app: Define a special exit code for no changes (77)

Used by upgrade and deploy to allow scripts to test for changes.

man/rpm-ostree.xml

@@ -103,6 +103,12 @@ Boston, MA 02111-1307, USA.
         any changes to take
         effect.</para>
 
+        <para>
+          In addition to exit status 0 for success and 1 for error, this
+          command also uses exit status 77 to indicate that no upgrade is
+          available.
+        </para>
+
         <para>
           <command>--reboot</command> or <command>-r </command> to initiate a reboot after upgrade is prepared.
         </para>
@@ -162,6 +168,12 @@ Boston, MA 02111-1307, USA.
             its SHA256 checksum, or by its "version" metadata value.
           </para>
 
+          <para>
+            In addition to exit status 0 for success and 1 for error, this
+            command also uses exit status 77 to indicate that no deployment
+            change occurred.
+          </para>
+
           <para>
             <option>--reboot</option> or <option>-r</option> to initiate a
             reboot after the downloaded tree is prepared.

src/app/rpmostree-builtin-deploy.c

@@ -145,12 +145,24 @@ rpmostree_builtin_deploy (int            argc,
                                                               error))
         goto out;
 
+      if (g_variant_n_children (result) == 0)
+        {
+          exit_status = RPM_OSTREE_EXIT_UNCHANGED;
+          goto out;
+        }
+
       rpmostree_print_package_diffs (result);
     }
-  else if (!opt_reboot && default_deployment != NULL)
+  else if (!opt_reboot)
     {
       const char *sysroot_path;
 
+      if (default_deployment == NULL)
+        {
+          exit_status = RPM_OSTREE_EXIT_UNCHANGED;
+          goto out;
+        }
+
       sysroot_path = rpmostree_sysroot_get_path (sysroot_proxy);
 
       if (!rpmostree_print_treepkg_diff_from_sysroot_path (sysroot_path,

src/app/rpmostree-builtin-upgrade.c

@@ -141,28 +141,32 @@ rpmostree_builtin_upgrade (int             argc,
                                                               error))
         goto out;
 
-      rpmostree_print_package_diffs (result);
-    }
-  else
-    {
-      /* nothing changed */
-      if (default_deployment == NULL)
+      if (g_variant_n_children (result) == 0)
         {
+          exit_status = RPM_OSTREE_EXIT_UNCHANGED;
           goto out;
         }
-      if (!opt_reboot)
+
+      rpmostree_print_package_diffs (result);
+    }
+  else if (!opt_reboot)
+    {
+      const char *sysroot_path;
+
+      if (default_deployment == NULL)
         {
-          const char *sysroot_path;
-
-          sysroot_path = rpmostree_sysroot_get_path (sysroot_proxy);
-
-          if (!rpmostree_print_treepkg_diff_from_sysroot_path (sysroot_path,
-                                                               cancellable,
-                                                               error))
-            goto out;
-
-          g_print ("Run \"systemctl reboot\" to start a reboot\n");
+          exit_status = RPM_OSTREE_EXIT_UNCHANGED;
+          goto out;
         }
+
+      sysroot_path = rpmostree_sysroot_get_path (sysroot_proxy);
+
+      if (!rpmostree_print_treepkg_diff_from_sysroot_path (sysroot_path,
+                                                           cancellable,
+                                                           error))
+        goto out;
+
+      g_print ("Run \"systemctl reboot\" to start a reboot\n");
     }
 
   exit_status = EXIT_SUCCESS;

src/app/rpmostree-builtins.h

@@ -25,6 +25,10 @@
 
 G_BEGIN_DECLS
 
+/* Exit code for no change after pulling commits.
+ * Use alongside EXIT_SUCCESS and EXIT_FAILURE. */
+#define RPM_OSTREE_EXIT_UNCHANGED  (77)
+
 typedef enum {
   RPM_OSTREE_BUILTIN_FLAG_NONE = 0,
   RPM_OSTREE_BUILTIN_FLAG_LOCAL_CMD = 1 << 0