Make header strings customizable via the environment

If no header string is specified in write_(min_)config() or
write_autoconf(), use the values of the environment variables
KCONFIG_CONFIG_HEADER and KCONFIG_AUTOHEADER_HEADER, respectively, if
set. KCONFIG_AUTOHEADER_HEADER is consistent with KCONFIG_AUTOHEADER
(the header path), which will be added soon.

Using environment variables avoids having to add separate flags to each
tool that writes configuration files or headers.

Like for $prefix and $CONFIG_, store the values of the environment
variables when the Kconfig instance is created, and expose them via
Kconfig.config_header and Kconfig.header_header. This if flexible and
avoids gotchas when working with multiple Kconfig instances.

Also remove the old default header and make the default no header. Less
advertising, but it felt a bit silly to add workarounds to keep it.

Came up in https://github.com/ulfalizer/Kconfiglib/pull/80.

1 files changed, 71 insertions, 38 deletions

diff --git a/kconfiglib.py b/kconfiglib.py
index 37ba501..079c363 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -773,8 +773,8 @@ class Kconfig(object):
       See Kconfig.load_config() as well.
 
     srctree:
-      The value of the $srctree environment variable when the configuration was
-      loaded, or the empty string if $srctree wasn't set. This gives nice
+      The value the $srctree environment variable had when the Kconfig instance
+      was created, or the empty string if $srctree wasn't set. This gives nice
       behavior with os.path.join(), which treats "" as the current directory,
       without adding "./".
 
@@ -789,13 +789,22 @@ class Kconfig(object):
       if multiple configurations are loaded with different values for $srctree.
 
     config_prefix:
-      The value of the $CONFIG_ environment variable when the configuration was
-      loaded. This is the prefix used (and expected) on symbol names in .config
-      files and C headers. Defaults to "CONFIG_". Used in the same way in the C
-      tools.
-
-      Like for srctree, only the value of $CONFIG_ when the configuration is
-      loaded matters.
+      The value the CONFIG_ environment variable had when the Kconfig instance
+      was created, or "CONFIG_" if CONFIG_ wasn't set. This is the prefix used
+      (and expected) on symbol names in .config files and C headers. Used in
+      the same way in the C tools.
+
+    config_header:
+      The value the KCONFIG_CONFIG_HEADER environment variable had when the
+      Kconfig instance was created, or the empty string if
+      KCONFIG_CONFIG_HEADER wasn't set. This string is inserted verbatim at the
+      beginning of configuration files. See write_config().
+
+    header_header:
+      The value the KCONFIG_AUTOHEADER_HEADER environment variable had when the
+      Kconfig instance was created, or the empty string if
+      KCONFIG_AUTOHEADER_HEADER wasn't set. This string is inserted verbatim at
+      the beginning of header files. See write_autoconf().
 
     filename/linenr:
       The current parsing location, for use in Python preprocessor functions.
@@ -810,11 +819,13 @@ class Kconfig(object):
         "_warn_assign_no_prompt",
         "choices",
         "comments",
+        "config_header",
         "config_prefix",
         "const_syms",
         "defconfig_list",
         "defined_syms",
         "env_vars",
+        "header_header",
         "kconfig_filenames",
         "m",
         "menus",
@@ -943,6 +954,9 @@ class Kconfig(object):
         self._unset_match = _re_match(r"# {}([^ ]+) is not set".format(
             self.config_prefix))
 
+        self.config_header = os.getenv("KCONFIG_CONFIG_HEADER", "")
+        self.header_header = os.getenv("KCONFIG_AUTOHEADER_HEADER", "")
+
         self.syms = {}
         self.const_syms = {}
         self.defined_syms = []
@@ -1349,8 +1363,7 @@ class Kconfig(object):
         elif self.warn_assign_override:
             self._warn(msg, filename, linenr)
 
-    def write_autoconf(self, filename,
-                       header="/* Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib) */\n"):
+    def write_autoconf(self, filename, header=None):
         r"""
         Writes out symbol values as a C header file, matching the format used
         by include/generated/autoconf.h in the kernel.
@@ -1367,19 +1380,26 @@ class Kconfig(object):
         filename:
           Self-explanatory.
 
-        header (default: "/* Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib) */\n"):
-          Text that will be inserted verbatim at the beginning of the file. You
-          would usually want it enclosed in '/* */' to make it a C comment,
-          and include a final terminating newline.
+        header (default: None):
+          Text inserted verbatim at the beginning of the file. You would
+          usually want it enclosed in '/* */' to make it a C comment, and
+          include a trailing newline.
+
+          If None (the default), the value of the environment variable
+          KCONFIG_AUTOHEADER_HEADER had when the Kconfig instance was created
+          will be used if it was set, and no header otherwise. See the
+          Kconfig.header_header attribute.
         """
         self._write_if_changed(filename, self._autoconf_contents(header))
 
     def _autoconf_contents(self, header):
         # write_autoconf() helper. Returns the contents to write as a string,
-        # with 'header' at the beginning.
+        # with 'header' or KCONFIG_AUTOHEADER_HEADER at the beginning.
 
-        # "".join()ed later
-        chunks = [header]
+        if header is None:
+            header = self.header_header
+
+        chunks = [header]  # "".join()ed later
         add = chunks.append
 
         for sym in self.unique_defined_syms:
@@ -1415,9 +1435,8 @@ class Kconfig(object):
 
         return "".join(chunks)
 
-    def write_config(self, filename=None,
-                     header="# Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib)\n",
-                     save_old=True, verbose=None):
+    def write_config(self, filename=None, header=None, save_old=True,
+                     verbose=None):
         r"""
         Writes out symbol values in the .config format. The format matches the
         C implementation, including ordering.
@@ -1445,10 +1464,15 @@ class Kconfig(object):
           KCONFIG_CONFIG is used if set, and ".config" otherwise. See
           standard_config_filename().
 
-        header (default: "# Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib)\n"):
-          Text that will be inserted verbatim at the beginning of the file. You
-          would usually want each line to start with '#' to make it a comment,
-          and include a final terminating newline.
+        header (default: None):
+          Text inserted verbatim at the beginning of the file. You would
+          usually want each line to start with '#' to make it a comment, and
+          include a trailing newline.
+
+          if None (the default), the value of the environment variable
+          KCONFIG_CONFIG_HEADER had when the Kconfig instance was created will
+          be used if it was set, and no header otherwise. See the
+          Kconfig.config_header attribute.
 
         save_old (default: True):
           If True and <filename> already exists, a copy of it will be saved to
@@ -1493,7 +1517,7 @@ class Kconfig(object):
 
     def _config_contents(self, header):
         # write_config() helper. Returns the contents to write as a string,
-        # with 'header' at the beginning.
+        # with 'header' or KCONFIG_CONFIG_HEADER at the beginning.
         #
         # More memory friendly would be to 'yield' the strings and
         # "".join(_config_contents()), but it was a bit slower on my system.
@@ -1505,13 +1529,15 @@ class Kconfig(object):
         for sym in self.unique_defined_syms:
             sym._visited = False
 
-        # Did we just print an '# end of ...' comment?
-        after_end_comment = False
+        if header is None:
+            header = self.config_header
 
-        # "".join()ed later
-        chunks = [header]
+        chunks = [header]  # "".join()ed later
         add = chunks.append
 
+        # Did we just print an '# end of ...' comment?
+        after_end_comment = False
+
         node = self.top_node
         while 1:
             # Jump to the next node with an iterative tree walk
@@ -1564,8 +1590,7 @@ class Kconfig(object):
                 add("\n#\n# {}\n#\n".format(node.prompt[0]))
                 after_end_comment = False
 
-    def write_min_config(self, filename,
-                         header="# Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib)\n"):
+    def write_min_config(self, filename, header=None):
         """
         Writes out a "minimal" configuration file, omitting symbols whose value
         matches their default value. The format matches the one produced by
@@ -1583,10 +1608,15 @@ class Kconfig(object):
         filename:
           Self-explanatory.
 
-        header (default: "# Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib)\n"):
-          Text that will be inserted verbatim at the beginning of the file. You
-          would usually want each line to start with '#' to make it a comment,
-          and include a final terminating newline.
+        header (default: None):
+          Text inserted verbatim at the beginning of the file. You would
+          usually want each line to start with '#' to make it a comment, and
+          include a final terminating newline.
+
+          if None (the default), the value of the environment variable
+          KCONFIG_CONFIG_HEADER had when the Kconfig instance was created will
+          be used if it was set, and no header otherwise. See the
+          Kconfig.config_header attribute.
 
         Returns a string with a message saying which file got saved. This is
         meant to reduce boilerplate in tools, which can do e.g.
@@ -1603,9 +1633,12 @@ class Kconfig(object):
 
     def _min_config_contents(self, header):
         # write_min_config() helper. Returns the contents to write as a string,
-        # with 'header' at the beginning.
+        # with 'header' or KCONFIG_CONFIG_HEADER at the beginning.
+
+        if header is None:
+            header = self.config_header
 
-        chunks = [header]
+        chunks = [header]  # "".join()ed later
         add = chunks.append
 
         for sym in self.unique_defined_syms: