Allow working on loop devices

README.md

@@ -27,7 +27,8 @@ Dependencies will be handled for you if you install alma from AUR.
 sudo alma create /dev/disk/by-id/usb-Generic_USB_Flash_Disk-0:0
 ```
 
-This will wipe the entire disk and create a bootable installation of Arch Linux.
+This will wipe the entire disk and create a bootable installation of Arch Linux. You can use either
+removable devices or loop devices. As a precaution, ALMA will not wipe non-removable devices.
 
 After the installation is done you can either boot from it immediately or use `arch-chroot` to
 perform further customizations before your first boot.

src/block.rs

@@ -23,7 +23,12 @@ impl BlockDevice {
             path, real_path, device_name
         );
 
-        Ok(Self { name: device_name })
+        let _self = Self { name: device_name };
+        if !(_self.is_removable()? || _self.is_loop_device()) {
+            return Err(ErrorKind::DangerousDevice)?;
+        }
+
+        Ok(_self)
     }
 
     fn sys_path(&self) -> PathBuf {
@@ -32,7 +37,7 @@ impl BlockDevice {
         path
     }
 
-    pub fn removable(&self) -> Result<bool, Error> {
+    fn is_removable(&self) -> Result<bool, Error> {
         let mut path = self.sys_path();
         path.push("removable");
 
@@ -43,6 +48,12 @@ impl BlockDevice {
         Ok(result == "1\n")
     }
 
+    fn is_loop_device(&self) -> bool {
+        let mut path = self.sys_path();
+        path.push("loop");
+        path.exists()
+    }
+
     pub fn device_path(&self) -> PathBuf {
         let mut path = PathBuf::from("/dev");
         path.push(self.name.clone());

src/error.rs

@@ -14,8 +14,8 @@ pub enum ErrorKind {
     #[fail(display = "Invalid device name")]
     InvalidDeviceName,
 
-    #[fail(display = "The given block device is not removable")]
-    NotRemovableDevice,
+    #[fail(display = "The given block device is neither removable nor a loop device")]
+    DangerousDevice,
 
     #[fail(display = "Partition {} does not exist", _0)]
     NoSuchPartition(u8),

src/main.rs

@@ -62,7 +62,7 @@ enum Command {
 struct CreateCommand {
     /// Path starting with /dev/disk/by-id for the USB drive
     #[structopt(parse(from_os_str),)]
-    disk: PathBuf,
+    block_device: PathBuf,
 
     /// Additional pacakges to install
     #[structopt(short = "p", long = "extra-packages", value_name = "package",)]
@@ -77,7 +77,7 @@ struct CreateCommand {
 struct ChrootCommand {
     /// Path starting with /dev/disk/by-id for the USB drive
     #[structopt(parse(from_os_str),)]
-    disk: PathBuf,
+    block_device: PathBuf,
 }
 
 fn create(command: CreateCommand) -> Result<(), Error> {
@@ -88,18 +88,14 @@ fn create(command: CreateCommand) -> Result<(), Error> {
     let mkfat = Tool::find("mkfs.fat")?;
     let mkbtrfs = Tool::find("mkfs.btrfs")?;
 
-    let disk = block::BlockDevice::from_path(command.disk)?;
-
-    if !disk.removable()? {
-        Err(ErrorKind::NotRemovableDevice)?;
-    }
+    let block_device = block::BlockDevice::from_path(command.block_device)?;
 
     let mount_point = tempdir().context(ErrorKind::TmpDirError)?;
     let boot_point = mount_point.path().join("boot");
     let mut mount_stack = MountStack::new();
-    let disk_path = disk.device_path();
+    let disk_path = block_device.device_path();
 
-    info!("Partitioning the disk");
+    info!("Partitioning the block device");
     debug!("{:?}", disk_path);
 
     sgdisk
@@ -118,14 +114,14 @@ fn create(command: CreateCommand) -> Result<(), Error> {
     thread::sleep(Duration::from_millis(1000));
 
     info!("Formatting filesystems");
-    let boot_partition = disk.partition_device_path(2)?;
+    let boot_partition = block_device.partition_device_path(2)?;
     mkfat
         .execute()
         .arg("-F32")
         .arg(&boot_partition)
         .run(ErrorKind::Formatting)?;
 
-    let root_partition = disk.partition_device_path(3)?;
+    let root_partition = block_device.partition_device_path(3)?;
     mkbtrfs
         .execute()
         .arg("-f")
@@ -219,18 +215,14 @@ fn create(command: CreateCommand) -> Result<(), Error> {
 
 fn chroot(command: ChrootCommand) -> Result<(), Error> {
     let arch_chroot = Tool::find("arch-chroot")?;
-    let disk = block::BlockDevice::from_path(command.disk)?;
-
-    if !disk.removable()? {
-        Err(ErrorKind::NotRemovableDevice)?;
-    }
+    let block_device = block::BlockDevice::from_path(command.block_device)?;
 
     let mount_point = tempdir().context(ErrorKind::TmpDirError)?;
     let boot_point = mount_point.path().join("boot");
     let mut mount_stack = MountStack::new();
 
     info!("Mounting filesystems to {}", mount_point.path().display());
-    let root_partition = disk.partition_device_path(3)?;
+    let root_partition = block_device.partition_device_path(3)?;
     mount_stack
         .mount(
             &root_partition,
@@ -239,7 +231,7 @@ fn chroot(command: ChrootCommand) -> Result<(), Error> {
             None,
         ).context(ErrorKind::Mounting)?;
 
-    let boot_partition = disk.partition_device_path(2)?;
+    let boot_partition = block_device.partition_device_path(2)?;
     mount_stack
         .mount(&boot_partition, &boot_point, Filesystem::Vfat, None)
         .context(ErrorKind::Mounting)?;