Correct User Input - x86 Linux Assembly - linux

Question

So I am working on an x86 Assembly program for Linux using NASM. This program basically asks the user for their name and their favorite color. After doing this and storing the two strings in variables declared in the .bss section, the program prints "No way name of user, favorite color is my favorite color, too!
The problem I am having is that there are enormous spaces in the output because I do not know how long the string was that the user entered, only the length that I declared the buffer to be.
section .data
greet: db 'Hello!', 0Ah, 'What is your name?', 0Ah ;simple greeting
greetL: equ $-greet ;greet length
colorQ: db 'What is your favorite color?' ;color question
colorL: equ $-colorQ ;colorQ length
suprise1: db 'No way '
suprise1L equ $-suprise1
suprise3: db ' is my favorite color, too!', 0Ah
section .bss
name: resb 20 ;user's name
color: resb 15 ;user's color
section .text
global _start
_start:
greeting:
mov eax, 4
mov ebx, 1
mov ecx, greet
mov edx, greetL
int 80 ;print greet
getname:
mov eax, 3
mov ebx, 0
mov ecx, name
mov edx, 20
int 80 ;get name
askcolor:
;asks the user's favorite color using colorQ
getcolor:
mov eax, 3
mov ebx, 0
mov ecx, name
mov edx, 20
int 80
thesuprise:
mov eax, 4
mov ebx, 1
mov ecx, suprise1
mov edx, suprise1L
int 80
mov eax, 4
mov ebx, 1
mov ecx, name
mov edx, 20
int 80
;write the color
;write the "suprise" 3
mov eax, 1
mov ebx, 0
int 80
The code for what I am doing is above. Does anyone have a good method for finding the length of the entered string, or of taking in a character at a time to find out the length of the string?
Thank you in advance.

Answer 1

After int80 in getname returns, EAX will contain the number of bytes actually read, or a negative error indication.
You should
check for error return
store the return value, as it gives you the length of input
Equivalent code in C:
char name[20];
int rc;
rc = syscall(SYS_read, 0, name, 20-1); // leave space for terminating NUL
if (rc < 0) {
// handle error
} else {
name[rc] = '\0'; // NUL terminate the string
}