From 12410fde93eab2fd615a929cdad0d8654c479e81 Mon Sep 17 00:00:00 2001
From: Alessandro Gatti <a.gatti@frob.it>
Date: Sun, 15 Mar 2026 10:21:32 +0100
Subject: [PATCH] machine: Retrieve an unique identifier if one is known.

This commit adds a proper implementation for "machine.unique_id" for
selected systems, as opposed to returning a fixed value in every case.

On a Unix system there are several incompatible ways to retrieve
something that can be called an unique machine identifier.  However, the
only semblance of a specification comes from freedesktop.org, which says
that a file called "/etc/machine-id" has to exist and must contain a
32-digits long hexadecimal identifier.

Given that the current specification is the DBus unique identifier
retrieval mechanism made official, if the identifier file is not found
the code will attempt to read the file provided by DBus.

These changes only apply to Linux and recent BSD systems.  On other
systems the old, fixed value for the machine identifier will be returned
instead - to avoid breaking compatibility with existing code.

The specification used in this commit is available at
https://www.freedesktop.org/software/systemd/man/latest/machine-id.html.

Signed-off-by: Alessandro Gatti <a.gatti@frob.it>
---
 unix-ffi/machine/machine/__init__.py | 13 +++++++++++++
 unix-ffi/machine/manifest.py         |  2 +-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/unix-ffi/machine/machine/__init__.py b/unix-ffi/machine/machine/__init__.py
index 80bf5da1a..72a5d9403 100644
--- a/unix-ffi/machine/machine/__init__.py
+++ b/unix-ffi/machine/machine/__init__.py
@@ -4,4 +4,17 @@
 
 
 def unique_id():
+    for base in ("/etc", "/var/lib/dbus"):
+        try:
+            with open(base + "/machine-id", "rb") as source:
+                data = source.read(32)
+                if len(data) == 32:
+                    for byte in data:
+                        if byte not in b"0123456789abcdef":
+                            break
+                    # unhexlify might not be available
+                    return bytes([int(data[i : i + 2], 16) for i in range(0, len(data), 2)])
+        except OSError as e:
+            if "ENOENT" not in str(e):
+                raise
     return b"upy-non-unique"
diff --git a/unix-ffi/machine/manifest.py b/unix-ffi/machine/manifest.py
index f7c11b81a..bdfb6a95f 100644
--- a/unix-ffi/machine/manifest.py
+++ b/unix-ffi/machine/manifest.py
@@ -1,4 +1,4 @@
-metadata(version="0.2.2")
+metadata(version="0.2.3")
 
 # Originally written by Paul Sokolovsky.