feat(zfs): add reusable dataset and snapshot operations

Cargo.lock

@@ -1179,6 +1179,7 @@ dependencies = [
  "signal",
  "tempfile",
  "toml",
+ "zfs",
 ]
 
 [[package]]
@@ -1839,14 +1840,6 @@ name = "zfs"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "chrono",
- "clap",
- "env_logger",
- "log",
- "serde",
- "signal",
- "tempfile",
- "toml",
 ]
 
 [[package]]

Cargo.toml

@@ -12,6 +12,7 @@ log = "0.4"
 serde = "1.0"
 serde_json = "1.0"
 signal = { path = "rust/signal" }
+zfs = { path = "rust/zfs" }
 
 [workspace.lints.clippy]
 all = { level = "deny", priority = -1 }

rust/zfs/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "zfs"
+version = "0.1.0"
+edition = "2024"
+description = "List ZFS datasets and manage snapshots through the zfs executable"
+license = "MIT"
+publish = false
+
+[dependencies]
+anyhow.workspace = true
+
+[lints]
+workspace = true

rust/zfs/src/lib.rs

@@ -0,0 +1,100 @@
+//! Manage ZFS datasets and snapshots using the `zfs` executable on `PATH`.
+//!
+//! ```no_run
+//! for snapshot in zfs::list_snapshots("pool/home")? {
+//!     println!("{snapshot}");
+//! }
+//! # Ok::<(), anyhow::Error>(())
+//! ```
+
+use std::process::Command;
+
+use anyhow::{Context, Result, bail};
+
+const ZFS_EXECUTABLE: &str = "zfs";
+
+fn zfs_command(args: &[&str]) -> Result<String> {
+    let output = Command::new(ZFS_EXECUTABLE)
+        .args(args)
+        .env("LC_ALL", "C")
+        .output()
+        .context("Failed to execute zfs")?;
+    if !output.status.success() {
+        let message = if output.stderr.is_empty() {
+            &output.stdout
+        } else {
+            &output.stderr
+        };
+        bail!(
+            "zfs {} failed ({}): {}",
+            args.join(" "),
+            output.status,
+            String::from_utf8_lossy(message).trim()
+        );
+    }
+    String::from_utf8(output.stdout).context("zfs returned invalid UTF-8")
+}
+
+/// List filesystem datasets, excluding pool roots.
+///
+/// # Errors
+///
+/// Returns an error if executing ZFS or decoding its output fails.
+pub fn list_datasets() -> Result<Vec<String>> {
+    let output = zfs_command(&["list", "-Hp", "-t", "filesystem", "-o", "name"])?;
+    Ok(output
+        .lines()
+        .filter(|name| name.contains('/'))
+        .map(String::from)
+        .collect())
+}
+
+/// List snapshot names belonging directly to `dataset`, excluding child datasets.
+///
+/// Returned names omit the `dataset@` prefix.
+///
+/// # Errors
+///
+/// Returns an error if executing ZFS or decoding its output fails.
+pub fn list_snapshots(dataset: &str) -> Result<Vec<String>> {
+    let output = zfs_command(&[
+        "list", "-Hp", "-t", "snapshot", "-o", "name", "-d", "1", dataset,
+    ])?;
+    Ok(output
+        .lines()
+        .filter_map(|name| {
+            let (owner, snapshot) = name.split_once('@')?;
+            (owner == dataset).then(|| snapshot.to_owned())
+        })
+        .collect())
+}
+
+/// Create `dataset@snapshot`.
+///
+/// # Errors
+///
+/// Returns an error if executing ZFS or decoding its output fails.
+pub fn create_snapshot(dataset: &str, snapshot: &str) -> Result<()> {
+    zfs_command(&["snapshot", &format!("{dataset}@{snapshot}")])?;
+    Ok(())
+}
+
+/// Delete `dataset@snapshot`.
+///
+/// Returns `None` on success, or `Some("snapshot has dependent clones")` when
+/// dependent clones prevent deletion.
+///
+/// # Errors
+///
+/// Returns an error for other ZFS failures, execution failures, or invalid UTF-8 output.
+pub fn delete_snapshot(dataset: &str, snapshot: &str) -> Result<Option<&'static str>> {
+    if let Err(error) = zfs_command(&["destroy", &format!("{dataset}@{snapshot}")]) {
+        if error.to_string().contains(&format!(
+            "cannot destroy '{dataset}@{snapshot}': snapshot has dependent clones"
+        )) {
+            return Ok(Some("snapshot has dependent clones"));
+        }
+        return Err(error);
+    }
+    Ok(None)
+}