# 快速连续点击拍照按钮，应用闪退

#### 问题现象

快速连续点击拍照按钮时，应用发生闪退。

#### 背景知识

*   CppCrash进程崩溃检测基于操作系统信号机制，目前支持的崩溃信号参考Cpp Crash（进程崩溃）检测。
*   CppCrash日志规格说明可以参考日志规格说明。

*   packToFile：指定编码参数，将PixelMap直接编码进文件。使用Promise形式返回结果。
*   crop：根据输入的尺寸对图片进行裁剪，使用Promise形式返回。
*   async/await：async/await是用于处理异步操作的Promise语法糖，使编写异步代码更加简单和易读。使用async关键字声明异步函数，并使用await关键字等待Promise的解析（完成或拒绝），以同步方式编写异步操作的代码。

#### 问题定位

1.  查看faultlogger目录下的故障日志，异常信号是SIGSEGV，无效内存访问。
    
    ```
    Reason:Signal:SIGSEGV(SEGV_MAPERR)@0x0000005ba5568000 
    Fault thread info:
    Tid:46346, Name:OS_FFRT_3_0
    #00 pc 000000000141f588 /system/lib64/libskia_canvaskit.z.so(jsimd_extrgbx_ycc_convert_neon+564)(60d1c4d658beecacdae715b752333a76)
    #01 pc 00000000013f449c /system/lib64/libskia_canvaskit.z.so(pre_process_data+152)(60d1c4d658beecacdae715b752333a76)
    #02 pc 00000000013ecedc /system/lib64/libskia_canvaskit.z.so(process_data_simple_main+208)(60d1c4d658beecacdae715b752333a76)
    #03 pc 00000000013d8b34 /system/lib64/libskia_canvaskit.z.so(jpeg_write_scanlines+176)(60d1c4d658beecacdae715b752333a76)
    #04 pc 00000000012ad848 /system/lib64/libskia_canvaskit.z.so(SkJpegEncoder::onEncodeRows(int)+372)(60d1c4d658beecacdae715b752333a76)
    #05 pc 00000000011663e8 /system/lib64/libskia_canvaskit.z.so(SkEncoder::encodeRows(int)+80)(60d1c4d658beecacdae715b752333a76)
    #06 pc 00000000012ad8d4 /system/lib64/libskia_canvaskit.z.so(SkJpegEncoder::Encode(SkWStream*, SkPixmap const&, SkJpegEncoder::Options const&)+64)(60d1c4d658beecacdae715b752333a76)
    #07 pc 0000000000fdf038 /system/lib64/libskia_canvaskit.z.so(SkEncodeImage(SkWStream*, SkPixmap const&, SkEncodedImageFormat, int)+252)(60d1c4d658beecacdae715b752333a76)
    #08 pc 0000000001166304 /system/lib64/libskia_canvaskit.z.so(SkEncodeImage(SkWStream*, SkBitmap const&, SkEncodedImageFormat, int)+148)(60d1c4d658beecacdae715b752333a76)
    #09 pc 000000000009c268 /system/lib64/platformsdk/libextplugin.z.so(OHOS::ImagePlugin::ExtEncoder::DoEncode(SkWStream*, SkBitmap const&, SkEncodedImageFormat const&)+280)(4f50f74b029138d69bf103f408e21784)
    #10 pc 000000000009c004 /system/lib64/platformsdk/libextplugin.z.so(OHOS::ImagePlugin::ExtEncoder::EncodeImageByBitmap(SkBitmap&, bool, SkWStream&)+320)(4f50f74b029138d69bf103f408e21784)
    #11 pc 000000000009a08c /system/lib64/platformsdk/libextplugin.z.so(OHOS::ImagePlugin::ExtEncoder::EncodeImageByPixelMap(OHOS::Media::PixelMap*, bool, SkWStream&)+968)(4f50f74b029138d69bf103f408e21784)
    #12 pc 0000000000099028 /system/lib64/platformsdk/libextplugin.z.so(OHOS::ImagePlugin::ExtEncoder::PixelmapEncode(OHOS::ImagePlugin::ExtWStream&)+132)(4f50f74b029138d69bf103f408e21784)
    #13 pc 0000000000098dcc /system/lib64/platformsdk/libextplugin.z.so(OHOS::ImagePlugin::ExtEncoder::FinalizeEncode()+824)(4f50f74b029138d69bf103f408e21784)
    #14 pc 00000000000c7430 /system/lib64/platformsdk/libimage_native.z.so(std::__h::__function::__func<OHOS::Media::ImagePacker::FinalizePacking()::$_3, std::__h::allocator<OHOS::Media::ImagePacker::FinalizePacking()::$_3>, unsigned int (OHOS::ImagePlugin::AbsImageEncoder*)>::operator()(OHOS::ImagePlugin::AbsImageEncoder*&&)+56)(bcd0c974911e66ecc960744f372db153)
    #15 pc 00000000000c53ac /system/lib64/platformsdk/libimage_native.z.so(OHOS::Media::ImagePacker::DoEncodingFunc(std::__h::function<unsigned int (OHOS::ImagePlugin::AbsImageEncoder*)>, bool)+300)(bcd0c974911e66ecc960744f372db153)
    #16 pc 00000000000c74e4 /system/lib64/platformsdk/libimage_native.z.so(OHOS::Media::ImagePacker::FinalizePacking(long&)+80)(bcd0c974911e66ecc960744f372db153)
    #17 pc 00000000000a531c /system/lib64/platformsdk/libimage_napi.z.so(OHOS::Media::PackToFileExec(napi_env__*, void*) (.cfi)+728)(ff41160588e3ec0d50afc636299767c8)
    ```
    
2.  查看故障堆栈，应用在调用packToFile函数时出现内存访问异常，需要排查在调用packToFile函数时编码的PixelMap资源是否被释放和修改。
3.  排查应用在调用packToFile函数前是否调用crop函数修改PixelMap。
    
    ```
    async function Packing(context: Context) {
      const resourceMgr = context.resourceManager;
      const rawFile = await resourceMgr.getRawFileContent("test.jpg");
      let ops: image.SourceOptions = {
        sourceDensity: 98,
      }
      let imageSource: image.ImageSource = image.createImageSource(rawFile.buffer as ArrayBuffer, ops);
      let pixelMap: image.PixelMap = await imageSource.createPixelMap();
      const imagePackerApi: image.ImagePacker = image.createImagePacker();
      let funcName = "Packing";
      if (imagePackerApi != null) {
        try {
          let opts: image.PackingOption = { format: "image/jpeg", quality: 98};
          pixelMap.crop({x : 1, y : 1, size: {width : 200, height: 200}})
          const path : string = context.cacheDir + "/pixel_map.jpg";
          let file = fs.openSync(path, fs.OpenMode.CREATE | fs.OpenMode.READ_WRITE);
          imagePackerApi.packToFile(pixelMap, file.fd, opts).then(() => {
            // 直接编码进文件。
          }).catch((error : BusinessError) => {
            console.error(funcName, `Failed to pack the image.code ${error.code},message is ${error.message}`);
          }).finally(()=>{
            fs.closeSync(file.fd);
          })
        } catch (error) {
          console.error(funcName, `Failed to pack the image.code ${error.code},message is ${error.message}`);
        }
      }
    }
    ```
    

#### 分析结论

在调用packToFile函数时编码的PixelMap资源被修改，导致应用闪退。

#### 修改建议

使用await等待crop函数执行结束，再执行packToFile函数。

```
import { image } from '@kit.ImageKit';
import { fileIo as fs } from '@kit.CoreFileKit';
import { BusinessError } from '@kit.BasicServicesKit';

async function Packing(context: Context) {
  const resourceMgr = context.resourceManager;
  const rawFile = await resourceMgr.getRawFileContent('test.jpg');
  let ops: image.SourceOptions = {
    sourceDensity: 98,
  };
  let imageSource: image.ImageSource = image.createImageSource(rawFile.buffer as ArrayBuffer, ops);
  let pixelMap: image.PixelMap = await imageSource.createPixelMap();
  const imagePackerApi: image.ImagePacker = image.createImagePacker();
  let funcName = 'Packing';
  if (imagePackerApi != null) {
    try {
      let opts: image.PackingOption = { format: 'image/jpeg', quality: 98 };
      await pixelMap.crop({ x: 1, y: 1, size: { width: 50, height: 50 } });
      const path: string = context.cacheDir + '/pixel_map.jpg';
      let file = fs.openSync(path, fs.OpenMode.CREATE | fs.OpenMode.READ_WRITE);
      imagePackerApi.packToFile(pixelMap, file.fd, opts).then(() => {
        // 直接编码进文件。
      }).catch((error: BusinessError) => {
        console.error(funcName, `Failed to pack the image.code ${error.code},message is ${error.message}`);
      }).finally(() => {
        fs.closeSync(file.fd);
      });
    } catch (error) {
      console.error(funcName, `Failed to image.code ${error.code},message is ${error.message}`);
    }
  }
}

@Entry
@Component
struct Index {
  message: string = 'Hello World';

  build() {
    RelativeContainer() {
      Button(this.message)
        .id('HelloWorld')
        .fontSize($r('app.float.page_text_font_size'))
        .fontWeight(FontWeight.Bold)
        .alignRules({
          center: { anchor: '__container__', align: VerticalAlign.Center },
          middle: { anchor: '__container__', align: HorizontalAlign.Center }
        })
        .onClick(() => {
          Packing(this.getUIContext().getHostContext() as Context);
        });
    }
    .height('100%')
    .width('100%');
  }
}
```