Error Rework / Code Refactor

Added in being able to return an error when the path to a WAD is
not a valid path. This patch is to address issue #6.

src/main.rs

@@ -5,7 +5,7 @@ use doomlevel::DoomLevel;
 use wadfile::WADFile;
 
 fn main() {
-    let wad_file = WADFile::from_path("WADs/doom1.wad");
+    let wad_file = WADFile::from_path("WADs/doom1.wad").unwrap();
     let level = DoomLevel::load_level(&wad_file, wad_file.get_index_from_name("e1m1").unwrap());
 
     println!(
@@ -66,7 +66,7 @@ Flags:
 \tSecret: {}
 \tBlocks Sound: {}
 \tNever Shows on Automap: {}
-\tAlways Shows on Automap {}",
+\tAlways Shows on Automap: {}",
         level.linedefs[test_linedef].start_vertex,
         level.linedefs[test_linedef].end_vertex,
         level.linedefs[test_linedef].flags,

src/wadfile.rs

@@ -4,6 +4,7 @@ use directory::Directory;
 use std::{
     fs::File,
     io::{Read, Seek, SeekFrom},
+    path::Path,
 };
 
 pub struct WADFile {
@@ -15,20 +16,26 @@ pub struct WADFile {
 }
 
 impl WADFile {
-    pub fn from_path(path: &str) -> Self {
+    pub fn from_path(path: &str) -> Result<Self, &str> {
+        let wad_file = Path::new(path);
+
+        if !(wad_file.exists()) {
+            return Err("Could not open file!");
+        }
+
         let header_data = get_header_data(path);
 
         let mut lump_dir: Vec<Directory> = Vec::with_capacity(header_data.1 as usize);
 
         get_lump_dir(path, &header_data.2, &header_data.1, &mut lump_dir);
 
-        Self {
+        Ok(Self {
             wad_path: path.to_string(),
             identifier: header_data.0,
             num_lumps: header_data.1,
             init_offset: header_data.2,
             lump_directory: lump_dir,
-        }
+        })
     }
 
     pub fn get_lump_name(&self, index: u32) -> String {
@@ -74,20 +81,15 @@ fn get_lump_dir(path: &str, dir_offset: &u32, num_lumps: &u32, lump_buffer: &mut
         let mut lump_pos = [0; 4];
         let mut lump_size = [0; 4];
         let mut lump_name = [0; 8];
-        let mut name = String::with_capacity(8);
 
         wad_data.read(&mut lump_pos).unwrap();
         wad_data.read(&mut lump_size).unwrap();
         wad_data.read(&mut lump_name).unwrap();
 
-        for letter in 0..lump_name.len() {
-            name.push(lump_name[letter] as char);
-        }
-
         lump_buffer.push(Directory {
             lump_pos: u32::from_le_bytes(lump_pos),
             lump_size: u32::from_le_bytes(lump_size),
-            lump_name: name,
+            lump_name: String::from_utf8(lump_name.to_vec()).unwrap(),
         })
     }
 }
@@ -95,23 +97,17 @@ fn get_lump_dir(path: &str, dir_offset: &u32, num_lumps: &u32, lump_buffer: &mut
 fn get_header_data(path: &str) -> (String, u32, u32) {
     let mut wad_data = File::open(&path).unwrap();
 
-    let mut header = [0; 12];
+    let mut wad_id = [0; 4];
+    let mut dir_size = [0; 4];
+    let mut dir_offset = [0; 4];
 
-    wad_data.read(&mut header).unwrap();
-
-    let mut wad_type = String::with_capacity(4);
-
-    wad_type.push(header[0] as char);
-    wad_type.push(header[1] as char);
-    wad_type.push(header[2] as char);
-    wad_type.push(header[3] as char);
-
-    let lump_bytes: [u8; 4] = [header[4], header[5], header[6], header[7]];
-    let offset_bytes: [u8; 4] = [header[8], header[9], header[10], header[11]];
+    wad_data.read(&mut wad_id).unwrap();
+    wad_data.read(&mut dir_size).unwrap();
+    wad_data.read(&mut dir_offset).unwrap();
 
     (
-        wad_type,
-        u32::from_le_bytes(lump_bytes),
-        u32::from_le_bytes(offset_bytes),
+        String::from_utf8(wad_id.to_vec()).unwrap(),
+        u32::from_le_bytes(dir_size),
+        u32::from_le_bytes(dir_offset),
     )
 }