Loop device support

Cargo.lock

@@ -1,9 +1,18 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "aho-corasick"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "memchr 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "alma"
 version = "0.6.0"
 dependencies = [
+ "byte-unit 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -90,6 +99,15 @@ dependencies = [
  "constant_time_eq 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "byte-unit"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "byteorder"
 version = "1.3.1"
@@ -185,6 +203,11 @@ dependencies = [
  "unicode-segmentation 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "libc"
 version = "0.2.55"
@@ -198,6 +221,11 @@ dependencies = [
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "memchr"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "nix"
 version = "0.12.0"
@@ -381,6 +409,26 @@ dependencies = [
  "redox_syscall 0.1.54 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "regex"
+version = "1.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "aho-corasick 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "memchr 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex-syntax 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "utf8-ranges 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "ucd-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "remove_dir_all"
 version = "0.5.1"
@@ -515,6 +563,14 @@ dependencies = [
  "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "thread_local"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "time"
 version = "0.1.42"
@@ -533,6 +589,11 @@ dependencies = [
  "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "ucd-util"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "unicode-segmentation"
 version = "1.3.0"
@@ -548,6 +609,11 @@ name = "unicode-xid"
 version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "utf8-ranges"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "vec_map"
 version = "0.8.1"
@@ -587,6 +653,7 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
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@@ -596,6 +663,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum backtrace-sys 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)" = "797c830ac25ccc92a7f8a7b9862bde440715531514594a6154e3d4a54dd769b6"
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+"checksum byte-unit 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "6754bb4703aa167bed5381f0c6842f1cc31a9ecde3b9443f726dde3ad3afb841"
 "checksum byteorder 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a019b10a2a7cdeb292db131fc8113e57ea2a908f6e7894b0c3c671893b65dbeb"
 "checksum cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)" = "39f75544d7bbaf57560d2168f28fd649ff9c76153874db88bdbdfd839b1a7e7d"
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@@ -608,8 +676,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "ea1063915fd7ef4309e222a5a07cf9c319fb9c7836b1f89b85458672dbb127e1"
 "checksum fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
+"checksum lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bc5729f27f159ddd61f4df6228e827e86643d4d3e7c32183cb30a1c08f604a14"
 "checksum libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)" = "42914d39aad277d9e176efbdad68acb1d5443ab65afe0e0e4f0d49352a950880"
 "checksum log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c84ec4b527950aa83a329754b01dbe3f58361d1c5efacd1f6d68c494d08a17c6"
+"checksum memchr 2.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2efc7bc57c883d4a4d6e3246905283d8dae951bb3bd32f49d6ef297f546e1c39"
 "checksum nix 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "921f61dc817b379d0834e45d5ec45beaacfae97082090a49c2cf30dcbc30206f"
 "checksum nodrop 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "2f9667ddcc6cc8a43afc9b7917599d7216aa09c463919ea32c59ed6cac8bc945"
 "checksum num-integer 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)" = "b85e541ef8255f6cf42bbfe4ef361305c6c135d10919ecc26126c4e5ae94bc09"
@@ -631,6 +701,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum redox_syscall 0.1.54 (registry+https://github.com/rust-lang/crates.io-index)" = "12229c14a0f65c4f1cb046a3b52047cdd9da1f4b30f8a39c5063c8bae515e252"
 "checksum redox_termios 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7e891cfe48e9100a70a3b6eb652fef28920c117d366339687bd5576160db0f76"
 "checksum redox_users 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3fe5204c3a17e97dde73f285d49be585df59ed84b50a872baf416e73b62c3828"
+"checksum regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "8f0a0bcab2fd7d1d7c54fa9eae6f43eddeb9ce2e7352f8518a814a4f65d60c58"
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 "checksum remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "3488ba1b9a2084d38645c4c08276a1752dcbf2c7130d74f1569681ad5d2799c5"
 "checksum rustc-demangle 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)" = "ccc78bfd5acd7bf3e89cffcf899e5cb1a52d6fafa8dec2739ad70c9577a57288"
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@@ -646,11 +718,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum term 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "edd106a334b7657c10b7c540a0106114feadeb4dc314513e97df481d5d966f42"
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+"checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
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+"checksum utf8-ranges 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "796f7e48bef87609f7ade7e06495a87d5cd06c7866e6a5cbfceffc558a243737"
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Cargo.toml

@@ -14,3 +14,4 @@ tempfile = "3.0.5"
 nix = "0.12.0"
 serde = { version = "1.0.92", features = ["derive"] }
 toml = "0.5.1"
+byte-unit = "2.1.0"

src/args.rs

@@ -1,6 +1,11 @@
+use byte_unit::Byte;
 use std::path::PathBuf;
 use structopt::StructOpt;
 
+fn parse_bytes(src: &str) -> Result<Byte, &'static str> {
+    Byte::from_string(src).map_err(|_| "Invalid image size")
+}
+
 #[derive(StructOpt)]
 #[structopt(name = "alma", about = "Arch Linux Mobile Appliance")]
 pub struct App {
@@ -26,9 +31,9 @@ pub enum Command {
 
 #[derive(StructOpt)]
 pub struct CreateCommand {
-    /// Path starting with /dev/disk/by-id for the USB drive
+    /// Either a path to a removable block device or a nonexiting file if --image is specified
     #[structopt(parse(from_os_str))]
-    pub block_device: PathBuf,
+    pub path: PathBuf,
 
     /// Additional pacakges to install
     #[structopt(short = "p", long = "extra-packages", value_name = "package")]
@@ -43,8 +48,16 @@ pub struct CreateCommand {
     pub encrypted_root: bool,
 
     /// Path to preset files
-    #[structopt(long = "presets")]
+    #[structopt(long = "presets", value_name = "preset")]
     pub presets: Vec<PathBuf>,
+
+    /// Create an image with a certain size in the given path instead of using an actual block device
+    #[structopt(
+        long = "image",
+        parse(try_from_str = "parse_bytes"),
+        value_name = "size"
+    )]
+    pub image: Option<Byte>,
 }
 
 #[derive(StructOpt)]

src/error.rs

@@ -82,6 +82,12 @@ pub enum ErrorKind {
 
     #[fail(display = "Error executing preset script")]
     PresetScript,
+
+    #[fail(display = "Error creating the image")]
+    Image,
+
+    #[fail(display = "Error setting up a loop device: {}", _0)]
+    Losetup(String),
 }
 
 impl Fail for Error {

src/main.rs

@@ -10,6 +10,7 @@ use crate::error::*;
 use crate::process::CommandExt;
 use crate::storage::*;
 use crate::tool::Tool;
+use byte_unit::Byte;
 use failure::{Fail, ResultExt};
 use log::{debug, error, info, warn};
 use nix::sys::signal;
@@ -75,6 +76,21 @@ fn fix_fstab(fstab: &str) -> String {
         .join("\n")
 }
 
+fn create_image(path: &Path, size: Byte) -> Result<LoopDevice, Error> {
+    {
+        let file = fs::OpenOptions::new()
+            .write(true)
+            .create_new(true)
+            .open(path)
+            .context(ErrorKind::Image)?;
+
+        file.set_len(size.get_bytes() as u64)
+            .context(ErrorKind::Image)?;
+    }
+
+    LoopDevice::create(path)
+}
+
 fn create(command: CreateCommand) -> Result<(), Error> {
     let presets = presets::Presets::load(&command.presets)?;
 
@@ -95,7 +111,21 @@ fn create(command: CreateCommand) -> Result<(), Error> {
         None
     };
 
-    let storage_device = storage::StorageDevice::from_path(command.block_device)?;
+    let image_loop = if let Some(size) = command.image {
+        Some(create_image(&command.path, size)?)
+    } else {
+        None
+    };
+
+    let storage_device = storage::StorageDevice::from_path(
+        image_loop
+            .as_ref()
+            .map(|loop_dev| {
+                info!("Using loop device at {}", loop_dev.path().display());
+                loop_dev.path()
+            })
+            .unwrap_or(&command.path),
+    )?;
     let mount_point = tempdir().context(ErrorKind::TmpDirError)?;
     let disk_path = storage_device.path();
 
@@ -300,7 +330,7 @@ fn chroot(command: ChrootCommand) -> Result<(), Error> {
         None
     };
 
-    let storage_device = storage::StorageDevice::from_path(command.block_device)?;
+    let storage_device = storage::StorageDevice::from_path(&command.block_device)?;
     let mount_point = tempdir().context(ErrorKind::TmpDirError)?;
 
     let boot_partition = storage_device.get_partition(BOOT_PARTITION_INDEX)?;

src/storage/loop_device.rs

@@ -0,0 +1,52 @@
+use crate::error::{Error, ErrorKind};
+use crate::tool::Tool;
+use failure::ResultExt;
+use log::info;
+use std::path::{Path, PathBuf};
+
+#[derive(Debug)]
+pub struct LoopDevice {
+    path: PathBuf,
+    losetup: Tool,
+}
+
+impl LoopDevice {
+    pub fn create(file: &Path) -> Result<Self, Error> {
+        let losetup = Tool::find("losetup")?;
+        let output = losetup
+            .execute()
+            .args(&["--find", "-P", "--show"])
+            .arg(file)
+            .output()
+            .context(ErrorKind::Image)?;
+
+        if !output.status.success() {
+            Err(ErrorKind::Losetup(
+                String::from_utf8(output.stderr).unwrap(),
+            ))?
+        }
+
+        Ok(LoopDevice {
+            path: PathBuf::from(String::from_utf8(output.stdout).unwrap().trim()),
+            losetup,
+        })
+    }
+
+    pub fn path(&self) -> &Path {
+        &self.path
+    }
+}
+
+impl Drop for LoopDevice {
+    fn drop(&mut self) {
+        info!("Detaching loop device {}", self.path.display());
+        self.losetup
+            .execute()
+            .arg("-d")
+            .arg(&self.path)
+            .spawn()
+            .unwrap()
+            .wait()
+            .ok();
+    }
+}

src/storage/mod.rs

@@ -1,5 +1,6 @@
 mod crypt;
 mod filesystem;
+mod loop_device;
 mod markers;
 mod mount_stack;
 mod partition;
@@ -7,6 +8,7 @@ mod storage_device;
 
 pub use crypt::EncryptedDevice;
 pub use filesystem::{Filesystem, FilesystemType};
+pub use loop_device::LoopDevice;
 pub use markers::BlockDevice;
 pub use mount_stack::MountStack;
 pub use storage_device::StorageDevice;

src/storage/storage_device.rs

@@ -4,16 +4,18 @@ use crate::error::{Error, ErrorKind};
 use failure::ResultExt;
 use log::debug;
 use std::fs::read_to_string;
+use std::marker::PhantomData;
 use std::path::{Path, PathBuf};
 
 #[derive(Debug)]
-pub struct StorageDevice {
+pub struct StorageDevice<'a> {
     name: String,
     path: PathBuf,
+    origin: PhantomData<&'a Origin>,
 }
 
-impl StorageDevice {
+impl<'a> StorageDevice<'a> {
-    pub fn from_path(path: PathBuf) -> Result<Self, Error> {
+    pub fn from_path(path: &'a Path) -> Result<Self, Error> {
         let real_path = path.canonicalize().context(ErrorKind::DeviceQuery)?;
         let device_name = real_path
             .file_name()
@@ -30,6 +32,7 @@ impl StorageDevice {
         let _self = Self {
             name: device_name,
             path: real_path,
+            origin: PhantomData,
         };
         if !(_self.is_removable_device()? || _self.is_loop_device()) {
             return Err(ErrorKind::DangerousDevice)?;
@@ -78,10 +81,10 @@ impl StorageDevice {
     }
 }
 
-impl BlockDevice for StorageDevice {
+impl<'a> BlockDevice for StorageDevice<'a> {
     fn path(&self) -> &Path {
         &self.path
     }
 }
 
-impl Origin for StorageDevice {}
+impl<'a> Origin for StorageDevice<'a> {}