build: generate config.h and implicitly include it

All source files will now depend on config.h, which is generated based
on the defaults in CONFIG and the command line arguments passed to make.

This ensures that any configuration changes, including on the command
line, cause a full rebuild.

Change-Id: I6b6fa3290941200dbcf32297c66df8dc5ee18e94
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>

Makefile

@@ -38,13 +38,21 @@ include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
 
 DIRS-y += lib test examples app
 
-.PHONY: all clean $(DIRS-y)
+.PHONY: all clean $(DIRS-y) config.h
 
 all: $(DIRS-y)
 clean: $(DIRS-y)
+	$(Q)rm -f config.h
 
 app: lib
 test: lib
 examples: lib
 
+$(DIRS-y): config.h
+
+config.h: CONFIG scripts/genconfig.py
+	$(Q)python scripts/genconfig.py $(MAKEFLAGS) > $@.tmp; \
+	cmp -s $@.tmp $@ || mv $@.tmp $@ ; \
+	rm -f $@.tmp
+
 include $(SPDK_ROOT_DIR)/mk/spdk.subdirs.mk

mk/spdk.common.mk

@@ -45,6 +45,8 @@ OS := $(shell uname)
 
 COMMON_CFLAGS = -g $(C_OPT) -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wmissing-declarations -fno-strict-aliasing -march=native -m64 -I$(SPDK_ROOT_DIR)/include
 
+COMMON_CFLAGS += -include $(SPDK_ROOT_DIR)/config.h
+
 ifeq ($(CONFIG_WERROR), y)
 COMMON_CFLAGS += -Werror
 endif

scripts/genconfig.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+
+import re
+import sys
+
+comment = re.compile('^\s*#')
+assign = re.compile('^\s*([a-zA-Z_]+)\s*(\?)?=\s*([^#]*)')
+
+with open('CONFIG') as f:
+    for line in f:
+        line = line.strip()
+        if not comment.match(line):
+            m = assign.match(line)
+            if m:
+                var = m.group(1).strip()
+                default = m.group(3).strip()
+                val = default
+                for arg in sys.argv:
+                    m = assign.match(arg)
+                    if m:
+                        argvar = m.group(1).strip()
+                        argval = m.group(3).strip()
+                        if argvar == var:
+                            val = argval
+                if default.lower() == 'y' or default.lower() == 'n':
+                    if val.lower() == 'y':
+                        boolval = 1
+                    else:
+                        boolval = 0
+                    print "#define SPDK_{} {}".format(var, boolval)
+                else:
+                    strval = val.replace('"', '\"')
+                    print "#define SPDK_{} \"{}\"".format(var, strval)