Mark Crispin wrote:
On Thu, 5 Aug 2004, Crispin Olson wrote:
I've dug around and found a few comments and even some examples of
how to
use these functions. However, it begs the question - why do these
functions
need callback drivers? Why cant they return the data in a string like
the
mail_fetch... functions?
The original intent of partial fetching was to permit resource-limited
clients to do so without requiring a potentially huge memory buffer.
You don't generally want to do a fetch-as-string for a 600MB video file.
I understand. And that was *exactly* the reason why I wanted to
implement using it. When I said "return a string" I meant a string that
was the size of the buffer requested.
A PHP script has, by default, 8MB max of memory allocated to it. In a
heavily loaded webserver even that is too high. Right now, deploying the
popular IMP webmail program requires a memory limit beyond 2x the max
attachment size (because the base 64 decode is also done in string
memory). Problems arise when someone puts a large attachment in a
shared IMAP folder, and a dozen people want to see it at the same time.
I don't think that a callback function is all that hard to write.
I think the issue was that the documentation on how to use string
drivers with mail_partial_body was hard to find - I found some examples
from you in postings on another imap list. I've submitted a working
patch to PHP-DEV. One thing I did find by experimentation was that the
4th and 5th parameters of "mail_partial_body" aren't start offset and
end offset (as the examples suggested), they are start and length (which
makes more sense anyway)
However to provide the best level of functionality I'd like to be able
to hook a body fetch up to a stream handle - that way it can also be
hooked through an inline decoding filter/pipe (e.g. base64 or UUencode)
and need a trivial amount of inprocess memory to deliver an attachment
to a webmail client. I don't suppose theres any direct way to achieve
this with C-Client (the string drivers only operate during a call to
e.g. mail_fetchbody as far as my reading of the documentation tells me)
? I would need to implement my own internal buffer, and call
mail_partial_body as needed to populate it?
Any help/advice is much appreciated.
Crispin Olson
