Re: STORAGE_ERROR : EXCEPTION_STACK_OVERFLOW

[Simon Wright <simon.j.wright@mac.com>]

I've just spent over half an hour getting this to compile (hint: use
zip, or restrict your line length to something your mailer won't
mangle!); the operating instructions are a tad lacking, but I've got
to the point of an EXC_BAD_ACCESS somewhere a way deeper in the stack
than (my) schema_types.adb:320:

319                 for x in  1 .. schemainfo.attributes'length loop
320                     temp(x) := new attribute'class'(from_disc(fin,
321     schemainfo.attributes(x).all));

I notice that in attribute_types.adb, you have

    procedure to_disc (fout: file_type; item: in out booleanattribute)
is
    begin
        item.byte_start := Integer'val (Index (fout));
        item.byte_end := Integer'val (Index (fout)) +
(booleanattribute'size / 8) - 7;
        booleanattribute'class'output(Stream(fout), item);
    end to_disc;

which looks wrong;

(a) the calculation of byte_end ought to say (foo'size + 7) / 8; but
it's irrelevant, because

(b) the disk size of the record written will not be equal to the
memory size, for two reasons: first, 'output writes tag and constraint
data as well as binary data, and second, the binary data is likely to
be packed differently -- GNAT writes in multiples of one byte per
item, without any alignment padding such as will be in memory.

Could you work out where the record is in the disk file by noting the
file position before and after the read?