void klog_write(int level, const char* fmt, ...) {
if (level > klog_level) return;
char buf[LOG_BUF_MAX];
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
buf[LOG_BUF_MAX - 1] = 0;
struct iovec iov[1];
iov[0].iov_base = buf;
iov[0].iov_len = strlen(buf);
klog_writev(level, iov, 1);
}
static void init_klog_vwrite(int level, const char* fmt, va_list ap) {
static const char* tag = basename(getprogname());
// The kernel's printk buffer is only 1024 bytes.
// TODO: should we automatically break up long lines into multiple lines?
// Or we could log but with something like "..." at the end?
char buf[1024];
size_t prefix_size = snprintf(buf, sizeof(buf), "<%d>%s: ", level, tag);
size_t msg_size = vsnprintf(buf + prefix_size, sizeof(buf) - prefix_size, fmt, ap);
if (msg_size >= sizeof(buf) - prefix_size) {
msg_size = snprintf(buf + prefix_size, sizeof(buf) - prefix_size,
"(%zu-byte message too long for printk)\n", msg_size);
}
iovec iov[1];
iov[0].iov_base = buf;
iov[0].iov_len = prefix_size + msg_size;
klog_writev(level, iov, 1);
}