feat: enma parsing

enmacompat/src/util.rs

@@ -0,0 +1,44 @@
+use std::io::{Read, Seek, SeekFrom};
+
+pub fn find_in_data<T: Read + Seek>(
+    data: &mut T,
+    target: &[u8],
+) -> Result<Vec<usize>, std::io::Error> {
+    let pos = data.stream_position()?;
+    let mut result = Vec::new();
+    let mut possible = vec![false; target.len()];
+    let mut possible_i = 0;
+
+    for (i, byte) in data.bytes().enumerate() {
+        let byte = byte?;
+        if possible[possible_i] {
+            result.push(i - target.len());
+        }
+        possible[possible_i] = byte == target[possible_i];
+
+        for j in 0..possible.len() {
+            let target_index = (possible_i + j) % target.len();
+
+            possible[j] = possible[j] && byte == target[target_index];
+        }
+
+        possible_i = (possible_i + 1) % target.len();
+    }
+
+    data.seek(SeekFrom::Start(pos))?;
+
+    Ok(result)
+}
+
+pub fn is_exactly<T: Read + Seek>(
+    data: &mut T,
+    location: usize,
+    target: &[u8],
+) -> Result<bool, std::io::Error> {
+    let pos = data.stream_position()?;
+    data.seek(SeekFrom::Start(location as u64))?;
+    let mut buf = [0; 8];
+    let result = data.read_exact(&mut buf);
+    data.seek(SeekFrom::Start(pos))?;
+    Ok(result.is_ok() && buf == target)
+}