Files
python/bin/inject_nanopb_options.py
Ian McEwen a7d13eb2c1 the fuzz
2026-05-31 10:17:27 -07:00

333 lines
11 KiB
Python

#!/usr/bin/env python3
"""Inject nanopb .options constraints as inline field options into a .proto file.
The nanopb .options file format is specific to the nanopb C generator and is
ignored by standard protoc (including --python_out). By injecting the options
directly into the proto file's field declarations, protoc will embed them in
the serialized descriptor, making them accessible in Python via:
from meshtastic.protobuf import mesh_pb2, nanopb_pb2
field = mesh_pb2.DESCRIPTOR.message_types_by_name['User'].fields_by_name['long_name']
opts = field.GetOptions().Extensions[nanopb_pb2.nanopb]
print(opts.max_size) # 40
Usage:
inject_nanopb_options.py <options_file> <proto_file>
The proto_file is modified in-place. Intended to operate on temporary copies
generated by regen-protobufs.sh, not the source .proto files.
"""
import re
import sys
from pathlib import Path
from typing import Any, Dict, List, Tuple
# IntSize enum values from nanopb.proto
INT_SIZE_ENUM = {8: "IS_8", 16: "IS_16", 32: "IS_32", 64: "IS_64"}
# Options that are valid proto FieldOptions and useful outside of C code generation.
# We skip C-only options (anonymous_oneof, no_unions, skip_message, packed_struct,
# packed_enum, mangle_names, callback_datatype, callback_function, descriptorsize,
# type_override) since they either don't apply to proto fields or are C-specific.
FIELD_OPTIONS = frozenset(
{
"max_size",
"max_length",
"max_count",
"int_size",
"fixed_length",
"fixed_count",
"long_names",
"proto3",
"default_has",
"sort_by_tag",
"msgid",
}
)
def parse_value(s: str) -> Any:
"""Convert an option value string to an appropriate Python type."""
if re.fullmatch(r"-?[0-9]+", s):
return int(s)
if s.lower() == "true":
return True
if s.lower() == "false":
return False
return s
def parse_options_file(
path: Path,
) -> Tuple[Dict[Tuple[str, ...], Dict[str, Any]], Dict[str, Dict[str, Any]]]:
"""Parse a nanopb .options file.
Returns:
specific: maps (message_path..., field_name) -> {option: value}
e.g. ('User', 'long_name') or ('Route', 'Link', 'uid')
wildcard: maps field_name -> {option: value}
applies to any field with this name in the same proto file
"""
specific: Dict[Tuple[str, ...], Dict[str, Any]] = {}
wildcard: Dict[str, Dict[str, Any]] = {}
with open(path, encoding="utf-8") as f:
for line in f:
# Strip inline comments
comment_pos = line.find("#")
if comment_pos >= 0:
line = line[:comment_pos]
line = line.strip().lstrip("*").strip()
if not line:
continue
tokens = line.split()
if len(tokens) < 2:
continue
pattern = tokens[0]
opts: Dict[str, Any] = {}
for tok in tokens[1:]:
if ":" in tok:
k, v = tok.split(":", 1)
if k in FIELD_OPTIONS:
opts[k] = parse_value(v)
if not opts:
continue
if "." in pattern:
# e.g. "User.long_name" -> key=('User', 'long_name')
# or "Route.Link.uid" -> key=('Route', 'Link', 'uid')
parts = tuple(pattern.split("."))
if parts in specific:
specific[parts].update(opts)
else:
specific[parts] = opts
else:
# wildcard: applies to any field with this name
if pattern in wildcard:
wildcard[pattern].update(opts)
else:
wildcard[pattern] = opts
return specific, wildcard
def format_nanopb_opts(opts: Dict[str, Any]) -> str:
"""Format a dict of nanopb options as a proto field options annotation string."""
parts = []
for k, v in opts.items():
if k == "int_size":
enum_val = INT_SIZE_ENUM.get(v, f"IS_{v}")
parts.append(f"(nanopb).int_size = {enum_val}")
elif isinstance(v, bool):
parts.append(f"(nanopb).{k} = {'true' if v else 'false'}")
else:
parts.append(f"(nanopb).{k} = {v}")
return ", ".join(parts)
def message_path_matches(
context_stack: List[Tuple[str, str]], msg_path: Tuple[str, ...]
) -> bool:
"""Check if the current message context ends with msg_path.
context_stack entries are ('message'|'oneof'|'enum', name).
msg_path is the tuple of message names from the options pattern,
e.g. ('User',) or ('Route', 'Link').
"""
msg_names = [name for kind, name in context_stack if kind == "message"]
n = len(msg_path)
return len(msg_names) >= n and tuple(msg_names[-n:]) == msg_path
def inject_into_proto(
content: str,
specific: Dict[Tuple[str, ...], Dict[str, Any]],
wildcard: Dict[str, Dict[str, Any]],
nanopb_import_path: str,
) -> str:
"""Inject nanopb field options into a proto file's text content.
Adds an import for nanopb.proto if not already present.
Returns the modified content.
"""
if not specific and not wildcard:
return content
lines = content.split("\n")
# Check if nanopb is already imported (after sed fixup, it will be
# 'meshtastic/protobuf/nanopb.proto')
nanopb_already_imported = any(
"nanopb.proto" in line
for line in lines
if line.strip().startswith("import")
)
# Track the index of the last import line so we can insert after it
last_import_idx = max(
(
i
for i, line in enumerate(lines)
if line.strip().startswith("import ") and line.strip().endswith(";")
),
default=-1,
)
# State
context_stack: List[Tuple[str, str]] = [] # ('message'|'oneof'|'enum', name)
result: List[str] = []
import_added = nanopb_already_imported
# Patterns for proto structural elements
message_re = re.compile(r"^(\s*)message\s+(\w+)\s*\{")
oneof_re = re.compile(r"^(\s*)oneof\s+(\w+)\s*\{")
enum_re = re.compile(r"^(\s*)enum\s+(\w+)\s*\{")
close_re = re.compile(r"^\s*\}")
# Pattern for field declarations:
# indent [optional|repeated] type name = number [options] ;
# We exclude map<> fields (different syntax, nanopb handles them differently)
# and enum value lines (no type keyword before the name).
field_re = re.compile(
r"^(\s*)" # (1) indent
r"(optional\s+|repeated\s+)?" # (2) optional qualifier
r"([\w.]+)\s+" # (3) field type (possibly qualified like google.protobuf.Any)
r"(\w+)\s*" # (4) field name
r"=\s*(\d+)" # (5) field number
r"(?:\s*\[([^\]]*)\])?" # (6) existing options, without brackets
r"\s*;" # trailing semicolon
)
for i, line in enumerate(lines):
# Insert nanopb import right after the last existing import line.
# Only do this when there IS an existing import (last_import_idx >= 0);
# if there are no imports we fall through to the syntax-line fallback below.
if not import_added and last_import_idx >= 0 and i == last_import_idx + 1:
result.append(f'import "{nanopb_import_path}";')
import_added = True
# --- Track message/oneof/enum nesting ---
m = message_re.match(line)
if m:
context_stack.append(("message", m.group(2)))
result.append(line)
continue
m = oneof_re.match(line)
if m:
context_stack.append(("oneof", m.group(2)))
result.append(line)
continue
m = enum_re.match(line)
if m:
context_stack.append(("enum", m.group(2)))
result.append(line)
continue
if close_re.match(line) and context_stack:
context_stack.pop()
result.append(line)
continue
# Skip field injection inside enum bodies (enum values look like fields
# but should not have nanopb options added)
in_enum = bool(context_stack) and context_stack[-1][0] == "enum"
# --- Try to match and modify a field declaration ---
m = field_re.match(line)
if m and not in_enum:
indent = m.group(1)
qualifier = m.group(2) or ""
ftype = m.group(3)
fname = m.group(4)
fnum = m.group(5)
existing_opts = m.group(6) or ""
# Collect applicable nanopb options (wildcard < specific)
extra: Dict[str, Any] = {}
# 1. Wildcard: any field with this name in this proto file
if fname in wildcard:
extra.update(wildcard[fname])
# 2. Specific: check all keys whose last element is fname and whose
# preceding path matches the current message context
for key, opts in specific.items():
if key[-1] == fname:
msg_path = key[:-1]
if message_path_matches(context_stack, msg_path):
extra.update(opts)
break
if extra:
nanopb_str = format_nanopb_opts(extra)
if existing_opts.strip():
opts_block = f"[{existing_opts}, {nanopb_str}]"
else:
opts_block = f"[{nanopb_str}]"
qual = qualifier.rstrip()
sep = " " if qual else ""
line = f"{indent}{qual}{sep}{ftype} {fname} = {fnum} {opts_block};"
result.append(line)
# Edge case: if there were no import lines, add nanopb import after syntax line
if not import_added:
for i, line in enumerate(result):
if line.strip().startswith("syntax") and line.strip().endswith(";"):
result.insert(i + 1, f'import "{nanopb_import_path}";')
break
return "\n".join(result)
def main() -> int:
"""Parse an .options file and inject its constraints into a .proto file in-place."""
if len(sys.argv) != 3:
print(
f"Usage: {sys.argv[0]} <options_file> <proto_file>",
file=sys.stderr,
)
return 1
opts_path = Path(sys.argv[1])
proto_path = Path(sys.argv[2])
if not opts_path.exists():
print(f"Options file not found: {opts_path}", file=sys.stderr)
return 1
if not proto_path.exists():
print(f"Proto file not found: {proto_path}", file=sys.stderr)
return 1
specific, wildcard = parse_options_file(opts_path)
total = len(specific) + len(wildcard)
if total == 0:
print(f" [{opts_path.name}] No injectable options found, skipping.")
return 0
content = proto_path.read_text(encoding="utf-8")
# After regen-protobufs.sh's sed fixup, the nanopb import path is:
nanopb_import_path = "meshtastic/protobuf/nanopb.proto"
modified = inject_into_proto(content, specific, wildcard, nanopb_import_path)
proto_path.write_text(modified, encoding="utf-8")
print(
f" [{opts_path.name}] Injected {len(specific)} specific + "
f"{len(wildcard)} wildcard option(s) into {proto_path.name}"
)
return 0
if __name__ == "__main__":
sys.exit(main())