Add support for overriding the default hash format

This change adds support for a new --hash-format parameter that can be used to
override the default hash format used by SCons. The default remains MD5, but
this allows consumers to opt into SHA1, SHA256, or any other hash algorithm
offered by their implementation of hashlib.

3 files changed, 16 insertions, 16 deletions

diff --git a/SCons/Node/Alias.py b/SCons/Node/Alias.py
index 55d94f9..00e3726 100644
--- a/SCons/Node/Alias.py
+++ b/SCons/Node/Alias.py
@@ -37,7 +37,7 @@ import collections
 import SCons.Errors
 import SCons.Node
 import SCons.Util
-from SCons.Util import MD5signature
+from SCons.Util import hash_signature
 
 class AliasNameSpace(collections.UserDict):
     def Alias(self, name, **kw):
@@ -167,7 +167,7 @@ class Alias(SCons.Node.Node):
             pass
 
         contents = self.get_contents()
-        csig = MD5signature(contents)
+        csig = hash_signature(contents)
         self.get_ninfo().csig = csig
         return csig
 
diff --git a/SCons/Node/FS.py b/SCons/Node/FS.py
index ad9dd6f..044b3b6 100644
--- a/SCons/Node/FS.py
+++ b/SCons/Node/FS.py
@@ -53,7 +53,7 @@ import SCons.Node
 import SCons.Node.Alias
 import SCons.Subst
 import SCons.Util
-from SCons.Util import MD5signature, MD5filesignature, MD5collect
+from SCons.Util import hash_signature, hash_file_signature, hash_collect
 import SCons.Warnings
 
 from SCons.Debug import Trace
@@ -1870,7 +1870,7 @@ class Dir(Base):
         node is called which has a child directory, the child
         directory should return the hash of its contents."""
         contents = self.get_contents()
-        return MD5signature(contents)
+        return hash_signature(contents)
 
     def do_duplicate(self, src):
         pass
@@ -2635,7 +2635,7 @@ class File(Base):
     BuildInfo = FileBuildInfo
 
     # Although the command-line argument is in kilobytes, this is in bytes.
-    md5_chunksize = 65536
+    hash_chunksize = 65536
 
     def diskcheck_match(self):
         diskcheck_match(self, self.isdir,
@@ -2734,10 +2734,10 @@ class File(Base):
         Compute and return the MD5 hash for this file.
         """
         if not self.rexists():
-            return MD5signature('')
+            return hash_signature('')
         fname = self.rfile().get_abspath()
         try:
-            cs = MD5filesignature(fname, chunksize=File.md5_chunksize)
+            cs = hash_file_signature(fname, chunksize=File.hash_chunksize)
         except EnvironmentError as e:
             if not e.filename:
                 e.filename = fname
@@ -3223,7 +3223,7 @@ class File(Base):
         if csig is None:
 
             try:
-                if self.get_size() < File.md5_chunksize:
+                if self.get_size() < File.hash_chunksize:
                     contents = self.get_contents()
                 else:
                     csig = self.get_content_hash()
@@ -3235,7 +3235,7 @@ class File(Base):
                 csig = ''
             else:
                 if not csig:
-                    csig = SCons.Util.MD5signature(contents)
+                    csig = SCons.Util.hash_signature(contents)
 
         ninfo.csig = csig
 
@@ -3624,7 +3624,7 @@ class File(Base):
 
         cachedir, cachefile = self.get_build_env().get_CacheDir().cachepath(self)
         if not self.exists() and cachefile and os.path.exists(cachefile):
-            self.cachedir_csig = MD5filesignature(cachefile, File.md5_chunksize)
+            self.cachedir_csig = MD5filesignature(cachefile, File.hash_chunksize)
         else:
             self.cachedir_csig = self.get_csig()
         return self.cachedir_csig
@@ -3644,7 +3644,7 @@ class File(Base):
 
         executor = self.get_executor()
 
-        result = self.contentsig = MD5signature(executor.get_contents())
+        result = self.contentsig = hash_signature(executor.get_contents())
         return result
 
     def get_cachedir_bsig(self):
@@ -3675,7 +3675,7 @@ class File(Base):
         sigs.append(self.get_internal_path())
 
         # Merge this all into a single signature
-        result = self.cachesig = MD5collect(sigs)
+        result = self.cachesig = hash_collect(sigs)
         return result
 
 default_fs = None
diff --git a/SCons/Node/__init__.py b/SCons/Node/__init__.py
index f7d9289..d64a468 100644
--- a/SCons/Node/__init__.py
+++ b/SCons/Node/__init__.py
@@ -58,7 +58,7 @@ from SCons.Debug import logInstanceCreation
 import SCons.Executor
 import SCons.Memoize
 import SCons.Util
-from SCons.Util import MD5signature
+from SCons.Util import hash_signature
 
 from SCons.Debug import Trace
 
@@ -1181,7 +1181,7 @@ class Node(object, metaclass=NoSlotsPyPy):
 
         if self.has_builder():
             binfo.bact = str(executor)
-            binfo.bactsig = MD5signature(executor.get_contents())
+            binfo.bactsig = hash_signature(executor.get_contents())
 
         if self._specific_sources:
             sources = [s for s in self.sources if s not in ignore_set]
@@ -1219,7 +1219,7 @@ class Node(object, metaclass=NoSlotsPyPy):
             return self.ninfo.csig
         except AttributeError:
             ninfo = self.get_ninfo()
-            ninfo.csig = MD5signature(self.get_contents())
+            ninfo.csig = hash_signature(self.get_contents())
             return self.ninfo.csig
 
     def get_cachedir_csig(self):
@@ -1510,7 +1510,7 @@ class Node(object, metaclass=NoSlotsPyPy):
 
         if self.has_builder():
             contents = self.get_executor().get_contents()
-            newsig = MD5signature(contents)
+            newsig = hash_signature(contents)
             if bi.bactsig != newsig:
                 if t: Trace(': bactsig %s != newsig %s' % (bi.bactsig, newsig))
                 result = True