newlib nano retarget _read never called

Hi,

i'm using newlib-nano retarget. As so, I overloaded the functions _write and _read, for using printf and scanf. The printf function, as long as I use '\n', is working. But the _read function is never called and I can't figure it out why.

I'm using a cortex-m0+ (frdm-kl05z) and I'm using the following command for compiling and linking:

arm-none-eabi-gcc -x assembler-with-cpp -mthumb -mcpu=cortex-m0plus -Iinclude -c src/startup.s -o build/startup.o
arm-none-eabi-gcc -mthumb -mcpu=cortex-m0plus -g -Iinclude -std=c99 -c src/retarget.c -o build/retarget.o
arm-none-eabi-gcc -mthumb -mcpu=cortex-m0plus -g -Iinclude -std=c99 -c src/uart.c -o build/uart.o
arm-none-eabi-gcc -mthumb -mcpu=cortex-m0plus -g -Iinclude -std=c99 -c src/main.c -o build/main.o
arm-none-eabi-gcc -mthumb -mcpu=cortex-m0plus --specs=nosys.specs -T ld/arm.ld --specs=nano.specs build/startup.o build/retarget.o build/uart.o build/main.o -o frdm-kl05z

Thanks.