Show file magic in --info, currently uses the file command

src/compression.rs

@@ -1,8 +1,9 @@
-use anyhow::{Result};
+use anyhow::{anyhow,Result,Context};
 use strum::IntoEnumIterator;
 use std::path::PathBuf;
 use std::io::{Read,Write};
 use std::io;
+use std::process::{Command,Stdio};
 
 use log::*;
 
@@ -12,6 +13,7 @@ extern crate enum_map;
 use enum_map::enum_map;
 use enum_map::{EnumMap,Enum};
 
+
 pub mod none;
 pub mod lz4;
 pub mod gzip;
@@ -50,6 +52,37 @@ pub trait CompressionEngine {
         Ok(())
     }
 
+    fn magic(&self, file_path: PathBuf) -> Result<String> {
+        let mut buffer = [0; libc::BUFSIZ as usize];
+        let mut reader = self.open(file_path)?;
+        let buffer_size = reader.read(&mut buffer[..])?;
+
+        //let cookie = magic::Cookie::open(magic::cookie::Flags::ERROR)?;
+
+        // load the system's default database
+        //let database = Default::default();
+        //let cookie = cookie.load(&database).map_err(|error| { anyhow!(error.to_string())})?;
+        //let magic = cookie.buffer(&buffer[0..n])?;
+
+        let program = "file";
+        let args = ["-bE", "-"];
+
+        let process = Command::new(program)
+            .args(args.clone())
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .spawn()
+            .context(anyhow!("Unable to spawn child process: {:?} {:?}", program, args))?;
+
+        let mut stdin = process.stdin.unwrap();
+        stdin.write_all(&buffer[0..buffer_size])?;
+        drop(stdin);
+
+        let mut magic = String::new();
+        process.stdout.unwrap().read_to_string(&mut magic)?;
+        Ok(magic)
+    }
+
     fn size(&self, file_path: PathBuf) -> Result<usize> {
         let mut reader = self.open(file_path)?;
         let mut buffer = [0; libc::BUFSIZ as usize];

src/main.rs

@@ -740,6 +740,19 @@ fn mode_info(cmd: &mut Command, args: Args, ids: &mut Vec<i64>, tags: &mut Vec<S
             file_size_cell
         ]));
 
+        let compression_engine = compression::get_engine(compression_type).expect("Unable to get compression engine");
+        let magic = compression_engine.magic(item_path.clone());
+
+        let file_magic_cell = match magic {
+            Ok(magic) => Cell::new(magic.as_str()),
+            Err(e) => Cell::new(&e.to_string()).with_style(Attr::ForegroundColor(color::RED)).with_style(Attr::Bold)
+        };
+
+        table.add_row(Row::new(vec![
+            Cell::new("File Magic").with_style(Attr::Bold),
+            file_magic_cell
+        ]));
+
         table.add_row(Row::new(vec![
             Cell::new("Tags").with_style(Attr::Bold),
             Cell::new(&item_tags.join(" "))