Bandit should gracefully handle file errors

[ericwb]

Bandit dumps tracebacks when it fails to access files. It would be preferrable if Bandit gracefully handled the exceptions and displayed a user appropriate error. Also, it should be checking for the existence of the output file prior to running the scan.

promd-1s-dhcp317:bandit browne$ bandit -r ../openstack/ -o /Library/
86 [0.. 50.. ]
Traceback (most recent call last):
File "/usr/local/bin/bandit", line 10, in
sys.exit(main())
File "/Library/Python/2.7/site-packages/bandit/bandit.py", line 88, in main
args.output_format)
File "/Library/Python/2.7/site-packages/bandit/core/manager.py", line 112, in output_results
output_format=output_format
File "/Library/Python/2.7/site-packages/bandit/core/result_store.py", line 393, in report
with open(output_filename, 'w') as fout:
IOError: [Errno 21] Is a directory: '/Library/'

promd-1s-dhcp317:bandit browne$ bandit -r ../openstack/ -o /Library/sfd
86 [0.. 50.. ]
Traceback (most recent call last):
File "/usr/local/bin/bandit", line 10, in
sys.exit(main())
File "/Library/Python/2.7/site-packages/bandit/bandit.py", line 88, in main
args.output_format)
File "/Library/Python/2.7/site-packages/bandit/core/manager.py", line 112, in output_results
output_format=output_format
File "/Library/Python/2.7/site-packages/bandit/core/result_store.py", line 393, in report
with open(output_filename, 'w') as fout:
IOError: [Errno 13] Permission denied: '/Library/sfd'

[ericwb]

Bad import of bug from launchpad. Closing..