Symlink support

- added some security checks so that symlinks can be supported
- also some code quality changes

lib/worker_multibuild.py

@@ -1,5 +1,5 @@
-from os import listdir
-from os.path import exists, isfile, join, islink
+from os import getcwd, listdir
+from os.path import exists, isfile, islink, join, realpath
 import requests
 import re
 from subprocess import Popen, PIPE
@@ -69,14 +69,23 @@ def list_jobs(directory=".buildbot"):
         flag = False
         for fname in files:
             filepath = join(directory, item, fname)
+            # must exist
             if not exists(filepath):
                 continue
-            if islink(filepath) or not isfile(filepath):
+            # must be a file
+            if not isfile(filepath):
+                flag = True
+                break
+            # symlink OK as long as it points to files within the repo
+            if islink(filepath) \
+                    and not realpath(filepath).startswith(getcwd()):
                 flag = True
                 break
         if flag:
             continue
-        if (exists(join(directory, item, 'Dockerfile')) and exists(join(directory, item, 'build.sh'))) or exists(join(directory, item, 'test.sh')):
+        if (exists(join(directory, item, 'Dockerfile'))
+                and exists(join(directory, item, 'build.sh'))) \
+                or exists(join(directory, item, 'test.sh')):
             results.append(item)
     return results
 
@@ -90,7 +99,8 @@ def get_revision(branch):
 
 def _get_dockerfile_contents(dockerfile):
     """
-    Read contents of a Dockerfile and add extra contents for the given os_codename
+    Read contents of a Dockerfile and add buildbot worker bootstrap
+    for a given os_codename
     """
     os_codename = 'bionic'
     res = ""
@@ -117,7 +127,8 @@ def _get_dockerfile_contents(dockerfile):
     return res + dockerfile_extra_contents[os_codename]
 
 
-def trigger_child_hooks(buildbotUrl: str, repository, branch, revision, directory=".buildbot"):
+def trigger_child_hooks(buildbotUrl: str, repository, branch, revision,
+                        directory=".buildbot"):
     request_url = buildbotUrl + ty
     # List all jobs in the directory
     jobs = list_jobs(directory)
@@ -160,8 +171,10 @@ def trigger_child_hooks(buildbotUrl: str, repository, branch, revision, director
             "project": "/".join(repository.split("/")[-2:]),
         }
 
-        retval = requests.post(request_url, headers=request_headers, json=request_data)
-        print("Triggered job for {} on {}: {}".format(job, request_url, retval.text))
+        retval = requests.post(request_url, headers=request_headers,
+                               json=request_data)
+        print("Triggered job for {} on {}: {}".format(job, request_url,
+                                                      retval.text))
 
 
 if __name__ == "__main__":