config.rs: better env variable matching

src/config.rs

@@ -57,31 +57,48 @@ pub struct PageMeta {
 
 pub fn get_path(xdg: &str) -> Result<String, (String, u32)> {
   let dir: String;
-  
-  if unsafe { libc::geteuid() } == 0 {
-    dir = match xdg {
-      "XDG_CACHE_HOME" => "/var".to_owned(),
-      "XDG_CONFIG_HOME" => "/etc".to_owned(),
-      _ => panic!("nya"),
-    };
-  } else {
-    dir = match env::var(xdg) {
-      Ok(var) => var,
-      Err(_) => {
-        match env::var("HOME") {
-          Ok(home) => format!("{}/.config", home),
-          Err(_) => {
-            return Err((
-              "Unable to determine path to current user’s home directory."
-                .to_string(),
-              EX_UNAVAILABLE
-            ));
-          },
-        }
-      },
-    };
-  }
+  let home_dir = match env::var("HOME").ok() {
+    Some(home) => home,
+    None => {
+      return Err((
+        "Unable to determine path to current user’s home directory."
+          .to_string(),
+        EX_UNAVAILABLE
+      ));
+    }
+  };
+  let mut root = false;
 
+  if unsafe { libc::geteuid() } == 0 { root = true; }
+
+  dir = match (root, env::var(xdg).ok()) {
+    (false, Some(var)) => var,
+    (su, None) => {
+      match xdg {
+        "XDG_CACHE_HOME" => {
+          if su { "/var".to_owned() }
+          else { format!("{}/.cache", home_dir) }
+        },
+        "XDG_CONFIG_HOME" => {
+          if su { "/etc".to_owned() }
+          else { format!("{}/.config", home_dir) }
+        },
+        "XDG_DATA_HOME" => {
+          if su { "/usr/share".to_owned() }
+          else { format!("{}/.local/share", home_dir) }
+        },
+        _ => {
+          return Err(
+            (format!("{}: Unimplemented variable.", xdg), EX_SOFTWARE)
+          );
+        },
+      }
+    },
+    _ => {
+      panic!("nya");
+    },
+  };
+  
   Ok(format!("{}/plaque", dir))
 }