[xmly] feat #5: implement xmly decipher

um_cli/Cargo.toml

@@ -11,4 +11,5 @@ umc_kgm = { path = "../um_crypto/kgm" }
 umc_kuwo = { path = "../um_crypto/kuwo" }
 umc_ncm = { path = "../um_crypto/ncm" }
 umc_qmc = { path = "../um_crypto/qmc" }
+umc_xmly = { path = "../um_crypto/xmly" }
 umc_utils = { path = "../um_crypto/utils" }

um_cli/src/cmd/mod.rs

@@ -5,6 +5,7 @@ pub mod kgm;
 pub mod ncm;
 pub mod qmc1;
 pub mod qmc2;
+pub mod xmly;
 
 #[derive(Subcommand)]
 pub enum Commands {
@@ -18,4 +19,6 @@ pub enum Commands {
     KGM(kgm::ArgsKGM),
     #[command(name = "joox")]
     JOOX(joox::ArgsJoox),
+    #[command(name = "xmly")]
+    XMLY(xmly::ArgsXimalaya),
 }

um_cli/src/cmd/xmly.rs

@@ -0,0 +1,94 @@
+use crate::Cli;
+use anyhow::{bail, Result};
+use clap::Args;
+use std::ffi::OsStr;
+use std::fs::File;
+use std::io;
+use std::io::{BufReader, BufWriter, Read, Seek, SeekFrom, Write};
+use std::path::PathBuf;
+
+#[derive(Debug, Clone, clap::ValueEnum)]
+enum XimalayaType {
+    /// Android: *.x2m
+    X2M,
+    /// Android: *.x3m
+    X3M,
+    /// PC: *.xm
+    XM,
+}
+
+/// Decrypt a X2M/X3M/XM file (Ximalaya)
+#[derive(Args)]
+pub struct ArgsXimalaya {
+    /// Path to output file, e.g. /export/Music/song.flac
+    #[clap(short, long)]
+    output: PathBuf,
+
+    /// Path to input file, e.g. /export/Music/song.x3m
+    #[arg(name = "input")]
+    input: PathBuf,
+
+    #[clap(short = 't', long = "type")]
+    file_type: Option<XimalayaType>,
+}
+
+impl ArgsXimalaya {
+    pub fn run(&self, cli: &Cli) -> Result<i32> {
+        let file_type = match &self.file_type {
+            Some(x) => x.clone(),
+            None => match self.input.extension().and_then(|ext: &OsStr| ext.to_str()) {
+                Some("x2m") => XimalayaType::X2M,
+                Some("x3m") => XimalayaType::X3M,
+                Some("xm") => XimalayaType::XM,
+                Some(ext) => bail!("invalid ext: {ext}"),
+                _ => bail!("ext not found"),
+            },
+        };
+        let mut read_stream = BufReader::with_capacity(cli.buffer_size, File::open(&self.input)?);
+        let mut write_stream =
+            BufWriter::with_capacity(cli.buffer_size, File::create(&self.output)?);
+
+        match file_type {
+            XimalayaType::X2M | XimalayaType::X3M => {
+                let android_type = match file_type {
+                    XimalayaType::X2M => umc_xmly::android::FileType::X2M,
+                    XimalayaType::X3M => umc_xmly::android::FileType::X3M,
+                    _ => bail!("this should not happen"),
+                };
+                let mut header = [0u8; 0x400];
+                read_stream.read_exact(&mut header)?;
+                umc_xmly::android::decrypt_android(android_type, &mut header);
+                write_stream.write_all(&header)?;
+                io::copy(&mut read_stream, &mut write_stream)?;
+            }
+            XimalayaType::XM => {
+                let mut header = vec![0u8; 1024];
+                read_stream.read_exact(&mut header)?;
+                let xm_file = match umc_xmly::pc::Header::from_buffer(&header) {
+                    Ok(hdr) => hdr,
+                    Err(umc_xmly::XmlyError::MetadataTooSmall(n)) => {
+                        let old_size = header.len();
+                        header.resize(n, 0);
+                        read_stream.read_exact(&mut header[old_size..])?;
+                        umc_xmly::pc::Header::from_buffer(&header)?
+                    }
+                    Err(err) => bail!("failed to parse file: {err}"),
+                };
+
+                // Copy header
+                write_stream.write_all(xm_file.copy_m4a_header().as_slice())?;
+
+                // Process encrypted data
+                read_stream.seek(SeekFrom::Start(xm_file.data_start_offset as u64))?;
+                let mut header = vec![0u8; xm_file.encrypted_header_size];
+                read_stream.read_exact(&mut header[..])?;
+                write_stream.write_all(xm_file.decrypt(&mut header[..])?)?;
+
+                // Copy rest of the file
+                io::copy(&mut read_stream, &mut write_stream)?;
+            }
+        }
+
+        Ok(0)
+    }
+}

um_cli/src/main.rs

@@ -32,6 +32,7 @@ fn run_command(cli: &Cli) -> Result<i32> {
         Some(Commands::NCM(cmd)) => cmd.run(&cli),
         Some(Commands::KGM(cmd)) => cmd.run(&cli),
         Some(Commands::JOOX(cmd)) => cmd.run(&cli),
+        Some(Commands::XMLY(cmd)) => cmd.run(&cli),
         None => {
             // https://github.com/clap-rs/clap/issues/3857#issuecomment-1161796261
             todo!("implement a sensible default command, similar to um/cli");