man: move more examples to stand-alone files and use 2-space indentation consistenty

Moving them out makes it easier to run them through a compiler, use automatic
indentation, and opens the possibility to provide a download link in the
future. I verified that all examples compile cleanly.

(2-space indentation is used because the examples are already significantly
indented in the man page, and we need to keep them narrow so that they display
well on standard terminals.)

man/id128-app-specific.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <systemd/sd-id128.h>
+
+#define OUR_APPLICATION_ID SD_ID128_MAKE(c2,73,27,73,23,db,45,4e,a6,3b,b9,6e,79,b5,3e,97)
+
+int main(int argc, char *argv[]) {
+  sd_id128_t id;
+  sd_id128_get_machine_app_specific(OUR_APPLICATION_ID, &id);
+  printf("Our application ID: " SD_ID128_FORMAT_STR "\n", SD_ID128_FORMAT_VAL(id));
+  return 0;
+}

man/journal-iterate-unique.c

@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include <string.h>
+#include <systemd/sd-journal.h>
+
+int main(int argc, char *argv[]) {
+  sd_journal *j;
+  const void *d;
+  size_t l;
+  int r;
+
+  r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY);
+  if (r < 0) {
+    fprintf(stderr, "Failed to open journal: %s\n", strerror(-r));
+    return 1;
+  }
+  r = sd_journal_query_unique(j, "_SYSTEMD_UNIT");
+  if (r < 0) {
+    fprintf(stderr, "Failed to query journal: %s\n", strerror(-r));
+    return 1;
+  }
+  SD_JOURNAL_FOREACH_UNIQUE(j, d, l)
+    printf("%.*s\n", (int) l, (const char*) d);
+  sd_journal_close(j);
+  return 0;
+}

man/sd_bus_new.xml

@@ -96,13 +96,13 @@
     block is left:</para>
 
     <programlisting>{
-        __attribute__((cleanup(sd_bus_unrefp)) sd_bus *bus = NULL;
-        int r;
-        …
-        r = sd_bus_default(&amp;bus);
-        if (r &lt; 0)
-                fprintf(stderr, "Failed to allocate bus: %s\n", strerror(-r));
-        …
+  __attribute__((cleanup(sd_bus_unrefp)) sd_bus *bus = NULL;
+  int r;
+  …
+  r = sd_bus_default(&amp;bus);
+  if (r &lt; 0)
+    fprintf(stderr, "Failed to allocate bus: %s\n", strerror(-r));
+  …
 }</programlisting>
 
     <para><function>sd_bus_ref()</function> and <function>sd_bus_unref()</function>

man/sd_id128_get_machine.xml

@@ -120,17 +120,7 @@
 
       <para>Here's a simple example for an application specific machine ID:</para>
 
-      <programlisting>#include &lt;systemd/sd-id128.h&gt;
-#include &lt;stdio.h&gt;
-
-#define OUR_APPLICATION_ID SD_ID128_MAKE(c2,73,27,73,23,db,45,4e,a6,3b,b9,6e,79,b5,3e,97)
-
-int main(int argc, char *argv[]) {
-        sd_id128_t id;
-        sd_id128_get_machine_app_specific(OUR_APPLICATION_ID, &amp;id);
-        printf("Our application ID: " SD_ID128_FORMAT_STR "\n", SD_ID128_FORMAT_VAL(id));
-        return 0;
-}</programlisting>
+      <programlisting><xi:include href="id128-app-specific.c" parse="text" /></programlisting>
     </example>
   </refsect1>
 

man/sd_journal_query_unique.xml

@@ -140,32 +140,7 @@
     following example lists all unit names referenced in the
     journal:</para>
 
-    <programlisting>#include &lt;stdio.h&gt;
-#include &lt;string.h&gt;
-#include &lt;systemd/sd-journal.h&gt;
-
-int main(int argc, char *argv[]) {
-        sd_journal *j;
-        const void *d;
-        size_t l;
-        int r;
-
-        r = sd_journal_open(&amp;j, SD_JOURNAL_LOCAL_ONLY);
-        if (r &lt; 0) {
-                fprintf(stderr, "Failed to open journal: %s\n", strerror(-r));
-                return 1;
-        }
-        r = sd_journal_query_unique(j, "_SYSTEMD_UNIT");
-        if (r &lt; 0) {
-                fprintf(stderr, "Failed to query journal: %s\n", strerror(-r));
-                return 1;
-        }
-        SD_JOURNAL_FOREACH_UNIQUE(j, d, l)
-                printf("%.*s\n", (int) l, (const char*) d);
-        sd_journal_close(j);
-        return 0;
-}</programlisting>
-
+    <programlisting><xi:include href="journal-iterate-unique.c" parse="text" /></programlisting>
   </refsect1>
 
   <refsect1>

man/sd_login_monitor_new.xml

@@ -115,13 +115,13 @@
     code block is left:</para>
 
     <programlisting>{
-        __attribute__((cleanup(sd_login_monitor_unrefp)) sd_login_monitor *m = NULL;
-        int r;
-        …
-        r = sd_login_monitor_default(&amp;m);
-        if (r &lt; 0)
-                fprintf(stderr, "Failed to allocate login monitor object: %s\n", strerror(-r));
-        …
+  __attribute__((cleanup(sd_login_monitor_unrefp)) sd_login_monitor *m = NULL;
+  int r;
+  …
+  r = sd_login_monitor_default(&amp;m);
+  if (r &lt; 0)
+    fprintf(stderr, "Failed to allocate login monitor object: %s\n", strerror(-r));
+  …
 }</programlisting>
 
     <para><function>sd_login_monitor_flush()</function> may be used to
@@ -176,13 +176,13 @@
 int msec;
 sd_login_monitor_get_timeout(m, &amp;t);
 if (t == (uint64_t) -1)
-         msec = -1;
+  msec = -1;
 else {
-         struct timespec ts;
-         uint64_t n;
-         clock_gettime(CLOCK_MONOTONIC, &amp;ts);
-         n = (uint64_t) ts.tv_sec * 1000000 + ts.tv_nsec / 1000;
-         msec = t > n ? (int) ((t - n + 999) / 1000) : 0;
+  struct timespec ts;
+  uint64_t n;
+  clock_gettime(CLOCK_MONOTONIC, &amp;ts);
+  n = (uint64_t) ts.tv_sec * 1000000 + ts.tv_nsec / 1000;
+  msec = t > n ? (int) ((t - n + 999) / 1000) : 0;
 }</programlisting>
 
     <para>The code above does not do any error checking for brevity's