Coverity issues in contrail-controller/agent_param.cc

I have run Coverity on branch R5.0 and it reported the
following issues in contrail-controller/agent_param.cc:
- buffer_size_warning: Calling strncpy with a maximum size
argument of 16 bytes on destination array ifrn.ifrn_name of
size 16 bytes might leave the destination string unterminated
in agent_param.cc:ValidateInterface
- leaked_storage: Variable f going out of scope leaks the storage
it points to in agent_param.cc:ValidateInterface

Indeed, for the 1st issue, the length of std::string::c_str() may be
greater than IF_NAMESIZE. In that case, after calling strncpy, ifrn.ifrn_name
will not be a NULL-terminated string.
For the 2nd issue, we need to close the file pointer before exiting the function.

Change-Id: Iceaf2490ae224b7134a4781f894b784f016e42a3
Closes-bug: #1770169
Signed-off-by: Anda Nicolae <anicolae@lenovo.com>

src/vnsw/agent/init/agent_param.cc

@@ -955,7 +955,7 @@ static bool ValidateInterface(bool test_mode, const std::string &ifname,
 
     struct ifreq ifr;
     memset(&ifr, 0, sizeof(ifr));
-    strncpy(ifr.ifr_name, ifname.c_str(), IF_NAMESIZE);
+    strncpy(ifr.ifr_name, ifname.c_str(), IF_NAMESIZE-1);
     int err = ioctl(fd, SIOCGIFFLAGS, (void *)&ifr);
     close (fd);
 
@@ -979,6 +979,7 @@ static bool ValidateInterface(bool test_mode, const std::string &ifname,
                 *eth_encap = "none";
             }
         }
+        fclose(f);
     }
 #endif