Android Q 修改Fingerprint_framework platform_min_supported_target_sdk_versio

Android 系统中fingerprint 在 build/make/core/Makefile 

# The string used to uniquely identify the combined build and product; used by the OTA server.
ifeq (,$(strip $(BUILD_FINGERPRINT)))
  ifeq ($(strip $(HAS_BUILD_NUMBER)),false)
    BF_BUILD_NUMBER := $(BUILD_USERNAME)$$($(DATE_FROM_FILE) +%m%d%H%M)
  else
    BF_BUILD_NUMBER := $(file <$(BUILD_NUMBER_FILE))
  endif
    BUILD_FINGERPRINT := $(PRODUCT_BRAND)/$(TARGET_PRODUCT)/$(TARGET_DEVICE):$(PLATFORM_VERSION)/$(BUILD_ID)/$(BF_BUILD_NUMBER):$(TARGET_BUILD_VARIANT)/$(BUILD_VERSION_TAGS)
endif

格式就是按照这样

$(PRODUCT_BRAND)/$(TARGET_PRODUCT)/$(TARGET_DEVICE):$(PLATFORM_VERSION)/$(BUILD_ID)/$(BF_BUILD_NUMBER):$(TARGET_BUILD_VARIANT)/$(BUILD_VERSION_TAGS)

这个地方定义的BUILD_FINGERPRINT 用于

[ro.bootimage.build.fingerprint]: [xxx/xxx/xxx:10/QKQ1.xxx/20201025.105558:userdebug/release-keys]
[ro.odm.build.fingerprint]: [xxx/xxx/xxx:10/QKQ1.xxx/20201025.105558:userdebug/release-keys]
[ro.product.build.fingerprint]: [xxx/xxx/xxx:10/QKQ1xxx/20201025.105558:userdebug/release-keys]
[ro.system.build.fingerprint]: [xxx/xxx/xxx:10/QKQ1xxx/20201025.105558:userdebug/release-keys]
[ro.vendor.build.fingerprint]: [xxx/xxx/xxx:10/QKQ1xxx/20201025.105558:userdebug/release-keys]

还有个ro.build.fingerprint 是在system/core/init/property_service.cpp 定义的

// If the ro.build.fingerprint property has not been set, derive it from constituent pieces
static void property_derive_build_fingerprint() {
    std::string build_fingerprint = GetProperty("ro.build.fingerprint", "");
    if (!build_fingerprint.empty()) {
        return;
    }
 
    const std::string UNKNOWN = "unknown";
    build_fingerprint = GetProperty("ro.product.brand", UNKNOWN);
    build_fingerprint += '/';
    build_fingerprint += GetProperty("ro.product.name", UNKNOWN);
    build_fingerprint += '/';
    build_fingerprint += GetProperty("ro.product.device", UNKNOWN);
    build_fingerprint += ':';
    build_fingerprint += GetProperty("ro.build.version.release", UNKNOWN);
    build_fingerprint += '/';
    build_fingerprint += GetProperty("ro.build.id", UNKNOWN);
    build_fingerprint += '/';
    build_fingerprint += GetProperty("ro.build.version.incremental", UNKNOWN);
    build_fingerprint += ':';
    build_fingerprint += GetProperty("ro.build.type", UNKNOWN);
    build_fingerprint += '/';
    build_fingerprint += GetProperty("ro.build.tags", UNKNOWN);
 
    LOG(INFO) << "Setting property 'ro.build.fingerprint' to '" << build_fingerprint << "'";
 
    std::string error;
    uint32_t res = PropertySet("ro.build.fingerprint", build_fingerprint, &error);
    if (res != PROP_SUCCESS) {
        LOG(ERROR) << "Error setting property 'ro.build.fingerprint': err=" << res << " (" << error
                   << ")";
    }
}

其中ro.build.version.incremental 看build/tools/buildinfo.sh 是从$BUILD_NUMBER 获取的

...
echo "ro.build.version.incremental=$BUILD_NUMBER"
...

看build/make/core/version_defaults.mk  BUILD_NUMBER是在这边赋值的，HAS_BUILD_NUMBER  默认为true

如果事先没有定义BUILD_NUMBER的话 就会用默认格式BUILD_NUMBER := eng.$(shell echo $${BUILD_USERNAME:0:6}).$(shell $(DATE) +%Y%m%d.%H%M%S)

# Everything should be using BUILD_DATETIME_FROM_FILE instead.
# BUILD_DATETIME and DATE can be removed once BUILD_NUMBER moves
# to soong_ui.
$(KATI_obsolete_var BUILD_DATETIME,Use BUILD_DATETIME_FROM_FILE)
 
HAS_BUILD_NUMBER := true
ifndef BUILD_NUMBER
  # BUILD_NUMBER should be set to the source control value that
  # represents the current state of the source code.  E.g., a
  # perforce changelist number or a git hash.  Can be an arbitrary string
  # (to allow for source control that uses something other than numbers),
  # but must be a single word and a valid file name.
  #
  # If no BUILD_NUMBER is set, create a useful "I am an engineering build
  # from this date/time" value.  Make it start with a non-digit so that
  # anyone trying to parse it as an integer will probably get "0".
  BUILD_NUMBER := eng.$(shell echo $${BUILD_USERNAME:0:6}).$(shell $(DATE) +%Y%m%d.%H%M%S)
  HAS_BUILD_NUMBER := false
endif
.KATI_READONLY := BUILD_NUMBER HAS_BUILD_NUMBER
 
ifndef PLATFORM_MIN_SUPPORTED_TARGET_SDK_VERSION
  # Used to set minimum supported target sdk version. Apps targeting sdk
  # version lower than the set value will result in a warning being shown
  # when any activity from the app is started.
  PLATFORM_MIN_SUPPORTED_TARGET_SDK_VERSION := 23
endif
.KATI_READONLY := PLATFORM_MIN_SUPPORTED_TARGET_SDK_VERSION

看build/make/core/Makefile  如果HAS_BUILD_NUMBER = true 会用BUILD_NUMBER_FILE 的值

  ifeq ($(strip $(HAS_BUILD_NUMBER)),false)
    BF_BUILD_NUMBER := $(BUILD_USERNAME)$$($(DATE_FROM_FILE) +%m%d%H%M)
  else
    BF_BUILD_NUMBER := $(file <$(BUILD_NUMBER_FILE))
  endif

BUILD_NUMBER_FILE 在build/make/core/main.mk   是从BUILD_NUMBER 获取的

# Write the build number to a file so it can be read back in
# without changing the command line every time.  Avoids rebuilds
# when using ninja.
$(shell mkdir -p $(OUT_DIR) && \
    echo -n $(BUILD_NUMBER) > $(OUT_DIR)/build_number.txt)
BUILD_NUMBER_FILE := $(OUT_DIR)/build_number.txt