bitbake: parse: Add support for addpylib conf file directive and BB_GLOBAL_PYMODULES

For many years OE-Core has injected it's own python modules into the
python namespace using an immediate expansion of a variable in base.bbclass.
It also added all entries from BBPATH to sys.path.

We really need this to become a first class citizen of the langauge, this new
addpylib directive allows that. Usage is of the form:

addpylib <directory> <namespace>

The namespace is imported and if there is an attribute BBIMPORT, that
list of names is iterated and imported too.

This mirrors what OE-Core has done for a long time with one difference in
implmentation, sys.path is only appended to. This means later imported
namespaces can't overwrite an earlier one and can't overwrite the main
python module space. In practice we've never done that and it isn't
something we should encourage or support.

The new directive is only applied for .conf files and not other filetypes
as it only makes sense in that context. It is also only allowed in the
"base configuration" context of cookerdata since adding it at the recipe
level wouldn't work properly due to the way it changes the global namespace.

At the same time, move the list of modules to place in the global namespace
into a BB_GLOBAL_PYMODULES variable. It is intended that only the core layer
should touch this and it is meant to be a very small list, usually os and sys.
BB_GLOBAL_PYMODULES is expected to be set before the first addpylib directive.

Layers adding a lib directory will now need to use this directive as BBPATH
is not going to be added automatically by OE-Core in future. The directives are
immediate operations so it does make modules available sooner than the current
OE-Core approach.

The new code appends to sys.path rather than prepends as core did, as
overwriting python standard library modules would be a bad idea and naturally
encouraging people to collaborate around our own core modules is desireable.

(Bitbake rev: afb8478d3853f6edf3669b93588314627d617d6b)

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

1 files changed, 27 insertions, 0 deletions

diff --git a/bitbake/lib/bb/parse/ast.py b/bitbake/lib/bb/parse/ast.py
index 9e0a0f5c98..862087c77d 100644
--- a/bitbake/lib/bb/parse/ast.py
+++ b/bitbake/lib/bb/parse/ast.py
@@ -9,6 +9,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 
+import sys
 import bb
 from bb import methodpool
 from bb.parse import logger
@@ -269,6 +270,29 @@ class BBHandlerNode(AstNode):
             data.setVarFlag(h, "handler", 1)
         data.setVar('__BBHANDLERS', bbhands)
 
+class PyLibNode(AstNode):
+    def __init__(self, filename, lineno, libdir, namespace):
+        AstNode.__init__(self, filename, lineno)
+        self.libdir = libdir
+        self.namespace = namespace
+
+    def eval(self, data):
+        global_mods = (data.getVar("BB_GLOBAL_PYMODULES") or "").split()
+        for m in global_mods:
+            if m not in bb.utils._context:
+                bb.utils._context[m] = __import__(m)
+
+        libdir = data.expand(self.libdir)
+        if libdir not in sys.path:
+            sys.path.append(libdir)
+        try:
+            bb.utils._context[self.namespace] = __import__(self.namespace)
+            toimport = getattr(bb.utils._context[self.namespace], "BBIMPORTS", [])
+            for i in toimport:
+                bb.utils._context[self.namespace] = __import__(self.namespace + "." + i)
+        except AttributeError as e:
+            bb.error("Error importing OE modules: %s" % str(e))
+
 class InheritNode(AstNode):
     def __init__(self, filename, lineno, classes):
         AstNode.__init__(self, filename, lineno)
@@ -320,6 +344,9 @@ def handleDelTask(statements, filename, lineno, m):
 def handleBBHandlers(statements, filename, lineno, m):
     statements.append(BBHandlerNode(filename, lineno, m.group(1)))
 
+def handlePyLib(statements, filename, lineno, m):
+    statements.append(PyLibNode(filename, lineno, m.group(1), m.group(2)))
+
 def handleInherit(statements, filename, lineno, m):
     classes = m.group(1)
     statements.append(InheritNode(filename, lineno, classes))