pylibfdt: Improved version extraction

Currently setup.py expects the library version in a VERSION environment
variable, or it exctracts the version from the Makefile.  The latter is
for the case where the script is run standalone, rather than from make.
But parsing the Makefile is ugly and fragile, and won't always get the
same version we put into the C code.

This changes to instead extracting the version from the trivial .h file we
already generate to put the version into C code.  It's still slightly ugly,
but it's simpler and since we can control the precise format of that .h,
not as fragile.

This lets us remove the remains of the makefile parsing code from setup.py.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Simon Glass <sjg@chromium.org>

pylibfdt/Makefile.pylibfdt

@@ -12,11 +12,10 @@ SETUPFLAGS += --quiet
 endif
 
 define run_setup
-	VERSION="$(dtc_version)"
 	$(SETUP) $(SETUPFLAGS) $(1)
 endef
 
-$(PYMODULE): $(PYLIBFDT_srcs) $(LIBFDT_archive) $(SETUP)
+$(PYMODULE): $(PYLIBFDT_srcs) $(LIBFDT_archive) $(SETUP) $(VERSION_FILE)
 	@$(VECHO) PYMOD $@
 	$(call run_setup, build_ext --build-lib=$(PYLIBFDT_objdir))
 

pylibfdt/setup.py

@@ -4,13 +4,6 @@
 setup.py file for SWIG libfdt
 Copyright (C) 2017 Google, Inc.
 Written by Simon Glass <sjg@chromium.org>
-
-Version is provided in VERSION
-
-If these variables are not given they are parsed from the Makefiles. This
-allows this script to be run stand-alone, e.g.:
-
-    ./pylibfdt/setup.py install [--prefix=...]
 """
 
 from distutils.core import setup, Extension
@@ -18,73 +11,16 @@ import os
 import re
 import sys
 
-# Decodes a Makefile assignment line into key and value (and plus for +=)
-RE_KEY_VALUE = re.compile('(?P<key>\w+) *(?P<plus>[+])?= *(?P<value>.*)$')
-
-
-def ParseMakefile(fname):
-    """Parse a Makefile to obtain its variables.
-
-    This collects variable assigments of the form:
-
-        VAR = value
-        VAR += more
 
-    It does not pick out := assignments, as these are not needed here. It does
-    handle line continuation.
-
-    Returns a dict:
-        key: Variable name (e.g. 'VAR')
-        value: Variable value (e.g. 'value more')
-    """
-    makevars = {}
-    with open(fname) as fd:
-        prev_text = ''  # Continuation text from previous line(s)
-        for line in fd.read().splitlines():
-          if line and line[-1] == '\\':  # Deal with line continuation
-            prev_text += line[:-1]
-            continue
-          elif prev_text:
-            line = prev_text + line
-            prev_text = ''  # Continuation is now used up
-          m = RE_KEY_VALUE.match(line)
-          if m:
-            value = m.group('value') or ''
-            key = m.group('key')
-
-            # Appending to a variable inserts a space beforehand
-            if 'plus' in m.groupdict() and key in makevars:
-              makevars[key] += ' ' + value
-            else:
-              makevars[key] = value
-    return makevars
-
-def GetEnvFromMakefiles():
-    """Scan the Makefiles to obtain the settings we need.
-
-    This assumes that this script is being run from the top-level directory,
-    not the pylibfdt directory.
-
-    Returns:
-        Tuple with:
-            Version string
-            List of extra C preprocessor flags needed
-    """
-    basedir = os.path.dirname(os.path.dirname(os.path.abspath(sys.argv[0])))
-    makevars = ParseMakefile(os.path.join(basedir, 'Makefile'))
-    version = '%s.%s.%s' % (makevars['VERSION'], makevars['PATCHLEVEL'],
-                            makevars['SUBLEVEL'])
-    return version
+VERSION_PATTERN = '^#define DTC_VERSION "DTC ([^"]*)"$'
 
 
-progname = sys.argv[0]
-version = os.environ.get('VERSION')
+def get_version():
+    version_file = "version_gen.h"
+    f = open(version_file, 'rt')
+    m = re.match(VERSION_PATTERN, f.readline())
+    return m.group(1)
 
-# If we were called directly rather than through our Makefile (which is often
-# the case with Python module installation), read the settings from the
-# Makefile.
-if not version:
-    version = GetEnvFromMakefiles()
 
 libfdt_module = Extension(
     '_libfdt',
@@ -96,7 +32,7 @@ libfdt_module = Extension(
 
 setup(
     name='libfdt',
-    version= version,
+    version= get_version(),
     author='Simon Glass <sjg@chromium.org>',
     description='Python binding for libfdt',
     ext_modules=[libfdt_module],