Fix unable to open local pdfs

js/preload/default.js

@@ -61,4 +61,20 @@ window.addEventListener('message', function (e) {
   if (e.data?.message === 'downloadFile') {
     ipc.send('downloadFile', e.data.url)
   }
+
+  if (e.data?.message === 'readLocalPDF') {
+    var requestId = e.data.requestId
+
+    if (typeof e.data.url !== 'string') {
+      window.postMessage({ message: 'readLocalPDFResult', requestId, error: 'invalid PDF URL' }, 'min://app')
+      return
+    }
+
+    ipc.invoke('readLocalPDF', e.data.url).then(function (fileData) {
+      var data = new Uint8Array(fileData)
+      window.postMessage({ message: 'readLocalPDFResult', requestId, data: data.buffer }, 'min://app')
+    }).catch(function (err) {
+      window.postMessage({ message: 'readLocalPDFResult', requestId, error: err?.message || 'unable to read local PDF' }, 'min://app')
+    })
+  }
 })

main/download.js

@@ -1,5 +1,64 @@
 const currrentDownloadItems = {}
 
+function isPDFViewerURL (url) {
+  return typeof url === 'string' && url.startsWith('min://app/pages/pdfViewer/index.html')
+}
+
+function getViewerSourceURL (viewerURL) {
+  if (!isPDFViewerURL(viewerURL)) {
+    return null
+  }
+
+  try {
+    var sourceURL = new URLSearchParams(new URL(viewerURL).search).get('url')
+    if (!sourceURL) {
+      return null
+    }
+
+    return new URL(sourceURL)
+  } catch (e) {
+    return null
+  }
+}
+
+function getAllowedLocalPDFPath (senderFrameURL, requestedURL) {
+  if (!isPDFViewerURL(senderFrameURL)) {
+    throw new Error('blocked local PDF read request')
+  }
+
+  if (typeof requestedURL !== 'string') {
+    throw new Error('invalid PDF URL')
+  }
+
+  var requestedFileURL
+  try {
+    requestedFileURL = new URL(requestedURL)
+  } catch (e) {
+    throw new Error('invalid PDF URL')
+  }
+
+  if (requestedFileURL.protocol !== 'file:') {
+    throw new Error('invalid PDF URL protocol')
+  }
+
+  var sourceURL = getViewerSourceURL(senderFrameURL)
+
+  if (!sourceURL || sourceURL.protocol !== 'file:' || sourceURL.toString() !== requestedFileURL.toString()) {
+    throw new Error('blocked local PDF read request')
+  }
+
+  return require('url').fileURLToPath(requestedFileURL)
+}
+
+ipc.handle('readLocalPDF', async function (event, requestedURL) {
+  if (!event.senderFrame) {
+    throw new Error('blocked local PDF read request')
+  }
+
+  var filePath = getAllowedLocalPDFPath(event.senderFrame.url, requestedURL)
+  return fs.promises.readFile(filePath)
+})
+
 ipc.on('cancelDownload', function (e, path) {
   if (currrentDownloadItems[path]) {
     currrentDownloadItems[path].cancel()

pages/pdfViewer/viewer.js

@@ -4,6 +4,7 @@ import '../../node_modules/pdfjs-dist/web/pdf_viewer.mjs'
 pdfjsLib.GlobalWorkerOptions.workerSrc = '../../node_modules/pdfjs-dist/build/pdf.worker.mjs'
 
 var url = new URLSearchParams(window.location.search.replace('?', '')).get('url')
+var localPDFRequestId = 0
 
 var eventBus = new pdfjsViewer.EventBus()
 
@@ -239,7 +240,61 @@ function setUpPageAnnotationLayer (pageView) {
   }
 }
 
-pdfjsLib.getDocument({ url: url, withCredentials: true }).promise.then(async function (_pdf) {
+function requestLocalPDFData (fileURL) {
+  return new Promise(function (resolve, reject) {
+    var requestId = ++localPDFRequestId
+
+    function onResponse (e) {
+      if (e.origin !== 'min://app') {
+        return
+      }
+
+      if (e.data?.message !== 'readLocalPDFResult' || e.data.requestId !== requestId) {
+        return
+      }
+
+      window.removeEventListener('message', onResponse)
+
+      if (e.data.error) {
+        reject(new Error(e.data.error))
+        return
+      }
+
+      if (!e.data.data) {
+        reject(new Error('missing local PDF data'))
+        return
+      }
+
+      resolve(new Uint8Array(e.data.data))
+    }
+
+    window.addEventListener('message', onResponse)
+    window.postMessage({ message: 'readLocalPDF', requestId, url: fileURL }, 'min://app')
+  })
+}
+
+function getPDFDocumentRequest (targetURL, requestLocalPDFData) {
+  if (typeof targetURL !== 'string') {
+    return Promise.reject(new Error('invalid PDF URL'))
+  }
+
+  if (targetURL.startsWith('file://')) {
+    return requestLocalPDFData(targetURL).then(function (fileData) {
+      return {
+        data: fileData
+      }
+    })
+  }
+
+  return Promise.resolve({
+    url: targetURL,
+    withCredentials: true
+  })
+}
+
+getPDFDocumentRequest(url, requestLocalPDFData).then(function (request) {
+  return pdfjsLib.getDocument(request).promise
+}).then(async function (_pdf) {
   pdf = _pdf
 
   pageCount = pdf.numPages