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