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codeparser: Use hashlib for hashing, not hash()

PATCH New Richard Purdie 1 participant 1 message Jun 3, 2016

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Richard Purdie

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PATCH 1/1 codeparser: Use hashlib for hashing, not hash()

"hash() is randomised by default each time you start a new instance of recent versions (Python3.3+) to prevent dictionary insertion DOS attacks"

which means we need to use hashlib.md5 to get consistent values for the codeparser cache under python 3. Prior to this, the codeparser cache was effectively useless under python3 as shown by performance regressions.

Signed-off-by Richard Purdie <[email protected]>
bitbake/lib/bb/codeparser.py +6 -2
index b1d067a..00551ba 100644
@@ -6,12 +6,16 @@ import pickle
 import bb.pysh as pysh
 import os.path
 import bb.utils, bb.data
+import hashlib
 from itertools import chain
 from bb.pysh import pyshyacc, pyshlex, sherrors
 from bb.cache import MultiProcessCache
 
 logger = logging.getLogger('BitBake.CodeParser')
 
+def bbhash(s):
+    return hashlib.md5(s.encode("utf-8")).hexdigest()
+
 def check_indent(codestr):
     """If the code is indented, add a top level piece of code to 'remove' the indentation"""
 

@@ -269,7 +273,7 @@ class PythonParser():
         if not node or not node.strip():
             return
 
-        h = hash(str(node))
+        h = bbhash(str(node))
 
         if h in codeparsercache.pythoncache:
             self.references = set(codeparsercache.pythoncache[h].refs)

@@ -314,7 +318,7 @@ class ShellParser():
         commands it executes.
         """
 
-        h = hash(str(value))
+        h = bbhash(str(value))
 
         if h in codeparsercache.shellcache:
             self.execs = set(codeparsercache.shellcache[h].execs)