Optional argument "source_path" ignored by build_fuzzers

[rlohning]

The help text shown when calling
python infra/helper.py build_fuzzers
without further arguments reads that an optional argument "source_path" can be passed. Some months ago, this used to build sources from that path instead of those in the Dockerfile.

When I try it now, this argument seems to be ignored and the fuzzers are always being build from the Dockerfile. Am I missing something? It looks to me like either build_fuzzers has a bug or the help text is outdated.

[DavidKorczynski]

Is this related to the qt project? I think it might be because of this commit: a0b3dc9 where the destination folder of the project being cloned switched from qt to qt5, and all of the source code used to be in the /src/qt folder but is now spread out across several folders instead.

The code for source_path is a bit hacky in that it relies on matching lines in the Dockerfile with project names, see e.g.:

oss-fuzz/infra/helper.py

Lines 507 to 528 in 5a889cf

	def workdir_from_lines(lines, default='/src'):
	"""Gets the WORKDIR from the given lines."""
	for line in reversed(lines): # reversed to get last WORKDIR.
	match = re.match(WORKDIR_REGEX, line)
	if match:
	workdir = match.group(1)
	workdir = workdir.replace('$SRC', '/src')
	if not os.path.isabs(workdir):
	workdir = os.path.join('/src', workdir)
	return os.path.normpath(workdir)
	return default
	def _workdir_from_dockerfile(project):
	"""Parses WORKDIR from the Dockerfile for the given project."""
	with open(project.dockerfile_path) as file_handle:
	lines = file_handle.readlines()
	return workdir_from_lines(lines, default=os.path.join('/src', project.name))

The specific code that adds the logic to the docker command is

oss-fuzz/infra/helper.py

Lines 656 to 669 in 5a889cf

	workdir = _workdir_from_dockerfile(project)
	if mount_path:
	command += [
	'-v',
	'%s:%s' % (_get_absolute_path(source_path), mount_path),
	]
	else:
	if workdir == '/src':
	logging.error('Cannot use local checkout with "WORKDIR: /src".')
	return False
	command += [
	'-v',
	'%s:%s' % (_get_absolute_path(source_path), workdir),

In the case of qt the identified workdir returned from _workdir_from_dockerfile is /src/qt which means when building the fuzzers the following is added to the Docker command: -v source_path_provided:/src/qt. As such, since the aforementioned commit has changed the locations of the source files in the Docker image (from qt to various subfolders?) then the content of the source path you provided is not used.

One way to solve this is to place all source code in the Dockefile inside of e.g. $SRC/qt/ again, and then that should work.