Do not require $srctree to be set for non-kernel projects.

(It was never required if you explicitly passed a 'base_dir', but it's a
bit silly to have to do that too.)

This is a bug. I expected os.path.expandvars() to replace references
non-set environment variables with nothing, but it leaves them as is.

Work around it by letting base_dir = None be special and the default. It
uses $srctree if set and the current directory otherwise. This has the
following advantages:

 - It avoids having to reimplement a different version of
   os.path.expandvars() and special-casing "" to mean the current
   directory.

 - It means '$' can appear in paths. (Though it probably never will.)

Maybe the expansion behavior could be removed too, but keep it for now
to be backwards compatible.

3 files changed, 26 insertions, 10 deletions

diff --git a/kconfiglib.py b/kconfiglib.py
index ed1d50c..5dd53cf 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -84,7 +84,7 @@ class Config(object):
 
     def __init__(self,
                  filename = "Kconfig",
-                 base_dir = "$srctree",
+                 base_dir = None,
                  print_warnings = True,
                  print_undef_assign = False):
         """Creates a new Config object, representing a Kconfig configuration.
@@ -98,15 +98,17 @@ class Config(object):
                  kconfiglib via 'make scriptconfig', the filename of the base
                  base Kconfig file will be in sys.argv[1].
 
-        base_dir (default: "$srctree") -- The base directory relative to which
-                'source' statements within Kconfig files will work. For the
-                Linux kernel this should be the top-level directory of the
-                kernel tree. $-references to environment variables will be
-                expanded.
+        base_dir (default: None) -- The base directory relative to which
+                 'source' statements within Kconfig files will work. For the
+                 Linux kernel this should be the top-level directory of the
+                 kernel tree. $-references to existing environment variables
+                 will be expanded.
 
-                The environment variable 'srctree' is set by the Linux makefiles
-                to the top-level kernel directory. A default of "." would not
-                work if an alternative build directory is used.
+                 If None (the default), the environment variable 'srctree' will
+                 be used if set, and the current directory otherwise. 'srctree'
+                 is set by the Linux makefiles to the top-level kernel
+                 directory. A default of "." would not work with an alternative
+                 build directory.
 
         print_warnings (default: True) -- Set to True if warnings related to
                        this configuration should be printed to stderr. This can
@@ -166,7 +168,10 @@ class Config(object):
             self.srctree = "."
 
         self.filename = filename
-        self.base_dir = os.path.expandvars(base_dir).rstrip("/")
+        if base_dir is None:
+            self.base_dir = self.srctree
+        else:
+            self.base_dir = os.path.expandvars(base_dir)
 
         # The 'mainmenu' text
         self.mainmenu_text = None
diff --git a/tests/Kbase_dir b/tests/Kbase_dir
new file mode 100644
index 0000000..9f8c55a
--- /dev/null
+++ b/tests/Kbase_dir
@@ -0,0 +1,2 @@
+# This will only work if 'base_dir' is set correctly
+source "empty"
diff --git a/testsuite.py b/testsuite.py
index 3407e0a..3a2ee0b 100644
--- a/testsuite.py
+++ b/testsuite.py
@@ -1234,6 +1234,15 @@ def run_selftests():
 
     verify_value("UNAME_RELEASE", os.uname()[2])
 
+    # Expansion of environment variables in Config.__init__'s base_dir
+    # parameter. Just make sure we don't crash when Kbase_dir 'source's a file
+    # from the same directory.
+
+    os.environ["EnV_VaR1"] = "Kconfigl"
+    os.environ["EnV_VaR2"] = "ib/tests"
+    kconfiglib.Config("Kconfiglib/tests/Kbase_dir",
+                      base_dir = "$EnV_VaR1$EnV_VaR2/")
+
     #
     # .config reading and writing
     #