// Copyright 2021 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Provides parts of crosvm as a library to communicate with running crosvm instances.
// Usually you would need to invoke crosvm with subcommands and you'd get the result on
// stdout.
use std::convert::{TryFrom, TryInto};
use std::ffi::CStr;
use std::panic::catch_unwind;
use std::path::{Path, PathBuf};

use libc::{c_char, ssize_t};

use vm_control::{
    client::*, BalloonControlCommand, BalloonStats, DiskControlCommand, UsbControlAttachedDevice,
    UsbControlResult, VmRequest, VmResponse,
};

fn validate_socket_path(socket_path: *const c_char) -> Option<PathBuf> {
    if !socket_path.is_null() {
        let socket_path = unsafe { CStr::from_ptr(socket_path) };
        Some(PathBuf::from(socket_path.to_str().ok()?))
    } else {
        None
    }
}

/// Stops the crosvm instance whose control socket is listening on `socket_path`.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_stop_vm(socket_path: *const c_char) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            vms_request(&VmRequest::Exit, &socket_path).is_ok()
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Suspends the crosvm instance whose control socket is listening on `socket_path`.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_suspend_vm(socket_path: *const c_char) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            vms_request(&VmRequest::Suspend, &socket_path).is_ok()
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Resumes the crosvm instance whose control socket is listening on `socket_path`.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_resume_vm(socket_path: *const c_char) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            vms_request(&VmRequest::Resume, &socket_path).is_ok()
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Adjusts the balloon size of the crosvm instance whose control socket is
/// listening on `socket_path`.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_balloon_vms(socket_path: *const c_char, num_bytes: u64) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            let command = BalloonControlCommand::Adjust { num_bytes };
            vms_request(&VmRequest::BalloonCommand(command), &socket_path).is_ok()
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Represents an individual attached USB device.
#[repr(C)]
pub struct UsbDeviceEntry {
    /// Internal port index used for identifying this individual device.
    port: u8,
    /// USB vendor ID
    vendor_id: u16,
    /// USB product ID
    product_id: u16,
}

impl From<&UsbControlAttachedDevice> for UsbDeviceEntry {
    fn from(other: &UsbControlAttachedDevice) -> Self {
        Self {
            port: other.port,
            vendor_id: other.vendor_id,
            product_id: other.product_id,
        }
    }
}

/// Returns all USB devices passed through the crosvm instance whose control socket is listening on `socket_path`.
///
/// The function returns the amount of entries written.
/// # Arguments
///
/// * `socket_path` - Path to the crosvm control socket
/// * `entries` - Pointer to an array of `UsbDeviceEntry` where the details about the attached
///               devices will be written to
/// * `entries_length` - Amount of entries in the array specified by `entries`
///
/// Crosvm supports passing through up to 255 devices, so pasing an array with 255 entries will
/// guarantee to return all entries.
#[no_mangle]
pub extern "C" fn crosvm_client_usb_list(
    socket_path: *const c_char,
    entries: *mut UsbDeviceEntry,
    entries_length: ssize_t,
) -> ssize_t {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            if let Ok(UsbControlResult::Devices(res)) = do_usb_list(&socket_path) {
                let mut i = 0;
                for entry in res.iter().filter(|x| x.valid()) {
                    if i >= entries_length {
                        break;
                    }
                    unsafe {
                        *entries.offset(i) = entry.into();
                        i += 1;
                    }
                }
                i
            } else {
                -1
            }
        } else {
            -1
        }
    })
    .unwrap_or(-1)
}

/// Attaches an USB device to crosvm instance whose control socket is listening on `socket_path`.
///
/// The function returns the amount of entries written.
/// # Arguments
///
/// * `socket_path` - Path to the crosvm control socket
/// * `bus` - USB device bus ID
/// * `addr` - USB device address
/// * `vid` - USB device vendor ID
/// * `pid` - USB device product ID
/// * `dev_path` - Path to the USB device (Most likely `/dev/bus/usb/<bus>/<addr>`).
/// * `out_port` - (optional) internal port will be written here if provided.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_usb_attach(
    socket_path: *const c_char,
    bus: u8,
    addr: u8,
    vid: u16,
    pid: u16,
    dev_path: *const c_char,
    out_port: *mut u8,
) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            if dev_path.is_null() {
                return false;
            }
            let dev_path = Path::new(unsafe { CStr::from_ptr(dev_path) }.to_str().unwrap_or(""));

            if let Ok(UsbControlResult::Ok { port }) =
                do_usb_attach(&socket_path, bus, addr, vid, pid, dev_path)
            {
                if !out_port.is_null() {
                    unsafe { *out_port = port };
                }
                true
            } else {
                false
            }
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Detaches an USB device from crosvm instance whose control socket is listening on `socket_path`.
/// `port` determines device to be detached.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_usb_detach(socket_path: *const c_char, port: u8) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            do_usb_detach(&socket_path, port).is_ok()
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Modifies the battery status of crosvm instance whose control socket is listening on
/// `socket_path`.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_modify_battery(
    socket_path: *const c_char,
    battery_type: *const c_char,
    property: *const c_char,
    target: *const c_char,
) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            if battery_type.is_null() || property.is_null() || target.is_null() {
                return false;
            }
            let battery_type = unsafe { CStr::from_ptr(battery_type) };
            let property = unsafe { CStr::from_ptr(property) };
            let target = unsafe { CStr::from_ptr(target) };

            do_modify_battery(
                &socket_path,
                &battery_type.to_str().unwrap(),
                &property.to_str().unwrap(),
                &target.to_str().unwrap(),
            )
            .is_ok()
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Resizes the disk of the crosvm instance whose control socket is listening on `socket_path`.
///
/// The function returns true on success or false if an error occured.
#[no_mangle]
pub extern "C" fn crosvm_client_resize_disk(
    socket_path: *const c_char,
    disk_index: u64,
    new_size: u64,
) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            if let Ok(disk_index) = usize::try_from(disk_index) {
                let request = VmRequest::DiskCommand {
                    disk_index,
                    command: DiskControlCommand::Resize { new_size },
                };
                vms_request(&request, &socket_path).is_ok()
            } else {
                false
            }
        } else {
            false
        }
    })
    .unwrap_or(false)
}

/// Similar to internally used `BalloonStats` but using i64 instead of
/// Option<u64>. `None` (or values bigger than i64::max) will be encoded as -1.
#[repr(C)]
pub struct BalloonStatsFfi {
    swap_in: i64,
    swap_out: i64,
    major_faults: i64,
    minor_faults: i64,
    free_memory: i64,
    total_memory: i64,
    available_memory: i64,
    disk_caches: i64,
    hugetlb_allocations: i64,
    hugetlb_failures: i64,
}

impl From<&BalloonStats> for BalloonStatsFfi {
    fn from(other: &BalloonStats) -> Self {
        let convert =
            |x: Option<u64>| -> i64 { x.map(|y| y.try_into().ok()).flatten().unwrap_or(-1) };
        Self {
            swap_in: convert(other.swap_in),
            swap_out: convert(other.swap_out),
            major_faults: convert(other.major_faults),
            minor_faults: convert(other.minor_faults),
            free_memory: convert(other.free_memory),
            total_memory: convert(other.total_memory),
            available_memory: convert(other.available_memory),
            disk_caches: convert(other.disk_caches),
            hugetlb_allocations: convert(other.hugetlb_allocations),
            hugetlb_failures: convert(other.hugetlb_failures),
        }
    }
}

/// Returns balloon stats of the crosvm instance whose control socket is listening on `socket_path`.
///
/// The parameters `stats` and `actual` are optional and will only be written to if they are
/// non-null.
///
/// The function returns true on success or false if an error occured.
///
/// # Note
///
/// Entries in `BalloonStatsFfi` that are not available will be set to `-1`.
#[no_mangle]
pub extern "C" fn crosvm_client_balloon_stats(
    socket_path: *const c_char,
    stats: *mut BalloonStatsFfi,
    actual: *mut u64,
) -> bool {
    catch_unwind(|| {
        if let Some(socket_path) = validate_socket_path(socket_path) {
            let request = &VmRequest::BalloonCommand(BalloonControlCommand::Stats {});
            if let Ok(VmResponse::BalloonStats {
                stats: ref balloon_stats,
                balloon_actual,
            }) = handle_request(request, &socket_path)
            {
                if !stats.is_null() {
                    unsafe {
                        *stats = balloon_stats.into();
                    }
                }

                if !actual.is_null() {
                    unsafe {
                        *actual = balloon_actual;
                    }
                }
                true
            } else {
                false
            }
        } else {
            false
        }
    })
    .unwrap_or(false)
}