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Date:      Tue, 30 Aug 2022 17:49:21 +0200
From:      Mateusz Piotrowski <0mp@FreeBSD.org>
To:        freebsd-dtrace@freebsd.org
Subject:   Converting int to a string in DTrace
Message-ID:  <317C65CC-5BF0-422D-80E9-4340CD241569@FreeBSD.org>
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Hello everyone,

Is it possible to convert an int to a string in DTrace?

E.g., I'd like the following script to work (it's an example from =
dtrace_io(4), but with device unit number added):

#!/usr/sbin/dtrace -s

#pragma D option quiet

io:::start
{
        this->unit_number =3D args[1]->unit_number >=3D 0 ? =
(string)args[1]->unit_number : "";
        @[args[1]->device_name, this->unit_number, execname, pid] =3D =
sum(args[0]->bio_bcount);
}

END
{
        printf("%10s%-3s %20s %10s %15s\n", "DEVICE", "", "APP", "PID", =
"BYTES");
        printa("%10s%-3s %20s %10d %15@d\n", @);
}

(Of course, the `(string)` cast does not work here because it's just not =
how DTrace works.)

Best,
Mateusz=

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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dus-ascii"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;" class=3D"">Hello=
 everyone,<div class=3D""><br class=3D""></div><div class=3D"">Is it =
possible to convert an int to a string in DTrace?</div><div class=3D""><br=
 class=3D""></div><div class=3D"">E.g., I'd like the following script to =
work (it's an example from dtrace_io(4), but with device unit number =
added):</div><div class=3D""><br class=3D""></div><blockquote =
style=3D"margin: 0 0 0 40px; border: none; padding: 0px;" class=3D""><div =
class=3D""><div class=3D"">#!/usr/sbin/dtrace -s</div></div><div =
class=3D""><div class=3D""><br class=3D""></div></div><div class=3D""><div=
 class=3D"">#pragma D option quiet</div></div><div class=3D""><div =
class=3D""><br class=3D""></div></div><div class=3D""><div =
class=3D"">io:::start</div></div><div class=3D""><div =
class=3D"">{</div></div><div class=3D""><div class=3D"">&nbsp; &nbsp; =
&nbsp; &nbsp; this-&gt;unit_number =3D args[1]-&gt;unit_number &gt;=3D 0 =
? (string)args[1]-&gt;unit_number : "";</div></div><div class=3D""><div =
class=3D"">&nbsp; &nbsp; &nbsp; &nbsp; @[args[1]-&gt;device_name, =
this-&gt;unit_number, execname, pid] =3D =
sum(args[0]-&gt;bio_bcount);</div></div><div class=3D""><div =
class=3D"">}</div></div><div class=3D""><div class=3D""><br =
class=3D""></div></div><div class=3D""><div class=3D"">END</div></div><div=
 class=3D""><div class=3D"">{</div></div><div class=3D""><div =
class=3D"">&nbsp; &nbsp; &nbsp; &nbsp; printf("%10s%-3s %20s %10s =
%15s\n", "DEVICE", "", "APP", "PID", "BYTES");</div></div><div =
class=3D""><div class=3D"">&nbsp; &nbsp; &nbsp; &nbsp; printa("%10s%-3s =
%20s %10d %15@d\n", @);</div></div><div class=3D""><div =
class=3D"">}</div></div></blockquote><div class=3D""><div class=3D""><br =
class=3D""></div></div><div class=3D"">(Of course, the `(string)` cast =
does not work here because it's just not how DTrace works.)</div><div =
class=3D""><br class=3D""></div><div class=3D"">Best,</div><div =
class=3D"">Mateusz</div></body></html>=

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