libfreemkv/src/scsi/windows.rs

//! Windows SCSI transport via SPTI (SCSI Pass-Through Interface).
//!
//! Sends SCSI commands through DeviceIoControl with IOCTL_SCSI_PASS_THROUGH_DIRECT.
//! Accepts device paths like `D:`, `E:`, `\\.\CdRom0`, or `\\.\D:`.
//!
//! Requires administrator privileges for raw SCSI access.

use super::{DataDirection, ScsiResult, ScsiTransport};
use crate::error::{Error, Result};
use std::path::Path;

// ── Windows constants ──────────────────────────────────────────────────────

const IOCTL_SCSI_PASS_THROUGH_DIRECT: u32 = 0x4D014;
const SCSI_IOCTL_DATA_OUT: u8 = 0;
const SCSI_IOCTL_DATA_IN: u8 = 1;
const SCSI_IOCTL_DATA_UNSPECIFIED: u8 = 2;

const GENERIC_READ: u32 = 0x80000000;
const GENERIC_WRITE: u32 = 0x40000000;
const FILE_SHARE_READ: u32 = 0x00000001;
const FILE_SHARE_WRITE: u32 = 0x00000002;
const OPEN_EXISTING: u32 = 3;
const FILE_ATTRIBUTE_NORMAL: u32 = 0x80;
const INVALID_HANDLE_VALUE: isize = -1;

const K_MAX_CDB_SIZE: usize = 16;
const K_SENSE_SIZE: usize = 32;

// ── SCSI_PASS_THROUGH_DIRECT structure ─────────────────────────────────────

#[repr(C)]
#[allow(non_snake_case)]
struct ScsiPassThroughDirect {
    Length: u16,
    ScsiStatus: u8,
    PathId: u8,
    TargetId: u8,
    Lun: u8,
    CdbLength: u8,
    SenseInfoLength: u8,
    DataIn: u8,
    _padding1: [u8; 3],
    DataTransferLength: u32,
    TimeOutValue: u32,
    DataBuffer: *mut u8,
    SenseInfoOffset: u32,
    Cdb: [u8; K_MAX_CDB_SIZE],
}

#[repr(C)]
struct SptwbDirect {
    spt: ScsiPassThroughDirect,
    sense: [u8; K_SENSE_SIZE],
}

// ── Windows FFI ────────────────────────────────────────────────────────────

unsafe extern "system" {
    fn CreateFileW(
        lpFileName: *const u16,
        dwDesiredAccess: u32,
        dwShareMode: u32,
        lpSecurityAttributes: *const std::ffi::c_void,
        dwCreationDisposition: u32,
        dwFlagsAndAttributes: u32,
        hTemplateFile: *const std::ffi::c_void,
    ) -> isize;

    fn CloseHandle(hObject: isize) -> i32;

    fn DeviceIoControl(
        hDevice: isize,
        dwIoControlCode: u32,
        lpInBuffer: *mut std::ffi::c_void,
        nInBufferSize: u32,
        lpOutBuffer: *mut std::ffi::c_void,
        nOutBufferSize: u32,
        lpBytesReturned: *mut u32,
        lpOverlapped: *mut std::ffi::c_void,
    ) -> i32;
}

// ── Transport implementation ───────────────────────────────────────────────

pub struct SptiTransport {
    handle: isize,
    /// Wide-encoded device path used by `try_recover()` to reopen the
    /// handle after a failed DeviceIoControl. Saved from `open()` so we
    /// don't have to re-resolve the device path on recovery.
    wide_path: Vec<u16>,
}

// SptiTransport contains an isize HANDLE and a Vec<u16>; both Send. The
// auto-derived Send is intentional. Sync is NOT — handle mutation in
// execute() requires &mut, enforced by the trait object dispatch.

/// Normalize a device path to Windows \\.\X: format.
///
/// NOTE: A near-identical `normalize_path` exists in `drive::windows`.
/// Both are kept because they live in separate `cfg(windows)` modules that
/// cannot easily share a helper without introducing cross-module coupling.
fn normalize_device_path(path: &str) -> String {
    if path.starts_with("\\\\.\\") {
        return path.to_string();
    }
    let trimmed = path.trim_end_matches('\\');
    if trimmed.len() == 2 && trimmed.as_bytes()[1] == b':' {
        return format!("\\\\.\\{}", trimmed);
    }
    if path.to_lowercase().starts_with("cdrom") {
        return format!("\\\\.\\{}", path);
    }
    format!("\\\\.\\{}", path)
}

impl SptiTransport {
    pub fn open(device: &Path) -> Result<Self> {
        let dev_str = device.to_str().ok_or_else(|| Error::DeviceNotFound {
            path: device.display().to_string(),
        })?;

        // Normalize device path to \\.\X: format
        let win_path = normalize_device_path(dev_str);
        let wide: Vec<u16> = win_path.encode_utf16().chain(std::iter::once(0)).collect();

        let handle = unsafe {
            CreateFileW(
                wide.as_ptr(),
                GENERIC_READ | GENERIC_WRITE,
                FILE_SHARE_READ | FILE_SHARE_WRITE,
                std::ptr::null(),
                OPEN_EXISTING,
                FILE_ATTRIBUTE_NORMAL,
                std::ptr::null(),
            )
        };

        if handle == INVALID_HANDLE_VALUE {
            // Map last-os-error → Error variant; don't embed English hints
            // in the path field (the CLI handles localization).
            let err = std::io::Error::last_os_error();
            return Err(if err.kind() == std::io::ErrorKind::PermissionDenied {
                Error::DevicePermission {
                    path: dev_str.to_string(),
                }
            } else {
                Error::DeviceNotFound {
                    path: dev_str.to_string(),
                }
            });
        }

        Ok(SptiTransport {
            handle,
            wide_path: wide,
        })
    }

    /// Recover the handle after a failed DeviceIoControl. Closes the bad
    /// handle and opens a fresh one synchronously (CloseHandle/CreateFileW
    /// are fast on Windows — no in-flight CDB to drain like Linux SG_IO).
    /// On success, `self.handle` is replaced and the next `execute()` call
    /// uses the new handle. On failure, `self.handle` is set to
    /// INVALID_HANDLE_VALUE and subsequent calls return `DeviceNotFound`.
    fn try_recover(&mut self) {
        if self.handle != INVALID_HANDLE_VALUE {
            unsafe { CloseHandle(self.handle) };
        }
        let new_handle = unsafe {
            CreateFileW(
                self.wide_path.as_ptr(),
                GENERIC_READ | GENERIC_WRITE,
                FILE_SHARE_READ | FILE_SHARE_WRITE,
                std::ptr::null(),
                OPEN_EXISTING,
                FILE_ATTRIBUTE_NORMAL,
                std::ptr::null(),
            )
        };
        self.handle = new_handle;
    }

    /// Reset the drive to a known good state.
    /// Opens the device, sends IOCTL_STORAGE_RESET_DEVICE to reset
    /// the USB/SCSI bus, then closes. Same concept as SG_SCSI_RESET on Linux.
    pub fn reset(device: &Path) -> Result<()> {
        const IOCTL_STORAGE_RESET_DEVICE: u32 = 0x002D1004;

        let dev_str = device.to_str().ok_or_else(|| Error::DeviceNotFound {
            path: device.display().to_string(),
        })?;
        let win_path = normalize_device_path(dev_str);
        let wide: Vec<u16> = win_path.encode_utf16().chain(std::iter::once(0)).collect();

        // Open
        let handle = unsafe {
            CreateFileW(
                wide.as_ptr(),
                GENERIC_READ | GENERIC_WRITE,
                FILE_SHARE_READ | FILE_SHARE_WRITE,
                std::ptr::null(),
                OPEN_EXISTING,
                FILE_ATTRIBUTE_NORMAL,
                std::ptr::null(),
            )
        };
        if handle == INVALID_HANDLE_VALUE {
            return Ok(()); // can't open — skip reset, not fatal
        }

        // Send device reset
        let mut returned: u32 = 0;
        unsafe {
            DeviceIoControl(
                handle,
                IOCTL_STORAGE_RESET_DEVICE,
                std::ptr::null_mut(),
                0,
                std::ptr::null_mut(),
                0,
                &mut returned,
                std::ptr::null_mut(),
            );
        }

        // Close and wait for drive to settle
        unsafe { CloseHandle(handle) };
        std::thread::sleep(std::time::Duration::from_secs(2));
        Ok(())
    }
}

/// Enumerate optical drives on Windows via `find_drives()` (CdRom0..15
/// scan) and re-shape into `DriveInfo`. Existing implementation already
/// returns `(path, DriveId)`; mapped here to the public struct.
pub(super) fn list_drives() -> Vec<super::DriveInfo> {
    crate::drive::windows::find_drives()
        .into_iter()
        .map(|(path, id)| super::DriveInfo {
            path,
            vendor: id.vendor_id.trim().to_string(),
            model: id.product_id.trim().to_string(),
            firmware: id.product_revision.trim().to_string(),
        })
        .collect()
}

/// TEST UNIT READY probe on Windows. No in-library recovery — see the
/// Linux `drive_has_disc` doc block for the rationale.
pub(super) fn drive_has_disc(path: &Path) -> Result<bool> {
    let mut transport = SptiTransport::open(path)?;
    let cdb = [crate::scsi::SCSI_TEST_UNIT_READY, 0, 0, 0, 0, 0];
    let mut buf = [0u8; 0];
    match transport.execute(
        &cdb,
        crate::scsi::DataDirection::None,
        &mut buf,
        crate::scsi::TUR_TIMEOUT_MS,
    ) {
        Ok(_) => Ok(true),
        Err(Error::ScsiError { sense_key: 2, .. }) => Ok(false),
        Err(e) => Err(e),
    }
}

impl Drop for SptiTransport {
    fn drop(&mut self) {
        if self.handle != INVALID_HANDLE_VALUE {
            unsafe {
                CloseHandle(self.handle);
            }
        }
    }
}

impl ScsiTransport for SptiTransport {
    fn execute(
        &mut self,
        cdb: &[u8],
        direction: DataDirection,
        data: &mut [u8],
        timeout_ms: u32,
    ) -> Result<ScsiResult> {
        // Per RIP_DESIGN.md §15.1: parity with Linux's recovery contract.
        // If a prior call invalidated the handle and try_recover() also
        // failed, fail fast.
        if self.handle == INVALID_HANDLE_VALUE {
            return Err(Error::DeviceNotFound {
                path: String::new(),
            });
        }

        // Zero the data buffer for reads to prevent returning uninitialized data
        // if the driver doesn't fully update DataTransferLength.
        if direction == DataDirection::FromDevice {
            data.fill(0);
        }

        let mut sptwb: SptwbDirect = unsafe { std::mem::zeroed() };

        let cdb_len = cdb.len().min(K_MAX_CDB_SIZE);
        sptwb.spt.Length = std::mem::size_of::<ScsiPassThroughDirect>() as u16;
        sptwb.spt.CdbLength = cdb_len as u8;
        sptwb.spt.SenseInfoLength = K_SENSE_SIZE as u8;
        sptwb.spt.DataIn = match direction {
            DataDirection::None => SCSI_IOCTL_DATA_UNSPECIFIED,
            DataDirection::FromDevice => SCSI_IOCTL_DATA_IN,
            DataDirection::ToDevice => SCSI_IOCTL_DATA_OUT,
        };
        sptwb.spt.DataTransferLength = data.len() as u32;
        // Round up to the next whole second so a 1500ms request gets at
        // least 2s, not 1s. SPTI's TimeOutValue is u32 seconds with no
        // sub-second resolution; biasing toward "more time" is safer than
        // truncating (truncation broke 1500ms fast-reads on Drive::read).
        sptwb.spt.TimeOutValue = ((timeout_ms + 999) / 1000).max(1);
        sptwb.spt.DataBuffer = if data.is_empty() {
            std::ptr::null_mut()
        } else {
            data.as_mut_ptr()
        };
        sptwb.spt.SenseInfoOffset = std::mem::offset_of!(SptwbDirect, sense) as u32;
        sptwb.spt.Cdb[..cdb_len].copy_from_slice(&cdb[..cdb_len]);

        let buf_size = std::mem::size_of::<SptwbDirect>() as u32;
        let mut bytes_returned: u32 = 0;

        let ok = unsafe {
            DeviceIoControl(
                self.handle,
                IOCTL_SCSI_PASS_THROUGH_DIRECT,
                &mut sptwb as *mut _ as *mut std::ffi::c_void,
                buf_size,
                &mut sptwb as *mut _ as *mut std::ffi::c_void,
                buf_size,
                &mut bytes_returned,
                std::ptr::null_mut(),
            )
        };

        if ok == 0 {
            // Driver-level failure (timeout, handle gone, etc.). Recover
            // the handle so the caller's retry loop can resume — same
            // observable contract as Linux's async fd recovery, but
            // synchronous because Windows's CloseHandle/CreateFileW don't
            // block on in-flight CDBs.
            self.try_recover();
            return Err(Error::ScsiError {
                opcode: cdb[0],
                status: 0xFF,
                sense_key: 0,
            });
        }

        if sptwb.spt.ScsiStatus != 0 {
            let sense_key = if sptwb.sense[2] != 0 {
                sptwb.sense[2] & 0x0F
            } else {
                0
            };
            return Err(Error::ScsiError {
                opcode: cdb[0],
                status: sptwb.spt.ScsiStatus,
                sense_key,
            });
        }

        let mut sense = [0u8; 32];
        sense.copy_from_slice(&sptwb.sense);

        Ok(ScsiResult {
            status: sptwb.spt.ScsiStatus,
            bytes_transferred: sptwb.spt.DataTransferLength as usize,
            sense,
        })
    }
}