Refactor compression into multiple files

src/compression/program.rs

@@ -0,0 +1,104 @@
+use anyhow::{Context, Result, anyhow};
+use std::fs::File;
+use std::io::Write;
+use std::process::{Command,Stdio};
+use std::path::PathBuf;
+use std::env;
+use std::fs;
+use std::os::unix::fs::PermissionsExt;
+use log::*;
+
+use crate::compression::CompressionEngine;
+
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct CompressionProgram {
+    pub program: String,
+    pub compress: Vec<String>,
+    pub decompress: Vec<String>,
+    pub supported: bool
+}
+
+
+impl CompressionProgram {
+    pub fn new(program: &str, compress: Vec<&str>, decompress: Vec<&str>) -> CompressionProgram {
+        let program_path = get_program_path(program);
+        let supported = program_path.is_ok();
+
+        CompressionProgram {
+            program: program_path.unwrap_or(program.to_string()),
+            compress: compress.iter().map(|s| {s.to_string()}).collect(),
+            decompress: decompress.iter().map(|s| {s.to_string()}).collect(),
+            supported
+        }
+    }
+}
+
+impl CompressionEngine for CompressionProgram {
+    fn is_supported(&self) -> bool {
+        self.supported
+    }
+
+    fn cat(&self, file_path: PathBuf) -> Result<()> {
+        debug!("COMPRESSION: Outputting {:?} to STDOUT using {:?}", file_path, *self);
+        let program = self.program.clone();
+        let args = self.decompress.clone();
+
+        debug!("COMPRESSION: Executing command: {:?} {:?} writing to {:?}", program, args, file_path);
+
+        let file = File::open(file_path).context("Unable to open file for reading")?;
+
+        let mut process = Command::new(program.clone())
+            .args(args.clone())
+            .stdin(file)
+            .spawn()
+            .context(anyhow!("Unable to spawn child process: {:?} {:?}", program, args))?;
+
+        let result = process.wait()
+            .context(anyhow!("Unable to wait for child process: {:?} {:?}", program, args))?;
+
+        if result.success() {
+            Ok(())
+        } else {
+            Err(anyhow!("Decompression program returned {}", result))
+        }
+    }
+
+    fn create(&self, file_path: PathBuf) -> Result<Box<dyn Write>> {
+        debug!("COMPRESSION: Writting to {:?} using {:?}", file_path, *self);
+
+        let program = self.program.clone();
+        let args = self.compress.clone();
+
+        debug!("COMPRESSION: Executing command: {:?} {:?} writing to {:?}", program, args, file_path);
+
+        let file = File::create(file_path).context("Unable to open file for writing")?;
+
+        let process = Command::new(program.clone())
+            .args(args.clone())
+            .stdin(Stdio::piped())
+            .stdout(file)
+            .spawn()
+            .context(anyhow!("Problem spawning child process: {:?} {:?}", program, args))?;
+
+        Ok(Box::new(process.stdin.unwrap()))
+    }
+}
+
+fn get_program_path(program: &str) -> Result<String> {
+    debug!("COMPRESSION: Looking for executable: {}", program);
+    if let Ok(path) = env::var("PATH") {
+        for p in path.split(':') {
+            let p_str = format!("{}/{}", p, program);
+            let stat = fs::metadata(p_str.clone());
+            if let Ok(stat) = stat {
+                let md = stat;
+                let permissions = md.permissions();
+                if md.is_file() && permissions.mode() & 0o111 != 0 {
+                    return Ok(p_str);
+                }
+            }
+        }
+    }
+    Err(anyhow!("Unable to find binary {} in PATH", program))
+}