On 6/3/2013 18:54, Hans-Peter Diettrich wrote:
waldo kitty schrieb:
const
INVALID_FILE_SIZE = DWORD($FFFFFFFF);
is the above correct? it would seem to be from what i can make out from MSDN
and the various C code files i've found it defined in...
Using unsigned constants with int64 filesizes would classify files of exactly
that size as invalid, while smaller or bigger files would be valid. This
certainly is *not* what the coder had in mind, so that I'd suggest to inspect
and fix all occurences of this (and similar) unsigned constants in user code.
have you read the links i provided? exactly this situation is discussed in
several of them ;)
i kind of have to laugh because on place i read spoke of examples checking the
result directly instead of using INVALID_FILE_SIZE and that this was not good
coding practice because m$ might change the value of INVALID_FILE_SIZE at any
time which would then break all of that code... i makes sense to me O:)
IMO such unsigned constants should be used only in specific cases, e.g. with OS
defined records containing part of an longer (int64) type. The FCL can use that
constant in Win32 platform code, the LCL or user code never should use it at
all.
without it, it makes porting harder... especially when one is not familiar with
the integral parts of any OS... while i've been coding for 30+ years, i've never
done any GUI coding so the easier it is to make conversions happen, the better
for all... IMHO, of course...
I also doubt that the MS documentation is up to date whenever above constant is
used with anything except struct fields of type DWORD. Even in 32 bit code
*both* low/high parts of a 64 bit filesize must be checked for
INVALID_FILE_SIZE, in order to determine a valid result.
as i point out above, the documentation speaks specifically about this and it
does give an alternative...
in specific to the code i'm looking to port, yes, the coders did intend this
because that is how things were done at that time... 4Gig files were/are unheard
of in that environment and still are today... there's no way we're going to be
transferring 4Gig files... we won't even transfer those of 200+Meg in our hobby
network... things may change in the future but until then, there are other
technologies available for transferring such large files... especially if one is
on dial-up making direct connections to the remote sites... i won't even mention
the use of 9600 "baud" radio for the same ;)
--
NOTE: No off-list assistance is given without prior approval.
Please keep mailing list traffic on the list unless
private contact is specifically requested and granted.
--
_______________________________________________
Lazarus mailing list
[email protected]
http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
