Implement configuration handling

This patch implements basic configuration handling that reads a
configuration file and stores the parsed data in the ExecCtx and RunCtx
structs.  It supports three configuration items:
- model (previously only --model)
- no_cache (previously only NITROCLI_NO_CACHE)
- verbosity (previously only --verbose)

1 files changed, 14 insertions, 1 deletions

diff --git a/src/args.rs b/src/args.rs
index 0f548e4..7f2dc31 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -18,7 +18,7 @@
 // *************************************************************************
 
 /// Provides access to a Nitrokey device
-#[derive(structopt::StructOpt)]
+#[derive(Debug, structopt::StructOpt)]
 #[structopt(name = "nitrocli")]
 pub struct Args {
   /// Increases the log level (can be supplied multiple times)
@@ -57,6 +57,19 @@ impl From<DeviceModel> for nitrokey::Model {
   }
 }
 
+impl<'de> serde::Deserialize<'de> for DeviceModel {
+  fn deserialize<D>(deserializer: D) -> Result<DeviceModel, D::Error>
+  where
+    D: serde::Deserializer<'de>,
+  {
+    use serde::de::Error as _;
+    use std::str::FromStr as _;
+
+    let s = String::deserialize(deserializer)?;
+    DeviceModel::from_str(&s).map_err(D::Error::custom)
+  }
+}
+
 Command! {
   /// A top-level command for nitrocli.
   Command, [