Implement basic data directory operations

gdn/src/data.rs

@@ -0,0 +1,42 @@
+mod datadir;
+mod lockfile;
+mod v0;
+mod v1;
+
+use std::path::PathBuf;
+
+use anyhow::Context;
+use directories::ProjectDirs;
+
+pub use self::{
+    datadir::{LockedDataDir, UnlockedDataDir},
+    v1::{load_state, save_state, VERSION},
+};
+
+fn migrate(dir: &LockedDataDir) -> anyhow::Result<()> {
+    loop {
+        match dir.read_version()? {
+            0 => v0::migrate(dir)?,
+            _ => break Ok(()),
+        }
+    }
+}
+
+pub fn open(path: PathBuf) -> anyhow::Result<UnlockedDataDir> {
+    let dir = UnlockedDataDir::new(path);
+    dir.require_version(VERSION)?;
+    Ok(dir)
+}
+
+pub fn open_and_migrate(path: PathBuf) -> anyhow::Result<LockedDataDir> {
+    let dir = UnlockedDataDir::new(path).lock()?;
+    migrate(&dir)?;
+    dir.require_version(VERSION)?;
+    Ok(dir)
+}
+
+pub fn path() -> anyhow::Result<PathBuf> {
+    let dirs = ProjectDirs::from("de", "plugh", crate::TECHNICAL_NAME)
+        .context("failed to locate data dir")?;
+    Ok(dirs.data_dir().to_path_buf())
+}