utils: add sysdeps_parser utility module

This functionality is used by the update manager to parse
the result from system dependency files.  By moving it
out of the update manager it becomes easier to test,
extend, and maintain.  Additionally it can be embedded
in the install script.

Signed-off-by: Eric Callahan <[email protected]>

moonraker/utils/sysdeps_parser.py

@@ -0,0 +1,171 @@
+# Helpers for parsing system dependencies
+#
+# Copyright (C) 2025 Eric Callahan <[email protected]>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license
+from __future__ import annotations
+import shlex
+import re
+import pathlib
+import logging
+
+from typing import Tuple, Dict, List, Any
+
+def _get_distro_info() -> Dict[str, Any]:
+    try:
+        # try importing the distro module first.  It can detect
+        # old/obscure releases that do not have the standard
+        # os-release fle.
+        import distro
+    except ModuleNotFoundError:
+        pass
+    else:
+        return dict(
+            distro_id=distro.id(),
+            distro_version=distro.version(),
+            aliases=distro.like().split()
+        )
+    # fall back to manual parsing of /etc/os-release
+    release_file = pathlib.Path("/etc/os-release")
+    release_info: Dict[str, str] = {}
+    with release_file.open("r") as f:
+        lexer = shlex.shlex(f, posix=True)
+        lexer.whitespace_split = True
+        for item in list(lexer):
+            if "=" in item:
+                key, val = item.split("=", maxsplit=1)
+                release_info[key] = val
+    return dict(
+        distro_id=release_info.get("ID", ""),
+        distro_version=release_info.get("VERSION_ID", ""),
+        aliases=release_info.get("ID_LIKE", "").split()
+    )
+
+def _convert_version(version: str) -> Tuple[str | int, ...]:
+    version = version.strip()
+    ver_match = re.match(r"\d+(\.\d+)*((?:-|\.).+)?", version)
+    if ver_match is not None:
+        return tuple([
+            int(part) if part.isdigit() else part
+            for part in re.split(r"\.|-", version)
+        ])
+    return (version,)
+
+class SysDepsParser:
+    def __init__(self, distro_info: Dict[str, Any] | None = None) -> None:
+        if distro_info is None:
+            distro_info = _get_distro_info()
+        self.distro_id: str = distro_info.get("distro_id", "")
+        self.aliases: List[str] = distro_info.get("aliases", [])
+        self.distro_version: Tuple[int | str, ...] = tuple()
+        version = distro_info.get("distro_version")
+        if version:
+            self.distro_version = _convert_version(version)
+
+    def _parse_spec(self, full_spec: str) -> str | None:
+        parts = full_spec.split(";", maxsplit=1)
+        if len(parts) == 1:
+            return full_spec
+        pkg_name = parts[0].strip()
+        expressions = re.split(r"( and | or )", parts[1].strip())
+        if not len(expressions) & 1:
+            # There should always be an odd number of expressions.  Each
+            # expression is separated by an "and" or "or" operator
+            logging.info(
+                f"Requirement specifier is missing an expression "
+                f"between logical operators : {full_spec}"
+            )
+            return None
+        last_result: bool = True
+        last_logical_op: str | None = "and"
+        for idx, exp in enumerate(expressions):
+            if idx & 1:
+                if last_logical_op is not None:
+                    logging.info(
+                        "Requirement specifier contains sequential logical "
+                        f"operators: {full_spec}"
+                    )
+                    return None
+                logical_op = exp.strip()
+                if logical_op not in ("and", "or"):
+                    logging.info(
+                        f"Invalid logical operator {logical_op} in requirement "
+                        f"specifier: {full_spec}")
+                    return None
+                last_logical_op = logical_op
+                continue
+            elif last_logical_op is None:
+                logging.info(
+                    f"Requirement specifier contains two seqential expressions "
+                    f"without a logical operator: {full_spec}")
+                return None
+            dep_parts = re.split(r"(==|!=|<=|>=|<|>)", exp.strip())
+            req_var = dep_parts[0].strip().lower()
+            if len(dep_parts) != 3:
+                logging.info(f"Invalid comparison, must be 3 parts: {full_spec}")
+                return None
+            elif req_var == "distro_id":
+                left_op: str | Tuple[int | str, ...] = self.distro_id
+                right_op = dep_parts[2].strip().strip("\"'")
+            elif req_var == "distro_version":
+                if not self.distro_version:
+                    logging.info(
+                        "Distro Version not detected, cannot satisfy requirement: "
+                        f"{full_spec}"
+                    )
+                    return None
+                left_op = self.distro_version
+                right_op = _convert_version(dep_parts[2].strip().strip("\"'"))
+            else:
+                logging.info(f"Invalid requirement specifier: {full_spec}")
+                return None
+            operator = dep_parts[1].strip()
+            try:
+                compfunc = {
+                    "<": lambda x, y: x < y,
+                    ">": lambda x, y: x > y,
+                    "==": lambda x, y: x == y,
+                    "!=": lambda x, y: x != y,
+                    ">=": lambda x, y: x >= y,
+                    "<=": lambda x, y: x <= y
+                }.get(operator, lambda x, y: False)
+                result = compfunc(left_op, right_op)
+                if last_logical_op == "and":
+                    last_result &= result
+                else:
+                    last_result |= result
+                last_logical_op = None
+            except Exception:
+                logging.exception(f"Error comparing requirements: {full_spec}")
+                return None
+        if last_result:
+            return pkg_name
+        return None
+
+    def parse_dependencies(self, sys_deps: Dict[str, List[str]]) -> List[str]:
+        if not self.distro_id:
+            logging.info(
+                "Failed to detect current distro ID, cannot parse dependencies"
+            )
+            return []
+        all_ids = [self.distro_id] + self.aliases
+        for distro_id in all_ids:
+            if distro_id in sys_deps:
+                if not sys_deps[distro_id]:
+                    logging.info(
+                        f"Dependency data contains an empty package definition "
+                        f"for linux distro '{distro_id}'"
+                    )
+                    continue
+                processed_deps: List[str] = []
+                for dep in sys_deps[distro_id]:
+                    parsed_dep = self._parse_spec(dep)
+                    if parsed_dep is not None:
+                        processed_deps.append(parsed_dep)
+                return processed_deps
+        else:
+            logging.info(
+                f"Dependency data has no package definition for linux "
+                f"distro '{self.distro_id}'"
+            )
+        return []