; this is especially thanks to:
; http://blog.markloiseau.com/2012/05/tiny-64-bit-elf-executables/

BITS 64
	org	0x00400000	; Program load offset

; 64-bit ELF header
ehdr:
	;  1), 0 (ABI ver.)
	db 0x7F, "ELF", 2, 1, 1, 0       ; e_ident
	times 8 db 0                     ; reserved (zeroes)

	dw 2              ; e_type:	Executable file
	dw 0x3e           ; e_machine:	AMD64
	dd 1              ; e_version:	current version
	dq _start         ; e_entry:	program entry address (0x78)
	dq phdr - $$      ; e_phoff	program header offset (0x40)
	dq 0              ; e_shoff	no section headers
	dd 0              ; e_flags	no flags
	dw ehdrsize       ; e_ehsize:	ELF header size (0x40)
	dw phdrsize       ; e_phentsize:	program header size (0x38)
	dw 1              ; e_phnum:	one program header
	dw 0              ; e_shentsize
	dw 0              ; e_shnum
	dw 0              ; e_shstrndx

ehdrsize equ $ - ehdr

; 64-bit ELF program header
phdr:
	dd 1              ; p_type:	loadable segment
	dd 5              ; p_flags	read and execute
	dq 0              ; p_offset
	dq $$             ; p_vaddr:	start of the current section
	dq $$             ; p_paddr:	"		"
	dq filesize       ; p_filesz
	dq filesize       ; p_memsz
	dq 0x200000       ; p_align:	2^11=200000 = section alignment

; program header size
phdrsize equ $ - phdr

; Hello World!/your program here
_start:

	; sys_write(stdout, message, length)
	mov	rax, 1           ; sys_write
	mov	rdi, 1           ; stdout
	mov	rsi, message     ; message address
	mov	rdx, length      ; message string length
	syscall

	; sys_exit(return_code)
	mov	rax, 60          ; sys_exit
	mov	rdi, 0           ; return 0 (success)
	syscall

	message:
		db 'Hello from Docker.', 0x0A
		db 'This message shows that your installation appears to be working correctly.', 0x0A
		db 0x0A
		db 'To generate this message, Docker took the following steps:', 0x0A
		db ' 1. The Docker client contacted the Docker daemon.', 0x0A
		db ' 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.', 0x0A
		db '    (Assuming that it was not already locally available.)', 0x0A
		db ' 3. The Docker daemon created a new container from that image which runs the', 0x0A
		db '    executable that produces the output you are currently reading.', 0x0A
		db ' 4. The Docker daemon streamed that output to the Docker client, which', 0x0A
		db '    placed it in your terminal.', 0x0A
		db 0x0A
		db 'To try something more ambitious, you can run an Ubuntu container with:', 0x0A
		db ' $ docker run -it ubuntu bash', 0x0A
		db 0x0A
		db 'For more examples and ideas, visit:', 0x0A
		db ' http://docs.docker.com/userguide/', 0x0A
	length: equ	$-message            ; message length calculation

; File size calculation
filesize equ $ - $$