nicer error handling, exit codes

Cargo.lock

@@ -167,6 +167,12 @@ dependencies = [
  "termcolor",
 ]
 
+[[package]]
+name = "exitcode"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de853764b47027c2e862a995c34978ffa63c1501f2e15f987ba11bd4f9bba193"
+
 [[package]]
 name = "fif"
 version = "0.2.2"
@@ -174,6 +180,7 @@ dependencies = [
  "cached",
  "clap",
  "env_logger",
+ "exitcode",
  "infer",
  "log",
  "mime_guess",

Cargo.toml

@@ -24,6 +24,7 @@ snailquote = "0.3.0"
 once_cell = "1.5.2"
 rayon = { version = "1.5.0", optional = true }
 infer = { version = "0.3.4", optional = true }
+exitcode = "1.1.2"
 
 # use git version while waiting on a release incorporating https://github.com/ebassi/xdg-mime-rs/commit/de5a6dd
 [target.'cfg(not(target_os = "windows"))'.dependencies]

src/main.rs

@@ -18,7 +18,7 @@ use std::io::{stdout, BufWriter};
 use std::path::{Path, PathBuf};
 
 use clap::Clap;
-use log::{debug, info, trace, warn};
+use log::{debug, info, trace, warn, error};
 use once_cell::sync::OnceCell;
 #[cfg(feature = "multi-threaded")]
 use rayon::prelude::*;
@@ -30,6 +30,7 @@ use crate::formats::{Format, Script};
 use crate::mimedb::MimeDb;
 use crate::parameters::OutputFormat;
 use crate::scanerror::ScanError;
+use std::process::exit;
 
 mod findings;
 mod formats;
@@ -154,6 +155,7 @@ fn scan_from_walkdir(entries: Vec<DirEntry>) -> Vec<Result<Findings, (ScanError,
 
 fn main() {
 	let args = parameters::Parameters::parse();
+
 	let mut builder = env_logger::Builder::from_default_env();
 	builder
 		// .format(|buf, r| writeln!(buf, "{} - {}", r.level(), r.args()))
@@ -190,38 +192,81 @@ fn main() {
 	debug!("Checking files with extensions: {:?}", extensions);
 
 	let stepper = WalkDir::new(&args.dirs).into_iter();
+	let mut probably_fatal_error= false;
 	let entries: Vec<DirEntry> = stepper
 		.filter_entry(|e| wanted_file(&args, &extensions, e)) // filter out unwanted files
-		.filter_map(|e| e.ok()) // ignore anything that fails, e.g. files we don't have read access on
+		.filter_map(|e| {
+			if let Err(err) = &e {
+				debug!("uh oh spaghettio!! {:#?}", e);
+				// log errors to stdout, and remove them from the iterator
+				let path = err
+					.path()
+					.map_or("General error".into(), Path::to_string_lossy);
+
+				if err.depth() == 0 {
+					// if something goes wrong while trying to read the root directory, we're probably not going to get much done
+					probably_fatal_error = true;
+				}
+
+				// TODO: is there a way to just say `map_or(x, |y| y).thing()` instead of `map_or(x.thing(), |y| y.thing())`?
+				// i don't care whether i'm returning a walkdir error or an io error, i just care about whether or not it
+				// implements ToString (which they both do). map_or doesn't work on trait objects though :(
+				error!("{}: {}", path, err.io_error().map_or(err.to_string(), |e|e.to_string()));
+				return None
+			}
+			e.ok()
+		})
 		.filter(|e| !e.file_type().is_dir()) // remove directories from the final list
 		.collect();
 
+	if entries.is_empty() {
+		if probably_fatal_error {
+			// no need to log anything for fatal errors - fif will already have printed something obvious like
+			// "[ERROR] /fake/path: No such file or directory (os error 2)". we can assume that if this has happened, the dir
+			// given as input doesn't exist or is otherwise unreadable.
+			exit(exitcode::NOINPUT);
+		}
+
+		warn!("No files matching requested options found.");
+		exit(exitcode::DATAERR);
+	}
+
 	trace!("Found {} items to check", entries.len());
 
-	let results = scan_from_walkdir(entries);
+	let results: Vec<_>  = scan_from_walkdir(entries)
+		.into_iter()
+		.filter(|result|
+			result.is_err()
+			|| !result.as_ref().unwrap().valid
+	    // TODO: find a way to trace! the valid files without doing ↓
+	    // || if result.as_ref().unwrap().valid { trace!("{:?} is fine", result.as_ref().unwrap().file); false } else { true }
+		)
+		.collect();
 
 	for result in &results {
 		match result {
 			Ok(r) => {
-				if !r.valid {
 				info!(
 					"{:?} should have file extension {}",
 					r.file,
-						r.recommended_extension().unwrap_or("???".into())
+					r.recommended_extension().unwrap_or_else(|| "???".into())
 				)
-				} else {
-					trace!("{:?} is totally fine", r.file)
-				}
 			}
 			Err(f) => warn!("{:#?}: Error 0uo - {}", f.1, f.0),
 		}
 	}
 
+	if results.is_empty() { info!("All files have valid extensions!") }
+
 	match args.output_format {
 		OutputFormat::Script => {
 			let s = Script::new();
-			s.write_all(&results, &mut BufWriter::new(stdout().lock()))
+			if s.write_all(
-				.expect("failed to output");
+				&results,
+				&mut BufWriter::new(stdout().lock())
+			).is_err() {
+				exit(exitcode::IOERR);
+			}
 		}
 		OutputFormat::Text => todo!(),
 	}

src/scanerror.rs

@@ -1,5 +1,6 @@
 use std::fmt::{Display, Formatter, Result};
 
+#[derive(Debug)]
 pub enum ScanError {
 	File,
 	Mime,