The upshot of this patch: Brigades deal with apr_off_t bytes, but a single bucket never deals with more than apr_size_t bytes :)
From: "Roy T. Fielding" <[EMAIL PROTECTED]>
Sent: Thursday, July 12, 2001 11:54 PM
> Bill wrote some time ago;
>
> > This means a huge file would need to be split by the caller into multiple
> > file
> > buckets, no longer than ssize_t [actually, apr_size_t]. Is this reasonable?
>
> Wouldn't that make it difficult to call sendfile on a file bucket that
> points to a huge file?
Good question, let's see, from FreeBSD...
int sendfile(int fd, int s, off_t offset, size_t nbytes,
struct sf_hdtr *hdtr, off_t *sbytes, int flags)
the offset is an off_t (that's healthy), but the bytes to send is a size_t.
Hmmm,
so we can't request more bytes, unless we leave it at 0. We are told that we
sent
up to off_t, a healthy big number.
It returns an off_t for bytes sent. Interesting mishmash.
>From Linux glibc2...
int sendfile(int out_fd, int in_fd, off_t *offset, size_t count)
Ok, same story here. Rather broken since we are only told of sending int bytes,
which is most definately a discrepancy (between 32 and 64 bit builds as well.)
Nothing in the man page about using count==0 to send the remainder of the file.
I'd argue that sendfile against a huge file bucket is inherantly non-portable.
Lo and
behold, we defined apr_sendfile in terms of a size_t.
At the same time, apr_brigade_consume and apr_brigade_length need to be playing
with apr_off_t,
since the aggregated size of all buckets (file+memory) can certainly exceed the
memory space!!!
Do we push these discrepancies on the apr implementor, or the user? In today's
patch,
I propose I push this back at the user. I'd move the definition of 'size
indeterminate' to
start of -1 (from the header, "If length == -1, start == -1") and length of
(apr_size_t)(-1)
so we can have a full apr_size_t of data in a bucket. Passing 0xffffffff for a
read isn't
necessarily bad, since the actual length read should be returned.
If we want to pull these off the user, then we need to first modify
apr_sendfile(),
and this patch can be used as the basis for changing the entire behavior.
Bill
apr-bucket-lengths.patch
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