russell@unturf.com
0a580b313d
Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com Patches, unit tests, benchmarks, whitepaper, and outreach briefs. Public domain — no copyright claimed. Use freely.
38 lines
1.5 KiB
Diff
38 lines
1.5 KiB
Diff
diff --git a/distlib/util.py b/distlib/util.py
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index 0d5bd7a..f5f3c83 100644
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--- a/distlib/util.py
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+++ b/distlib/util.py
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@@ -1154,6 +1154,8 @@ class Sequencer(object):
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# http://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
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index_counter = [0]
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stack = []
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+ # CWE-407 fix: set for O(1) stack membership test (list `in` is O(n))
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+ stack_set = set()
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lowlinks = {}
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index = {}
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result = []
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@@ -1166,6 +1168,7 @@ class Sequencer(object):
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lowlinks[node] = index_counter[0]
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index_counter[0] += 1
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stack.append(node)
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+ stack_set.add(node)
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# Consider successors
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try:
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@@ -1177,7 +1180,7 @@ class Sequencer(object):
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# Successor has not yet been visited
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strongconnect(successor)
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lowlinks[node] = min(lowlinks[node], lowlinks[successor])
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- elif successor in stack:
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+ elif successor in stack_set:
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# the successor is in the stack and hence in the current
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# strongly connected component (SCC)
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lowlinks[node] = min(lowlinks[node], index[successor])
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@@ -1188,6 +1191,7 @@ class Sequencer(object):
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while True:
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successor = stack.pop()
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+ stack_set.discard(successor)
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connected_component.append(successor)
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if successor == node:
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break
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