bitbake: include varflags in checksums

Add a dependency to each variable on a filtered list of its varflags.
This is intended to catch things such as SRC_URI checksums, varflags
controlling extra functionality from classes (e.g. the recently updated
update-alternatives class in OE-Core), etc. and ensure their values
influence the sstate checksums.

There is an exclusion list which needs to be set via bitbake.conf
(BB_SIGNATURE_EXCLUDE_FLAGS), if this is not set then the functionality
is disabled. The existing vardepsexclude mechanism can also be used to
exclude undesired varflags, but they must be fully specified, e.g.:

do_patch[vardepsexclude] += "do_patch[someflag]"

Implements [YOCTO #2517].

(Bitbake rev: 56c1ab18fcaf4ac245dcb412ed55e8e0af07883b)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/data.py

@@ -279,7 +279,12 @@ def build_dependencies(key, keys, shelldeps, vardepvals, d):
     deps = set()
     vardeps = d.getVarFlag(key, "vardeps", True)
     try:
-        value = d.getVar(key, False)
+        if key[-1] == ']':
+            vf = key[:-1].split('[')
+            value = d.getVarFlag(vf[0], vf[1], False)
+        else:
+            value = d.getVar(key, False)
+
         if key in vardepvals:
            value =  d.getVarFlag(key, "vardepvalue", True)
         elif d.getVarFlag(key, "func"):
@@ -301,6 +306,19 @@ def build_dependencies(key, keys, shelldeps, vardepvals, d):
             parser = d.expandWithRefs(value, key)
             deps |= parser.references
             deps = deps | (keys & parser.execs)
+
+        # Add varflags, assuming an exclusion list is set
+        varflagsexcl = d.getVar('BB_SIGNATURE_EXCLUDE_FLAGS', True)
+        if varflagsexcl:
+            varfdeps = []
+            varflags = d.getVarFlags(key)
+            if varflags:
+                for f in varflags:
+                    if f not in varflagsexcl:
+                        varfdeps.append('%s[%s]' % (key, f))
+            if varfdeps:
+                deps |= set(varfdeps)
+
         deps |= set((vardeps or "").split())
         deps -= set((d.getVarFlag(key, "vardepsexclude", True) or "").split())
     except:

bitbake/lib/bb/siggen.py

@@ -108,6 +108,10 @@ class SignatureGeneratorBasic(SignatureGenerator):
                 data = data + dep
                 if dep in lookupcache:
                     var = lookupcache[dep]
+                elif dep[-1] == ']':
+                    vf = dep[:-1].split('[')
+                    var = d.getVarFlag(vf[0], vf[1], False)
+                    lookupcache[dep] = var
                 else:
                     var = d.getVar(dep, False)
                     lookupcache[dep] = var