ref: b99f42232b1640f6c0fe17becba28e62e2c932ce
dir: /sys/src/cmd/unix/drawterm/libc/utfecpy.c/
#include <u.h>
#include <libc.h>
char*
utfecpy(char *to, char *e, char *from)
{
char *end;
if(to >= e)
return to;
end = memccpy(to, from, '\0', e - to);
if(end == nil){
end = e-1;
while(end>to && (*--end&0xC0)==0x80)
;
*end = '\0';
}else{
end--;
}
return end;
}