[fread]
fp: posix/stdio/rw/fread
include: stdio.h
prep: unsigned char buf[1024]; ssize_t r; FILE *fp = fopen("/dev/zero", "r");
call: r = fread(buf, 1, 1024, fp);
success_cond: r == 1024 && ferror(fp) == 0
failure_cond: r == 0 && ferror(fp) != 0
errno_on_fail: EIO