day5 compilation error

[zengxinhui]

Got this error in archlinux:

gcc -Wall -Wno-format -Wno-unused -std=gnu99 -static -m32 -I ../libc/include -ffunction-sections -nostdlib -nostdinc -fno-builtin -ffreestanding -fno-pie -c ../libc/stdio/stdio.c -o ../libc/stdio/stdio.bin
ld -m elf_i386 --oformat binary -o kernel.sys -T kernel.ld bootpack.bin io.bin pm.bin hankaku.bin ../libc/stdio/stdio.bin
ld: ../libc/stdio/stdio.bin: in function `sprintf':
stdio.c:(.text.sprintf+0x48): undefined reference to `__stack_chk_fail'

Temp workaround is to modify Makefile by adding "-fno-stack-protector" to CFLAGS:
CFLAGS += -ffunction-sections -nostdlib -nostdinc -fno-builtin -ffreestanding -fno-stack-protector

[ghosind]

Hello, thank you for your issue about this problem.

I've added a stack protector placeholder function, and this issue should be fixed. The -fno-stack-protector option is also a choice to fix it.