Mips Assembly. Connect, read, and write - sockets

Question

My objective is to open a socket, connect to that socket on a port, and then whenever that socket sends data to me, I want to write it to stdout.
My code works fine, but for some reason the string that is writing doesn't null terminate? I'm not so sure what the issue is and I have yet to find anything online about it.
#socket(2,1,0)
li $t7, -6
nor $t7, $t7, $zero
addi $a0, $t7, -3
addi $a1, $t7, -3
slti $a2, $zero, -1
li $v0, 4183
syscall 0x40404
sw $v0, -4($sp)
#connect(3, &addr, 16)
lw $a0, -4($sp)
li $t7, -3
nor $t7, $t7, $zero
sw $t7,-32($sp)
lui $t6,0x7a69
ori $t6,$t6,0x7a69
sw $t6, -28($sp)
lui $t5, 0x7F00
ori $t5, $t5, 0x1
sw $t5, -26($sp)
addiu $a1, $sp, -30
li $t4, -17
nor $a2, $t4, $zero
li $v0, 4170
syscall 0x40404
#read(3, addr, 50)
nex:
lw $a0, -4($sp)
addiu $a1, $sp,-64
li $a2, 50
addi $a2, $a2, -1
li $v0, 4003
syscall 0x40404
beqz $a3, next
move $a2,$v0
negu $a2,$v0
next:
blez $a2,nextt
#write(1, addr, 50)
li $a0, 1
li $v0, 4004
syscall 0x40404
j nex
nextt:
Here is the strace of me writing a\n to the socket, and it writing a\n\0\0\0\0\0\0\0\0 to stdout.
socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 3
connect(3, {sa_family=AF_INET, sin_port=htons(31337), sin_addr=inet_addr("127.0.0.1")}, 16) = 0
read(3, "a\n", 49) = 2
write(1, "a\n\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 49a
zi3▒ݤ) = 49
As you can see, it prints out some weird characters at the end. Thanks for any help!

Answer 1

Notice in your strace output that your read syscall returns a value of 2 [in $v0].
Also notice that your write syscall has a length much greater than 2.
After your read syscall you have:
move $a2,$v0 # this reg has 2
negu $a2,$v0 # BUG: this changes it to -2 (0xFFFFFFFE)
The length for the write was interpreted as an unsigned number [and a very large one]
Change this to just [i.e. remove the negu]:
move $a2,$v0