Date: Sun, 2 Mar 2008 13:00:42 GMT From: Nick Hibma <nick@anywi.com> To: freebsd-gnats-submit@FreeBSD.org Subject: bin/121287: dd ignores any conversions if 'bs' was specified Message-ID: <200803021300.m22D0gbg091187@www.freebsd.org> Resent-Message-ID: <200803021310.m22DA13p008216@freefall.freebsd.org>
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>Number: 121287
>Category: bin
>Synopsis: dd ignores any conversions if 'bs' was specified
>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: Sun Mar 02 13:10:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator: Nick Hibma
>Release: 6-STABLE
>Organization:
AnyWi Technologies
>Environment:
System: FreeBSD hind.van-laarhoven.org 6.3-PRERELEASE FreeBSD 6.3-PRERELEASE #20: Fri Dec 14 13:39:34 CET 2007
root@hind.van-laarhoven.org:/usr/src/sys/i386/compile/HIND i386
>Description:
If you specify a block size with bs (probably with ibs and obs as well) any conversions will be ignored, notable bs.
If you copy a large file (CF image file in my case) reading in large block sizes is preferrable, especially on for example USB devices.
>How-To-Repeat:
nick@hind:/usr/home/nick % dd bs=1M count=1 if=/dev/zero of=sparsefile.1
1+0 records in
1+0 records out
1048576 bytes transferred in 0.098494 secs (10646084 bytes/sec)
nick@hind:/usr/home/nick % dd count=1 if=/dev/zero of=sparsefile.2
1+0 records in
1+0 records out
512 bytes transferred in 0.000175 secs (2925727 bytes/sec)
nick@hind:/usr/home/nick % du -sk sparsefile.*
1040 sparsefile.1
2 sparsefile.2
>Fix:
The following code fragment shows the problematic code:
src/bin/dd.c:349: rev.1.43
/*
* POSIX states that if bs is set and no other conversions
* than noerror, notrunc or sync are specified, the block
* is output without buffering as it is read.
*/
if (ddflags & C_BS) {
out.dbcnt = in.dbcnt;
dd_out(1);
in.dbcnt = 0;
continue;
}
>Release-Note:
>Audit-Trail:
>Unformatted:
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