feat: allow override of buffer size

um_cli/src/cmd/qmc1.rs

@@ -3,6 +3,7 @@ use clap::Args;
 use std::fs::File;
 use std::io::{Read, Write};
 use std::path::PathBuf;
+use crate::Cli;
 
 /// Decrypt a QMCv1 file
 #[derive(Args)]
@@ -16,16 +17,13 @@ pub struct ArgsQMCv1 {
     input: PathBuf,
 }
 
-// 4MiB buffer is working well on my machine.
-const BUFFER_SIZE: usize = 4 * 1024 * 1024;
-
 impl ArgsQMCv1 {
-    pub fn run(&self) -> Result<i32> {
+    pub fn run(&self, cli: &Cli) -> Result<i32> {
         let mut file_input = File::open(&self.input)?;
         let mut file_output = File::create(&self.output)?;
 
         let mut offset = 0usize;
-        let mut buffer = vec![0u8; BUFFER_SIZE].into_boxed_slice();
+        let mut buffer = vec![0u8; cli.buffer_size].into_boxed_slice();
         while let Ok(n) = file_input.read(&mut buffer) {
             if n == 0 {
                 break;