feat: allow qmc2 to read ekey from external file

um_cli/src/cmd/qmc2.rs

@@ -1,6 +1,7 @@
 use crate::Cli;
 use anyhow::{bail, Result};
 use clap::Args;
+use std::fs;
 use std::fs::File;
 use std::io::{BufReader, BufWriter, Read, Seek, SeekFrom, Write};
 use std::path::PathBuf;
@@ -20,6 +21,7 @@ pub struct ArgsQMCv2 {
 
     /// Override EKey for this file.
     /// Prefix with "decrypted:" to use base64 encoded raw key.
+    /// Prefix with "@" to read ekey from external file
     #[arg(short = 'K', long = "ekey")]
     ekey: Option<String>,
 
@@ -28,6 +30,35 @@ pub struct ArgsQMCv2 {
     info_only: bool,
 }
 
+fn read_ekey(ekey: &str) -> Result<Box<[u8]>> {
+    let mut external_file = false;
+    let mut decrypt_ekey = true;
+
+    let mut ekey = ekey;
+    loop {
+        if let Some(stripped) = ekey.strip_prefix("@") {
+            ekey = stripped;
+            external_file = true;
+        } else if let Some(stripped) = ekey.strip_prefix("decrypted:") {
+            ekey = stripped;
+            decrypt_ekey = false;
+        } else {
+            break;
+        }
+    }
+
+    let ekey = match external_file {
+        true => fs::read_to_string(ekey)?,
+        false => ekey.into(),
+    };
+    let ekey = ekey.trim();
+    let ekey = match decrypt_ekey {
+        true => umc_qmc::ekey::decrypt(ekey)?,
+        false => base64::decode(ekey)?.into_boxed_slice(),
+    };
+    Ok(ekey)
+}
+
 impl ArgsQMCv2 {
     pub fn run(&self, cli: &Cli) -> Result<i32> {
         let mut file_input = File::open(&self.input)?;
@@ -60,10 +91,7 @@ impl ArgsQMCv2 {
 
         let key = match ekey {
             None => bail!("--ekey is required when embedded ekey is not present."),
-            Some(ekey) => match ekey.strip_suffix("decrypted:") {
-                Some(decrypted) => base64::decode(decrypted)?.into_boxed_slice(),
-                None => umc_qmc::ekey::decrypt(ekey)?,
-            },
+            Some(ekey) => read_ekey(ekey.as_str())?,
         };
         let cipher = QMCv2Cipher::new(key)?;