TypeError: compile() expected string without null bytes

[adiroiban]

See https://travis-ci.org/twisted/twisted/jobs/148667038

this is produced if we run twistedchecker

we also got this errors in the past, is just that they were hidden among the many linter errors.

Traceback (most recent call last):
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/pylint/lint.py", line 586, in get_astng
    return MANAGER.astng_from_file(filepath, modname, source=True)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/manager.py", line 104, in astng_from_file
    return ASTNGBuilder(self).file_build(filepath, modname)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 128, in file_build
    node = self.string_build(data, modname, path)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 134, in string_build
    module = self._data_build(data, modname, path)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 150, in _data_build
    node = parse(data + '\n')
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 39, in parse
    return compile(string, "<string>", 'exec', PyCF_ONLY_AST)
TypeError: compile() expected string without null bytes
Traceback (most recent call last):
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/pylint/lint.py", line 586, in get_astng
    return MANAGER.astng_from_file(filepath, modname, source=True)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/manager.py", line 104, in astng_from_file
    return ASTNGBuilder(self).file_build(filepath, modname)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 128, in file_build
    node = self.string_build(data, modname, path)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 134, in string_build
    module = self._data_build(data, modname, path)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 150, in _data_build
    node = parse(data + '\n')
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 39, in parse
    return compile(string, "<string>", 'exec', PyCF_ONLY_AST)
TypeError: compile() expected string without null bytes
Traceback (most recent call last):
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/pylint/lint.py", line 586, in get_astng
    return MANAGER.astng_from_file(filepath, modname, source=True)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/manager.py", line 104, in astng_from_file
    return ASTNGBuilder(self).file_build(filepath, modname)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 128, in file_build
    node = self.string_build(data, modname, path)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 134, in string_build
    module = self._data_build(data, modname, path)
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 150, in _data_build
    node = parse(data + '\n')
  File "/home/travis/build/twisted/twisted/build/txchecker-travis/lib/python2.7/site-packages/logilab/astng/builder.py", line 39, in parse
    return compile(string, "<string>", 'exec', PyCF_ONLY_AST)
TypeError: compile() expected string without null bytes

[tomprince]

This is caused by

src/twisted/test/raiser.so
src/twisted/runner/portmap.so
src/twisted/python/_sendmsg.so

trying to be opened as python files.

This happens in two places, once in twistedchecker/core/exceptionfinder.py and once somewhere inside pylint.

[tomprince]

diff --git a/twistedchecker/core/exceptionfinder.py b/twistedchecker/core/exceptionfinder.py
index 1557cdb..b8cc0d3 100644
--- a/twistedchecker/core/exceptionfinder.py
+++ b/twistedchecker/core/exceptionfinder.py
@@ -73,7 +73,9 @@ def findAllExceptions(pathToCheck):
     """
     finder = PatternFinder()
     if os.path.isfile(pathToCheck):
-        findPatternsInFile(open(pathToCheck).read(), finder)
+        _, extname = os.path.splitext(pathToCheck)
+        if extname == ".py":
+            findPatternsInFile(open(pathToCheck).read(), finder)
     else:
         for path, dirs, files in os.walk(pathToCheck):
             for file in files:

fixes the first error, uncovering the second. I'm not sure if the second can be addressed without changing pylint.