i3bar: Add default bar_id

Instead of erroring, request the list of bar configs from i3 and use the
first one.

i3bar/include/configuration.h

@@ -74,6 +74,13 @@ extern config_t config;
  */
 void parse_config_json(char *json);
 
+/**
+ * Start parsing the received bar configuration list. The only usecase right
+ * now is to automatically get the first bar id.
+ *
+ */
+void parse_get_first_i3bar_config(char *json);
+
 /**
  * free()s the color strings as soon as they are not needed anymore.
  *

i3bar/include/ipc.h

@@ -18,7 +18,7 @@
  * socket_path must be a valid path to the ipc_socket of i3
  *
  */
-int init_connection(const char *socket_path);
+void init_connection(const char *socket_path);
 
 /*
  * Destroy the connection to i3.

i3bar/src/config.c

@@ -367,14 +367,12 @@ static yajl_callbacks outputs_callbacks = {
  *
  */
 void parse_config_json(char *json) {
-    yajl_handle handle;
-    yajl_status state;
-    handle = yajl_alloc(&outputs_callbacks, NULL, NULL);
+    yajl_handle handle = yajl_alloc(&outputs_callbacks, NULL, NULL);
 
     TAILQ_INIT(&(config.bindings));
     TAILQ_INIT(&(config.tray_outputs));
 
-    state = yajl_parse(handle, (const unsigned char *)json, strlen(json));
+    yajl_status state = yajl_parse(handle, (const unsigned char *)json, strlen(json));
 
     /* FIXME: Proper error handling for JSON parsing */
     switch (state) {
@@ -390,6 +388,25 @@ void parse_config_json(char *json) {
     yajl_free(handle);
 }
 
+static int i3bar_config_string_cb(void *params_, const unsigned char *val, size_t _len) {
+    sasprintf(&config.bar_id, "%.*s", (int)_len, val);
+    return 0; /* Stop parsing */
+}
+
+/*
+ * Start parsing the received bar configuration list. The only usecase right
+ * now is to automatically get the first bar id.
+ *
+ */
+void parse_get_first_i3bar_config(char *json) {
+    yajl_callbacks configs_callbacks = {
+        .yajl_string = i3bar_config_string_cb,
+    };
+    yajl_handle handle = yajl_alloc(&configs_callbacks, NULL, NULL);
+    yajl_parse(handle, (const unsigned char *)json, strlen(json));
+    yajl_free(handle);
+}
+
 /*
  * free()s the color strings as soon as they are not needed anymore.
  *

i3bar/src/ipc.c

@@ -85,6 +85,20 @@ static void got_output_reply(char *reply) {
  *
  */
 static void got_bar_config(char *reply) {
+    if (!config.bar_id) {
+        DLOG("Received bar list \"%s\"\n", reply);
+        parse_get_first_i3bar_config(reply);
+
+        if (!config.bar_id) {
+            ELOG("No bar configuration found, please configure a bar block in your i3 config file.\n");
+            exit(EXIT_FAILURE);
+        }
+
+        LOG("Using first bar config: %s. Use --bar_id to manually select a different bar configuration.\n", config.bar_id);
+        i3_send_msg(I3_IPC_MESSAGE_TYPE_GET_BAR_CONFIG, config.bar_id);
+        return;
+    }
+
     DLOG("Received bar config \"%s\"\n", reply);
     /* We initiate the main function by requesting infos about the outputs and
      * workspaces. Everything else (creating the bars, showing the right workspace-
@@ -328,13 +342,12 @@ int i3_send_msg(uint32_t type, const char *payload) {
  * socket_path must be a valid path to the ipc_socket of i3
  *
  */
-int init_connection(const char *socket_path) {
+void init_connection(const char *socket_path) {
     sock_path = socket_path;
     int sockfd = ipc_connect(socket_path);
     i3_connection = smalloc(sizeof(ev_io));
     ev_io_init(i3_connection, &got_data, sockfd, EV_READ);
     ev_io_start(main_loop, i3_connection);
-    return 1;
 }
 
 /*

i3bar/src/main.c

@@ -56,9 +56,9 @@ static char *expand_path(char *path) {
 }
 
 static void print_usage(char *elf_name) {
-    printf("Usage: %s -b bar_id [-s sock_path] [-t] [-h] [-v] [-V]\n", elf_name);
+    printf("Usage: %s [-b bar_id] [-s sock_path] [-t] [-h] [-v] [-V]\n", elf_name);
     printf("\n");
-    printf("-b, --bar_id       <bar_id>\tBar ID for which to get the configuration\n");
+    printf("-b, --bar_id       <bar_id>\tBar ID for which to get the configuration, defaults to the first bar from the i3 config\n");
     printf("-s, --socket       <sock_path>\tConnect to i3 via <sock_path>\n");
     printf("-t, --transparency Enable transparency (RGBA colors)\n");
     printf("-h, --help         Display this help message and exit\n");
@@ -133,13 +133,6 @@ int main(int argc, char **argv) {
         }
     }
 
-    if (!config.bar_id) {
-        /* TODO: maybe we want -f which will automatically ask i3 for the first
-         * configured bar (and error out if there are too many)? */
-        ELOG("No bar_id passed. Please let i3 start i3bar or specify --bar_id\n");
-        exit(EXIT_FAILURE);
-    }
-
     main_loop = ev_default_loop(0); /* needed in init_xcb_early */
     char *atom_sock_path = init_xcb_early();
 
@@ -166,10 +159,13 @@ int main(int argc, char **argv) {
     init_dpi();
 
     init_outputs();
-    if (init_connection(socket_path)) {
-        /* Request the bar configuration. When it arrives, we fill the config array. */
-        i3_send_msg(I3_IPC_MESSAGE_TYPE_GET_BAR_CONFIG, config.bar_id);
-    }
+
+    init_connection(socket_path);
+    /* Request the bar configuration. When it arrives, we fill the config
+     * array. In case that config.bar_id is empty, we will receive a list of
+     * available configs and then request the configuration for the first bar.
+     * See got_bar_config for more. */
+    i3_send_msg(I3_IPC_MESSAGE_TYPE_GET_BAR_CONFIG, config.bar_id);
     free(socket_path);
 
     /* We listen to SIGTERM/QUIT/INT and try to exit cleanly, by stopping the main loop.