Implement include command

The include command (`include <path>`) makes it possible to include sub
config files from the main config file (or from within other sub config
files).

The include command uses the following rules for including config files:

* the `path` can be either a full path or a path that is relative to the
  parent config. Shell expansion is supported, so it's possible to do
  `include ~/.config/sway.d/*`.
* The same config file can only be included once (to prevent include
  cycles). If a config is included multiple times it will just be
  ignored after it has been included once.
* Including a sub config file is the same as inserting the content of
  that file into the parent config, thus rules about overwriting
  bindsyms etc. works the same as for a single config.

Implement #542

4 files changed, 155 insertions, 37 deletions

diff --git a/include/config.h b/include/config.h
index 9356140d..4bcf55e8 100644
--- a/include/config.h
+++ b/include/config.h
@@ -184,15 +184,27 @@ struct sway_config {
         bool smart_gaps;
         int gaps_inner;
         int gaps_outer;
+
+        list_t *config_chain;
+        const char *current_config;
 };
 
 /**
- * Loads the config from the given path.
+ * Loads the main config from the given path. is_active should be true when
+ * reloading the config.
  */
-bool load_config(const char *file);
-/** Reads the config from the given FILE.
+bool load_main_config(const char *path, bool is_active);
+
+/**
+ * Loads an included config. Can only be used after load_main_config.
  */
-bool read_config(FILE *file, bool is_active);
+bool load_include_configs(const char *path, struct sway_config *config);
+
+/**
+ * Reads the config from the given FILE.
+ */
+bool read_config(FILE *file, struct sway_config *config);
+
 /**
  * Free config struct
  */
diff --git a/sway/commands.c b/sway/commands.c
index 26fa771e..bc8c42eb 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -55,6 +55,7 @@ static sway_cmd cmd_font;
 static sway_cmd cmd_for_window;
 static sway_cmd cmd_fullscreen;
 static sway_cmd cmd_gaps;
+static sway_cmd cmd_include;
 static sway_cmd cmd_input;
 static sway_cmd cmd_kill;
 static sway_cmd cmd_layout;
@@ -1141,6 +1142,19 @@ static struct cmd_results *input_cmd_tap(int argc, char **argv) {
         return cmd_results_new(CMD_SUCCESS, NULL, NULL);
 }
 
+static struct cmd_results *cmd_include(int argc, char **argv) {
+        struct cmd_results *error = NULL;
+        if ((error = checkarg(argc, "include", EXPECTED_EQUAL_TO, 1))) {
+                return error;
+        }
+
+        if (!load_include_configs(argv[0], config)) {
+                return cmd_results_new(CMD_INVALID, "include", "Failed to include sub configuration file: %s", argv[0]);
+        }
+
+        return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}
+
 static struct cmd_results *cmd_input(int argc, char **argv) {
         struct cmd_results *error = NULL;
         if ((error = checkarg(argc, "input", EXPECTED_AT_LEAST, 2))) {
@@ -1541,7 +1555,7 @@ static struct cmd_results *cmd_reload(int argc, char **argv) {
         if ((error = checkarg(argc, "reload", EXPECTED_EQUAL_TO, 0))) {
                 return error;
         }
-        if (!load_config(NULL)) return cmd_results_new(CMD_FAILURE, "reload", "Error(s) reloading config.");
+        if (!load_main_config(NULL, true)) return cmd_results_new(CMD_FAILURE, "reload", "Error(s) reloading config.");
 
         load_swaybars();
 
@@ -2053,6 +2067,7 @@ static struct cmd_handler handlers[] = {
         { "for_window", cmd_for_window },
         { "fullscreen", cmd_fullscreen },
         { "gaps", cmd_gaps },
+        { "include", cmd_include },
         { "input", cmd_input },
         { "kill", cmd_kill },
         { "layout", cmd_layout },
diff --git a/sway/config.c b/sway/config.c
index a5fdf850..d54ce213 100644
--- a/sway/config.c
+++ b/sway/config.c
@@ -2,6 +2,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <libgen.h>
 #include <wordexp.h>
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -126,6 +127,7 @@ void free_config(struct sway_config *config) {
         list_free(config->output_configs);
 
         list_free(config->active_bar_modifiers);
+        free_flat_list(config->config_chain);
         free(config->font);
         free(config);
 }
@@ -175,6 +177,9 @@ static void config_defaults(struct sway_config *config) {
         config->gaps_outer = 0;
 
         config->active_bar_modifiers = create_list();
+
+        config->config_chain = create_list();
+        config->current_config = NULL;
 }
 
 static int compare_modifiers(const void *left, const void *right) {
@@ -237,16 +242,7 @@ static char *get_config_path(void) {
         return NULL; // Not reached
 }
 
-bool load_config(const char *file) {
-        input_init();
-
-        char *path;
-        if (file != NULL) {
-                path = strdup(file);
-        } else {
-                path = get_config_path();
-        }
-
+static bool load_config(const char *path, struct sway_config *config) {
         sway_log(L_INFO, "Loading config from %s", path);
 
         if (path == NULL) {
@@ -257,20 +253,12 @@ bool load_config(const char *file) {
         FILE *f = fopen(path, "r");
         if (!f) {
                 sway_log(L_ERROR, "Unable to open %s for reading", path);
-                free(path);
                 return false;
         }
-        free(path);
 
-        bool config_load_success;
-        if (config) {
-                config_load_success = read_config(f, true);
-        } else {
-                config_load_success = read_config(f, false);
-        }
+        bool config_load_success = read_config(f, config);
         fclose(f);
 
-        update_active_bar_modifiers();
 
         if (!config_load_success) {
                 sway_log(L_ERROR, "Error(s) loading config!");
@@ -279,17 +267,129 @@ bool load_config(const char *file) {
         return true;
 }
 
-bool read_config(FILE *file, bool is_active) {
+bool load_main_config(const char *file, bool is_active) {
+        input_init();
+
+        char *path;
+        if (file != NULL) {
+                path = strdup(file);
+        } else {
+                path = get_config_path();
+        }
+
         struct sway_config *old_config = config;
         config = calloc(1, sizeof(struct sway_config));
 
         config_defaults(config);
-        config->reading = true;
         if (is_active) {
                 sway_log(L_DEBUG, "Performing configuration file reload");
                 config->reloading = true;
                 config->active = true;
         }
+
+        config->current_config = path;
+        list_add(config->config_chain, path);
+
+        config->reading = true;
+        bool success = load_config(path, config);
+
+        if (is_active) {
+                config->reloading = false;
+        }
+
+        if (old_config) {
+                free_config(old_config);
+        }
+        config->reading = false;
+
+        if (success) {
+                update_active_bar_modifiers();
+        }
+
+        return success;
+}
+
+static bool load_include_config(const char *path, const char *parent_dir, struct sway_config *config) {
+        // save parent config
+        const char *parent_config = config->current_config;
+
+        char *full_path = strdup(path);
+        int len = strlen(path);
+        if (len >= 1 && path[0] != '/') {
+                len = len + strlen(parent_dir) + 2;
+                full_path = malloc(len * sizeof(char));
+                snprintf(full_path, len, "%s/%s", parent_dir, path);
+        }
+
+        char *real_path = realpath(full_path, NULL);
+        free(full_path);
+
+        // check if config has already been included
+        int j;
+        for (j = 0; j < config->config_chain->length; ++j) {
+                char *old_path = config->config_chain->items[j];
+                if (strcmp(real_path, old_path) == 0) {
+                        sway_log(L_DEBUG, "%s already included once, won't be included again.", real_path);
+                        free(real_path);
+                        return false;
+                }
+        }
+
+        config->current_config = real_path;
+        list_add(config->config_chain, real_path);
+        int index = config->config_chain->length - 1;
+
+        if (!load_config(real_path, config)) {
+                free(real_path);
+                config->current_config = parent_config;
+                list_del(config->config_chain, index);
+                return false;
+        }
+
+        // restore current_config
+        config->current_config = parent_config;
+        return true;
+}
+
+bool load_include_configs(const char *path, struct sway_config *config) {
+        char *wd = getcwd(NULL, 0);
+        char *parent_path = strdup(config->current_config);
+        const char *parent_dir = dirname(parent_path);
+
+        if (chdir(parent_dir) < 0) {
+                free(parent_path);
+                free(wd);
+                return false;
+        }
+
+        wordexp_t p;
+
+        if (wordexp(path, &p, 0) < 0) {
+                free(parent_path);
+                free(wd);
+                return false;
+        }
+
+        char **w = p.we_wordv;
+        size_t i;
+        for (i = 0; i < p.we_wordc; ++i) {
+                load_include_config(w[i], parent_dir, config);
+        }
+        free(parent_path);
+        wordfree(&p);
+
+        // restore wd
+        if (chdir(wd) < 0) {
+                free(wd);
+                sway_log(L_ERROR, "failed to restore working directory");
+                return false;
+        }
+
+        free(wd);
+        return true;
+}
+
+bool read_config(FILE *file, struct sway_config *config) {
         bool success = true;
         enum cmd_status block = CMD_BLOCK_END;
 
@@ -386,15 +486,6 @@ bool read_config(FILE *file, bool is_active) {
                 free(res);
         }
 
-        if (is_active) {
-                config->reloading = false;
-                arrange_windows(&root_container, -1, -1);
-        }
-        if (old_config) {
-                free_config(old_config);
-        }
-
-        config->reading = false;
         return success;
 }
 
diff --git a/sway/main.c b/sway/main.c
index c4a5d497..4aaac556 100644
--- a/sway/main.c
+++ b/sway/main.c
@@ -206,11 +206,11 @@ int main(int argc, char **argv) {
         init_layout();
 
         if (validate) {
-                bool valid = load_config(config_path);
+                bool valid = load_main_config(config_path, false);
                 return valid ? 0 : 1;
         }
 
-        if (!load_config(config_path)) {
+        if (!load_main_config(config_path, false)) {
                 sway_terminate(EXIT_FAILURE);
         }