ConfHandler: Allow the '@' character in variable flag names

This patch enables the usage of the '@' character in variable flag
names.

One use case of variable flags is to assign the network namespaces of
some systemd services/targets to configure other parts of the build
process of some system. The filenames of systemd services/targets might
contain the '@' character if they are template unit files that can take
in a single parameter/argument and be instanced multiple times, as
indicated by systemd's official manual page.

The '@' character is disallowed as the first character in a variable
flag name. Imposing more restrictions on the first character is a
compromise to make parsing easier and to allow for more options in the
future to extend the syntax.

This patch is successfully verified by creating a custom BitBake recipe
that sets and unsets the value of a variable flag with the '@' character
in its name and ensuring that no ParseError is being thrown. Regression
tests have also been added to `bb.parse`.

`bin/bitbake-selftest` has also been successfully executed and all tests
passed.

Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

2 files changed, 23 insertions, 2 deletions

diff --git a/lib/bb/parse/parse_py/ConfHandler.py b/lib/bb/parse/parse_py/ConfHandler.py
index 307606728..05c627ec8 100644
--- a/lib/bb/parse/parse_py/ConfHandler.py
+++ b/lib/bb/parse/parse_py/ConfHandler.py
@@ -21,7 +21,7 @@ __config_regexp__  = re.compile( r"""
     ^
     (?P<exp>export\s+)?
     (?P<var>[a-zA-Z0-9\-_+.${}/~:]+?)
-    (\[(?P<flag>[a-zA-Z0-9\-_+.]+)\])?
+    (\[(?P<flag>[a-zA-Z0-9\-_+.][a-zA-Z0-9\-_+.@]+)\])?
 
     \s* (
         (?P<colon>:=) |
@@ -45,7 +45,7 @@ __include_regexp__ = re.compile( r"include\s+(.+)" )
 __require_regexp__ = re.compile( r"require\s+(.+)" )
 __export_regexp__ = re.compile( r"export\s+([a-zA-Z0-9\-_+.${}/~]+)$" )
 __unset_regexp__ = re.compile( r"unset\s+([a-zA-Z0-9\-_+.${}/~]+)$" )
-__unset_flag_regexp__ = re.compile( r"unset\s+([a-zA-Z0-9\-_+.${}/~]+)\[([a-zA-Z0-9\-_+.]+)\]$" )
+__unset_flag_regexp__ = re.compile( r"unset\s+([a-zA-Z0-9\-_+.${}/~]+)\[([a-zA-Z0-9\-_+.][a-zA-Z0-9\-_+.@]+)\]$" )
 __addpylib_regexp__      = re.compile(r"addpylib\s+(.+)\s+(.+)" )
 
 def init(data):
diff --git a/lib/bb/tests/parse.py b/lib/bb/tests/parse.py
index ee7f2534f..d27c7c6f1 100644
--- a/lib/bb/tests/parse.py
+++ b/lib/bb/tests/parse.py
@@ -218,3 +218,24 @@ VAR = " \\
         with self.assertRaises(bb.BBHandledException):
             d = bb.parse.handle(f.name, self.d)['']
 
+
+    at_sign_in_var_flag = """
+A[flag@.service] = "nonet"
+B[flag@.target] = "ntb"
+
+unset A[flag@.service]
+"""
+    def test_parse_at_sign_in_var_flag(self):
+        f = self.parsehelper(self.at_sign_in_var_flag)
+        d = bb.parse.handle(f.name, self.d)['']
+        self.assertEqual(d.getVar("A"), None)
+        self.assertEqual(d.getVar("B"), None)
+        self.assertEqual(d.getVarFlag("A","flag@.service"), None)
+        self.assertEqual(d.getVarFlag("B","flag@.target"), "ntb")
+
+    def test_parse_invalid_at_sign_in_var_flag(self):
+        invalid_at_sign = self.at_sign_in_var_flag.replace("B[f", "B[@f")
+        f = self.parsehelper(invalid_at_sign)
+        with self.assertRaises(bb.parse.ParseError):
+            d = bb.parse.handle(f.name, self.d)['']
+