[RFC PATCH] cli: avoid requiring specific modem if only a single modem is found in the system

[Aleksander Morgado]

This change will allow running mmcli operations without needing to specify
neither the index nor the path of the modem object, but only if a single modem
is found in the system. E.g.:

Enabling the modem, when it is the only one in the system, would just be:
   $ sudo mmcli --enable
   successfully enabled the modem

But if multiple modems are found in the system:
   $ sudo mmcli --enable
   error: multiple modems found: need specific modem to run the operation

In particular, the special operation without actions that we had before to print
the info of a given modem will now also be implicit even if no index or path is
given:

So, when a single modem is found in the system:
   $ sudo mmcli
   /org/freedesktop/ModemManager1/Modem/1 (device id '51e23d10a4180fcf08a1a55e4c01dce693b17e66')
     -------------------------
     Hardware |   manufacturer: 'Sierra Wireless, Incorporated'
              |          model: 'MC7304'
              |       revision: 'SWI9X15C_05.05.16.02 r21040 carmd-fwbuild1 2014/03/17 23:49:48'
              |      supported: 'gsm-umts
   ...

But if multiple modems are found:
   $ sudo mmcli
   error: multiple modems found: need specific modem to run the operation
---

What does this look like?

I'm not totally sure about the special operation without explicit action requested, where we
just showed the modem info. Should we still do that even if no modem index or path is given?

---
 cli/mmcli-common.c | 43 ++++++++++++++++++++++++++++++++++---------
 cli/mmcli-modem.c  |  2 +-
 cli/mmcli.c        |  7 -------
 3 files changed, 35 insertions(+), 17 deletions(-)

diff --git a/cli/mmcli-common.c b/cli/mmcli-common.c
index 2d7f66e..e040a97 100644
--- a/cli/mmcli-common.c
+++ b/cli/mmcli-common.c
@@ -117,18 +117,43 @@ find_modem (MMManager *manager,
             const gchar *modem_path)
 {
     GList *modems;
-    GList *l;
     MMObject *found = NULL;

     modems = g_dbus_object_manager_get_objects (G_DBUS_OBJECT_MANAGER (manager));
-    for (l = modems; l; l = g_list_next (l)) {
-        MMObject *modem = MM_OBJECT (l->data);

-        if (g_str_equal (mm_object_get_path (modem), modem_path)) {
-            found = g_object_ref (modem);
-            break;
+    /* Single modem expected? */
+    if (!modem_path) {
+        guint n_modems;
+
+        n_modems = g_list_length (modems);
+
+        /* More than one modem found, error out */
+        if (n_modems > 1) {
+            g_printerr ("error: multiple modems found: need specific modem to run the operation\n");
+            exit (EXIT_FAILURE);
+        }
+
+        /* No modems found, error out */
+        if (!n_modems) {
+            g_printerr ("error: no modems found: need specific modem to run the operation\n");
+            exit (EXIT_FAILURE);
+        }
+
+        found = g_object_ref (MM_OBJECT (modems->data));
+    } else {
+        GList *l;
+
+        /* Iterate list of modems and try to patch one by path */
+        for (l = modems; l; l = g_list_next (l)) {
+            MMObject *modem = MM_OBJECT (l->data);
+
+            if (g_str_equal (mm_object_get_path (modem), modem_path)) {
+                found = g_object_ref (modem);
+                break;
+            }
         }
     }
+
     g_list_free_full (modems, (GDestroyNotify) g_object_unref);

     if (!found) {
@@ -136,7 +161,7 @@ find_modem (MMManager *manager,
         exit (EXIT_FAILURE);
     }

-    g_debug ("Modem found at '%s'\n", modem_path);
+    g_debug ("Modem found at '%s'\n", mm_object_get_path (found));

     return found;
 }
@@ -211,8 +236,8 @@ get_modem_path (const gchar *path_or_index)

     /* We must have a given modem specified */
     if (!path_or_index) {
-        g_printerr ("error: no modem was specified\n");
-        exit (EXIT_FAILURE);
+        g_debug ("Assuming single modem...");
+        return NULL;
     }

     /* Modem path may come in two ways: full DBus path or just modem index.
diff --git a/cli/mmcli-modem.c b/cli/mmcli-modem.c
index f119f6e..a0a7448 100644
--- a/cli/mmcli-modem.c
+++ b/cli/mmcli-modem.c
@@ -174,7 +174,7 @@ mmcli_modem_options_enabled (void)
                  !!set_preferred_mode_str +
                  !!set_current_bands_str);

-    if (n_actions == 0 && mmcli_get_common_modem_string ()) {
+    if (n_actions == 0) {
         /* default to info */
         info_flag = TRUE;
         n_actions++;
diff --git a/cli/mmcli.c b/cli/mmcli.c
index a4e6a4f..c1fc369 100644
--- a/cli/mmcli.c
+++ b/cli/mmcli.c
@@ -247,13 +247,6 @@ main (gint argc, gchar **argv)

     /* Manager options? */
     if (mmcli_manager_options_enabled ()) {
-        /* Ensure options from different groups are not enabled */
-        if (mmcli_modem_options_enabled ()) {
-            g_printerr ("error: cannot use manager and modem options "
-                        "at the same time\n");
-            exit (EXIT_FAILURE);
-        }
-
         if (async_flag)
             mmcli_manager_run_asynchronous (connection, cancellable);
         else
--
2.3.6