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      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 <sys/stat.h>
     18 #include <sys/types.h>
     19 #include <fcntl.h>
     20 #include <stdarg.h>
     21 #include <stdio.h>
     22 #include <stdlib.h>
     23 #include <string.h>
     24 #include <unistd.h>
     25 
     26 #include <cutils/klog.h>
     27 
     28 static int klog_fd = -1;
     29 static int klog_level = KLOG_DEFAULT_LEVEL;
     30 
     31 void klog_set_level(int level) {
     32     klog_level = level;
     33 }
     34 
     35 void klog_init(void)
     36 {
     37     static const char *name = "/dev/__kmsg__";
     38 
     39     if (klog_fd >= 0) return; /* Already initialized */
     40 
     41     if (mknod(name, S_IFCHR | 0600, (1 << 8) | 11) == 0) {
     42         klog_fd = open(name, O_WRONLY);
     43         if (klog_fd < 0)
     44                 return;
     45         fcntl(klog_fd, F_SETFD, FD_CLOEXEC);
     46         unlink(name);
     47     }
     48 }
     49 
     50 #define LOG_BUF_MAX 512
     51 
     52 void klog_write(int level, const char *fmt, ...)
     53 {
     54     char buf[LOG_BUF_MAX];
     55     va_list ap;
     56 
     57     if (level > klog_level) return;
     58     if (klog_fd < 0) klog_init();
     59     if (klog_fd < 0) return;
     60 
     61     va_start(ap, fmt);
     62     vsnprintf(buf, LOG_BUF_MAX, fmt, ap);
     63     buf[LOG_BUF_MAX - 1] = 0;
     64     va_end(ap);
     65     write(klog_fd, buf, strlen(buf));
     66 }
     67