Perform mount using API (fix #10 fix #6)

src/main.rs

@@ -1,16 +1,19 @@
 #[macro_use]
 extern crate log;
 extern crate failure;
+extern crate nix;
 extern crate simplelog;
 extern crate structopt;
 extern crate tempfile;
 extern crate which;
 
 mod error;
+mod mountstack;
 mod tool;
 
 use error::*;
 use failure::{Fail, ResultExt};
+use mountstack::{Filesystem, MountStack};
 use simplelog::*;
 use std::fs;
 use std::path::PathBuf;
@@ -90,10 +93,9 @@ fn create(disk: PathBuf) -> Result<(), Error> {
     let pacstrap = Tool::find("pacstrap")?;
     let arch_chroot = Tool::find("arch-chroot")?;
     let genfstab = Tool::find("genfstab")?;
-    let mount = Tool::find("mount")?;
-    let umount = Tool::find("umount")?;
     let mkfat = Tool::find("mkfs.fat")?;
     let mkbtrfs = Tool::find("mkfs.btrfs")?;
+    let mut mount_stack = MountStack::new();
 
     if !(disk.starts_with("/dev/disk/by-id")
         && (disk
@@ -137,20 +139,24 @@ fn create(disk: PathBuf) -> Result<(), Error> {
         .run(ErrorKind::Creation)?;
 
     info!("Mounting filesystems to {}", mount_point.path().display());
-    mount
-        .execute()
-        .arg(format!("{}-part3", disk.display()))
-        .arg(mount_point.path())
-        .run(ErrorKind::Creation)?;
+    mount_stack
+        .mount(
+            &PathBuf::from(format!("{}-part3", disk.display())),
+            &mount_point.path(),
+            Filesystem::Btrfs,
+            Some("compress=zstd"),
+        ).context(ErrorKind::Creation)?;
 
     let boot_point = mount_point.path().join("boot");
     fs::create_dir(&boot_point).context(ErrorKind::Creation)?;
 
-    mount
-        .execute()
-        .arg(format!("{}-part2", disk.display()))
-        .arg(&boot_point)
-        .run(ErrorKind::Creation)?;
+    mount_stack
+        .mount(
+            &PathBuf::from(format!("{}-part2", disk.display())),
+            &boot_point,
+            Filesystem::Vfat,
+            None,
+        ).context(ErrorKind::Creation)?;
 
     info!("Bootstrapping system");
     pacstrap
@@ -199,12 +205,7 @@ fn create(disk: PathBuf) -> Result<(), Error> {
         .run(ErrorKind::Creation)?;
 
     info!("Unmounting filesystems");
-    umount
-        .execute()
-        .arg(boot_point)
-        .arg(mount_point.path())
-        .run(ErrorKind::Creation)?;
-
+    drop(mount_stack);
     sync.execute().run(ErrorKind::Creation)?;
 
     Ok(())

src/mountstack.rs

@@ -0,0 +1,60 @@
+use nix;
+use nix::mount::{mount, umount, MsFlags};
+use std::path::{Path, PathBuf};
+
+#[derive(Debug)]
+pub enum Filesystem {
+    Btrfs,
+    Vfat,
+}
+
+impl Filesystem {
+    fn to_type(self) -> &'static str {
+        match self {
+            Filesystem::Btrfs => "btrfs",
+            Filesystem::Vfat => "vfat",
+        }
+    }
+}
+
+pub struct MountStack {
+    targets: Vec<PathBuf>,
+}
+
+impl MountStack {
+    pub fn new() -> Self {
+        MountStack {
+            targets: Vec::new(),
+        }
+    }
+
+    #[must_use]
+    pub fn mount(
+        &mut self,
+        source: &Path,
+        target: &Path,
+        filesystem: Filesystem,
+        options: Option<&str>,
+    ) -> nix::Result<()> {
+        debug!("Mounting {:?} ({:?}) to {:?}", source, filesystem, target);
+        mount(
+            Some(source),
+            target,
+            Some(filesystem.to_type()),
+            MsFlags::empty(),
+            options,
+        )?;
+        self.targets.push(target.to_owned());
+        Ok(())
+    }
+}
+
+impl Drop for MountStack {
+    fn drop(&mut self) {
+        while let Some(target) = self.targets.pop() {
+            if !umount(&target).is_ok() {
+                warn!("Unable to mount {}", target.display());
+            };
+        }
+    }
+}