--- In Jim Jackson <> wrote:
>
>
>
> On Tue, 4 Oct 2005, Keith Gilman wrote:
>
> > Newbie to Linux trying to set up a webserver with the TS7250. I
have
> > the server up but I want to be able to read the onboard
temperature.
> > I'm using the test-cgi script that shipped with the board with
the
> > following two lines added:
> >
> > echo UPTIME=`uptime`
> > echo TEMP=`./tempSensor' #tempSensor.c downloaded from the TS
website
> >
> > The uptime works as expected but the tempSensor logs the
following
> > error to the apache error logger:
> >
> > tempSensor.c:42 main:Assertion 'fd != -1' failed.
> >
> > The source is:
> >
> > int fd = open("/dev/mem", O_RDWR);
> > assert(fd != -1);
> >
>
> It's probably because the web server runs as user nobody as a
security
> measure. And you'll find that the permissions on /dev/mem are
wrong.
>
> 2 options
>
> first the bad one...
>
> change permissions on /dev/mem/ to allow anyone to read/write it
>
> not good security
>
> second the not so bad one :-) ......
>
> make your sure your program is owned by root, and executable by
all,
> and set the setuid bit
>
> chmod +s tempSensor
>
> so when the program is run, it will run AS IF root ran it and so
> it will have relevant permissions for accessing /dev/mem
>
> Jim
Jim,
Thanks, that did it. I knew about the setuid bit but couldn't
remember how to set it!
I owe you one :-)
-Keith
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