man: mention that sd_id128_get_boot() and friend may return -ENOSYS

And drop to mention sd_id128_get_boot_app_specific() may return -ENOENT
or -ENOMEDIUM. The function does not read /etc/machine-id. But reads a
file in the procfs, which is a kind of the kernel API. Hence the
failures are caused only when the system has wrong setup.

diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml
index 8bc76b686b684ab80e22635c75dec279bae05cdf..dbc6d4885d5b9e4b6c3e40244c658e122e4f3042 100644 (file)
--- a/man/sd_id128_get_machine.xml
+++ b/man/sd_id128_get_machine.xml
@@ -129,19 +129,17 @@
         <varlistentry>
           <term><constant>-ENOENT</constant></term>
 
-          <listitem><para>Returned by <function>sd_id128_get_machine()</function>,
-          <function>sd_id128_get_machine_app_specific()</function>, and
-          <function>sd_id128_get_boot_app_specific()</function> when <filename>/etc/machine-id</filename> is
-          missing.</para></listitem>
+          <listitem><para>Returned by <function>sd_id128_get_machine()</function> and
+          <function>sd_id128_get_machine_app_specific()</function> when <filename>/etc/machine-id</filename>
+          is missing.</para></listitem>
         </varlistentry>
 
         <varlistentry>
           <term><constant>-ENOMEDIUM</constant></term>
 
-          <listitem><para>Returned by <function>sd_id128_get_machine()</function>,
-          <function>sd_id128_get_machine_app_specific()</function>, and
-          <function>sd_id128_get_boot_app_specific()</function> when <filename>/etc/machine-id</filename> is
-          empty or all zeros.</para></listitem>
+          <listitem><para>Returned by <function>sd_id128_get_machine()</function> and
+          <function>sd_id128_get_machine_app_specific()</function> when <filename>/etc/machine-id</filename>
+          is empty or all zeros.</para></listitem>
         </varlistentry>
 
         <varlistentry>
@@ -152,6 +150,14 @@
           <filename>/etc/machine-id</filename> is <literal>uninitialized</literal>.</para></listitem>
         </varlistentry>
 
+        <varlistentry>
+          <term><constant>-ENOSYS</constant></term>
+
+          <listitem><para>Returned by <function>sd_id128_get_boot()</function> and
+          <function>sd_id128_get_boot_app_specific()</function> when <filename>/proc/</filename> is not
+          mounted.</para></listitem>
+        </varlistentry>
+
         <varlistentry>
           <term><constant>-ENXIO</constant></term>