[Qemu-block] [PATCH for-2.6?] qemu-iotests: iotests: fail hard if not run via "check"

[Sascha Silbe]

Running an iotests-based Python test directly might appear to work,
but may fail in subtle ways and is insecure:

- It creates files with predictable file names in a world-writable
  location (/var/tmp).

- Tests expect the environment to be set up by check. E.g. 041 and 055
  may take the wrong code paths if QEMU_DEFAULT_MACHINE is not
  set. This can lead to false negatives.

Instead fail hard and tell the user we want to be run via "check".

Signed-off-by: Sascha Silbe <address@hidden>
Reviewed-by: Bo Tu <address@hidden>
---
It's possible to fix iotests.py to work even outside of check, but
that requires reimplementing parts of what check currently does. I'd
prefer not to do that this late in the cycle.

It would be nice to have this in 2.6, just in case someone even tries
running a Python-based test directly instead of using ./check like for
the shell-based tests. But it's not crucial.
---
 tests/qemu-iotests/iotests.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 0c0b533..8c7138f 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -46,7 +46,7 @@ if os.environ.get('QEMU_OPTIONS'):
 
 imgfmt = os.environ.get('IMGFMT', 'raw')
 imgproto = os.environ.get('IMGPROTO', 'file')
-test_dir = os.environ.get('TEST_DIR', '/var/tmp')
+test_dir = os.environ.get('TEST_DIR')
 output_dir = os.environ.get('OUTPUT_DIR', '.')
 cachemode = os.environ.get('CACHEMODE')
 qemu_default_machine = os.environ.get('QEMU_DEFAULT_MACHINE')
@@ -441,6 +441,10 @@ def verify_quorum():
 def main(supported_fmts=[], supported_oses=['linux']):
     '''Run tests'''
 
+    if test_dir is None or qemu_default_machine is None:
+        sys.stderr.write('Please run this test via ./check\n')
+        sys.exit(os.EX_USAGE)
+
     debug = '-d' in sys.argv
     verbosity = 1
     verify_image_format(supported_fmts)
-- 
1.9.1