1 files changed, 54 insertions, 0 deletions
diff --git a/pym/portage/checksum.py b/pym/portage/checksum.py
index daf4a0cbf..de4cc668a 100644
--- a/pym/portage/checksum.py
+++ b/pym/portage/checksum.py
@@ -217,6 +217,60 @@ def _filter_unaccelarated_hashes(digests):
 
 	return digests
 
+class _hash_filter(object):
+	"""
+	Implements filtering for PORTAGE_CHECKSUM_FILTER.
+	"""
+
+	__slots__ = ('transparent', '_tokens',)
+
+	def __init__(self, filter_str):
+		tokens = filter_str.upper().split()
+		if not tokens or tokens[-1] == "*":
+			del tokens[:]
+		self.transparent = not tokens
+		tokens.reverse()
+		self._tokens = tuple(tokens)
+
+	def __call__(self, hash_name):
+		if self.transparent:
+			return True
+		matches = ("*", hash_name)
+		for token in self._tokens:
+			if token in matches:
+				return True
+			elif token[:1] == "-":
+				if token[1:] in matches:
+					return False
+		return False
+
+def _apply_hash_filter(digests, hash_filter):
+	"""
+	Return a new dict containing the filtered digests, or the same
+	dict if no changes are necessary. This will always preserve at
+	at least one digest, in order to ensure that they are not all
+	discarded.
+	"""
+	if hash_filter.transparent:
+		return digests
+
+	verifiable_hash_types = set(digests).intersection(hashfunc_map)
+	verifiable_hash_types.discard("size")
+	modified = False
+	if len(verifiable_hash_types) > 1:
+		for k in list(verifiable_hash_types):
+			if not hash_filter(k):
+				modified = True
+				verifiable_hash_types.remove(k)
+				if len(verifiable_hash_types) == 1:
+					break
+
+	if modified:
+		digests = dict((k, v) for (k, v) in digests.items()
+			if k == "size" or k in verifiable_hash_types)
+
+	return digests
+
 def verify_all(filename, mydict, calc_prelink=0, strict=0):
 	"""
 	Verify all checksums against a file.