/*
 Derived from source code of TrueCrypt 7.1a, which is
 Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
 by the TrueCrypt License 3.0.

 Modifications and additions to the original source code (contained in this file)
 and all other portions of this file are Copyright (c) 2013-2017 IDRIX
 and are governed by the Apache License 2.0 the full text of which is
 contained in the file License.txt included in VeraCrypt binary and source
 code distribution packages.
*/

#ifndef TC_HEADER_Platform_Time
#define TC_HEADER_Platform_Time

#include "PlatformBase.h"

namespace VeraCrypt
{
	class Time
	{
	public:
		Time () { }
		virtual ~Time () { }

		static uint64 GetCurrent (); // Returns time in hundreds of nanoseconds since 1601/01/01

	private:
		Time (const Time &);
		Time &operator= (const Time &);
	};
}

#endif // TC_HEADER_Platform_Time

;
; Derived from source code of TrueCrypt 7.1a, which is
; Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
; by the TrueCrypt License 3.0.
;
; Modifications and additions to the original source code (contained in this file)
; and all other portions of this file are Copyright (c) 2013-2017 IDRIX
; and are governed by the Apache License 2.0 the full text of which is
; contained in the file License.txt included in VeraCrypt binary and source
; code distribution packages.
;

.MODEL tiny
.386
_TEXT SEGMENT USE16

INCLUDE BootDefs.i

ORG 7C00h	; Standard boot sector offset

start:
	; BIOS executes boot sector from 0:7C00 or 7C0:0000 (default CD boot loader address).
	; Far jump to the next instruction sets IP to the standard offset 7C00.
	db 0EAh				; jmp 0:main
	dw main, 0

loader_name_msg:
	db ' VeraCrypt Boot Loader', 13, 10, 0

main:
	cli
	xor ax, ax
	mov ds, ax
	mov ss, ax
	mov sp, 7C00h
	sti

	; Display boot loader name
	test byte ptr [start + TC_BOOT_SECTOR_USER_CONFIG_OFFSET], TC_BOOT_USER_CFG_FLAG_SILENT_MODE
	jnz skip_loader_name_msg

	lea si, loader_name_msg
	call print
skip_loader_name_msg:

    ; Determine boot loader segment
    mov ax, word ptr [ds:413h]      ;available kB from BIOS
    sub ax, TC_BOOT_MEMORY_REQUIRED ;minus TC_BOOT_MEMORY_REQUIRED
    jc mem_toolow
    and ax, 0FFE0h                  ;32K align
    shl ax, 6                       ;convert kB to segment addr (*1024/16)
    cmp ax, 8000h
    jb mem_toolow                   ;we can't load below 8000h
    cmp ax, TC_BOOT_LOADER_SEGMENT
    jbe memory_ok                   ;don't load above TC_BOOT_LOADER_SEGMENT (9000h)
    mov ax, TC_BOOT_LOADER_SEGMENT
    jmp memory_ok

mem_toolow:
    mov ax, TC_BOOT_LOADER_LOWMEM_SEGMENT

memory_ok:
    mov es, ax

	; Clear BSS section
	xor al, al
	mov di, TC_COM_EXECUTABLE_OFFSET
	mov cx, TC_BOOT_MEMORY_REQUIRED * 1024 - TC_COM_EXECUTABLE_OFFSET - 1
	cld
	rep stosb

	mov ax, es
	sub ax, TC_BOOT_LOADER_DECOMPRESSOR_MEMORY_SIZE / 16	; Decompressor segment
	mov es, ax

	; Load decompressor
	mov cl, TC_BOOT_LOADER_DECOMPRESSOR_START_SECTOR
retry_backup:
	mov al, TC_BOOT_LOADER_DECOMPRESSOR_SECTOR_COUNT
	mov bx, TC_COM_EXECUTABLE_OFFSET
	call read_sectors

	; Decompressor checksum
	xor ebx, ebx
	mov si, TC_COM_EXECUTABLE_OFFSET
	mov cx, TC_BOOT_LOADER_DECOMPRESSOR_SECTOR_COUNT * TC_LB_SIZE
	call checksum
	push ebx

	; Load compressed boot loader
	mov bx, TC_BOOT_LOADER_COMPRESSED_BUFFER_OFFSET
	mov cl, TC_BOOT_LOADER_START_SECTOR
	mov al, TC_MAX_BOOT_LOADER_SECTOR_COUNT

	test backup_loader_used, 1
	jz non_backup
	mov al, TC_BOOT_LOADER_BACKUP_SECTOR_COUNT - TC_BOOT_LOADER_DECOMPRESSOR_SECTOR_COUNT
	mov cl, TC_BOOT_LOADER_START_SECTOR + TC_BOOT_LOADER_BACKUP_SECTOR_COUNT

non_backup:
	call read_sectors

	; Boot loader checksum
	pop ebx
	mov si, TC_BOOT_LOADER_COMPRESSED_BUFFER_OFFSET
	mov cx, word ptr [start + TC_BOOT_SECTOR_LOADER_LENGTH_OFFSET]
	call checksum

	; Verify checksum
	cmp ebx, dword ptr [start + TC_BOOT_SECTOR_LOADER_CHECKSUM_OFFSET]
	je checksum_ok

	; Checksum incorrect - try using backup if available
	test backup_loader_used, 1
	jnz loader_damaged

	mov backup_loader_used, 1
	mov cl, TC_BOOT_LOADER_DECOMPRESSOR_START_SECTOR + TC_BOOT_LOADER_BACKUP_SECTOR_COUNT

	test TC_BOOT_CFG_FLAG_BACKUP_LOADER_AVAILABLE, byte ptr [start + TC_BOOT_SECTOR_CONFIG_OFFSET]
	jnz retry_backup

loader_damaged:
	lea si, loader_damaged_msg
	call print
	lea si, loader_name_msg
	call print
	jmp $
checksum_ok:

	; Set up decompressor segment
	mov ax, es
	mov ds, ax
	cli
	mov ss, ax
	mov sp, TC_BOOT_LOADER_DECOMPRESSOR_MEMORY_SIZE
	sti

	push dx

	; Decompress boot loader
	mov cx, word ptr cs:[start + TC_BOOT_SECTOR_LOADER_LENGTH_OFFSET]
	sub cx, TC_GZIP_HEADER_SIZE
	push cx																		; Compressed data size
	push TC_BOOT_LOADER_COMPRESSED_BUFFER_OFFSET + TC_GZIP_HEADER_SIZE			; Compressed data
	push TC_MAX_BOOT_LOADER_DECOMPRESSED_SIZE									; Output buffer size
	push TC_BOOT_LOADER_DECOMPRESSOR_MEMORY_SIZE + TC_COM_EXECUTABLE_OFFSET		; Output buffer

	push cs
	push decompressor_ret
	push es
	push TC_COM_EXECUTABLE_OFFSET
	retf
decompressor_ret:

	add sp, 8
	pop dx

	; Restore boot sector segment
	push cs
	pop ds

	; Check decompression result
	test ax, ax
	jz decompression_ok

	lea si, loader_damaged_msg
	call print
	jmp $
decompression_ok:

	; DH = boot sector flags
	mov dh, byte ptr [start + TC_BOOT_SECTOR_CONFIG_OFFSET]

	; Set up boot loader segment
	mov ax, es
	add ax, TC_BOOT_LOADER_DECOMPRESSOR_MEMORY_SIZE / 16
	mov es, ax
	mov ds, ax
	cli
	mov ss, ax
	mov sp, TC_BOOT_LOADER_STACK_TOP
	sti

	; Execute boot loader
	push es
	push TC_COM_EXECUTABLE_OFFSET
	retf

	; Print string
print:
	xor bx, bx
	mov ah, 0eh
	cld

@@:	lodsb
	test al, al
	jz print_end

	int 10h
	jmp @B

print_end:
	ret

	; Read sectors of the first cylinder
read_sectors:
	mov ch, 0           ; Cylinder
	mov dh, 0           ; Head
						; DL = drive number passed from BIOS
	mov ah, 2
	int 13h
	jnc read_ok

	lea si, disk_error_msg
	call print
read_ok:
	ret

	; Calculate checksum
checksum:
	push ds
	push es
	pop ds
	xor eax, eax
	cld

@@:	lodsb
	add ebx, eax
	rol ebx, 1
	loop @B

	pop ds
	ret

backup_loader_used		db 0

disk_error_msg			db 'Disk error', 13, 10, 7, 0
loader_damaged_msg		db 7, 'Loader damaged! Repair with Rescue Disk', 0

ORG 7C00h + 510
	dw 0AA55h			; Boot sector signature

_TEXT ENDS
END start