1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <errno.h>
18#include <fcntl.h>
19#include <stdarg.h>
20#include <stdio.h>
21#include <stdlib.h>
22#include <string.h>
23#include <sys/stat.h>
24#include <sys/types.h>
25#include <unistd.h>
26
27#include <cutils/klog.h>
28
29static int klog_fd = -1;
30static int klog_level = KLOG_DEFAULT_LEVEL;
31
32int klog_get_level(void) {
33    return klog_level;
34}
35
36void klog_set_level(int level) {
37    klog_level = level;
38}
39
40void klog_init(void) {
41    if (klog_fd >= 0) return; /* Already initialized */
42
43    klog_fd = open("/dev/kmsg", O_WRONLY | O_CLOEXEC);
44    if (klog_fd >= 0) {
45        return;
46    }
47
48    static const char* name = "/dev/__kmsg__";
49    if (mknod(name, S_IFCHR | 0600, (1 << 8) | 11) == 0) {
50        klog_fd = open(name, O_WRONLY | O_CLOEXEC);
51        unlink(name);
52    }
53}
54
55#define LOG_BUF_MAX 512
56
57void klog_writev(int level, const struct iovec* iov, int iov_count) {
58    if (level > klog_level) return;
59    if (klog_fd < 0) klog_init();
60    if (klog_fd < 0) return;
61    TEMP_FAILURE_RETRY(writev(klog_fd, iov, iov_count));
62}
63
64void klog_write(int level, const char* fmt, ...) {
65    if (level > klog_level) return;
66    char buf[LOG_BUF_MAX];
67    va_list ap;
68    va_start(ap, fmt);
69    vsnprintf(buf, sizeof(buf), fmt, ap);
70    va_end(ap);
71
72    buf[LOG_BUF_MAX - 1] = 0;
73
74    struct iovec iov[1];
75    iov[0].iov_base = buf;
76    iov[0].iov_len = strlen(buf);
77    klog_writev(level, iov, 1);
78}
79