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      1 /*
      2 ** Copyright 2007, 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 <stdio.h>
     18 #include <stdlib.h>
     19 #include <string.h>
     20 
     21 #include <cutils/cpu_info.h>
     22 
     23 // we cache the serial number here.
     24 // this is also used as a fgets() line buffer when we are reading /proc/cpuinfo
     25 static char serial_number[100] = { 0 };
     26 
     27 extern const char* get_cpu_serial_number(void)
     28 {
     29     if (serial_number[0] == 0)
     30     {
     31         FILE* file;
     32         char* chp, *end;
     33         char* whitespace;
     34 
     35         // read serial number from /proc/cpuinfo
     36         file = fopen("proc/cpuinfo", "r");
     37         if (! file)
     38             return NULL;
     39 
     40         while ((chp = fgets(serial_number, sizeof(serial_number), file)) != NULL)
     41         {
     42             // look for something like "Serial          : 999206122a03591c"
     43 
     44             if (strncmp(chp, "Serial", 6) != 0)
     45                 continue;
     46 
     47             chp = strchr(chp, ':');
     48             if (!chp)
     49                 continue;
     50 
     51              // skip colon and whitespace
     52             while ( *(++chp) == ' ') {}
     53 
     54             // truncate trailing whitespace
     55             end = chp;
     56             while (*end && *end != ' ' && *end != '\t' && *end != '\n' && *end != '\r')
     57                 ++end;
     58             *end = 0;
     59 
     60             whitespace = strchr(chp, ' ');
     61             if (whitespace)
     62                 *whitespace = 0;
     63             whitespace = strchr(chp, '\t');
     64             if (whitespace)
     65                 *whitespace = 0;
     66             whitespace = strchr(chp, '\r');
     67             if (whitespace)
     68                 *whitespace = 0;
     69             whitespace = strchr(chp, '\n');
     70             if (whitespace)
     71                 *whitespace = 0;
     72 
     73             // shift serial number to beginning of the buffer
     74             memmove(serial_number, chp, strlen(chp) + 1);
     75             break;
     76         }
     77 
     78         fclose(file);
     79     }
     80 
     81     return (serial_number[0] ? serial_number : NULL);
     82 }
     83