Add --appendconfig option.

conf/config_file.c

@@ -312,6 +312,23 @@ static bool parse_line(config_file_t *conf, struct entry_list *list, char *line)
    return true;
 }
 
+bool config_append_file(config_file_t *conf, const char *path)
+{
+   config_file_t *new_conf = config_file_new(path);
+   if (!new_conf)
+      return false;
+
+   if (new_conf->tail)
+   {
+      new_conf->tail->next = conf->entries;
+      conf->entries        = new_conf->entries; // Pilfer.
+      new_conf->entries    = NULL;
+   }
+
+   config_file_free(new_conf);
+   return true;
+}
+
 static config_file_t *config_file_new_internal(const char *path, unsigned depth)
 {
    struct config_file *conf = (struct config_file*)calloc(1, sizeof(*conf));

conf/config_file.h

@@ -40,6 +40,10 @@ config_file_t *config_file_new(const char *path);
 // Frees config file.
 void config_file_free(config_file_t *conf);
 
+// Loads a new config, and appends its data to conf.
+// The key-value pairs of the new config file takes priority over the old.
+bool config_append_file(config_file_t *conf, const char *path);
+
 // All extract functions return true when value is valid and exists.
 // Returns false otherwise.
 

docs/retroarch.1

@@ -67,6 +67,12 @@ If PATH is a directory, RetroArch will treat this as the config file directory,
 When loading a rom from stdin, the path must be a full path, however.
 If a config cannot be found when using directory path, the default config path will be used instead.
 
+.TP
+\fB--appendconfig PATH\fR
+Appends a different set of config files to the config file loaded in -c (or default).
+Multiple config files are delimited by ','.
+Every config file will be appended in order where the key-value pairs of the next config file takes priority over the old ones.
+
 .IP
 Unix-like systems will look in $XDG_CONFIG_HOME/retroarch/retroarch.cfg first. Then it will try $HOME/.retroarch.cfg. Last, it will try /etc/retroarch.cfg. If no configuration is found, default settings will be assumed. A configuration file does not need to define every possible option, only those that should be overridden.
 

general.h

@@ -308,6 +308,7 @@ struct global
 
 #ifdef HAVE_CONFIGFILE
    char config_path[PATH_MAX];
+   char append_config_path[PATH_MAX];
 #endif
    
    char basename[PATH_MAX];

retroarch.c

@@ -594,6 +594,8 @@ static void print_help(void)
    puts("\t-S/--savestate: Path to use for save states. If not selected, *.state will be assumed.");
 #ifdef HAVE_CONFIGFILE
    puts("\t-c/--config: Path for config file." RARCH_DEFAULT_CONF_PATH_STR);
+   puts("\t--appendconfig: Extra config files are loaded in, and take priority over config selected in -c (or default).");
+   puts("\t\tMultiple configs are delimited by ','.");
 #endif
 #ifdef HAVE_DYNAMIC
    puts("\t-L/--libretro: Path to libretro implementation. Overrides any config setting.");
@@ -768,6 +770,7 @@ static void parse_input(int argc, char *argv[])
       { "gameboy", 1, NULL, 'g' },
 #ifdef HAVE_CONFIGFILE
       { "config", 1, NULL, 'c' },
+      { "appendconfig", 1, &val, 'C' },
 #endif
       { "mouse", 1, NULL, 'm' },
       { "nodevice", 1, NULL, 'N' },
@@ -1048,6 +1051,10 @@ static void parse_input(int argc, char *argv[])
                   break;
 #endif
 
+               case 'C':
+                  strlcpy(g_extern.append_config_path, optarg, sizeof(g_extern.append_config_path));
+                  break;
+
                case 'B':
                   strlcpy(g_extern.bps_name, optarg, sizeof(g_extern.bps_name));
                   g_extern.bps_pref = true;

settings.c

@@ -336,6 +336,19 @@ bool config_load_file(const char *path)
    if (conf == NULL)
       return true;
 
+   char *save;
+   char tmp_append_path[PATH_MAX]; // Don't destroy append_config_path.
+   strlcpy(tmp_append_path, g_extern.append_config_path, sizeof(tmp_append_path));
+   const char *extra_path = strtok_r(tmp_append_path, ",", &save);
+   while (extra_path)
+   {
+      RARCH_LOG("Appending config \"%s\"\n", extra_path);
+      bool ret = config_append_file(conf, extra_path);
+      if (!ret)
+         RARCH_ERR("Failed to append config \"%s\"\n", extra_path);
+      extra_path = strtok_r(NULL, ";", &save);
+   }
+
    if (g_extern.verbose)
    {
       fprintf(stderr, "=== Config ===\n");