Isolate Hasher behind typed installer adapter

1 files changed, 95 insertions, 0 deletions

diff --git a/src/hasher.rs b/src/hasher.rs
new file mode 100644
index 0000000..0be1808
--- /dev/null
+++ b/src/hasher.rs
@@ -0,0 +1,95 @@
+use std::ffi::OsString;
+use std::process::Command;
+
+use anyhow::{bail, Context, Result};
+
+use crate::package_installer::{PackageInstaller, PackageRequest};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Invocation {
+    program: OsString,
+    arguments: Vec<OsString>,
+}
+
+impl Invocation {
+    pub fn new(
+        program: impl Into<OsString>,
+        arguments: impl IntoIterator<Item = impl Into<OsString>>,
+    ) -> Self {
+        Self {
+            program: program.into(),
+            arguments: arguments.into_iter().map(Into::into).collect(),
+        }
+    }
+
+    pub fn program(&self) -> &OsString {
+        &self.program
+    }
+
+    pub fn arguments(&self) -> &[OsString] {
+        &self.arguments
+    }
+}
+
+pub trait CommandRunner {
+    fn run(&self, invocation: Invocation) -> Result<()>;
+}
+
+#[derive(Debug, Default, Clone, Copy)]
+pub struct ProcessRunner;
+
+impl CommandRunner for ProcessRunner {
+    fn run(&self, invocation: Invocation) -> Result<()> {
+        let status = Command::new(&invocation.program)
+            .args(&invocation.arguments)
+            .status()
+            .with_context(|| format!("run {}", invocation.program.to_string_lossy()))?;
+        if !status.success() {
+            bail!(
+                "{} exited with {status}",
+                invocation.program.to_string_lossy()
+            );
+        }
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+pub struct HasherInstaller<R> {
+    runner: R,
+}
+
+impl<R> HasherInstaller<R> {
+    pub fn new(runner: R) -> Self {
+        Self { runner }
+    }
+
+    pub fn runner(&self) -> &R {
+        &self.runner
+    }
+}
+
+impl<R: CommandRunner> PackageInstaller for HasherInstaller<R> {
+    fn install(&self, request: &PackageRequest) -> Result<()> {
+        self.runner.run(Invocation::new(
+            "hsh",
+            [
+                "--mountpoints=/proc".into(),
+                "--initroot-only".into(),
+                "--apt-config".into(),
+                request.apt_config().as_path().as_os_str().to_owned(),
+                "--workdir".into(),
+                request.workdir().as_os_str().to_owned(),
+            ],
+        ))?;
+
+        let mut arguments = vec![
+            OsString::from("--mountpoints=/proc"),
+            OsString::from("--workdir"),
+            request.workdir().as_os_str().to_owned(),
+        ];
+        arguments.extend(request.selectors().iter().map(OsString::from));
+        arguments.extend(request.packages().iter().map(OsString::from));
+        self.runner.run(Invocation::new("hsh-install", arguments))
+    }
+}