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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 <fcntl.h>
     18 #include <stdlib.h>
     19 #include <string.h>
     20 #if defined(__linux__)
     21 #include <sys/prctl.h>
     22 #endif
     23 #include <sys/stat.h>
     24 #include <sys/types.h>
     25 #include <unistd.h>
     26 
     27 #include <cutils/process_name.h>
     28 #if defined(__ANDROID__)
     29 #include <cutils/properties.h>
     30 #endif
     31 
     32 #define PROCESS_NAME_DEVICE "/sys/qemu_trace/process_name"
     33 
     34 static const char* process_name = "unknown";
     35 #if defined(__ANDROID__)
     36 static int running_in_emulator = -1;
     37 #endif
     38 
     39 void set_process_name(const char* new_name) {
     40 #if defined(__ANDROID__)
     41     char  propBuf[PROPERTY_VALUE_MAX];
     42 #endif
     43 
     44     if (new_name == NULL) {
     45         return;
     46     }
     47 
     48     // We never free the old name. Someone else could be using it.
     49     int len = strlen(new_name);
     50     char* copy = (char*) malloc(len + 1);
     51     strcpy(copy, new_name);
     52     process_name = (const char*) copy;
     53 
     54 #if defined(__linux__)
     55     if (len < 16) {
     56         prctl(PR_SET_NAME, (unsigned long) new_name, 0, 0, 0);
     57     } else {
     58         prctl(PR_SET_NAME, (unsigned long) new_name + len - 15, 0, 0, 0);
     59     }
     60 #endif
     61 
     62 #if defined(__ANDROID__)
     63     // If we know we are not running in the emulator, then return.
     64     if (running_in_emulator == 0) {
     65         return;
     66     }
     67 
     68     // If the "running_in_emulator" variable has not been initialized,
     69     // then do it now.
     70     if (running_in_emulator == -1) {
     71         property_get("ro.kernel.qemu", propBuf, "");
     72         if (propBuf[0] == '1') {
     73             running_in_emulator = 1;
     74         } else {
     75             running_in_emulator = 0;
     76             return;
     77         }
     78     }
     79 
     80     // If the emulator was started with the "-trace file" command line option
     81     // then we want to record the process name in the trace even if we are
     82     // not currently tracing instructions (so that we will know the process
     83     // name when we do start tracing instructions).  We do not need to execute
     84     // this code if we are just running in the emulator without the "-trace"
     85     // command line option, but we don't know that here and this function
     86     // isn't called frequently enough to bother optimizing that case.
     87     int fd = open(PROCESS_NAME_DEVICE, O_RDWR);
     88     if (fd < 0)
     89         return;
     90     write(fd, process_name, strlen(process_name) + 1);
     91     close(fd);
     92 #endif
     93 }
     94 
     95 const char* get_process_name(void) {
     96     return process_name;
     97 }
     98