Reading Emojis through a pipe in C

I have a pipe with an endless amount of strings being written to it. These strings are a mix of ASCII and Emojis. The problem I am having is I am reading them like this

char msg[100];int length = read(fd,&msg,99);msg[length] =0;

But sometimes the emoji I'm guessing is multibyte and it is getting cut in half and then when I print to the screen I get the diamond question mark unknown UTF-8 symbol.

If anyone knows how to prevent this please fill me in; I've been searching for a while now.