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      1 /*
      2  * Copyright (C) 2007-2016 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 /*
     18  * Some OS specific dribs and drabs (locking etc).
     19  */
     20 
     21 #if !defined(_WIN32)
     22 #include <pthread.h>
     23 #endif
     24 
     25 #include <private/android_filesystem_config.h>
     26 
     27 #include "logger.h"
     28 
     29 LIBLOG_HIDDEN uid_t __android_log_uid()
     30 {
     31 #if defined(_WIN32)
     32     return AID_SYSTEM;
     33 #else
     34     static uid_t last_uid = AID_ROOT; /* logd *always* starts up as AID_ROOT */
     35 
     36     if (last_uid == AID_ROOT) { /* have we called to get the UID yet? */
     37         last_uid = getuid();
     38     }
     39     return last_uid;
     40 #endif
     41 }
     42 
     43 LIBLOG_HIDDEN pid_t __android_log_pid()
     44 {
     45     static pid_t last_pid = (pid_t) -1;
     46 
     47     if (last_pid == (pid_t) -1) {
     48         last_pid = getpid();
     49     }
     50     return last_pid;
     51 }
     52 
     53 #if !defined(_WIN32)
     54 static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER;
     55 #endif
     56 
     57 LIBLOG_HIDDEN void __android_log_lock()
     58 {
     59 #if !defined(_WIN32)
     60     /*
     61      * If we trigger a signal handler in the middle of locked activity and the
     62      * signal handler logs a message, we could get into a deadlock state.
     63      */
     64     pthread_mutex_lock(&log_init_lock);
     65 #endif
     66 }
     67 
     68 LIBLOG_HIDDEN int __android_log_trylock()
     69 {
     70 #if !defined(_WIN32)
     71     return pthread_mutex_trylock(&log_init_lock);
     72 #else
     73     return 0;
     74 #endif
     75 }
     76 
     77 LIBLOG_HIDDEN void __android_log_unlock()
     78 {
     79 #if !defined(_WIN32)
     80     pthread_mutex_unlock(&log_init_lock);
     81 #endif
     82 }
     83