config validation

src/config.rs

@@ -3,7 +3,11 @@ use std::{
     path::{
 	PathBuf,
     },
+    error,
+    fmt,
+    io
 };
+use tokio::fs;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Config
@@ -17,8 +21,55 @@ impl Default for Config
     fn default() -> Self
     {
 	Self {
-	    base_dir: PathBuf::default(),
+	    base_dir: PathBuf::from("/tmp/videl"),
 	}
     }
 }
 
+impl Config
+{
+    /// Validate this config
+    pub async fn validate(&self) -> Result<(), Error>
+    {
+	let exists = self.base_dir.exists();
+	if exists && !self.base_dir.is_dir() {
+	    return Err(Error::InvalidDestination);
+	} else if !exists {
+	    fs::create_dir_all(&self.base_dir).await?;
+	}
+	Ok(())
+    }
+}
+
+#[derive(Debug)]
+pub enum Error {
+    IO(io::Error),
+    InvalidDestination,
+}
+impl error::Error for Error
+{
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+	match &self {
+	    Self::IO(io) => Some(io),
+	    _ => None,
+	}
+    }
+}
+impl fmt::Display for Error
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    {
+	match self {
+	    Self::IO(_) => write!(f, "i/o error"),
+	    Self::InvalidDestination => write!(f, "invalid base destination for videl databases"),
+	}
+    }
+}
+
+impl From<io::Error> for Error
+{
+    #[inline] fn from(from: io::Error) -> Self
+    {
+	Self::IO(from)
+    }
+}

src/main.rs

@@ -64,10 +64,22 @@ async fn process(config: Arc<config::Config>, file: String)
 	     .with_suggestion(|| "Are you sure this database location is correct"));
 }
 
+async fn validate_config(config: config::Config) -> eyre::Result<config::Config>
+{
+    config.validate().await
+	.with_section(|| format!("{:#?}", config).header("Config was"))
+	.with_suggestion(|| "Are you sure the base directory is a valid pathspec?")
+	.with_suggestion(|| "Are you sure the base directory is not already occupied by a non-directory?")
+	.with_suggestion(|| format!("Are you sure we have read-write access to {:?}?", config.base_dir))?;
+    Ok(config)
+}
+
 async fn begin() -> eyre::Result<i32>
 {
     install()?;
-    let config = Arc::new(config::Config::default());
+    let config = Arc::new(validate_config(config::Config::default()).await
+			  .wrap_err(eyre!("Failed to validate config"))?);
+    println!("Validated config OK");
     if args::process(|file| {
 	let config = Arc::clone(&config);
 	process(config, file)