On Mar 16 03:14, Brian Dessent wrote: > I debugged this and found the > strangest thing, when you call QueryDosDevice (NULL, fnbuf, len) to get > the list of all DOS devices and len >= 65536, Win32 always returns 0 > with GetLastError set to ERROR_MORE_DATA. Since len was being set as > "sizeof (OBJECT_NAME_INFORMATION) + NT_MAX_PATH * sizeof (WCHAR)" this > always happened, causing handle_to_fn() to simply give up and copy the > Win32 name into the POSIX name and return. The attached patch fixes the > problem by just clamping the size of the buffer to under 64k.
<insert lament here> > Another observation that I had while debugging this is that calling > strncasematch() in this function is probably wrong -- it expands to > cygwin_strncasecmp(), which is a wrapper that first converts both > arguments to temporary UNICODE strings and then calls > RtlCompareUnicodeString() -- we're doing this on strings that we had > just converted *out* of UNICODE. I think ascii_strncasematch() is > probably what we want here instead, either that or try to stay in > unicode throughout. Using ascii_strncasematch here is right because the DEVICE_PREFIX is plain ascii anyway. But, yes, the function should be converted to do everything in WCHAR/UNICODE_STRING and only convert to char * when creating the final posix_fn. > + /* For some reason QueryDosDevice will fail with Win32 errno 234 > + (ERROR_MORE_DATA) if you try to pass a buffer larger than 64k */ > + size_t qddlen = len < 65536 ? len : 65535; len is a const value. Checking len for being < 65536 is a constant expression which always results in qddlen being 65535 so the ?: is a noop, more or less. Did you test if QueryDosDeviceW has the same problem as QueryDosDeviceA? If not, we should use that function. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat
