libasm/ft_read.s

global ft_read
extern __errno_location

ft_read:
	mov rax, 0 ; syscall read, other arguments should be good accord to calling convention
	syscall
	cmp eax, -1 ; linux syscalls errors are always in the range -4095 to -1
	jg .done
	cmp eax, -4095
	jl .done
	mov rcx, rax ; save return value of syscall
	call __errno_location WRT ..plt; put address of errno in rax
	neg rcx ; errno should be positive
	mov [rax], rcx ; set errno
	mov rax, -1 ; set return value of ft_read to -1
	ret

.done:
	ret