feat(env): Make rustic more portable

config/README.md

@@ -55,11 +55,40 @@ options. Therefore `commandline arguments` have the highest precedence.
 
 ## Profiles
 
+To use different configurations for different repositories, you can use
+profiles.
+
+For example, you can create a profile called `myconfig` and use it with the `-P`
+option, e.g. `rustic -P myconfig`. The configuration file for the profile
+`myconfig` should be named `myconfig.toml`. Examples for different configuration
+files can be found here in the [/config/](/config) directory.
+
+### Profile Locations
+
+#### \*nix
+
 Configuration files can be placed in the user's local config directory, e.g.
-`~/.config/rustic/` or in the global config dir, e.g. `/etc/rustic/`. You can
-use different config files, e.g. `myconfig.toml` and use the `-P` option to
-specify the profile name, e.g. `rustic -P myconfig`. Examples for different
-configuration files can be found here in the [/config/](/config) directory.
+`~/.config/rustic/` or in the global config dir, e.g. `/etc/rustic/`.
+
+#### Windows
+
+On Windows, the configuration file can be placed in the user's local config
+directory, e.g. `C:\Users\username\AppData\Roaming\rustic\` or in the global
+config dir, e.g. `C:\ProgramData\rustic\config`. The global config directory is
+usually not created by the installer, so you may have to create it yourself. You
+can also use your User Profile directory, e.g. `C:\Users\username\` and place
+the configuration file in the `.rustic` or `.config\rustic` directory.
+
+#### MacOS
+
+On MacOS, the configuration file can be placed in the user's local config
+directory, e.g. `~/Library/Application Support/rustic/`.
+
+#### Custom Directory
+
+If you prefer to use your custom `rustic` directory, you can set `RUSTIC_HOME`
+environment variable to point to your custom directory. In it you can place your
+configuration file in the `config` subdirectory.
 
 ## Services
 

src/config.rs

@@ -175,20 +175,61 @@ pub struct GlobalOptions {
 ///
 /// A vector of [`PathBuf`]s to the config files
 fn get_config_paths(filename: &str) -> Vec<PathBuf> {
-    [
+    // we need this mut here, because we want to add data to the Vec
+    // depending on the OS. Our CI is running on Unix, and doesn't have knowledge of
+    // us mutating that vector
+    #[allow(unused_mut)]
+    let mut paths = vec![
+        get_home_config_path(),
         ProjectDirs::from("", "", "rustic")
             .map(|project_dirs| project_dirs.config_dir().to_path_buf()),
         get_global_config_path(),
         Some(PathBuf::from(".")),
-    ]
-    .into_iter()
-    .filter_map(|path| {
-        path.map(|mut p| {
-            p.push(filename);
-            p
-        })
+    ];
+
+    #[cfg(target_os = "windows")]
+    {
+        if let Some(win_compatibility_paths) = get_windows_portability_config_directories() {
+            paths.extend(win_compatibility_paths);
+        };
+    }
+
+    paths
+        .into_iter()
+        .filter_map(|path| path.map(|p| p.join(filename)))
+        .collect::<Vec<_>>()
+}
+
+/// Get the path to the home config directory.
+///
+/// # Returns
+///
+/// The path to the home config directory.
+///
+/// # Note
+///
+/// If the environment variable `RUSTIC_HOME` is not set, `None` is returned.
+fn get_home_config_path() -> Option<PathBuf> {
+    std::env::var_os("RUSTIC_HOME").map(|home_dir| PathBuf::from(home_dir).join("config"))
+}
+
+/// Get the paths to the user profile config directories on Windows.
+///
+/// # Returns
+///
+/// A collection of possible paths to the user profile config directory on Windows.
+///
+/// # Note
+///
+/// If the environment variable `USERPROFILE` is not set, `None` is returned.
+#[cfg(target_os = "windows")]
+fn get_windows_portability_config_directories() -> Option<Vec<Option<PathBuf>>> {
+    std::env::var_os("USERPROFILE").map(|path| {
+        vec![
+            Some(PathBuf::from(path.clone()).join(r".config\rustic")),
+            Some(PathBuf::from(path).join(".rustic")),
+        ]
     })
-    .collect()
 }
 
 /// Get the path to the global config directory on Windows.
@@ -199,11 +240,8 @@ fn get_config_paths(filename: &str) -> Vec<PathBuf> {
 /// If the environment variable `PROGRAMDATA` is not set, `None` is returned.
 #[cfg(target_os = "windows")]
 fn get_global_config_path() -> Option<PathBuf> {
-    std::env::var_os("PROGRAMDATA").map(|program_data| {
-        let mut path = PathBuf::from(program_data);
-        path.push(r"rustic\config");
-        path
-    })
+    std::env::var_os("PROGRAMDATA")
+        .map(|program_data| PathBuf::from(program_data).join(r"rustic\config"))
 }
 
 /// Get the path to the global config directory on ios and wasm targets.