mstar: add sparse_write and LZO compression support + some fixes

src/utils/sparse.rs

@@ -0,0 +1,61 @@
+use binrw::{BinRead, BinReaderExt};
+use std::fs::OpenOptions;
+use std::path::{PathBuf};
+use std::io::{Cursor, Seek, SeekFrom, Write};
+
+use crate::common;
+
+#[derive(BinRead)]
+struct SparseHeader {
+    #[br(count = 4)] magic_bytes: Vec<u8>,
+    _major_version: u16,
+    _minor_version: u16,
+    _file_header_size: u16,
+    _chunk_header_size: u16,
+    block_size: u32,
+    _total_blocks: u32,
+    total_chunks: u32,
+    _image_checksum: u32
+}
+
+#[derive(BinRead, Debug)]
+struct ChunkHeader {
+    chunk_type: u16,
+    _reserved1: u16,
+    chunk_size: u32,
+    total_size: u32,
+}
+
+pub fn unsparse_to_file(data: &[u8], file_path: PathBuf) -> Result<(), Box<dyn std::error::Error>> {
+    let mut data_reader = Cursor::new(data);
+    let file_header: SparseHeader = data_reader.read_le()?;
+    if file_header.magic_bytes != b"\x3A\xFF\x26\xED" {
+        return Err("Invalid magic!".into());
+    }
+
+    let mut out_file = OpenOptions::new().create(true).read(true).write(true).open(file_path)?;
+
+    for _i in 0..file_header.total_chunks{
+        let chunk_header: ChunkHeader = data_reader.read_le()?;
+        let chunk_data = common::read_exact(&mut data_reader, chunk_header.total_size as usize - 12)?;
+
+        if chunk_header.chunk_type == 0xCAC1 { //"raw" type chunk (actual data)
+            out_file.write_all(&chunk_data)?; 
+        } else if chunk_header.chunk_type == 0xCAC3 { // "dont care" type chunk (skip over)
+            let skip_size = file_header.block_size as u64 * chunk_header.chunk_size as u64;
+            let current_pos = out_file.stream_position()?;
+            let new_pos = current_pos + skip_size;
+
+            //enlarge file with zeros if the seek is larger than file
+            let current_file_size = out_file.metadata()?.len();
+            if new_pos > current_file_size {
+                out_file.set_len(new_pos)?;
+            }
+            
+            out_file.seek(SeekFrom::Start(new_pos))?;
+        }
+    }
+
+    Ok(())
+
+}