Merge pull request joltup#128 from mmathewsTableau/master

Adding File Transforms

Author: RonRadtke

README.md

@@ -303,6 +303,26 @@ ReactNativeBlobUtil
 
 **These files won't be removed automatically, please refer to [Cache File Management](#user-content-cache-file-management)**
 
+**Use File Transformer**
+
+If you need to perform any processing on the bytes prior to it being written into storage (e.g. if you want it to be encrypted) then you can use `transform` option.  NOTE: you will need to set a transformer on the libray (see [Setting a File Transformer](#Setting-A-File-Transformer))
+
+```js
+ReactNativeBlobUtil
+        .config({
+            // response data will be saved to this path if it has access right.
+            path: dirs.DocumentDir + '/path-to-file.anything',
+            transform: true
+        })
+        .fetch('GET', 'http://www.example.com/file/example.zip', {
+            //some headers ..
+        })
+        .then((res) => {
+            // the path should be dirs.DocumentDir + 'path-to-file.anything'
+            console.log('The file saved to ', res.path())
+        })
+```
+
 #### Upload example : Dropbox [files-upload](https://www.dropbox.com/developers/documentation/http/documentation#files-upload) API
 
 `react-native-blob-util` will convert the base64 string in `body` to binary format using native API, this process is done in a separated thread so that it won't block your GUI.
@@ -676,6 +696,14 @@ await ReactNativeBlobUtil.MediaCollection.writeToMediafile('content://....', //
 );
 ````
 
+Copies and tranforms data from a file in the apps storage to an existing entry of the Media Store. NOTE: you must set a transformer on the file in order for the transformation to happen (see [Setting a File Transformer](#Setting-A-File-Transformer)).
+
+````js
+await ReactNativeBlobUtil.MediaCollection.writeToMediafileWithTransform('content://....', // content uri of the entry in the media storage
+        localpath // path to the file that should be copied
+);
+````
+
 #### copyToInternal
 Copies an entry form the media storage to the apps internal storage.
 ````js
@@ -697,8 +725,10 @@ File Access APIs
 - [dirs](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#dirs)
 - [createFile](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#createfilepath-data-encodingpromise)
 - [writeFile (0.6.0)](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#writefilepathstring-contentstring--array-encodingstring-appendbooleanpromise)
+- writeFileWithTransform
 - [appendFile (0.6.0) ](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#appendfilepathstring-contentstring--arraynumber-encodingstring-promisenumber)
 - [readFile (0.6.0)](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#readfilepath-encodingpromise)
+- readFileWithTransform
 - [readStream](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#readstreampath-encoding-buffersize-interval-promisernfbreadstream)
 - [hash (0.10.9)](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#hashpath-algorithm-promise)
 - [writeStream](https://github.com/RonRadtke/react-native-blob-util/wiki/File-System-Access-API#writestreampathstring-encodingstringpromise)
@@ -903,13 +933,59 @@ ReactNativeBlobUtil.config({
         })
 ```
 
+### Transform Files
+
+Sometimes you may need the files to be transformed after reading from storage or before writing into storage (eg encryption/decyrption). In order to perform the transformations, use `readFileWithTransform` and `writeFileWithTransform`. NOTE: you must set a transformer on the file in order for the transformation to happen (see [Setting a File Transformer](#Setting-A-File-Transformer)).
+
 ## Web API Polyfills
 
 After `0.8.0` we've made some [Web API polyfills](https://github.com/RonRadtke/react-native-blob-util/wiki/Web-API-Polyfills-(experimental)) that makes some browser-based library available in RN.
 
 - Blob
 - XMLHttpRequest (Use our implementation if you're going to use it with Blob)
 
+
+## Setting A File Transformer
+
+Setting a file transformer will allow you to specify how data should be transformed whenever the library is writing into storage or reading from storage. A use case for this is if you want the files handled by this library to be encrypted. 
+
+If you want to use a file transformer, you must implement an interface defined in:
+
+[ReactNativeBlobUtilFileTransformer.h (iOS)](/ios/ReactNativeBlobUtilFileTransformer.h)
+
+[ReactNativeBlobUtilFileTransformer.java (Android)](/android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilFileTransformer.java)
+
+Then you set the File Transformer during app startup
+
+Android:
+```java
+public class MainApplication extends Application implements ReactApplication {
+    ...
+    @Override
+    public void onCreate() {
+       ...
+       ReactNativeBlobUtilFileTransformer.sharedFileTransformer = new MyCustomEncryptor(); 
+       ...
+    }
+```
+
+iOS:
+```m
+@implementation AppDelegate
+...
+- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
+{
+    ...
+    [ReactNativeBlobUtilFileTransformer setFileTransformer: MyCustomEncryptor.new];
+    ...
+}
+```
+
+Here are the places where the transformer would apply 
+- Reading a file from the file system  
+- Writing a file into the file system
+- Http response is downloaded to storage directly
+
 ## Performance Tips
 
 **Read Stream and Progress Event Overhead**

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtil.java

@@ -233,11 +233,11 @@ public void removeSession(ReadableArray paths, Callback callback) {
     }
 
     @ReactMethod
-    public void readFile(final String path, final String encoding, final Promise promise) {
+    public void readFile(final String path, final String encoding, final boolean transformFile, final Promise promise) {
         threadPool.execute(new Runnable() {
             @Override
             public void run() {
-                ReactNativeBlobUtilFS.readFile(path, encoding, promise);
+                ReactNativeBlobUtilFS.readFile(path, encoding, transformFile, promise);
             }
         });
     }
@@ -253,11 +253,11 @@ public void run() {
     }
 
     @ReactMethod
-    public void writeFile(final String path, final String encoding, final String data, final boolean append, final Promise promise) {
+    public void writeFile(final String path, final String encoding, final String data, final boolean transformFile, final boolean append, final Promise promise) {
         threadPool.execute(new Runnable() {
             @Override
             public void run() {
-                ReactNativeBlobUtilFS.writeFile(path, encoding, data, append, promise);
+                ReactNativeBlobUtilFS.writeFile(path, encoding, data, transformFile, append, promise);
             }
         });
     }
@@ -438,8 +438,8 @@ public void createMediaFile(ReadableMap filedata, String mt, Promise promise) {
     }
 
     @ReactMethod
-    public void writeToMediaFile(String fileUri, String path, Promise promise) {
-        boolean res = ReactNativeBlobUtilMediaCollection.writeToMediaFile(Uri.parse(fileUri), path, promise);
+    public void writeToMediaFile(String fileUri, String path, boolean transformFile, Promise promise) {
+        boolean res = ReactNativeBlobUtilMediaCollection.writeToMediaFile(Uri.parse(fileUri), path, transformFile, promise);
         if(res) promise.resolve("Success");
     }
 
@@ -478,7 +478,7 @@ public void copyToMediaStore(ReadableMap filedata, String mt, String path, Promi
             return;
         }
 
-        boolean res = ReactNativeBlobUtilMediaCollection.writeToMediaFile(fileuri, path, promise);
+        boolean res = ReactNativeBlobUtilMediaCollection.writeToMediaFile(fileuri, path, false, promise);
         if(res) promise.resolve(fileuri.toString());
     }
 

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilConfig.java

@@ -8,6 +8,7 @@
 class ReactNativeBlobUtilConfig {
 
     public Boolean fileCache;
+    public Boolean transformFile;
     public String path;
     public String appendExt;
     public ReadableMap addAndroidDownloads;
@@ -26,6 +27,7 @@ class ReactNativeBlobUtilConfig {
         if (options == null)
             return;
         this.fileCache = options.hasKey("fileCache") && options.getBoolean("fileCache");
+        this.transformFile = options.hasKey("transformFile") ? options.getBoolean("transformFile") : false;
         this.path = options.hasKey("path") ? options.getString("path") : null;
         this.appendExt = options.hasKey("appendExt") ? options.getString("appendExt") : "";
         this.trusty = options.hasKey("trusty") && options.getBoolean("trusty");

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilFS.java

@@ -122,7 +122,7 @@ static boolean writeFile(String path, String encoding, String data, final boolea
      * @param data     Array passed from JS context.
      * @param promise  RCT Promise
      */
-    static void writeFile(String path, String encoding, String data, final boolean append, final Promise promise) {
+    static void writeFile(String path, String encoding, String data, final boolean transformFile, final boolean append, final Promise promise) {
         try {
             int written;
             File f = new File(path);
@@ -170,6 +170,12 @@ static void writeFile(String path, String encoding, String data, final boolean a
                 }
             } else {
                 byte[] bytes = ReactNativeBlobUtilUtils.stringToBytes(data, encoding);
+                if (transformFile) {
+                    if (ReactNativeBlobUtilFileTransformer.sharedFileTransformer == null) {
+                        throw new IllegalStateException("Write file with transform was specified but the shared file transformer is not set");
+                    }
+                    bytes = ReactNativeBlobUtilFileTransformer.sharedFileTransformer.onWriteFile(bytes);
+                }
                 FileOutputStream fout = new FileOutputStream(f, append);
                 try {
                     fout.write(bytes);
@@ -238,7 +244,7 @@ static void writeFile(String path, ReadableArray data, final boolean append, fin
      * @param encoding Encoding of read stream.
      * @param promise  JS promise
      */
-    static void readFile(String path, String encoding, final Promise promise) {
+    static void readFile(String path, String encoding, final boolean transformFile, final Promise promise) {
         String resolved = ReactNativeBlobUtilUtils.normalizePath(path);
         if (resolved != null)
             path = resolved;
@@ -281,6 +287,13 @@ else if (resolved == null) {
                 return;
             }
 
+            if (transformFile) {
+                if (ReactNativeBlobUtilFileTransformer.sharedFileTransformer == null) {
+                    throw new IllegalStateException("Read file with transform was specified but the shared file transformer is not set");
+                }
+                bytes = ReactNativeBlobUtilFileTransformer.sharedFileTransformer.onReadFile(bytes);
+            }
+
             switch (encoding.toLowerCase(Locale.ROOT)) {
                 case "base64":
                     promise.resolve(Base64.encodeToString(bytes, Base64.NO_WRAP));

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilFileTransformer.java

@@ -0,0 +1,10 @@
+package com.ReactNativeBlobUtil;
+
+public class ReactNativeBlobUtilFileTransformer {
+    public interface FileTransformer {
+        public byte[] onWriteFile(byte[] data);
+        public byte[] onReadFile(byte[] data);
+    }
+
+    public static ReactNativeBlobUtilFileTransformer.FileTransformer sharedFileTransformer;
+}

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilMediaCollection.java

@@ -124,7 +124,7 @@ public static Uri createNewMediaFile(FileDescription file, MediaType mt, ReactAp
         return null;
     }
 
-    public static boolean writeToMediaFile(Uri fileUri, String data, Promise promise) {
+    public static boolean writeToMediaFile(Uri fileUri, String data, boolean transformFile, Promise promise) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
             try {
                 Context appCtx = ReactNativeBlobUtil.RCTContext.getApplicationContext();
@@ -151,16 +151,31 @@ public static boolean writeToMediaFile(Uri fileUri, String data, Promise promise
                             promise.reject("ENOENT", "No such file ('" + normalizedData + "')");
                             return false;
                         }
-                        byte[] buf = new byte[10240];
-                        int read;
+
 
                         FileInputStream fin = new FileInputStream(src);
                         FileOutputStream out = new FileOutputStream(descr.getFileDescriptor());
 
-                        while ((read = fin.read(buf)) > 0) {
-                            out.write(buf, 0, read);
+                        if (transformFile) {
+                            // in order to transform file, we must load the entire file onto memory
+                            int length = (int) src.length();
+                            byte[] bytes = new byte[length];
+                            fin.read(bytes);
+                            if (ReactNativeBlobUtilFileTransformer.sharedFileTransformer == null) {
+                                throw new IllegalStateException("Write to media file with transform was specified but the shared file transformer is not set");
+                            }
+                            byte[] transformedBytes = ReactNativeBlobUtilFileTransformer.sharedFileTransformer.onWriteFile(bytes);
+                            out.write(transformedBytes);
+                        } else  {
+                            byte[] buf = new byte[10240];
+                            int read;
+
+                            while ((read = fin.read(buf)) > 0) {
+                                out.write(buf, 0, read);
+                            }
                         }
 
+
                         fin.close();
                         out.close();
                         descr.close();

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilReq.java

@@ -87,6 +87,12 @@ enum ResponseFormat {
         BASE64
     }
 
+    private boolean shouldTransformFile() {
+        return this.options.transformFile &&
+            // Can only process if it's written to a file
+            (this.options.fileCache || this.options.path != null);
+    }
+
     public static HashMap<String, Call> taskTable = new HashMap<>();
     public static HashMap<String, Long> androidDownloadManagerTaskTable = new HashMap<>();
     static HashMap<String, ReactNativeBlobUtilProgressConfig> progressReport = new HashMap<>();
@@ -124,7 +130,9 @@ public ReactNativeBlobUtilReq(ReadableMap options, String taskId, String method,
         this.rawRequestBodyArray = arrayBody;
         this.client = client;
 
-        if (this.options.fileCache || this.options.path != null)
+        // If transformFile is specified, we first want to get the response back in memory so we can
+        // encrypt it wholesale and at that point, write it into the file storage.
+        if((this.options.fileCache || this.options.path != null) && !this.shouldTransformFile())
             responseType = ResponseType.FileStorage;
         else
             responseType = ResponseType.KeepInMemory;
@@ -557,6 +565,26 @@ private void done(Response resp) {
                     // response data directly pass to JS context as string.
                     else {
                         byte[] b = resp.body().bytes();
+                        // If process file option is turned on, we first keep response in memory and then stream that content
+                        // after processing
+                        if (this.shouldTransformFile()) {
+                            if (ReactNativeBlobUtilFileTransformer.sharedFileTransformer == null) {
+                                throw new IllegalStateException("Write file with transform was specified but the shared file transformer is not set");
+                            }
+                            this.destPath = this.destPath.replace("?append=true", "");
+                            File file = new File(this.destPath);
+                            if (!file.exists()) {
+                                file.createNewFile();
+                            }
+                            try (FileOutputStream fos = new FileOutputStream(file)) {
+                                fos.write(ReactNativeBlobUtilFileTransformer.sharedFileTransformer.onWriteFile(b));
+                            } catch(Exception e) {
+                                callback.invoke("Error from file transformer:" + e.getLocalizedMessage(), null);
+                                return;
+                            }
+                            callback.invoke(null, ReactNativeBlobUtilConst.RNFB_RESPONSE_PATH, this.destPath);
+                            return;
+                        }
                         if (responseFormat == ResponseFormat.BASE64) {
                             callback.invoke(null, ReactNativeBlobUtilConst.RNFB_RESPONSE_BASE64, android.util.Base64.encodeToString(b, Base64.NO_WRAP));
                             return;

fs.js

@@ -160,7 +160,20 @@ function readFile(path: string, encoding: string = 'utf8'): Promise<any> {
     if (typeof path !== 'string') {
         return Promise.reject(addCode('EINVAL', new TypeError('Missing argument "path" ')));
     }
-    return ReactNativeBlobUtil.readFile(path, encoding);
+    return ReactNativeBlobUtil.readFile(path, encoding, false);
+}
+
+/**
+ * Reads the file, then transforms it before returning the content
+ * @param  {string} path Path of the file.
+ * @param  {'base64' | 'utf8' | 'ascii'} encoding Encoding of read stream.
+ * @return {Promise<Array<number> | string>}
+ */
+function readFileWithTransform(path: string, encoding: string = 'utf8'): Promise<any> {
+    if (typeof path !== 'string') {
+        return Promise.reject(addCode('EINVAL', new TypeError('Missing argument "path" ')))
+    }
+    return ReactNativeBlobUtil.readFile(path, encoding, true);
 }
 
 /**
@@ -186,7 +199,31 @@ function writeFile(path: string, data: string | Array<number>, encoding: ?string
             return Promise.reject(addCode('EINVAL', new TypeError(`"data" must be a String when encoding is "utf8" or "base64", but it is "${typeof data}"`)));
         }
         else
-            return ReactNativeBlobUtil.writeFile(path, encoding, data, false);
+            return ReactNativeBlobUtil.writeFile(path, encoding, data, false, false);
+    }
+}
+
+/**
+ * Transforms the data and then writes to the file.
+ * @param  {string} path  Path of the file.
+ * @param  {string | number[]} data Data to write to the file.
+ * @param  {string} encoding Encoding of data (Optional).
+ * @return {Promise}
+ */
+function writeFileWithTransform(path: string, data: string | Array<number>, encoding: ?string = 'utf8'): Promise {
+    if (typeof path !== 'string') {
+        return Promise.reject(addCode('EINVAL', new TypeError('Missing argument "path" ')))
+    }
+    if (encoding.toLocaleLowerCase() === 'ascii') {
+        return Promise.reject(addCode('EINVAL', new TypeError('ascii is not supported for converted files')))
+    }
+    else {
+        if (typeof data !== 'string') {
+            return Promise.reject(addCode('EINVAL', new TypeError(`"data" must be a String when encoding is "utf8" or "base64", but it is "${typeof data}"`)))
+        }
+
+        else
+            return ReactNativeBlobUtil.writeFile(path, encoding, data, true, false)
     }
 }
 
@@ -415,6 +452,8 @@ export default {
     cp,
     writeStream,
     writeFile,
+    writeFileWithTransform,
+    readFileWithTransform,
     appendFile,
     pathForAppGroup,
     syncPathAppGroup,