Date: Thu, 26 Jul 2012 22:56:53 GMT From: Garrett Cooper <yanegomi@gmail.com> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/170203: [kern] piped dd's don't behave sanely when dealing with a fifo Message-ID: <201207262256.q6QMurVf077480@red.freebsd.org> Resent-Message-ID: <201207262300.q6QN0Lsf023313@freefall.freebsd.org>
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>Number: 170203 >Category: kern >Synopsis: [kern] piped dd's don't behave sanely when dealing with a fifo >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Thu Jul 26 23:00:21 UTC 2012 >Closed-Date: >Last-Modified: >Originator: Garrett Cooper >Release: 9-STABLE >Organization: EMC Isilon >Environment: FreeBSD forza.west.isilon.com 9.1-PRERELEASE FreeBSD 9.1-PRERELEASE #1 r238738M: Mon Jul 23 22:39:40 PDT 2012 gcooper@forza.west.isilon.com:/usr/obj/usr/src/sys/FORZA amd64 >Description: Creating a fifo and then dd'ing across the fifo using /dev/zero doesn't seem to yield the behavior one would expect to have; dd should either exit thanks to SIGPIPE being sent or the count being completed. Furthermore, the count is bogus: Terminal 1: $ dd if=fifo bs=512k count=4 0+4 records in 0+4 records out 32768 bytes transferred in 0.002121 secs (15449523 bytes/sec) $ dd if=fifo bs=512k count=4 0+4 records in 0+4 records out 32768 bytes transferred in 0.001483 secs (22096295 bytes/sec) $ dd if=fifo bs=512M count=4 0+4 records in 0+4 records out 32768 bytes transferred in 0.003908 secs (8384514 bytes/sec) Terminal 2: $ dd if=/dev/zero bs=512k count=4 of=fifo ^T load: 0.40 cmd: dd 1779 [sbwait] 2.63r 0.00u 0.00s 0% 1800k 1+0 records in 0+0 records out 0 bytes transferred in 2.639078 secs (0 bytes/sec) ^T load: 0.37 cmd: dd 1779 [sbwait] 8.19r 0.00u 0.00s 0% 1804k 1+0 records in 0+1 records out 40960 bytes transferred in 8.191172 secs (5001 bytes/sec) >How-To-Repeat: mkfifo fifo Terminal 1: dd if=fifo bs=512k count=4 Terminal 2: dd if=/dev/zero bs=512k count=4 of=fifo >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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