Init commit

src/git_fs/index.rs

@@ -0,0 +1,56 @@
+use std::{
+    io::{
+        self,
+        Error,
+    },
+};
+
+use crate::GIT_DIR;
+
+#[derive(Debug)]
+pub struct IndexEntry {
+    file_size: u32,
+    hash: [u8; 20],
+    name: String,
+}
+
+impl IndexEntry {
+    fn from_bytes(bytes: Vec<u8>) -> io::Result<Self> {
+
+        return Err(Error::other("Not implemented"))
+    }
+}
+
+#[derive(Debug)]
+pub struct Index {
+    version: u32,
+    entries: Vec<IndexEntry>,
+}
+
+impl Index {
+    pub fn from_bytes(bytes: Vec<u8>) -> io::Result<Self> {
+        let magic: [u8; 4] = match bytes.first_chunk() {
+            None => return Err(Error::other("Error parsing index")),
+            Some(magic) => *magic,
+        };
+
+        match str::from_utf8(&magic) {
+            Ok("DIRC") => (),
+            _ => return Err(Error::other("Invalid index"))
+        };
+
+        let version_bytes = <[u8; 4]>::try_from(&bytes.as_slice()[4..8]).unwrap();
+        let version = u32::from_be_bytes(version_bytes);
+
+        let count_bytes = <[u8; 4]>::try_from(&bytes.as_slice()[8..12]).unwrap();
+        let count = u32::from_be_bytes(count_bytes);
+
+        let entries: Vec<IndexEntry> = Vec::with_capacity(usize::try_from(count).unwrap());
+
+        for i in 0..=count {
+
+        };
+
+        return Ok(Index { version, entries});
+    }
+}