On Sun, Mar 16, 2008 at 04:22:13PM +0100, Corinna Vinschen wrote:
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.
This is basically my function. I'll try to convert it to use Unicode
today.
cgf
