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: "(x@y.com) " */

"\\((.+?)\\) " + /* 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" + // x@y.com #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`.