ref: 2f850b4e65c8750b40a4447d11f4b0e0217997a2
dir: /sys/src/ape/lib/ap/plan9/9readn.c/
#include "sys9.h" long _READN(int f, void *av, long n) { char *a; long m, t; a = av; t = 0; while(t < n){ m = _READ(f, a+t, n-t); if(m <= 0){ if(t == 0) return m; break; } t += m; } return t; }