Support writing binary file to local disk (#580)

Co-authored-by: Lucas Fernandes Nogueira <lucasfernandesnog@gmail.com>
Co-authored-by: Lucas Fernandes Nogueira <lucas@tauri.studio>

README.md

@@ -70,6 +70,7 @@ If you are interested in making a tauri-app, please visit the [documentation web
 - [x] renameFile - rename a file
 - [x] copyFile - copy a file to a new destination
 - [x] writeFile - write file to local filesystem
+- [x] writeBinaryFile - write binary file to local filesystem
 - [x] readBinaryFile - read binary file from local filesystem
 - [x] readTextFile - read text file from local filesystem
 

cli/tauri.js/api/fs/index.js

@@ -39,6 +39,56 @@ function writeFile (file, options = {}) {
   return tauri.writeFile(file, options)
 }
 
+const CHUNK_SIZE = 65536;
+
+/**
+ * convert an Uint8Array to ascii string
+ *
+ * @param {Uint8Array} arr
+ * @return {String}
+ */
+function uint8ArrayToString(arr) {
+  if (arr.length < CHUNK_SIZE) {
+    return String.fromCharCode.apply(null, arr)
+  }
+
+  let result = ''
+  const arrLen = arr.length
+  for (let i = 0; i < arrLen; i++) {
+    const chunk = arr.subarray(i * CHUNK_SIZE, (i + 1) * CHUNK_SIZE)
+    result += String.fromCharCode.apply(null, chunk)
+  }
+  return result
+}
+
+/**
+ * convert an ArrayBuffer to base64 encoded string
+ *
+ * @param {ArrayBuffer} buffer
+ * @return {String}
+ */
+function arrayBufferToBase64(buffer) {
+  const str = uint8ArrayToString(new Uint8Array(buffer))
+  return btoa(str)
+}
+
+/**
+ * writes a binary file
+ *
+ * @param {Object} file
+ * @param {String} file.path path of the file
+ * @param {ArrayBuffer} file.contents contents of the file
+ * @param {Object} [options] configuration object
+ * @param {BaseDirectory} [options.dir] base directory
+ * @return {Promise<void>}
+ */
+function writeBinaryFile(file, options = {}) {
+  return tauri.writeBinaryFile({
+    ...file,
+    contents: arrayBufferToBase64(file.contents)
+  }, options)
+}
+
 /**
  * @typedef {Object} FileEntry
  * @property {String} path
@@ -131,6 +181,7 @@ export {
   readTextFile,
   readBinaryFile,
   writeFile,
+  writeBinaryFile,
   readDir,
   createDir,
   removeDir,

cli/tauri.js/templates/tauri.esm.js

@@ -205,6 +205,28 @@ window.tauri = {
       <% } %>
   },
 
+<% if (ctx.dev) { %>
+  /**
+   * @name writeBinaryFile
+   * @description Write a binary file to the Local Filesystem.
+   * Permissions based on the app's PID owner
+   * @param {Object} cfg
+   * @param {String} cfg.file
+   * @param {String|Binary} cfg.contents
+   */
+<% } %>
+  writeBinaryFile (cfg) {
+  <% if (tauri.whitelist.writeBinaryFile === true || tauri.whitelist.all === true) { %>
+    Object.freeze(cfg)
+    this.invoke({ cmd: 'writeBinaryFile', file: cfg.file, contents: cfg.contents })
+    <% } else { %>
+  <% if (ctx.dev) { %>
+      __whitelistWarning('writeBinaryFile')
+      <% } %>
+    return __reject
+      <% } %>
+  },
+
 <% if (ctx.dev) { %>
   /**
    * @name listFiles

cli/tauri.js/templates/tauri.js

@@ -43,7 +43,7 @@ switch (navigator.platform) {
   case "Win32":
   case "Win64":
     break;
-  default: 
+  default:
     window.external = this
     invoke = function (x) {
       window.webkit.messageHandlers.external.postMessage(x);
@@ -320,6 +320,37 @@ switch (navigator.platform) {
           <% } %>
     },
 
+    <% if (ctx.dev) { %>
+      /**
+       * @name writeBinaryFile
+       * @description Write a binary file to the Local Filesystem.
+       * Permissions based on the app's PID owner
+       * @param {Object} cfg
+       * @param {String} cfg.file
+       * @param {String|Binary} cfg.contents
+       * @param {Object} [options]
+       * @param {BaseDirectory} [options.dir]
+       */
+    <% } %>
+    writeBinaryFile: function writeBinaryFile(cfg, options) {
+      <% if (tauri.whitelist.writeBinaryFile === true || tauri.whitelist.all === true) { %>
+        if (_typeof(cfg) === 'object') {
+          Object.freeze(cfg);
+        }
+        return this.promisified({
+          cmd: 'writeBinaryFile',
+          file: cfg.file,
+          contents: cfg.contents,
+          options: options
+        });
+      <% } else { %>
+        <% if (ctx.dev) { %>
+            return __whitelistWarning('writeBinaryFile')
+            <% } %>
+          return __reject()
+          <% } %>
+    },
+
     <% if (ctx.dev) { %>
       /**
        * @name readDir
@@ -343,8 +374,7 @@ switch (navigator.platform) {
         <% if (ctx.dev) { %>
             return __whitelistWarning('readDir')
             <% } %>
-          return __reject()
-          <% } %>
+      <% } %>
     },
 
     <% if (ctx.dev) { %>

tauri/src/endpoints.rs

@@ -52,6 +52,16 @@ pub(crate) fn handle<T: 'static>(webview: &mut WebView<'_, T>, arg: &str) -> cra
         } => {
           file_system::write_file(webview, file, contents, options, callback, error);
         }
+        #[cfg(any(feature = "all-api", feature = "write-binary-file"))]
+        WriteBinaryFile {
+          file,
+          contents,
+          options,
+          callback,
+          error,
+        } => {
+          file_system::write_binary_file(webview, file, contents, options, callback, error);
+        }
         #[cfg(any(feature = "all-api", feature = "read-dir"))]
         ReadDir {
           path,

tauri/src/endpoints/cmd.rs

@@ -65,6 +65,14 @@ pub enum Cmd {
     callback: String,
     error: String,
   },
+  #[cfg(any(feature = "all-api", feature = "write-binary-file"))]
+  WriteBinaryFile {
+    file: String,
+    contents: String,
+    options: Option<FileOperationOptions>,
+    callback: String,
+    error: String,
+  },
   #[cfg(any(feature = "all-api", feature = "read-dir"))]
   ReadDir {
     path: String,

tauri/src/endpoints/file_system.rs

@@ -194,6 +194,34 @@ pub fn write_file<T: 'static>(
   );
 }
 
+pub fn write_binary_file<T: 'static>(
+  webview: &mut WebView<'_, T>,
+  file: String,
+  contents: String,
+  options: Option<FileOperationOptions>,
+  callback: String,
+  error: String,
+) {
+  crate::execute_promise(
+    webview,
+    move || {
+      base64::decode(contents)
+        .map_err(|e| e.into())
+        .and_then(|c| {
+        File::create(resolve_path(file, options.and_then(|o| o.dir))?)
+          .map_err(|e| e.into())
+          .and_then(|mut f| {
+          f.write_all(&c)
+            .map_err(|err| err.into())
+            .map(|_| "".to_string())
+        })
+      })
+    },
+    callback,
+    error,
+  );
+}
+
 pub fn read_text_file<T: 'static>(
   webview: &mut WebView<'_, T>,
   path: String,