Hi,

In File.rawWrite() (in std.stdio), there is the following error checking code:

        auto result =
            .fwrite(buffer.ptr, T.sizeof, buffer.length, p.handle);
        if (result == result.max) result = 0;
        errnoEnforce(result == buffer.length,
                text("Wrote ", result, " instead of ", buffer.length,
                        " objects of type ", T.stringof, " to file `",
                        p.name, "'"));

Call me silly, but I don't understand the `result == result.max` check. See:

* http://www.cplusplus.com/reference/clibrary/cstdio/fwrite/
* http://pubs.opengroup.org/onlinepubs/007904875/functions/fwrite.html
* http://linux.die.net/man/3/fwrite
* https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man3/fwrite.3.html
* http://www.unix.com/man-page/freebsd/3/fwrite/

From none of these can I derive the reason for resetting result to 0 if size_t.max is returned.

Can anyone shed some light on this?

Thanks and regards,
Alex
_______________________________________________
phobos mailing list
phobos@puremagic.com
http://lists.puremagic.com/mailman/listinfo/phobos

On 13.06.2012 13:16, Alex Rønne Petersen wrote:
> Hi,
>
> In File.rawWrite() (in std.stdio), there is the following error checking code:
>
>          auto result =
>              .fwrite(buffer.ptr, T.sizeof, buffer.length, p.handle);
>          if (result == result.max) result = 0;
>          errnoEnforce(result == buffer.length,
>                  text("Wrote ", result, " instead of ", buffer.length,
>                          " objects of type ", T.stringof, " to file `",
>                          p.name, "'"));
>
> Call me silly, but I don't understand the `result == result.max` check. See:

Obviously it counts on fwrite to return -1 on error. I'd say it's a carry over from when code (supposedly) used POSIX write call directly.


-- 
Dmitry Olshansky

_______________________________________________
phobos mailing list
phobos@puremagic.com
http://lists.puremagic.com/mailman/listinfo/phobos