init: initial commit of packager

pkgfile/src/lib.rs

@@ -0,0 +1,36 @@
+pub struct PKGFile {
+    pub manifest: String,
+    pub data: Vec<u8>,
+}
+
+impl TryFrom<Vec<u8>> for PKGFile {
+    type Error = ();
+
+    fn try_from(value: Vec<u8>) -> Result<Self, ()> {
+        match value[0] {
+            1 => {
+                let header: Vec<u32> = value[..3]
+                    .iter()
+                    .map(|v| u32::from(*v))
+                    .collect();
+                let manifest_size: u32 = ((header[1] << 8) | header[2]);
+                if manifest_size > value.len() as u32 {
+                    return Err(());
+                }
+                Ok(PKGFile {
+                    manifest: match String::from_utf8(
+                        value[
+                            3..(manifest_size as usize)
+                            ].to_vec()
+                        )
+                    {
+                        Ok(s) => s,
+                        _ => return Err(())
+                    },
+                    data: value[(manifest_size as usize)..].to_vec(),
+                })
+            }
+            _ => Err(())
+        }
+    }
+}