add init subcommand to export the default configuration

syncat/src/config.rs

@@ -44,6 +44,37 @@ fn config_exists<P: AsRef<Path>>(file: P) -> bool {
         .any(|res| res.unwrap().path().unwrap().as_ref() == file.as_ref())
 }
 
+pub(crate) fn dump_config<P: AsRef<Path>>(file: P) -> crate::Result<()> {
+    let mut config_reader = DEFAULT_CONFIG;
+    for mut entry in tar::Archive::new(&mut config_reader)
+        .entries()
+        .unwrap()
+        .map(|entry| entry.unwrap())
+    {
+        let input_path = entry.path().unwrap();
+        let output_path = file.as_ref().join(input_path);
+        let parent_path = output_path.parent().unwrap();
+        if !parent_path.exists() {
+            fs::create_dir(parent_path).map_err(|er| {
+                crate::Error::new("failed to unpack directory")
+                    .with_source(er)
+                    .with_path(parent_path)
+            })?;
+        }
+        let mut file = fs::File::create(&output_path).map_err(|er| {
+            crate::Error::new("failed to create file")
+                .with_source(er)
+                .with_path(&output_path)
+        })?;
+        io::copy(&mut entry, &mut file).map_err(|er| {
+            crate::Error::new("failed to write file")
+                .with_source(er)
+                .with_path(&output_path)
+        })?;
+    }
+    Ok(())
+}
+
 pub(crate) fn read_to_string<P: AsRef<Path>>(file: P) -> crate::Result<String> {
     let path = config().join(&file);
     if path.exists() {

syncat/src/main.rs

@@ -70,6 +70,14 @@ pub struct Opts {
 
 #[derive(Parser, Debug)]
 enum Subcommand {
+    /// Initialize the config directory by filling it with the default configuration.
+    ///
+    /// If the config directory already exists, it will not be created. An alternative path
+    /// may be specified.
+    Init {
+        #[arg(short, long)]
+        out: Option<PathBuf>,
+    },
     /// Installs all languages listed in the `languages.toml` file. Previously installed packages
     /// will be updated, if updates are available. This process may take a long time, depending on
     /// how many languages are being installed.

syncat/src/package_manager.rs

@@ -1,5 +1,5 @@
-use crate::config::stylesheet_existence;
-use crate::dirs::libraries;
+use crate::config::{dump_config, stylesheet_existence};
+use crate::dirs::{config, libraries};
 use crate::language::{Lang, LangMap};
 use crate::Subcommand;
 use cc::Build;
@@ -156,6 +156,23 @@ pub(crate) fn main(opts: &Subcommand) -> crate::Result<()> {
     }
 
     match opts {
+        Subcommand::Init { out } => {
+            let out = out.clone().unwrap_or(config());
+            if out.exists() {
+                eprintln!(
+                    "syncat: {}: configuration directory already exists, will not overwrite",
+                    out.display()
+                );
+                std::process::exit(1);
+            }
+            fs::create_dir_all(&out).map_err(|er| {
+                crate::Error::new("failed to create config directory")
+                    .with_source(er)
+                    .with_path(&out)
+                    .with_hint("ensure you have adequate permissions to create the new directory and try again")
+            })?;
+            dump_config(&out)?;
+        }
         Subcommand::Install { languages } => {
             let mut any_errors = false;
             if languages.is_empty() {