make sccache_dir() return proper Result instead of Option and pass it…

… through sccache_dir()

src/commands/sccache.rs

@@ -17,6 +17,7 @@ use chrono::prelude::*;
 use humansize::{file_size_opts, FileSize};
 use walkdir::WalkDir;
 
+use crate::library;
 use crate::tables::format_table;
 
 #[derive(Debug, Clone)]
@@ -35,26 +36,24 @@ fn percentage_of_as_string(fraction: u64, total: u64) -> String {
 }
 
 /// get the location of a local sccache path
-fn sccache_dir() -> Option<PathBuf> {
+fn sccache_dir() -> Result<PathBuf, library::Error> {
     if let Some(path) = env::var_os("SCCACHE_DIR").map(PathBuf::from) {
-        Some(path)
+        Ok(path)
     } else {
         // if SCCACHE_DIR variable is not present, get the cache dir from "dirs" crate
         let mut cache_dir: Option<PathBuf> = dirs::cache_dir();
 
         if let Some(cache_dir) = cache_dir.as_mut() {
             cache_dir.push("sccache");
-            Some(cache_dir.to_path_buf())
+            Ok(cache_dir.to_path_buf())
         } else {
-            cache_dir
+            Err(library::Error::NoSccacheDir)
         }
     }
 }
 
-pub(crate) fn sccache_stats() {
-    let sccache_path: PathBuf = sccache_dir()
-        .expect("Failed to get a valid sccache cache dir such as \"~/.cache/sccache\"");
-    //@TODO ^ turn this into a proper error message ^ !
+pub(crate) fn sccache_stats() -> Result<(), library::Error> {
+    let sccache_path: PathBuf = sccache_dir()?;
 
     // of all the files inside the sccache cache, gather last access time and path
     let files = WalkDir::new(sccache_path.display().to_string())
@@ -176,4 +175,5 @@ pub(crate) fn sccache_stats() {
     let table = format_table(&table_vec, 1); // need so strip whitespaces added by the padding
     let table_trimmed = table.trim();
     println!("{}", table_trimmed);
+    Ok(())
 }

src/library.rs

@@ -90,6 +90,8 @@ pub(crate) enum Error {
     DateParseFailure(String, String),
     // cargo metadata failed to parse a cargo manifest
     UnparsableManifest(PathBuf, cargo_metadata::Error),
+    // could not find sccache cache dir
+    NoSccacheDir,
 }
 
 impl fmt::Display for Error {
@@ -183,6 +185,8 @@ impl fmt::Display for Error {
             ),
             Self::UnparsableManifest(path, error) => write!(f,
             "Failed to parse Cargo.toml at '{}': '{:?}'", path.display(), error),
+            Self::NoSccacheDir => write!(f,
+                "Could not find sccache cache directory at ~/.cache/sccache or ${{SCCACHE_DIR}}"),
         }
     }
 }

src/main.rs

@@ -119,8 +119,15 @@ fn main() {
     };
 
     if config.is_present("sc") || config.is_present("sccache") {
-        sccache::sccache_stats();
-        process::exit(0);
+        match sccache::sccache_stats() {
+            Ok(()) => {
+                process::exit(0);
+            }
+            Err(e) => {
+                eprintln!("{}", e);
+                process::exit(1);
+            }
+        }
     }
 
     // indicates if size changed and whether we should print a before/after size diff