mtk_pkg_old: add support for LZHS compression old variant

src/formats/mtk_pkg_old.rs

@@ -5,6 +5,7 @@ use binrw::{BinRead, BinReaderExt};
 
 use crate::utils::common;
 use crate::utils::mtk_crypto::{decrypt};
+use crate::utils::lzhs::{decompress_lzhs_fs_file2file_old};
 
 static KEY: u32 = 0x94102909; //09 29 10 94
 // first 4 bytes of header and content are additionally XORed, they have different masks although only differ by half a byte
@@ -47,6 +48,9 @@ impl PartEntry {
     fn is_encrypted(&self) -> bool {
         (self.flags & 1 << 0) == 1 << 0
     }
+    fn is_compressed(&self) -> bool { //lzhs fs
+        (self.flags & 1 << 8) != 0
+    }
 }
 
 pub fn is_mtk_pkg_old_file(mut file: &File) -> bool {
@@ -82,7 +86,8 @@ pub fn extract_mtk_pkg_old(mut file: &File, output_folder: &str) -> Result<(), B
         part_n += 1;
         let part_entry: PartEntry = file.read_le()?;
 
-        println!("\n#{} - {}, Size: {} {}", part_n, part_entry.name(), part_entry.size, if part_entry.is_encrypted() {"[ENCRYPTED]"} else {""} );
+        println!("\n#{} - {}, Size: {}{} {}", 
+                part_n, part_entry.name(), part_entry.size, if part_entry.is_compressed() {" [COMPRESSED]"} else {""}, if part_entry.is_encrypted() {"[ENCRYPTED]"} else {""} );
 
         let data = common::read_exact(&mut file, part_entry.size as usize)?;
         let out_data; 
@@ -108,14 +113,27 @@ pub fn extract_mtk_pkg_old(mut file: &File, output_folder: &str) -> Result<(), B
             0
         };
 
-        let output_path = Path::new(&output_folder).join(part_entry.name() + ".bin");
+        //for compressed part create temp file
+        let output_path = Path::new(&output_folder).join(part_entry.name() + if part_entry.is_compressed() {".lzhs"} else {".bin"});
         fs::create_dir_all(&output_folder)?;
-        let mut out_file = OpenOptions::new()
-            .write(true)
-            .create(true)
-            .open(output_path)?;
+        let mut out_file = OpenOptions::new().write(true).read(true)/* for lzhs */.create(true).open(&output_path)?;
         out_file.write_all(&out_data[extra_header_len as usize..])?;
 
+        if part_entry.is_compressed() {
+            let lzhs_out_path = Path::new(&output_folder).join(part_entry.name() + ".bin");
+            match decompress_lzhs_fs_file2file_old(&out_file, lzhs_out_path) {
+                Ok(()) => {
+                    println!("- Decompressed Successfully!");
+                    //after successfull decompression remove the temporary .lzhs file
+                    fs::remove_file(&output_path)?;
+                },
+                Err(e) => {
+                    eprintln!("Failed to decompress partition!, Error: {}. Saving compressed data...", e);
+                    //if the decompression is not successfull leave out compressed data.
+                }
+            }   
+        }
+
         println!("-- Saved file!");
     }
 

src/utils/lzhs.rs

@@ -14,6 +14,12 @@ struct LzhsHeader {
     #[br(count = 6)] padding: Vec<u8>,
 }
 
+#[derive(BinRead)]
+struct LzhsOldSegmentHdr {
+    _uncompressed_size: u32,
+    _compressed_size: u32,
+}
+
 pub fn decompress_lzhs_fs_file2file(mut file: &File, output_file: PathBuf) -> Result<(), Box<dyn std::error::Error>> {
     let file_size = file.metadata()?.len();
     let mut out_file = OpenOptions::new().append(true).create(true).open(&output_file)?;
@@ -82,6 +88,45 @@ pub fn decompress_lzhs_fs_file2file(mut file: &File, output_file: PathBuf) -> Re
     Ok(())
 }
 
+// OLD VARIANT use in old mtk pkg
+pub fn decompress_lzhs_fs_file2file_old(mut file: &File, output_file: PathBuf) -> Result<(), Box<dyn std::error::Error>> {
+    let file_size = file.metadata()?.len();
+    let mut out_file = OpenOptions::new().append(true).create(true).open(&output_file)?;
+    file.seek(SeekFrom::Start(0))?;
+
+    let mut uncompressed_heading = vec![0u8; 0x200]; //first 512b is uncompressed
+    file.read_exact(&mut uncompressed_heading)?;
+    out_file.write_all(&uncompressed_heading)?;
+
+    while file.stream_position().unwrap() < file_size {
+        let _segment_header: LzhsOldSegmentHdr = file.read_le()?;
+        let lzhs_header: LzhsHeader = file.read_le()?;
+
+        println!("[LZHS] Segment - Compressed size: {}, Decompressed size: {}, Expected Checksum: 0x{:02x?}",
+                lzhs_header.compressed_size, lzhs_header.uncompressed_size, lzhs_header.checksum_or_seg_idx);
+
+        let mut compressed_data = vec![0u8; lzhs_header.compressed_size as usize];
+        file.read_exact(&mut compressed_data)?;
+        let mut out_data;
+        let out_huff = unhuff(&compressed_data);
+        out_data = unlzss(&out_huff, lzhs_header.uncompressed_size as usize);
+        arm_thumb_convert(&mut out_data, 0, false);
+
+        let checksum = calc_checksum(&out_data);
+        println!("-- Calculated checksum: 0x{:02x?}", checksum);
+        if u16::from(checksum) != lzhs_header.checksum_or_seg_idx {
+            println!("--- Checksum mismatch! Expected: 0x{:02x?}, Got: 0x{:02x?}!", lzhs_header.checksum_or_seg_idx, checksum);
+            return Err("Checksum mismatch!".into());
+        } else {
+            println!("--- Checksum OK!")
+        }
+        
+        out_file.write_all(&out_data)?;
+    }
+
+    Ok(())
+}
+
 #[derive(Debug)]
 struct HuffmanCtx {
     c: u8,