Date: Fri, 18 Jan 2008 00:47:32 -0800 (PST) From: Michael Allman <msa@allman.ms> To: Greg Lewis <glewis@eyesbeyond.com> Cc: landonf@macports.org, freebsd-java@freebsd.org Subject: Re: bsd implementation of Java_sun_nio_ch_FileChannelImpl_transferTo0 ignores "count" argument Message-ID: <20080118002952.M20016@yvyyl.pfbsg.arg> In-Reply-To: <20080118081554.GA4645@misty.eyesbeyond.com> References: <20080117200016.P64623@yvyyl.pfbsg.arg> <20080118081554.GA4645@misty.eyesbeyond.com>
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On Fri, 18 Jan 2008, Greg Lewis wrote:
> On Thu, Jan 17, 2008 at 08:13:00PM -0800, Michael Allman wrote:
>> I can attempt to provide a patch, but C is not my thing, and I could not
>> make a reliable claim as to the correctness of my patch. Also, there's
>> the whole license issue. Fixing this seems simple enough, though. I
>> would like to help insofar as I can.
>
> Something like this maybe? (Untested)
>
> --- ../../j2se/src/solaris/native/sun/nio/ch/FileChannelImpl.c 6 Mar 2007 17:45:05 -0000 1.11
> +++ ../../j2se/src/solaris/native/sun/nio/ch/FileChannelImpl.c 18 Jan 2008 08:11:36 -0000
> @@ -264,11 +264,12 @@
> return IOS_THROWN;
> }
>
> - while ((r = pread(srcFD, buf, 4096, offset)) > 0) {
> + while (count > 0 && (r = pread(srcFD, buf, (count < 4096) ? count : 4096, offset)) > 0) {
> w = write(dstFD, buf, r);
> if (w == -1)
> break;
> offset += w;
> + count -= w;
> }
> free(buf);
You're reading my mind.
>> Also, I know this is getting pushy, but it seems like fixing this issue
>> would be a great time to replace the current implementation of this method
>> with a true bsd sendfile() call. I could give that a try, too.
>
> As noted in the comments, you can't since the BSD implementation of
> sendfile(2) expects to be sending the file to a socket, not just any old
> file descriptor. Solaris and Linux are both ok with any old fd.
I think the calling code can handle a failure gracefully. See
FileChannelImpl.java, transferToDirectly().
I am going to have a go at this (sendfile support) in leopard. The
freebsd call is a little different, and I don't have ready access to a
freebsd machine.
Michael
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