platform_system_core/init/log.cpp
Nick Kralevich 5db8d6aafa logging: avoid unnecessary printfs
Don't spend CPU cycles formatting a bunch of strings if we're
just going to throw them away later. Maybe make booting faster.

Change-Id: I4d8eb99fb3fa873ca91cf776933d0ad01988abf5
2016-01-16 16:20:24 -08:00

69 lines
2.1 KiB
C++

/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "log.h"
#include <stdlib.h>
#include <string.h>
#include <sys/uio.h>
#include <selinux/selinux.h>
#include <android-base/stringprintf.h>
static void init_klog_vwrite(int level, const char* fmt, va_list ap) {
static const char* tag = basename(getprogname());
if (level > klog_get_level()) return;
// 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);
}
void init_klog_write(int level, const char* fmt, ...) {
va_list ap;
va_start(ap, fmt);
init_klog_vwrite(level, fmt, ap);
va_end(ap);
}
int selinux_klog_callback(int type, const char *fmt, ...) {
int level = KLOG_ERROR_LEVEL;
if (type == SELINUX_WARNING) {
level = KLOG_WARNING_LEVEL;
} else if (type == SELINUX_INFO) {
level = KLOG_INFO_LEVEL;
}
va_list ap;
va_start(ap, fmt);
init_klog_vwrite(level, fmt, ap);
va_end(ap);
return 0;
}