[Crash-utility] [PATCH] address compiler warning for extensions/trace.c

[Dave Anderson]

----- Original Message -----
> Hello Dave,
> 
> On 07/07/2015 11:20 PM, Dave Anderson wrote:
> > Hello Qiao,
> >
> > With more recent versions of gcc, extensions/trace.c generates this
> > warning:
> >
> >    $ make extensions
> >    ...
> >    gcc -Wall -g -shared -rdynamic -o trace.so trace.c -fPIC -DX86_64 -DLZO -DSNAPPY -DGDB_7_6
> >    /tmp/ccSOIphT.o: In function 'ftrace_show':
> >    /root/crash.git/extensions/trace.c:1560: warning: the use of 'mktemp' is dangerous, better use 'mkstemp'
> >    ...
> >    $
> >
> > I've attached an untested patch that replaces the mktemp() call with mkstemp().
> > I believe the only behavioral difference is that mkstemp() will create the file
> > automatically with permissions 600 and open flags of O_EXCL, whereas it is
> > currently being opened with permissions 644 and flags (O_WRONLY | O_CREAT |
> > O_TRUNC).
> 
> It seems good to me.
> 
> Acked-by: Qiao Nuohan <qiaonuohan at cn.fujitsu.com>


Thanks Qiao -- queued for crash-7.1.2:

  https://github.com/crash-utility/crash/commit/203853b71e3e615a587a8ea8f7f655820dc3a79c

Dave



> 
> >
> > Can you either ACK the patch, or address the warning as you would prefer?
> >
> > Thanks,
> >    Dave
> >
> >
> > use_mkstemp.patch
> >
> >
> > diff --git a/extensions/trace.c b/extensions/trace.c
> > index 8639fb2..9f81568 100644
> > --- a/extensions/trace.c
> > +++ b/extensions/trace.c
> > @@ -1533,7 +1533,6 @@ static void ftrace_show(int argc, char *argv[])
> >   	FILE *file;
> >   	size_t ret;
> >   	size_t nitems __attribute__ ((__unused__));
> > -	char *unused __attribute__ ((__unused__));
> >
> >   	/* check trace-cmd */
> >   	if (env_trace_cmd)
> > @@ -1557,8 +1556,9 @@ static void ftrace_show(int argc, char *argv[])
> >   	}
> >
> >   	/* dump trace.dat to the temp file */
> > -	unused = mktemp(tmp);
> > -	fd = open(tmp, O_WRONLY | O_CREAT | O_TRUNC, 0644);
> > +	fd = mkstemp(tmp);
> 
> "tmp" will be modified to the path of the temporary file, good.
> 
> > +	if (fd < 0)
> > +		return;
> >   	if (trace_cmd_data_output(fd) < 0)
> >   		goto out;
> >
> 
> 
> --
> Regards
> Qiao Nuohan
>