VPP-189 Some bugfixes for issues reported by Coverity

VPP-189 Some bugfixes for issues reported by Coverity

CID 130914 Buffer not null terminated
CID 130916 Unchecked return value
CID 130938 Unchecked return value from library
CID 130939 Unchecked return value from library
CID 130940 Unchecked return value from library
CID 131042 Argument cannot be negative
CID 131222 Resource leak
CID 131223 Resource leak
CID 131334 Double close
CID 131335 Read from pointer after free
CID 131211 Resource leak
CID 131212 Resource leak

Change-Id: Idd80b91f621278e0be15911f2ed4354dbe4fc7f2
Signed-off-by: Chris Luke <chrisy@flirble.org>