config file is dropped to disk when installing via cargo

Cargo.toml

@@ -19,6 +19,7 @@ maintenance = { status = "actively-developed" }
 clap = "2.33"
 regex = "1"
 lazy_static = "1.4"
+dirs = "3.0"
 
 [dependencies]
 futures = { version = "0.3.14"}

build.rs

@@ -1,6 +1,7 @@
-use std::fs::OpenOptions;
+use std::fs::{copy, create_dir_all, OpenOptions};
 use std::io::{Read, Seek, SeekFrom, Write};
 extern crate clap;
+extern crate dirs;
 
 use clap::Shell;
 
@@ -47,4 +48,30 @@ fn main() {
     bash_file
         .write_all(contents.as_bytes())
         .expect("Couldn't write updated bash completion script to disk");
+
+    // hunter0x8 let me know that when installing via cargo, it would be nice if we dropped a
+    // config file during the build process. The following code will place an example config in
+    // the user's configuration directory
+    //   - linux: $XDG_CONFIG_HOME or $HOME/.config
+    //   - macOS: $HOME/Library/Application Support
+    //   - windows: {FOLDERID_RoamingAppData}
+    let mut config_dir = dirs::config_dir().expect("Couldn't resolve user's config directory");
+    config_dir = config_dir.join("feroxbuster"); // $HOME/.config/feroxbuster
+
+    if !config_dir.exists() {
+        // recursively create the feroxbuster directory and all of its parent components if
+        // they are missing
+        create_dir_all(&config_dir)
+            .expect("Couldn't create one or more directories needed to copy the config file");
+    }
+
+    // hard-coding config name here to not rely on the crate we're building, if DEFAULT_CONFIG_NAME
+    // ever changes, this will need to be updated
+    let config_file = config_dir.join("ferox-config.toml");
+
+    if !config_file.exists() {
+        // config file doesn't exist, add it to the config directory
+        copy("ferox-config.toml.example", config_file)
+            .expect("Couldn't copy example config into config directory");
+    }
 }