devices/virtio/block/

mod.rs

// Copyright 2021 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#[cfg(windows)]
use std::num::NonZeroU32;
use std::path::PathBuf;

use cros_async::ExecutorKind;
use serde::Deserialize;
use serde::Deserializer;
use serde::Serialize;
use serde::Serializer;

use crate::PciAddress;

pub mod asynchronous;
pub(crate) mod sys;

pub use asynchronous::BlockAsync;

fn block_option_sparse_default() -> bool {
    true
}
fn block_option_lock_default() -> bool {
    true
}
fn block_option_block_size_default() -> u32 {
    512
}
// TODO(b/237829580): Move to sys module once virtio block sys is refactored to
// match the style guide.
#[cfg(windows)]
fn block_option_io_concurrency_default() -> NonZeroU32 {
    NonZeroU32::new(1).unwrap()
}

/// Maximum length of a `DiskOption` identifier.
///
/// This is based on the virtio-block ID length limit.
pub const DISK_ID_LEN: usize = 20;

pub fn serialize_disk_id<S: Serializer>(
    id: &Option<[u8; DISK_ID_LEN]>,
    serializer: S,
) -> Result<S::Ok, S::Error> {
    match id {
        None => serializer.serialize_none(),
        Some(id) => {
            // Find the first zero byte in the id.
            let len = id.iter().position(|v| *v == 0).unwrap_or(DISK_ID_LEN);
            serializer.serialize_some(
                std::str::from_utf8(&id[0..len])
                    .map_err(|e| serde::ser::Error::custom(e.to_string()))?,
            )
        }
    }
}

fn deserialize_disk_id<'de, D: Deserializer<'de>>(
    deserializer: D,
) -> Result<Option<[u8; DISK_ID_LEN]>, D::Error> {
    let id = Option::<String>::deserialize(deserializer)?;

    match id {
        None => Ok(None),
        Some(id) => {
            if id.len() > DISK_ID_LEN {
                return Err(serde::de::Error::custom(format!(
                    "disk id must be {DISK_ID_LEN} or fewer characters"
                )));
            }

            let mut ret = [0u8; DISK_ID_LEN];
            // Slicing id to value's length will never panic
            // because we checked that value will fit into id above.
            ret[..id.len()].copy_from_slice(id.as_bytes());
            Ok(Some(ret))
        }
    }
}

#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq, serde_keyvalue::FromKeyValues)]
#[serde(deny_unknown_fields, rename_all = "kebab-case")]
pub struct DiskOption {
    pub path: PathBuf,
    #[serde(default, rename = "ro")]
    pub read_only: bool,
    #[serde(default)]
    /// Whether this disk should be the root device. Can only be set once. Only useful for adding
    /// specific command-line options.
    pub root: bool,
    #[serde(default = "block_option_sparse_default")]
    pub sparse: bool,
    // camel_case variant allowed for backward compatibility.
    #[serde(default, alias = "o_direct")]
    pub direct: bool,
    /// Whether to lock the disk files. Uses flock on Unix and FILE_SHARE_* flags on Windows.
    #[serde(default = "block_option_lock_default")]
    pub lock: bool,
    // camel_case variant allowed for backward compatibility.
    #[serde(default = "block_option_block_size_default", alias = "block_size")]
    pub block_size: u32,
    #[serde(
        default,
        serialize_with = "serialize_disk_id",
        deserialize_with = "deserialize_disk_id"
    )]
    pub id: Option<[u8; DISK_ID_LEN]>,
    // Deprecated: Use async_executor=overlapped[concurrency=N]"
    // camel_case variant allowed for backward compatibility.
    #[cfg(windows)]
    #[serde(
        default = "block_option_io_concurrency_default",
        alias = "io_concurrency"
    )]
    pub io_concurrency: NonZeroU32,
    #[serde(default)]
    /// Experimental option to run multiple worker threads in parallel. If false, only single
    /// thread runs by default. Note this option is not effective for vhost-user blk device.
    pub multiple_workers: bool,
    #[serde(default, alias = "async_executor")]
    /// The async executor kind to simulate the block device with. This option takes
    /// precedence over the async executor kind specified by the subcommand's option.
    /// If None, the default or the specified by the subcommand's option would be used.
    pub async_executor: Option<ExecutorKind>,
    #[serde(default)]
    //Option to choose virtqueue type. If true, use the packed virtqueue. If false
    //or by default, use split virtqueue
    pub packed_queue: bool,

    /// Specify the boot index for this device that the BIOS will use when attempting to boot from
    /// bootable devices. For example, if bootindex=2, then the BIOS will attempt to boot from the
    /// device right after booting from the device with bootindex=1 fails.
    pub bootindex: Option<usize>,

    /// Specify PCI address will be used to attach this device
    pub pci_address: Option<PciAddress>,
    /// Specify whether to cache reads/writes.
    #[serde(default)]
    pub dontcache: bool,
}

impl Default for DiskOption {
    fn default() -> Self {
        Self {
            path: PathBuf::new(),
            read_only: false,
            root: false,
            sparse: block_option_sparse_default(),
            direct: false,
            lock: block_option_lock_default(),
            block_size: block_option_block_size_default(),
            id: None,
            #[cfg(windows)]
            io_concurrency: block_option_io_concurrency_default(),
            multiple_workers: false,
            async_executor: None,
            packed_queue: false,
            bootindex: None,
            pci_address: None,
            dontcache: false,
        }
    }
}

#[cfg(test)]
mod tests {
    #[cfg(any(target_os = "android", target_os = "linux"))]
    use cros_async::sys::linux::ExecutorKindSys;
    #[cfg(windows)]
    use cros_async::sys::windows::ExecutorKindSys;
    use serde_keyvalue::*;

    use super::*;

    fn from_block_arg(options: &str) -> Result<DiskOption, ParseError> {
        from_key_values(options)
    }

    #[test]
    fn check_default_matches_from_key_values() {
        let path = "/path/to/disk.img";
        let disk = DiskOption {
            path: PathBuf::from(path),
            ..Default::default()
        };
        assert_eq!(disk, from_key_values(path).unwrap());
    }

    #[test]
    fn params_from_key_values() {
        // Path argument is mandatory.
        let err = from_block_arg("").unwrap_err();
        assert_eq!(
            err,
            ParseError {
                kind: ErrorKind::SerdeError("missing field `path`".into()),
                pos: 0,
            }
        );

        // Path is the default argument.
        let params = from_block_arg("/path/to/disk.img").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                ..Default::default()
            }
        );

        // bootindex
        let params = from_block_arg("/path/to/disk.img,bootindex=5").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                bootindex: Some(5),
                ..Default::default()
            }
        );

        // Explicitly-specified path.
        let params = from_block_arg("path=/path/to/disk.img").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                ..Default::default()
            }
        );

        // read_only
        let params = from_block_arg("/some/path.img,ro").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                read_only: true,
                ..Default::default()
            }
        );

        // root
        let params = from_block_arg("/some/path.img,root").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                root: true,
                ..Default::default()
            }
        );

        // sparse
        let params = from_block_arg("/some/path.img,sparse").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                ..Default::default()
            }
        );
        let params = from_block_arg("/some/path.img,sparse=false").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                sparse: false,
                ..Default::default()
            }
        );

        // direct
        let params = from_block_arg("/some/path.img,direct").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                direct: true,
                ..Default::default()
            }
        );

        // o_direct (deprecated, kept for backward compatibility)
        let params = from_block_arg("/some/path.img,o_direct").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                direct: true,
                ..Default::default()
            }
        );

        // block-size
        let params = from_block_arg("/some/path.img,block-size=128").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                block_size: 128,
                ..Default::default()
            }
        );

        // block_size (deprecated, kept for backward compatibility)
        let params = from_block_arg("/some/path.img,block_size=128").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                block_size: 128,
                ..Default::default()
            }
        );

        // io_concurrency
        #[cfg(windows)]
        {
            let params = from_block_arg("/some/path.img,io_concurrency=4").unwrap();
            assert_eq!(
                params,
                DiskOption {
                    path: "/some/path.img".into(),
                    io_concurrency: NonZeroU32::new(4).unwrap(),
                    ..Default::default()
                }
            );
            let params = from_block_arg("/some/path.img,async-executor=overlapped").unwrap();
            assert_eq!(
                params,
                DiskOption {
                    path: "/some/path.img".into(),
                    async_executor: Some(ExecutorKindSys::Overlapped { concurrency: None }.into()),
                    ..Default::default()
                }
            );
            let params =
                from_block_arg("/some/path.img,async-executor=\"overlapped,concurrency=4\"")
                    .unwrap();
            assert_eq!(
                params,
                DiskOption {
                    path: "/some/path.img".into(),
                    async_executor: Some(
                        ExecutorKindSys::Overlapped {
                            concurrency: Some(4)
                        }
                        .into()
                    ),
                    ..Default::default()
                }
            );
        }

        // id
        let params = from_block_arg("/some/path.img,id=DISK").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                id: Some(*b"DISK\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"),
                ..Default::default()
            }
        );
        let err = from_block_arg("/some/path.img,id=DISK_ID_IS_WAY_TOO_LONG").unwrap_err();
        assert_eq!(
            err,
            ParseError {
                kind: ErrorKind::SerdeError("disk id must be 20 or fewer characters".into()),
                pos: 0,
            }
        );

        // async-executor
        #[cfg(windows)]
        let (ex_kind, ex_kind_opt) = (ExecutorKindSys::Handle.into(), "handle");
        #[cfg(any(target_os = "android", target_os = "linux"))]
        let (ex_kind, ex_kind_opt) = (ExecutorKindSys::Fd.into(), "epoll");
        let params =
            from_block_arg(&format!("/some/path.img,async-executor={ex_kind_opt}")).unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                async_executor: Some(ex_kind),
                ..Default::default()
            }
        );

        // packed queue
        let params = from_block_arg("/path/to/disk.img,packed-queue").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                packed_queue: true,
                ..Default::default()
            }
        );

        // pci-address
        let params = from_block_arg("/path/to/disk.img,pci-address=00:01.1").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                pci_address: Some(PciAddress {
                    bus: 0,
                    dev: 1,
                    func: 1,
                }),
                ..Default::default()
            }
        );

        // lock=true
        let params = from_block_arg("/path/to/disk.img,lock=true").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                ..Default::default()
            }
        );
        // lock=false
        let params = from_block_arg("/path/to/disk.img,lock=false").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                lock: false,
                ..Default::default()
            }
        );

        // dontcache
        let params = from_block_arg("/path/to/disk.img,dontcache").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                dontcache: true,
                ..Default::default()
            }
        );
        let params = from_block_arg("/path/to/disk.img,dontcache=false").unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/path/to/disk.img".into(),
                dontcache: false,
                ..Default::default()
            }
        );

        // All together
        let params = from_block_arg(&format!(
            "/some/path.img,block_size=256,ro,root,sparse=false,id=DISK_LABEL\
            ,direct,async-executor={ex_kind_opt},packed-queue=false,pci-address=00:01.1"
        ))
        .unwrap();
        assert_eq!(
            params,
            DiskOption {
                path: "/some/path.img".into(),
                read_only: true,
                root: true,
                sparse: false,
                direct: true,
                block_size: 256,
                id: Some(*b"DISK_LABEL\0\0\0\0\0\0\0\0\0\0"),
                async_executor: Some(ex_kind),
                pci_address: Some(PciAddress {
                    bus: 0,
                    dev: 1,
                    func: 1,
                }),
                ..Default::default()
            }
        );
    }

    #[test]
    fn diskoption_serialize_deserialize() {
        // With id == None
        let original = DiskOption {
            path: "./rootfs".into(),
            ..Default::default()
        };
        let json = serde_json::to_string(&original).unwrap();
        let deserialized = serde_json::from_str(&json).unwrap();
        assert_eq!(original, deserialized);

        // With id == Some
        let original = DiskOption {
            path: "./rootfs".into(),
            id: Some(*b"BLK\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"),
            async_executor: Some(ExecutorKind::default()),
            ..Default::default()
        };
        let json = serde_json::to_string(&original).unwrap();
        let deserialized = serde_json::from_str(&json).unwrap();
        assert_eq!(original, deserialized);

        // With id taking all the available space.
        let original = DiskOption {
            path: "./rootfs".into(),
            id: Some(*b"QWERTYUIOPASDFGHJKL:"),
            async_executor: Some(ExecutorKind::default()),
            ..Default::default()
        };
        let json = serde_json::to_string(&original).unwrap();
        let deserialized = serde_json::from_str(&json).unwrap();
        assert_eq!(original, deserialized);
    }
}