From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Wed, 16 May 2018 11:55:12 +0000 (+0200)
Subject: sd-id128: return -ENOMEDIUM on null id
X-Git-Tag: v239~172^2~24
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ea03f6ba0d66374594d716fc0e84e4d65906d2c3;p=thirdparty%2Fsystemd.git

sd-id128: return -ENOMEDIUM on null id

We currently return -ENOMEDIUM when /etc/machine-id is empty, and -EINVAL when
it is all zeros. But -EINVAL is also used for invalid args. The distinction
between empty and all-zero is not very important, let's use the same return
code.

Also document -ENOENT and -ENOMEDIUM since they can be a bit surprising.
---

diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml
index 3622bbd9f2c..827756d135d 100644
--- a/man/sd_id128_get_machine.xml
+++ b/man/sd_id128_get_machine.xml
@@ -116,9 +116,11 @@
   <refsect1>
     <title>Return Value</title>
 
-    <para>The two calls return 0 on success (in which case
-    <parameter>ret</parameter> is filled in), or a negative
-    errno-style error code.</para>
+    <para>Those calls return 0 on success (in which case <parameter>ret</parameter> is filled in),
+    or a negative errno-style error code. In particular, <function>sd_id128_get_machine()</function>
+    and <function>sd_id128_get_machine_app_specific()</function> return <constant>-ENOENT</constant>
+    if <filename>/etc/machine-id</filename> is missing, and <constant>-ENOMEDIUM</constant> if is
+    empty or all zeros.</para>
   </refsect1>
 
   <refsect1>
diff --git a/src/libsystemd/sd-id128/sd-id128.c b/src/libsystemd/sd-id128/sd-id128.c
index af2ff8353ab..80548fdfcf9 100644
--- a/src/libsystemd/sd-id128/sd-id128.c
+++ b/src/libsystemd/sd-id128/sd-id128.c
@@ -98,7 +98,7 @@ _public_ int sd_id128_get_machine(sd_id128_t *ret) {
                         return r;
 
                 if (sd_id128_is_null(saved_machine_id))
-                        return -EINVAL;
+                        return -ENOMEDIUM;
         }
 
         *ret = saved_machine_id;