALWAYS, 0, 0);
        if (hf == INVALID_HANDLE_VALUE) {
                std::cout << GetLastError() << std::endl;
        } else {
                ::CloseHandle(hf);
                std::cout << "Success" << std::endl;
        }
        return 0;
}

The value returned is ERROR_INVALID_NAME == 123L from winerror.h 

However, boost::filesystem::path::windows_name does not have a problem 
with a question mark or asterisk.  Also, the implementation seems to
attempt to validate any name unless it has these characters whereas it
could use a "valid list" like the unix implementation does.  A missing
character from the valid list will probably be an inconvenience but not
as much of a problem as a missing character from the invalid list.  My
guess is that an implementation that wishes to support Unicode characters
will need to use the GetStringTypeW or IsCharAlphaNumeric functions to 
determine if a letter is an alphanumeric character.  Perhaps it is best to 
use an implementation that runs "CreateFile(filename, GENERIC_READ, 0, NULL, 
OPEN_EXISTING, 0, 0)" and checks the error code for ERROR_INVALID_NAME to
decide if it is a valid filename or not.

Yitzhak Sapir