config: allow config path to be a dir or a file

For dir, as before, the mail and state dirs default to the config dir.
For file, the defaults will be computed per previous commit.

Author: robn

src/config.rs

@@ -276,8 +276,12 @@ fn default_convert_dos_to_unix() -> bool {
 }
 
 impl Config {
-    pub fn from_dir(path: &PathBuf) -> Result<Self> {
-        let filename = path.join("mujmap.toml");
+    pub fn from_path(path: &PathBuf) -> Result<Self> {
+        let filename = if path.is_dir() {
+            path.join("mujmap.toml")
+        } else {
+            path.clone()
+        };
 
         let contents = fs::read_to_string(&filename).context(ReadConfigFileSnafu {
             filename: filename.clone(),
@@ -287,11 +291,13 @@ impl Config {
         })?;
 
         // In directory mode, if paths aren't offered then we use the config dir itself.
-        if config.mail_dir.is_none() {
-            config.mail_dir = Some(path.clone());
-        }
-        if config.state_dir.is_none() {
-            config.state_dir = Some(path.clone());
+        if path.is_dir() {
+            if config.mail_dir.is_none() {
+                config.mail_dir = Some(path.clone());
+            }
+            if config.state_dir.is_none() {
+                config.state_dir = Some(path.clone());
+            }
         }
 
         // Perform final validation.

src/main.rs

@@ -61,9 +61,8 @@ fn try_main(stdout: &mut StandardStream) -> Result<(), Error> {
         .to_owned();
 
     // Determine working directory and load all data files.
-    let config_dir = args.path.clone().unwrap_or_else(|| PathBuf::from("."));
-
-    let config = Config::from_dir(&config_dir).context(OpenConfigFileSnafu {})?;
+    let config_path = args.path.clone().unwrap_or_else(|| PathBuf::from("."));
+    let config = Config::from_path(&config_path).context(OpenConfigFileSnafu {})?;
     debug!("Using config: {:?}", config);
 
     match args.command {