AndroidQ(10.0) 内核版本增加linux编译用户信息

版本对比

O 版本设置界面中内核信息

Q 版本设置界面中内核信息

解决办法

frameworks\base\packages\SettingsLib\src\com\android\settingslib\DeviceInfoUtils.java

@@ -88,11 +88,15 @@ public class DeviceInfoUtils {
             return context.getString(R.string.status_unavailable);
         }
 
+        String user = android.os.SystemProperties.get("ro.build.user", "");
+        String host = android.os.SystemProperties.get("ro.build.host", "");
+
         // Example output:
         // 4.9.29-g958411d
         // #1 Wed Jun 7 00:06:03 CST 2017
         return new StringBuilder().append(uname.release)
                 .append("\n")
+                .append(user + "@" + host)
                 .append(m.group(1))
                 .append(" ")
                 .append(m.group(2)).toString();

补充知识

内核版本信息对应 /proc/version 文件内容

可以通过adb shell， cat /proc/version 进行查看，我们在系统设置中看到的信息是经过裁剪后的，完整的如下

10.0 对应内核信息
cat /proc/version
Linux version 4.9.190 (nobody@android-build) (Android (5484270 based on r353983c) clang version 9.0.3 (https://android.googlesource.com/toolchain/clang 745b335211bb9eadfa6aa6301f84715cee4b37c5) (https://android.googlesource.com/toolchain/llvm 60cf23e54e46c807513f7a36d0a7b777920b5881) (based on LLVM 9.0.3svn)) #3 SMP PREEMPT Fri Jul 10 17:13:42 CST 2020

8.0 对应内核信息
cat /proc/version
Linux version 3.18.79 (ntu@ubuntu) (gcc version 6.3.1 20170109 (Linaro GCC 6.3-2017.02) ) #1 SMP PREEMPT Sun Jun 28 10:45:30 CST 2020

可以看到10.0 中不包含linux编译用户名信息，我们来跟踪下源码

Setting 中对应内核信息 Preference 获取值的地方

vendor\mediatek\proprietary\packages\apps\MtkSettings\src\com\android\settings\deviceinfo\firmwareversion\KernelVersionPreferenceController.java

import com.android.settingslib.DeviceInfoUtils;

public class KernelVersionPreferenceController extends BasePreferenceController {

    public KernelVersionPreferenceController(Context context, String preferenceKey) {
        super(context, preferenceKey);
    }

    @Override
    public int getAvailabilityStatus() {
        return AVAILABLE;
    }

    @Override
    public CharSequence getSummary() {
        return DeviceInfoUtils.getFormattedKernelVersion(mContext);
    }
}

通过 DeviceInfoUtils.getFormattedKernelVersion(mContext) 获取文本

10.0 对应 DeviceInfoUtils

frameworks\base\packages\SettingsLib\src\com\android\settingslib\DeviceInfoUtils.java

    public static String getFormattedKernelVersion(Context context) {
            return formatKernelVersion(context, Os.uname());
    }

    @VisibleForTesting
    static String formatKernelVersion(Context context, StructUtsname uname) {
        if (uname == null) {
            return context.getString(R.string.status_unavailable);
        }
        // Example:
        // 4.9.29-g958411d
        // #1 SMP PREEMPT Wed Jun 7 00:06:03 CST 2017
        final String VERSION_REGEX =
                "(#\\d+) " +              /* group 1: "#1" */
                "(?:.*?)?" +              /* ignore: optional SMP, PREEMPT, and any CONFIG_FLAGS */
                "((Sun|Mon|Tue|Wed|Thu|Fri|Sat).+)"; /* group 2: "Thu Jun 28 11:02:39 PDT 2012" */
        Matcher m = Pattern.compile(VERSION_REGEX).matcher(uname.version);
        if (!m.matches()) {
            Log.e(TAG, "Regex did not match on uname version " + uname.version);
            return context.getString(R.string.status_unavailable);
        }

        String user = android.os.SystemProperties.get("ro.build.user", "");
        String host = android.os.SystemProperties.get("ro.build.host", "");

        // Example output:
        // 4.9.29-g958411d
        // #1 Wed Jun 7 00:06:03 CST 2017
        return new StringBuilder().append(uname.release)
                .append("\n")
                .append(user + "@" + host)
                .append(m.group(1))
                .append(" ")
                .append(m.group(2)).toString();
    }

8.0 对应 DeviceInfoUtils

frameworks\base\packages\SettingsLib\src\com\android\settingslib\DeviceInfoUtils.java

private static final String FILENAME_PROC_VERSION = "/proc/version";

 public static String getFormattedKernelVersion() {
        try {
            return formatKernelVersion(readLine(FILENAME_PROC_VERSION));
        } catch (IOException e) {
            Log.e(TAG, "IO Exception when getting kernel version for Device Info screen",
                    e);

            return "Unavailable";
        }
    }

    public static String formatKernelVersion(String rawKernelVersion) {
        // Example (see tests for more):
        // Linux version 4.9.29-g958411d (android-build@xyz) (Android clang version 3.8.256229 \
        //       (based on LLVM 3.8.256229)) #1 SMP PREEMPT Wed Jun 7 00:06:03 CST 2017
        // Linux version 4.9.29-geb63318482a7 (android-build@xyz) (gcc version 4.9.x 20150123 \
        //       (prerelease) (GCC) ) #1 SMP PREEMPT Thu Jun 1 03:41:57 UTC 2017
        final String PROC_VERSION_REGEX =
                "Linux version (\\S+) " + /* group 1: "3.0.31-g6fb96c9" */
                "\\((\\S+?)\\) " +        /* group 2: "([email protected]) " */
                "\\((.+?)\\) " +          /* group 3:  kernel toolchain version information */
                "(#\\d+) " +              /* group 4: "#1" */
                "(?:.*?)?" +              /* ignore: optional SMP, PREEMPT, and any CONFIG_FLAGS */
                "((Sun|Mon|Tue|Wed|Thu|Fri|Sat).+)"; /* group 5: "Thu Jun 28 11:02:39 PDT 2012" */

        Matcher m = Pattern.compile(PROC_VERSION_REGEX).matcher(rawKernelVersion);
        if (!m.matches()) {
            Log.e(TAG, "Regex did not match on /proc/version: " + rawKernelVersion);
            return "Unavailable";
        } else if (m.groupCount() < 4) {
            Log.e(TAG, "Regex match on /proc/version only returned " + m.groupCount()
                    + " groups");
            return "Unavailable";
        }
        return m.group(1) + " ("+ m.group(3) + ")\n" +   // 3.0.31-g6fb96c9 (toolchain version)
                m.group(2) + " " + m.group(4) + "\n" +   // [email protected] #1
                m.group(5);                              // Thu Jun 28 11:02:39 PDT 2012
    }

那么我们只需要在 formatKernelVersion() 中返回值做点手脚即可，增加编译用户信息，那么问题来了，如何知道是谁编译的系统呢？

答案就在 buil.prop 中，此文件包含了系统全面信息，从cpu 架构到版本号各种信息，当然里面也有我们需要的编译用户姓名。

out\target\product\k62v1_64_bsp\system\build.prop

ro.build.version.release=10
ro.build.version.security_patch=2020-02-05
ro.build.version.base_os=
ro.build.version.min_supported_target_sdk=23
ro.build.date=Sat Jul 11 09:13:46 CST 2020
ro.build.date.utc=1594430026
ro.build.type=user
ro.build.user=ntu
ro.build.host=ubuntu

可以看到 ro.build.user 和 ro.build.host 正是我们所需要的，通过 SystemProperties api 读取即可

那这两个字段是在那里写入的呢？答案就在 buildinfo.sh 中

build\tools\buildinfo.sh

echo "ro.build.type=$TARGET_BUILD_TYPE"
echo "ro.build.user=$BUILD_USERNAME"
echo "ro.build.host=$BUILD_HOSTNAME"

那 BUILD_USERNAME 和 BUILD_HOSTNAME 又是谁赋值的呢？答案如下

./soong/ui/build/kati.go:	if _, ok := cmd.Environment.Get("BUILD_USERNAME"); !ok {
./soong/ui/build/kati.go:		cmd.Environment.Set("BUILD_USERNAME", u.Username)
./make/tools/buildinfo.sh:echo "ro.build.user=$BUILD_USERNAME"
./make/Changes.md:make variable `BUILD_USERNAME` for now.
./make/core/main.mk:  FILE_NAME_TAG := eng.$(BUILD_USERNAME)
./make/core/config.mk:$(KATI_deprecated_var USER,Use BUILD_USERNAME instead. See $(CHANGES_URL)#USER)
./make/core/version_defaults.mk:  BUILD_NUMBER := eng.$(shell echo $${BUILD_USERNAME:0:6}).$(shell $(DATE) +%Y%m%d.%H%M%S)

./soong/ui/build/kati.go:	if _, ok := cmd.Environment.Get("BUILD_HOSTNAME"); !ok {
./soong/ui/build/kati.go:		cmd.Environment.Set("BUILD_HOSTNAME", hostname)
./make/tools/buildinfo.sh:echo "ro.build.host=$BUILD_HOSTNAME"
./make/Changes.md:of `android-build`. The real value is available as `BUILD_HOSTNAME`.