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// Copyright (c) 2018 Colin Finck, RWTH Aachen University
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

//! Determining and providing information about the environment (unikernel
//! vs. multi-kernel, hypervisor, etc.) as well as central parsing of the
//! command-line parameters.

#[cfg(target_arch = "x86_64")]
pub use arch::x86_64::kernel::{
	get_base_address, get_cmdline, get_cmdsize, get_image_size, get_tls_filesz, get_tls_memsz,
	get_tls_start, is_single_kernel, is_uhyve,
};

#[cfg(target_arch = "aarch64")]
pub use arch::aarch64::kernel::{
	get_base_address, get_cmdline, get_cmdsize, get_image_size, is_single_kernel, is_uhyve,
};

use core::{slice, str};

static mut COMMAND_LINE_CPU_FREQUENCY: u16 = 0;
static mut IS_PROXY: bool = false;

unsafe fn parse_command_line() {
	let cmdsize = get_cmdsize();
	if cmdsize == 0 {
		return;
	}

	// Convert the command-line into a Rust string slice.
	let cmdline = get_cmdline() as *const u8;
	let slice = slice::from_raw_parts(cmdline, cmdsize);
	let cmdline_str = str::from_utf8_unchecked(slice);

	// Check for the -freq option.
	if let Some(freq_index) = cmdline_str.find("-freq") {
		let cmdline_freq_str = cmdline_str.split_at(freq_index + "-freq".len()).1;
		let mhz_str = cmdline_freq_str
			.split(' ')
			.next()
			.expect("Invalid -freq command line");
		COMMAND_LINE_CPU_FREQUENCY = mhz_str
			.parse()
			.expect("Could not parse -freq command line as number");
	}

	// Check for the -proxy option.
	IS_PROXY = cmdline_str.find("-proxy").is_some();
}

pub fn init() {
	unsafe {
		parse_command_line();

		if is_uhyve() || is_single_kernel() {
			// We are running under uhyve or baremetal, which implies unikernel mode and no communication with "proxy".
			IS_PROXY = false;
		} else {
			// We are running side-by-side to Linux, which implies communication with "proxy".
			IS_PROXY = true;
		}
	}
}

/// CPU Frequency in MHz if given through the -freq command-line parameter, otherwise zero.
pub fn get_command_line_cpu_frequency() -> u16 {
	unsafe { COMMAND_LINE_CPU_FREQUENCY }
}

/// Whether HermitCore shall communicate with the "proxy" application over a network interface.
/// Only valid after calling init()!
pub fn is_proxy() -> bool {
	unsafe { IS_PROXY }
}