Add optional systemd integration

[tinc] / version.py

diff --git a/version.py b/version.py
index ff491bb..3213e32 100755 (executable)
--- a/version.py
+++ b/version.py
@@ -1,26 +1,51 @@
 #!/usr/bin/env python3
 
-from sys import argv, exit
+"""Print current tinc version for using in build scripts.
+
+First try to determine the latest version using git tags. If this fails (because
+the .git directory is missing, git is not installed, or for some other reason),
+fall back to using the VERSION file. If it is not present or could not be read,
+use 'unknown'.
+"""
+
+from os import path, environ
+from sys import argv, stderr
 import subprocess as subp
+import typing as T
 
-prefix = "release-"
+PREFIX = "release-"
+SOURCE_ROOT = path.dirname(path.realpath(__file__))
+SOURCE_ROOT = environ.get("MESON_SOURCE_ROOT", SOURCE_ROOT)
 
 cmd = [
     "git",
+    "--git-dir",
+    path.join(SOURCE_ROOT, ".git"),
     "describe",
     "--always",
     "--tags",
-    "--match=" + prefix + "*",
+    "--match=" + PREFIX + "*",
 ]
 
 if "short" in argv:
     cmd.append("--abbrev=0")
 
-result = subp.run(cmd, stdout=subp.PIPE, encoding="utf-8")
-version = result.stdout
+version: T.Optional[str] = None
+
+try:
+    result = subp.run(cmd, stdout=subp.PIPE, encoding="utf-8", check=False)
+    if not result.returncode:
+        version = result.stdout
+except FileNotFoundError:
+    pass
 
-if not result.returncode and version and version.startswith(prefix):
-    version = version[len(prefix):].strip()
+if not version:
+    try:
+        with open(path.join(SOURCE_ROOT, "VERSION"), "r", encoding="utf-8") as f:
+            version = f.read().strip()
+    except OSError as e:
+        print("could not read version from file", e, file=stderr)
+elif version.startswith(PREFIX):
+    version = version[len(PREFIX) :].strip()
 
 print(version if version else "unknown", end="")
-exit(not version)