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Re: Analysis of clang results against the nmap-npingchanges branch for nping directory only.
From: James Rogers <jamesmrogers () gmail com>
Date: Wed, 13 Jun 2012 15:06:22 -0400

On Wed, Jun 13, 2012 at 2:09 PM, David Fifield <david () bamsoftware com> wrote:
On Wed, Jun 13, 2012 at 02:05:55PM -0400, James Rogers wrote:
Only found two real issues:

API           Argument with 'nonnull' attribute passed null   nping
/common_modified.cc   490     20
490   s = strchr(addy[i],',');
      20 Null pointer passed as an argument to a 'nonnull' parameter

      Is a bug.  hostexp is never checked to make sure it is not NULL.
      371     char *hostexp = strdup(target_expr);
      386     addy[0] = addy[1] = addy[2] = addy[3] = addy[4] = NULL;
      387     addy[0] = r = hostexp;

Dead store    Dead assignment                                 nping /EchoServer.cc            1507    1
1507  loopret=nsock_loop(nsp, 1000);

      Value stored to 'loopret' is never read

      This is a bug.  Easy to fix.
      There were a lot more references to loopret that have been removed in
this branch, this looks like the last one remaining.

The rest of the bugs were generated by clang not recognizing that
nping_fatal() and fatal() do not return.

Is there a way to annotate these functions so that Clang can know they
don't return? In nmap_error.h we have for example,

void fatal(const char *fmt, ...)
    __attribute__ ((noreturn))

But that's missing in nping/output.h. If you add it, do those spurious
warnings go away?

David Fifield

The documentation talked about ways to mark things in general, but I
didn't see any detailed explanation of how to do that.

I'll add that attribute to the nmap-npingchanges version I have and
see if it stops these bugs from being reported when I run the tool

James Rogers
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