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- To: alleg-developers@xxxxxxxxxx
- Subject: Re: [AD] al_find file size
- From: Chris <chris.kcat@xxxxxxxxxx>
- Date: Mon, 7 Nov 2005 17:02:09 -0800
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On Monday 07 November 2005 04:01 pm, Evert Glebbeek wrote:
> Afraid not, at least not for 4.2. For one thing, doing so will break
> binarycompatibility. For another, long long is not C89. For 4.3 and up,
> possibly, depending on what we want to do with the file functions.
> I'm curious though, how do the operating system API's deal with this issue?
> Have they always returned a 64 bit integer for filesize?
According to my man pages, fseek and ftell both use long. On Linux, there are
the functions fseeko and ftello which use the off_t type:
The fseeko() and ftello() functions are identical to fseek() and ftell()
(see fseek(3)), respectively, except that the offset argument of fseeko() and
the return value of ftello() is of type off_t instead of long.
On many architectures both off_t and long are 32-bit types, but compilation
with
#define _FILE_OFFSET_BITS 64
will turn off_t into a 64-bit type.
Unfortunately those functions conform to SUSv2, and probably won't work on
Windows. My copy of XMinGW, however, has the functions fseeko64/ftello64 and
use the off64_t type.
Probably the best thing to do would be to use (u)int64_t, define
_FILE_OFFSET_BITS to 64, and just use the compiler-specific fseek/ftell
function, casting as needed.