physis/src/sqpack.rs

use std::io::{Read, Seek, SeekFrom};
use crc::{Crc, CRC_32_JAMCRC};
use crate::compression::no_header_decompress;
use crate::dat::{BlockHeader, CompressionMode};
use binrw::BinRead;

const JAMCRC: Crc<u32> = Crc::<u32>::new(&CRC_32_JAMCRC);

/// Calculates a hash for `index` files from a game path.
pub fn calculate_hash(path: &str) -> u64 {
    let lowercase = path.to_lowercase();

    let pos = lowercase.rfind('/').unwrap();

    let (directory, filename) = lowercase.split_at(pos);

    let directory_crc = JAMCRC.checksum(directory.as_bytes());
    let filename_crc = JAMCRC.checksum(filename[1..filename.len()].as_bytes());

    (directory_crc as u64) << 32 | (filename_crc as u64)
}

pub fn read_data_block<T : Read + Seek>(mut buf : T, starting_position: u64) -> Option<Vec<u8>> {
    buf.seek(SeekFrom::Start(starting_position)).ok()?;

    let block_header = BlockHeader::read(&mut buf).unwrap();

    match block_header.compression {
        CompressionMode::Compressed { compressed_length, decompressed_length } => {
            let mut compressed_data: Vec<u8> = vec![0; compressed_length as usize];
            buf.read_exact(&mut compressed_data).ok()?;

            let mut decompressed_data: Vec<u8> = vec![0; decompressed_length as usize];
            if !no_header_decompress(&mut compressed_data, &mut decompressed_data) {
                return None;
            }

            Some(decompressed_data)
        }
        CompressionMode::Uncompressed { file_size } => {
            let mut local_data: Vec<u8> = vec![0; file_size as usize];
            buf.read_exact(&mut local_data).ok()?;

            Some(local_data)
        }
    }
}

/// A fixed version of read_data_block accounting for differing compressed block sizes in ZiPatch files.
pub fn read_data_block_patch<T : Read + Seek>(mut buf : T) -> Option<Vec<u8>> {
    let block_header = BlockHeader::read(&mut buf).unwrap();

    match block_header.compression {
        CompressionMode::Compressed { compressed_length, decompressed_length } => {
            let compressed_length : usize = ((compressed_length as usize + 143) & 0xFFFFFF80) - (block_header.size as usize);

            let mut compressed_data: Vec<u8> = vec![0; compressed_length as usize];
            buf.read_exact(&mut compressed_data).ok()?;

            let mut decompressed_data: Vec<u8> = vec![0; decompressed_length as usize];
            if !no_header_decompress(&mut compressed_data, &mut decompressed_data) {
                return None;
            }

            Some(decompressed_data)
        }
        CompressionMode::Uncompressed { file_size } => {
            let new_file_size : usize = (file_size as usize + 143) & 0xFFFFFF80;

            let mut local_data: Vec<u8> = vec![0; file_size as usize];
            buf.read_exact(&mut local_data).ok()?;

            buf.seek(SeekFrom::Current((new_file_size as usize - block_header.size as usize - file_size as usize) as i64)).ok()?;

            Some(local_data)
        }
    }
}