x64-httpd/client.s

; Returns:
; rax - 0
; Errors (in rax):
; rax - 0 - EOF
; rax - -1024 - line too long
; rax - other negative - from read(2)
; Arguments:
; rdi - fd
; rsi - address of client within clients array
; rdx - pollfds index
; Variables:
; rbx - pollfds index
; r12 - client buffer
; r13 - start of line scanning
; r14 - client buffer end
client__pollin:
    push rbx
    push r12
    push r13
    push r14

    mov rbx, rdx
    mov r12, rsi
    add r12, OFFSET_CLIENT_BUFFER
    mov r13, 0
    mov r13b, [rsi + OFFSET_CLIENT_BUFFER_LEN]
    add r13, r12
    mov r14, r12
    add r14, 255

    mov rax, SYS_READ
    mov rsi, r13
    mov rdx, 255
    sub dl, [rsi + OFFSET_CLIENT_BUFFER_LEN]
    syscall

    cmp rax, 0
    jle client__pollin__return  ; TODO verify this shit

    ; buffer_len += read(2) length
    add [r12 - OFFSET_CLIENT_BUFFER + OFFSET_CLIENT_BUFFER_LEN], al

    mov rdi, r13
    mov rsi, rax
    call scanline

    cmp rax, 0
    je client__pollin__no_line

    mov rax, 1
    mov word [pollfds + rbx * pollfd_size + 4], POLLOUT

client__pollin__return:
    pop r14
    pop r13
    pop r12
    pop rbx
    ret

client__pollin__no_line:
    mov r10, r13
    add r10, rax
    cmp r10, r14
    jge client__pollin__line_too_long
    mov rax, 1
    jmp client__pollin__return

client__pollin__line_too_long:
    mov rax, -1024
    jmp client__pollin__return


; Errors:
; rax - negative or zero - from write(2)
; Arguments:
; rdi - fd
; rsi - address of client within clients array
; rdx - pollfds index
; Variables:
; rbp - fd
; rbx - pollfds index
; r12 - address of client within clients array
; r13 - line start
; r14 - line end
; r15 - client buffer end
; r11 - client buffer, length of last incomplete line
client__pollout:
    push rbp
    push rbx
    push r12
    push r13
    push r14
    push r15

    mov rbp, rdi
    mov rbx, rdx
    mov r12, rsi
    mov r13, rsi
    add r13, OFFSET_CLIENT_BUFFER
    mov r15, r13
    add r15, 255

    mov rdi, rbp
    mov rsi, r12
    call client__pollout__before_fresh_lines

    cmp rax, 0
    jle client__pollout__return

client__pollout__scan:
    mov rdi, r13
    mov rsi, 0
    mov sil, [r12 + OFFSET_CLIENT_BUFFER_LEN]
    call scanline

    cmp rax, 0
    jle client__pollout__set_pollin  ; no lines left

    sub [r12 + OFFSET_CLIENT_BUFFER_LEN], al

    ; line_end = line_start + line_len
    mov r14, r13
    add r14, rax

    mov rdi, rbp
    mov rsi, r12
    mov rdx, r13
    mov rcx, r14
    sub rcx, r13
    call client__pollout__line

    mov r13, r14

    cmp rax, 0
    jle client__pollout__shunt
    jmp client__pollout__scan

client__pollout__set_pollin:
    mov word [pollfds + rbx * pollfd_size + 4], POLLIN
    mov rax, 1

client__pollout__shunt:
    mov r10, 0
    mov r11, 0
    mov r11b, [r12 + OFFSET_CLIENT_BUFFER_LEN]
    add r11, r12
    add r11, OFFSET_CLIENT_BUFFER
    sub r11, r13

client__pollout__shunt__loop:
    cmp r10, r11
    jge client__pollout__shunt__finished
    mov r8b, [r10 + r13]
    mov [r10], r8b
    add r10, 1
    jmp client__pollout__shunt__loop

client__pollout__shunt__finished:
    mov r10, r13
    sub r10, r12
    sub r10, OFFSET_CLIENT_BUFFER

client__pollout__return:
    pop r15
    pop r14
    pop r13
    pop r12
    pop rbx
    pop rbp
    ret

; Errors:
; rax - -1024 - some scratch buffer bytes remain, stop write(2)ing
; rax - other negative or zero - from write(2)
; Arguments:
; rdi - fd
; rsi - address of client within clients array
client__pollout__before_fresh_lines:
    mov rdx, 0
    mov dl, [rsi + OFFSET_CLIENT_SCRATCH_LEN]

    cmp rdx, 0
    jle client__pollout__before_fresh_lines__return__succ

    mov rax, SYS_WRITE
    push rdx
    add rsi, OFFSET_CLIENT_SCRATCH
    push rsi
    syscall

    pop rsi
    pop rdx

    cmp rax, 0
    jle return

    sub [rsi - OFFSET_CLIENT_SCRATCH + OFFSET_CLIENT_SCRATCH_LEN], al

    mov r10, rsi
    mov r11, rsi
    add r11, rdx
    sub r11, rax

client__pollout__before_fresh_lines__shunt:
    cmp r10, r11
    jge client__pollout__before_fresh_lines__return
    mov r8b, [r10 + rax]
    mov [r10], r8b
    add r10, 1
    jmp client__pollout__before_fresh_lines__shunt

client__pollout__before_fresh_lines__return:
    cmp rax, rdx
    jl client__pollout__before_fresh_lines__return__fail

client__pollout__before_fresh_lines__return__succ:
    mov rax, 1
    ret

client__pollout__before_fresh_lines__return__fail:
    mov rax, -1024
    ret

; Errors:
; rax - negative or zero - from write(2)
; Arguments:
; rdi - fd
; rsi - address of client within clients array
; rdx - line start
; rcx - line length
; Variables:
; rsi - client scratch
; r10 - line write(2) end
; r9 - line end
; Assumptions:
; scratch is empty, bc it was emptied by client__pollout__before_fresh_lines
; we must deal with the whole line we are given
client__pollout__line:
    ; TODO we've got a line
    ; - try writing it
    ; - if socket is fucked: return
    ; - if ok: cool
    ; - if couldn't do the whole thing: you have scratch available, if it's needed for the protocol

    push rdx
    push rcx

    mov rax, SYS_WRITE
    mov rsi, rdx
    mov rdx, rcx
    syscall

    pop rcx
    pop rdx

    ; TODO continue here also not sure calling fn is correct yet
    ; check that changes to server.s haven't fucked anything up

    ; error from write(2)
    cmp rax, 0
    jl client__pollout__line__error

    cmp rax, rcx
    jl client__pollout__line__incomplete

    mov rax, 1
    ret

client__pollout__line__error:
    mov r10, 0
    jmp client__pollout__line__write_scratch

client__pollout__line__incomplete:
    mov r10, rax

client__pollout__line__write_scratch:
    add rsi, OFFSET_CLIENT_SCRATCH
    add r10, rdx
    mov r11, 0
    mov r9, rcx
    add r9, rdx

client__pollout__line__write_scratch__loop:
    cmp r10, r9
    jge return
    mov r8b, [r10 + r11]
    mov [rsi + r11], r8b
    add r11, 1
    jmp client__pollout__line__write_scratch__loop


; Arguments:
; rdi - fd
client__shutdown_close:
    mov rax, SYS_SHUTDOWN
    push rdi
    mov rsi, SHUT_RDWR
    syscall

    mov rax, SYS_CLOSE
    pop rdi
    syscall

    ret