Hendrik Boom <[EMAIL PROTECTED]> writes:
[...]
> What I don't know is how to seek around the file in a machine-independent
> manner, and avoid future headaches.
[...]
> (a) use fgetpos and fsetpos
> This will presumably do random access to anything the machine's file
> system will handle, but the disk address I get from fgetpos are
> unliky to be usable on another system.
> (b) use ftell and fseek
> Now these will solve the problem as long as my files stay small.
> They provide byte counts from the start of the file, which are
> semantically independent of the platform, but are just long int, which,
> last I heard, was 32 bits almost everywhere (and, because of the sign
> bit are limited to 31 bits in practise).
>
> Is there something else available? Is there another way to use the tools
> I have already mentioned? Is there a clean way to move to 64-bit
> relatively system-independent disk addresses? Is there a standard way?
The very low-level function you are looking for is lseek or lseek64.
That won't play well with the stdio library, unfortunately, but you
may find fseeko() and ftello() will work. They use a file position
that is of type "off_t", which is usually be 64-bit on newer Unixes
(or at least can be with the right compilation options). See:
http://www.unix.org/version2/whatsnew/lfs20mar.html
and the appropriate manpages, and I think that will set you on the
right track.
Good luck!
----Scott.
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