Add oldconfig.py example script

Implements the standard 'make oldconfig' functionality, prompting the
user for the values of new symbols to update an old .config file.

This came up in
https://github.com/zephyrproject-rtos/zephyr/issues/5426.

1 files changed, 283 insertions, 0 deletions

diff --git a/examples/oldconfig.py b/examples/oldconfig.py
new file mode 100644
index 0000000..3cb60f0
--- /dev/null
+++ b/examples/oldconfig.py
@@ -0,0 +1,283 @@
+# Implements oldconfig-like functionality:
+#
+#   1. Load existing .config
+#   2. Prompt the user for the value of all changeable symbols/choices
+#      that aren't already set in the .config
+#   3. Write new .config
+#
+# Unlike 'make oldconfig', this script doesn't print menu titles and
+# comments, but instead gives the Kconfig locations of all symbols and
+# choices. Printing menu titles and comments as well would be pretty easy to
+# add (look at the parents of each item and print all menu prompts and
+# comments unless they have already been printed).
+#
+# Sample session:
+#
+#   OldconfigExample contents:
+#
+#     config MODULES
+#             def_bool y
+#             option modules
+#
+#     config BOOL_SYM
+#             bool "BOOL_SYM prompt"
+#             default y
+#
+#     config TRISTATE_SYM
+#             tristate "TRISTATE_SYM prompt"
+#             default m
+#
+#     config STRING_SYM
+#             string "STRING_SYM prompt"
+#             default "foo"
+#
+#     config INT_SYM
+#             int "INT_SYM prompt"
+#
+#     config HEX_SYM
+#             hex "HEX_SYM prompt"
+#
+#     choice
+#             bool "A choice that defaults to CHOICE_B"
+#             default CHOICE_B
+#
+#     config CHOICE_A
+#             bool "CHOICE_A's prompt"
+#
+#     config CHOICE_B
+#             bool "CHOICE_B's prompt"
+#
+#     config CHOICE_C
+#             bool "CHOICE_C's prompt"
+#
+#     endchoice
+#
+#
+#   Running:
+#
+#     $ touch .config  # Run with empty .config
+#
+#     $ python oldconfig.py Kconfig
+#     BOOL_SYM prompt (BOOL_SYM, defined at Kconfig:5) [n/Y] foo
+#     Invalid tristate value
+#     BOOL_SYM prompt (BOOL_SYM, defined at Kconfig:5) [n/Y] n
+#     TRISTATE_SYM prompt (TRISTATE_SYM, defined at Kconfig:9) [n/M/y]
+#     STRING_SYM prompt (STRING_SYM, defined at Kconfig:13) [foo] bar
+#     INT_SYM prompt (INT_SYM, defined at Kconfig:17) [] 0x123
+#     warning: the value '0x123' is invalid for INT_SYM (defined at Kconfig:17), which has type int. Assignment ignored.
+#     INT_SYM prompt (INT_SYM, defined at Kconfig:17) [] 123
+#     HEX_SYM prompt (HEX_SYM, defined at Kconfig:20) [] 0x123
+#     A choice that default to B (defined at Kconfig:23)
+#       1. CHOICE_A's prompt (CHOICE_A)
+#     > 2. CHOICE_B's prompt (CHOICE_B)
+#       3. CHOICE_C's prompt (CHOICE_C)
+#     choice[1-3]: 5
+#     Bad index
+#     A choice that default to B (defined at Kconfig:23)
+#       1. CHOICE_A's prompt (CHOICE_A)
+#     > 2. CHOICE_B's prompt (CHOICE_B)
+#       3. CHOICE_C's prompt (CHOICE_C)
+#     choice[1-3]: 3
+#     Configuration written to .config
+#
+#     $ cat .config
+#     # Generated by Kconfiglib (https://github.com/ulfalizer/Kconfiglib)
+#     CONFIG_MODULES=y
+#     # CONFIG_BOOL_SYM is not set
+#     CONFIG_TRISTATE_SYM=m
+#     CONFIG_STRING_SYM="bar"
+#     CONFIG_INT_SYM=123
+#     CONFIG_HEX_SYM=0x123
+#     # CONFIG_CHOICE_A is not set
+#     # CONFIG_CHOICE_B is not set
+#     CONFIG_CHOICE_C=y
+#
+#     $ python oldconfig.py Kconfig  # Everything's already up to date
+#     Configuration written to .config
+from __future__ import print_function
+from kconfiglib import Kconfig, Symbol, Choice, BOOL, TRISTATE, HEX, STR_TO_TRI
+import os
+import sys
+
+# Python 2/3 compatibility hack
+if sys.version_info[0] < 3:
+    input = raw_input
+
+def eprint(*args):
+    print(*args, file=sys.stderr)
+
+def name_and_loc_str(sym):
+    """
+    Helper for printing the symbol name along with the location(s) in the
+    Kconfig files where it is defined
+    """
+    return "{}, defined at {}".format(
+        sym.name,
+        ", ".join("{}:{}".format(node.filename, node.linenr)
+                  for node in sym.nodes))
+
+def default_value_str(sym):
+    """
+    Returns the "m/M/y" string in e.g.
+
+      TRISTATE_SYM prompt (TRISTATE_SYM, defined at Kconfig:9) [n/M/y]:
+
+    For string/int/hex, returns the default value as-is.
+    """
+    if sym.type in (BOOL, TRISTATE):
+        res = []
+
+        if 0 in sym.assignable:
+            res.append("N" if sym.tri_value == 0 else "n")
+
+        if 1 in sym.assignable:
+            res.append("M" if sym.tri_value == 1 else "m")
+
+        if 2 in sym.assignable:
+            res.append("Y" if sym.tri_value == 2 else "y")
+
+        return "/".join(res)
+
+    # string/int/hex
+    return sym.str_value
+
+def do_oldconfig_for_node(node):
+    """
+    Prompts the user for a value for the menu node item, where applicable in
+    oldconfig mode
+    """
+    # Only symbols and choices can be configured
+    if not isinstance(node.item, (Symbol, Choice)):
+        return
+
+    # Skip symbols and choices that aren't visible
+    if not node.item.visibility:
+        return
+
+    # Skip symbols and choices that don't have a prompt (at this location)
+    if not node.prompt:
+        return
+
+    if isinstance(node.item, Symbol):
+        sym = node.item
+
+        # Skip symbols that already have a user value
+        if sym.user_value is not None:
+            return
+
+        # Skip symbols that can only have a single value, due to selects
+        if len(sym.assignable) == 1:
+            return
+
+        # Skip symbols in choices in y mode. We ask once for the entire choice
+        # instead.
+        if sym.choice and sym.choice.tri_value == 2:
+            return
+
+        # Loop until the user enters a valid value or enters a blank string
+        # (for the default value)
+        while True:
+            val = input("{} ({}) [{}] ".format(
+                            node.prompt[0], name_and_loc_str(sym),
+                            default_value_str(sym)))
+
+            # Substitute a blank string with the default value the symbol
+            # would get
+            if not val:
+                val = sym.str_value
+
+            if sym.type in (BOOL, TRISTATE):
+                if val not in STR_TO_TRI:
+                    eprint("Invalid tristate value")
+                    continue
+                val = STR_TO_TRI[val]
+
+            # Automatically add a "0x" prefix for hex symbols, like the
+            # menuconfig interface does. This isn't done when loading .config
+            # files, hence why set_value() doesn't do it automatically.
+            if sym.type == HEX and not val.startswith(("0x", "0X")):
+                val = "0x" + val
+
+            # Kconfiglib itself will print a warning here if the value
+            # is invalid, so we don't need to bother
+            if sym.set_value(val):
+                # Valid value input. We're done with this node.
+                return
+
+    else:
+        choice = node.item
+
+        # Skip choices that already have a visible user selection
+        if choice.user_selection and choice.user_selection.visibility == 2:
+            return
+
+        # Get a list of available selections. The mode of the choice limits
+        # the visibility of the choice value symbols, so this will indirectly
+        # skip choices in n and m mode.
+        options = [sym for sym in choice.syms if sym.visibility == 2]
+
+        # No y-visible choice value symbols
+        if not options:
+            return
+
+        # Loop until the user enters a valid selection or a blank string (for
+        # the default selection)
+        while True:
+            print("{} (defined at {}:{})".format(
+                node.prompt[0], node.filename, node.linenr))
+
+            for i, sym in enumerate(options, 1):
+                print("{} {}. {} ({})".format(
+                    ">" if choice.selection is sym else " ",
+                    i,
+                    # Assume people don't define choice symbols with multiple
+                    # prompts. That generates a warning anyway.
+                    sym.nodes[0].prompt[0],
+                    sym.name))
+
+            sel_index = input("choice[1-{}]: ".format(len(options)))
+
+            # Pick the default selection if the string is blank
+            if not sel_index:
+                choice.selection.set_value(2)
+                return
+
+            try:
+                sel_index = int(sel_index)
+            except ValueError:
+                eprint("Bad index")
+                continue
+
+            if not 1 <= sel_index <= len(options):
+                eprint("Bad index")
+                continue
+
+            # Valid selection
+            options[sel_index - 1].set_value(2)
+            return
+
+def do_oldconfig(node):
+    while node:
+        do_oldconfig_for_node(node)
+
+        if node.list:
+            do_oldconfig(node.list)
+
+        node = node.next
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        eprint("error: pass name of base Kconfig file as argument")
+        sys.exit(1)
+
+    if not os.path.exists(".config"):
+        eprint("error: no existing .config")
+        sys.exit(1)
+
+    kconf = Kconfig(sys.argv[1])
+
+    kconf.load_config(".config")
+    do_oldconfig(kconf.top_node)
+    kconf.write_config(".config")
+
+    print("Configuration written to .config")