element.py: Accept absolute paths in overlap whitelists

This allows use of variables such as %{prefix} and matches the documentation.

To avoid breaking compatibility with older bst 1.x versions, it still accepts
paths without the leading slash.

based on 1ae17968

Fixes #721

buildstream/element.py

@@ -2362,7 +2362,7 @@ class Element(Plugin):
             if include_file and not exclude_file:
                 yield filename.lstrip(os.sep)
 
-    def __file_is_whitelisted(self, pattern):
+    def __file_is_whitelisted(self, path):
         # Considered storing the whitelist regex for re-use, but public data
         # can be altered mid-build.
         # Public data is not guaranteed to stay the same for the duration of
@@ -2374,7 +2374,7 @@ class Element(Plugin):
             whitelist_expressions = [utils._glob2re(self.__variables.subst(exp.strip())) for exp in whitelist]
             expression = ('^(?:' + '|'.join(whitelist_expressions) + ')$')
             self.__whitelist_regex = re.compile(expression)
-        return self.__whitelist_regex.match(pattern)
+        return self.__whitelist_regex.match(path) or self.__whitelist_regex.match(os.path.join(os.sep, path))
 
     # __extract():
     #

tests/frontend/overlaps.py

@@ -47,20 +47,22 @@ def test_overlaps_error(cli, datafiles, use_fatal_warnings):
 
 
 @pytest.mark.datafiles(DATA_DIR)
-def test_overlaps_whitelist(cli, datafiles):
+@pytest.mark.parametrize("element", ["collect-whitelisted.bst", "collect-whitelisted-abs.bst"])
+def test_overlaps_whitelist(cli, datafiles, element):
     project_dir = str(datafiles)
     gen_project(project_dir, True)
     result = cli.run(project=project_dir, silent=True, args=[
-        'build', 'collect-whitelisted.bst'])
+        'build', element])
     result.assert_success()
 
 
 @pytest.mark.datafiles(DATA_DIR)
-def test_overlaps_whitelist_ignored(cli, datafiles):
+@pytest.mark.parametrize("element", ["collect-whitelisted.bst", "collect-whitelisted-abs.bst"])
+def test_overlaps_whitelist_ignored(cli, datafiles, element):
     project_dir = str(datafiles)
     gen_project(project_dir, False)
     result = cli.run(project=project_dir, silent=True, args=[
-        'build', 'collect-whitelisted.bst'])
+        'build', element])
     result.assert_success()
 
 

tests/frontend/overlaps/a-whitelisted-abs.bst

+kind: import
+config:
+  source: /
+  target: /
+depends:
+- b-whitelisted.bst
+sources:
+- kind: local
+  path: "a"
+public:
+  bst:
+    overlap-whitelist:
+    - "/file*"

tests/frontend/overlaps/b-whitelisted-abs.bst

+kind: import
+config:
+  source: /
+  target: /
+depends:
+- c.bst
+sources:
+- kind: local
+  path: "b"
+variables:
+  FILE: /file
+public:
+  bst:
+    overlap-whitelist:
+    - /file2
+    - "%{FILE}3"

tests/frontend/overlaps/c-whitelisted-abs.bst

+kind: import
+config:
+  source: /
+  target: /
+sources:
+- kind: local
+  path: "c"
+public:
+  bst:
+    overlap-whitelist:
+    - "/file*"

tests/frontend/overlaps/collect-whitelisted-abs.bst

+kind: compose
+
+depends:
+- filename: a-whitelisted-abs.bst
+  type: build
+- filename: b-whitelisted-abs.bst
+  type: build
+- filename: c.bst
+  type: build