lib/oe: Add sstatesig, OE specific signature generator classes

This patch adds SignatureGenerator classes specific to OE. For now,
these emulate the previous behaviour with the exception that
dependencies on quilt-native are now ignored for checksum purposes.

The intent is to allow easier experimentation and customisation of
this code in future as a result of these changes.

Note that these changes require pending bitbake patches.

(From OE-Core rev: cb73cf4299a192e6065d567fae700987c3f937aa)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/base.bbclass

@@ -9,7 +9,7 @@ inherit utility-tasks
 inherit metadata_scm
 inherit logging
 
-OE_IMPORTS += "os sys time oe.path oe.utils oe.data oe.packagegroup"
+OE_IMPORTS += "os sys time oe.path oe.utils oe.data oe.packagegroup oe.sstatesig"
 OE_IMPORTS[type] = "list"
 
 def oe_import(d):

meta/lib/oe/sstatesig.py

@@ -0,0 +1,48 @@
+import bb.siggen
+
+def sstate_rundepfilter(fn, recipename, task, dep, depname):
+    # Return True if we should keep the dependency, False to drop it
+    def isNative(x):
+        return x.endswith("-native")
+    def isCross(x):
+        return x.endswith("-cross") or x.endswith("-cross-initial") or x.endswith("-cross-intermediate")
+    def isNativeSDK(x):
+        return x.endswith("-nativesdk")
+
+    # Always include our own inter-task dependencies
+    if recipename == depname:
+        return True
+
+    # Quilt (patch application) changing isn't likely to affect anything
+    if depname == "quilt-native":
+        return False
+    # Don't change native/cross/nativesdk recipe dependencies any further
+    if isNative(recipename) or isCross(recipename) or isNativeSDK(recipename):
+        return True
+
+    # Only target packages beyond here
+
+    # Drop native/cross/nativesdk dependencies from target recipes
+    if isNative(depname) or isCross(depname) or isNativeSDK(depname):
+        return False
+
+    # Default to keep dependencies
+    return True
+
+class SignatureGeneratorOEBasic(bb.siggen.SignatureGeneratorBasic):
+    name = "OEBasic"
+    def init_rundepcheck(self, data):
+        pass
+    def rundep_check(self, fn, recipename, task, dep, depname):
+        return sstate_rundepfilter(fn, recipename, task, dep, depname)
+
+class SignatureGeneratorOEBasicHash(bb.siggen.SignatureGeneratorBasicHash):
+    name = "OEBasicHash"
+    def init_rundepcheck(self, data):
+        pass
+    def rundep_check(self, fn, recipename, task, dep, depname):
+        return sstate_rundepfilter(fn, recipename, task, dep, depname)
+
+# Insert these classes into siggen's namespace so it can see and select them
+bb.siggen.SignatureGeneratorOEBasic = SignatureGeneratorOEBasic
+bb.siggen.SignatureGeneratorOEBasicHash = SignatureGeneratorOEBasicHash