libfreemkv 0.13.1

//! SCSI/MMC command interface.
//!
//! Platform backends are in separate files:
//!   - `linux.rs` — SG_IO ioctl
//!   - `macos.rs` — IOKit SCSITaskDeviceInterface
//!   - `windows.rs` — SPTI (SCSI Pass-Through Interface)

#[cfg(target_os = "linux")]
mod linux;
#[cfg(target_os = "macos")]
mod macos;
#[cfg(target_os = "windows")]
mod windows;

#[allow(unused_imports)]
use crate::error::{Error, Result};
use std::path::Path;

// ── SCSI opcodes (SPC-4, MMC-6) ────────────────────────────────────────────

pub const SCSI_INQUIRY: u8 = 0x12;
pub const SCSI_READ_CAPACITY: u8 = 0x25;
pub const SCSI_READ_10: u8 = 0x28;
pub const SCSI_READ_BUFFER: u8 = 0x3C;
pub const SCSI_READ_TOC: u8 = 0x43;
pub const SCSI_GET_CONFIGURATION: u8 = 0x46;
pub const SCSI_SET_CD_SPEED: u8 = 0xBB;
pub const SCSI_SEND_KEY: u8 = 0xA3;
pub const SCSI_REPORT_KEY: u8 = 0xA4;
pub const SCSI_READ_12: u8 = 0xA8;
pub const SCSI_READ_DISC_STRUCTURE: u8 = 0xAD;

/// AACS key class for REPORT KEY / SEND KEY commands.
pub const AACS_KEY_CLASS: u8 = 0x02;

// ── Types ───────────────────────────────────────────────────────────────────

#[derive(Debug, Clone, Copy, PartialEq)]
pub enum DataDirection {
    None,
    FromDevice,
    ToDevice,
}

#[derive(Debug)]
pub struct ScsiResult {
    pub status: u8,
    pub bytes_transferred: usize,
    pub sense: [u8; 32],
}

/// Low-level SCSI transport — one implementation per platform.
pub trait ScsiTransport: Send {
    fn execute(
        &mut self,
        cdb: &[u8],
        direction: DataDirection,
        data: &mut [u8],
        timeout_ms: u32,
    ) -> Result<ScsiResult>;
}

// ── Platform-agnostic open / reset ──────────────────────────────────────────

/// Open a SCSI transport for the given device path.
/// Selects the right backend for the current platform.
pub fn open(device: &Path) -> Result<Box<dyn ScsiTransport>> {
    #[cfg(target_os = "linux")]
    {
        Ok(Box::new(linux::SgIoTransport::open(device)?))
    }

    #[cfg(target_os = "macos")]
    {
        Ok(Box::new(macos::MacScsiTransport::open(device)?))
    }

    #[cfg(target_os = "windows")]
    {
        Ok(Box::new(windows::SptiTransport::open(device)?))
    }

    #[cfg(not(any(target_os = "linux", target_os = "macos", target_os = "windows")))]
    {
        Err(Error::UnsupportedPlatform {
            target: std::env::consts::OS.to_string(),
        })
    }
}

/// Default upper bound on `scsi::reset()`. The platform-specific reset
/// sequence does ~15 s of bounded sleeps + ioctls in the happy path, so
/// 30 s is roughly 2× the worst-case happy time — long enough that a
/// healthy-but-slow drive isn't false-positively timed out, short enough
/// that a kernel-wedged ioctl doesn't take down the caller's poll loop
/// for minutes.
pub const DEFAULT_RESET_TIMEOUT_SECS: u64 = 30;

/// Reset a SCSI device to a known good state, with a hard wallclock
/// bound (`DEFAULT_RESET_TIMEOUT_SECS`). On Linux: open/close fd cycle +
/// TUR + SG_SCSI_RESET escalation.
///
/// **Why the timeout matters.** SG_SCSI_RESET is an ioctl that can block
/// indefinitely on a kernel-wedged USB target (the kernel waits for the
/// SCSI subsystem to ack the reset, which never comes from a dead-bus
/// device). Without an outer bound, the call hangs the caller's thread
/// forever — observed in production on a wedged BU40N where the autorip
/// poll loop sat in the ioctl for 60+ s. The bounded version returns
/// `DeviceResetFailed` after `DEFAULT_RESET_TIMEOUT_SECS`; the inner
/// thread keeps running until the kernel eventually unblocks it (we
/// can't cancel a Linux ioctl from userspace), so this leaks one OS
/// thread per wedge — acceptable cost for a daemon that recovers
/// instead of hanging.
pub fn reset(device: &Path) -> Result<()> {
    reset_with_timeout(device, std::time::Duration::from_secs(DEFAULT_RESET_TIMEOUT_SECS))
}

/// Reset with a caller-specified timeout. See [`reset`] for the full
/// rationale on why an outer wallclock bound is required.
pub fn reset_with_timeout(device: &Path, timeout: std::time::Duration) -> Result<()> {
    let device_owned = device.to_path_buf();
    let (tx, rx) = std::sync::mpsc::channel();

    // Detach a worker thread for the actual reset. We never `join` it —
    // if the kernel ioctl is wedged, the join would block forever, which
    // is the very thing we're protecting the caller from. The thread will
    // exit on its own when the kernel eventually returns from the ioctl
    // (or never, if the device is permanently dead — process exit cleans
    // it up).
    std::thread::Builder::new()
        .name("scsi-reset".into())
        .spawn(move || {
            let r = reset_blocking(&device_owned);
            let _ = tx.send(r);
        })
        .map_err(|_| Error::DeviceResetFailed {
            path: device.display().to_string(),
        })?;

    match rx.recv_timeout(timeout) {
        Ok(result) => result,
        Err(std::sync::mpsc::RecvTimeoutError::Timeout) => Err(Error::DeviceResetFailed {
            path: device.display().to_string(),
        }),
        Err(std::sync::mpsc::RecvTimeoutError::Disconnected) => {
            // The worker thread panicked before sending. Surface as a
            // reset failure rather than a generic error.
            Err(Error::DeviceResetFailed {
                path: device.display().to_string(),
            })
        }
    }
}

/// Inner reset — runs on the worker thread. May block indefinitely if
/// the kernel's SCSI subsystem is wedged. Callers must use the bounded
/// `reset()` wrapper above; this raw function isn't exposed.
fn reset_blocking(device: &Path) -> Result<()> {
    #[cfg(target_os = "linux")]
    {
        linux::SgIoTransport::reset(device)
    }

    #[cfg(target_os = "macos")]
    {
        macos::MacScsiTransport::reset(device)
    }

    #[cfg(target_os = "windows")]
    {
        windows::SptiTransport::reset(device)
    }

    #[cfg(not(any(target_os = "linux", target_os = "macos", target_os = "windows")))]
    {
        let _ = device;
        Ok(())
    }
}

// ── CDB builders (platform-agnostic) ────────────────────────────────────────

/// SCSI INQUIRY response.
#[derive(Debug, Clone)]
pub struct InquiryResult {
    pub vendor_id: String,
    pub model: String,
    pub firmware: String,
    pub raw: Vec<u8>,
}

/// Send INQUIRY and parse standard response fields.
pub fn inquiry(scsi: &mut dyn ScsiTransport) -> Result<InquiryResult> {
    let cdb = [SCSI_INQUIRY, 0x00, 0x00, 0x00, 0x60, 0x00];
    let mut buf = [0u8; 96];
    scsi.execute(&cdb, DataDirection::FromDevice, &mut buf, 5_000)?;

    Ok(InquiryResult {
        vendor_id: String::from_utf8_lossy(&buf[8..16]).trim().to_string(),
        model: String::from_utf8_lossy(&buf[16..32]).trim().to_string(),
        firmware: String::from_utf8_lossy(&buf[32..36]).trim().to_string(),
        raw: buf.to_vec(),
    })
}

/// Send GET CONFIGURATION for feature 0x010C (Firmware Information).
pub fn get_config_010c(scsi: &mut dyn ScsiTransport) -> Result<Vec<u8>> {
    let cdb = [
        SCSI_GET_CONFIGURATION,
        0x02,
        0x01,
        0x0C,
        0x00,
        0x00,
        0x00,
        0x00,
        0x10,
        0x00,
    ];
    let mut buf = [0u8; 16];
    scsi.execute(&cdb, DataDirection::FromDevice, &mut buf, 5_000)?;
    Ok(buf.to_vec())
}

/// Build a READ BUFFER CDB.
pub fn build_read_buffer(mode: u8, buffer_id: u8, offset: u32, length: u32) -> [u8; 10] {
    [
        SCSI_READ_BUFFER,
        mode,
        buffer_id,
        (offset >> 16) as u8,
        (offset >> 8) as u8,
        offset as u8,
        (length >> 16) as u8,
        (length >> 8) as u8,
        length as u8,
        0x00,
    ]
}

/// Build a SET CD SPEED CDB.
pub fn build_set_cd_speed(read_speed: u16) -> [u8; 12] {
    [
        SCSI_SET_CD_SPEED,
        0x00,
        (read_speed >> 8) as u8,
        read_speed as u8,
        0xFF,
        0xFF,
        0x00,
        0x00,
        0x00,
        0x00,
        0x00,
        0x00,
    ]
}

/// Build a READ(10) CDB with the raw read flag.
pub fn build_read10_raw(lba: u32, count: u16) -> [u8; 10] {
    [
        SCSI_READ_10,
        0x08,
        (lba >> 24) as u8,
        (lba >> 16) as u8,
        (lba >> 8) as u8,
        lba as u8,
        0x00,
        (count >> 8) as u8,
        count as u8,
        0x00,
    ]
}