The tips are appreciated. AFAICT, the limit on total resource sizes is
within a kB or 2 of 2 or 4 GB, with the limitation that the last
resource must start within the first ~16 MB. Given the fact that the
files I'm opening are in the 1-300k range, I suspect I have bigger
problems than the resource file format if I start to approach that
limit.
One thing I can't figure out though... why is the limit 2727? Assuming
you have only 1 resource type and no names, you can fit exactly twice
that many references in the map. It's not relevant to my problem, but
I am curious.
-Dan
On Apr 24, 2008, at 5:52 AM, Uli Kusterer wrote:
Am 24.04.2008 um 09:16 schrieb Daniel DeCovnick:
I read that. I'm not sure I completely know what the resource map
is. The resource manager keeps track of a table of resource types,
and subtables of resource names or ID's as the key in a key-value
pair, where the resources themselves are the values. Is that what
the map is, that whole data structure that the manager keeps track
of?
Yes. The resource map is the table of contents of a resource file.
It uses offsets into the file to point from the type, ID number (and
optional name) of a file to its actual contents. Since resources
have been around pretty much since the days of the first Macintosh
operating system, they use rather small number types for today's
computers.
FWIW, as far as manipulating resource forks go, I was planning to
use the NDResourceFork classes (see further up this thread about 20
posts). If what that does is the wrong way to go (I suspect it's
not), let me know. And, if I'm wrong about what the map is, if by
using NDResourceFork I don't need to concern myself with what a
resource map actually is so long as I make sure I stick to my own
crazy 4-char resource type (say, dåNd, or s¥$w) and valid resource
ID ranges, let me know that also. :-)
Apple has documentation about what resource types are reserved for
use by Apple. IIRC they must contain at least one uppercase
character. I'd recommend you use the signature registry on Apple's
web site to register a signature, and use that. That decreases
chances of your type colliding with any in use. Though you'll still
have to make sure it doesn't collide with a well-known resource
type. Check out the Cocoa-Dev and Carbon-Dev archives, there was a
thread on one of these lists whether signatures (creator codes) are
still needed today, and we dug out the documentation about what
resource types are reserved in the process.
And if I do have a substantial part of that right, what are the
limits I need to worry about? Uli mentioned a limit of 2727
resources per fork. While that seems absurdly low, it's not like
I'd be using a resource for every piece of data I need to keep
track of.
It's a technical limit. That's the point at which one of its offsets
overflows, IIRC. You need to be careful with that, as the resource
manager will simply crash when you exceed that.
Far simpler just to serialize my data and write it to a single
resource if that sort of limit exists; shove my XML or binary data
into blah.blah>resource fork>s¥$w>128. I know that a single
resource can be at least 3 MB*. What's the limit there, for instance?
I'll try if I can find a backup of my blog posting on the topic. I
don't have the nerve to go back to Inside Macintosh: More Macintosh
Toolbox to re-read the documentation of the resource file format.
However, if anyone else wants to, the format is documented here:
http://developer.apple.com/documentation/mac/MoreToolbox/MoreToolbox-99.html#HEADING99-0
One of the limits that immediately comes to mind is that the
beginning of the resource map has to be within 64k bytes from both
the resource type list and the name list, which puts a hard limit on
the size of the resource map (see Fig. 1-14). Similar limits seem to
be on the name list and a few other lists. Note that the 2727 limit
is a "well-known bug", so to say, I don't think Apple has documented
it anywhere.
Cheers,
-- Uli Kusterer
"The Witnesses of TeachText are everywhere..."
http://www.zathras.de
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