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      1 /* libs/cutils/cpu_info.c
      2 **
      3 ** Copyright 2007, The Android Open Source Project
      4 **
      5 ** Licensed under the Apache License, Version 2.0 (the "License");
      6 ** you may not use this file except in compliance with the License.
      7 ** You may obtain a copy of the License at
      8 **
      9 **     http://www.apache.org/licenses/LICENSE-2.0
     10 **
     11 ** Unless required by applicable law or agreed to in writing, software
     12 ** distributed under the License is distributed on an "AS IS" BASIS,
     13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14 ** See the License for the specific language governing permissions and
     15 ** limitations under the License.
     16 */
     17 
     18 #include <cutils/cpu_info.h>
     19 #include <stdlib.h>
     20 #include <stdio.h>
     21 #include <string.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         int length;
     35 
     36         // read serial number from /proc/cpuinfo
     37         file = fopen("proc/cpuinfo", "r");
     38         if (! file)
     39             return NULL;
     40 
     41         while ((chp = fgets(serial_number, sizeof(serial_number), file)) != NULL)
     42         {
     43             // look for something like "Serial          : 999206122a03591c"
     44 
     45             if (strncmp(chp, "Serial", 6) != 0)
     46                 continue;
     47 
     48             chp = strchr(chp, ':');
     49             if (!chp)
     50                 continue;
     51 
     52              // skip colon and whitespace
     53             while ( *(++chp) == ' ') {}
     54 
     55             // truncate trailing whitespace
     56             end = chp;
     57             while (*end && *end != ' ' && *end != '\t' && *end != '\n' && *end != '\r')
     58                 ++end;
     59             *end = 0;
     60 
     61             whitespace = strchr(chp, ' ');
     62             if (whitespace)
     63                 *whitespace = 0;
     64             whitespace = strchr(chp, '\t');
     65             if (whitespace)
     66                 *whitespace = 0;
     67             whitespace = strchr(chp, '\r');
     68             if (whitespace)
     69                 *whitespace = 0;
     70             whitespace = strchr(chp, '\n');
     71             if (whitespace)
     72                 *whitespace = 0;
     73 
     74             // shift serial number to beginning of the buffer
     75             memmove(serial_number, chp, strlen(chp) + 1);
     76             break;
     77         }
     78 
     79         fclose(file);
     80     }
     81 
     82     return (serial_number[0] ? serial_number : NULL);
     83 }
     84