3 files changed, 142 insertions, 0 deletions

diff --git a/src/library_fs.js b/src/library_fs.js
index e1397356..9c8223ab 100644
--- a/src/library_fs.js
+++ b/src/library_fs.js
@@ -802,6 +802,90 @@ mergeInto(LibraryManager.library, {
       }
     },
 
+    indexedDB: function() {
+      return window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;
+    },
+
+    DB_NAME: function() {
+      return 'EM_FS_' + window.location.pathname;
+    },
+    DB_VERSION: 20,
+    DB_STORE_NAME: 'FILE_DATA',
+
+    // asynchronously saves a list of files to an IndexedDB. The DB will be created if not already existing.
+    saveFilesToDB: function(paths, onload, onerror) {
+      onload = onload || function(){};
+      onerror = onerror || function(){};
+      var indexedDB = FS.indexedDB();
+      try {
+        var openRequest = indexedDB.open(FS.DB_NAME(), FS.DB_VERSION);
+      } catch (e) {
+        return onerror(e);
+      }
+      openRequest.onupgradeneeded = function() {
+        console.log('creating db');
+        var db = openRequest.result;
+        db.createObjectStore(FS.DB_STORE_NAME);
+      };
+      openRequest.onsuccess = function() {
+        var db = openRequest.result;
+        var transaction = db.transaction([FS.DB_STORE_NAME], 'readwrite');
+        var files = transaction.objectStore(FS.DB_STORE_NAME);
+        var ok = 0, fail = 0, total = paths.length;
+        function finish() {
+          if (fail == 0) onload(); else onerror();
+        }
+        paths.forEach(function(path) {
+          var putRequest = files.put(FS.analyzePath(path).object.contents, path);
+          putRequest.onsuccess = function() { ok++; if (ok + fail == total) finish() };
+          putRequest.onerror = function() { fail++; if (ok + fail == total) finish() };
+        });
+        transaction.onerror = onerror;
+      };
+      openRequest.onerror = onerror;
+    },
+
+    // asychronously loads a file from IndexedDB.
+    loadFilesFromDB: function(paths, onload, onerror) {
+      onload = onload || function(){};
+      onerror = onerror || function(){};
+      var indexedDB = FS.indexedDB();
+      try {
+        var openRequest = indexedDB.open(FS.DB_NAME(), FS.DB_VERSION);
+      } catch (e) {
+        return onerror(e);
+      }
+      openRequest.onupgradeneeded = onerror; // no database to load from
+      openRequest.onsuccess = function() {
+        var db = openRequest.result;
+        try {
+          var transaction = db.transaction([FS.DB_STORE_NAME], 'readonly');
+        } catch(e) {
+          onerror(e);
+          return;
+        }
+        var files = transaction.objectStore(FS.DB_STORE_NAME);
+        var ok = 0, fail = 0, total = paths.length;
+        function finish() {
+          if (fail == 0) onload(); else onerror();
+        }
+        paths.forEach(function(path) {
+          var getRequest = files.get(path);
+          getRequest.onsuccess = function() {
+            if (FS.analyzePath(path).exists) {
+              FS.unlink(path);
+            }
+            FS.createDataFile(PATH.dirname(path), PATH.basename(path), getRequest.result, true, true, true);
+            ok++;
+            if (ok + fail == total) finish();
+          };
+          getRequest.onerror = function() { fail++; if (ok + fail == total) finish() };
+        });
+        transaction.onerror = onerror;
+      };
+      openRequest.onerror = onerror;
+    },
+
     //
     // general
     //
diff --git a/tests/file_db.cpp b/tests/file_db.cpp
new file mode 100644
index 00000000..ebb3bb30
--- /dev/null
+++ b/tests/file_db.cpp
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <emscripten.h>
+
+void later(void *) {}
+
+int main() {
+#if FIRST
+  FILE *f = fopen("waka.txt", "w");
+  fputc('a', f);
+  fputc('z', f);
+  fclose(f);
+
+  EM_ASM(
+    FS.saveFilesToDB(['waka.txt', 'moar.txt'], function() {
+      Module.print('save ok');
+      var xhr = new XMLHttpRequest();
+      xhr.open('GET', 'http://localhost:8888/report_result?1');
+      xhr.send();
+      setTimeout(function() { window.close() }, 1000);
+    }, function(e) {
+      abort('saving should succeed ' + e);
+    });
+  );
+#else
+  EM_ASM(
+    FS.loadFilesFromDB(['waka.txt', 'moar.txt'], function() {
+      function stringy(arr) {
+        return Array.prototype.map.call(arr, function(x) { return String.fromCharCode(x) }).join('');
+      }
+      assert(stringy(FS.analyzePath('waka.txt').object.contents) == 'az');
+      var secret = stringy(FS.analyzePath('moar.txt').object.contents);
+      Module.print('load: ' + secret);
+      var xhr = new XMLHttpRequest();
+      xhr.open('GET', 'http://localhost:8888/report_result?' + secret);
+      xhr.send();
+      setTimeout(function() { window.close() }, 1000);
+    }, function() {
+      abort('loading should succeed');
+    });
+  );
+#endif
+
+  emscripten_async_call(later, NULL, 100); // keep runtime alive
+
+  return 0;
+}
+
diff --git a/tests/test_browser.py b/tests/test_browser.py
index 1c9cbfad..32b29966 100644
--- a/tests/test_browser.py
+++ b/tests/test_browser.py
@@ -794,6 +794,17 @@ If manually bisecting:
   def test_glut_touchevents(self):
     self.btest('glut_touchevents.c', '1')
 
+  def test_file_db(self):
+    secret = str(time.time())
+    open('moar.txt', 'w').write(secret)
+    self.btest('file_db.cpp', '1', args=['--preload-file', 'moar.txt', '-DFIRST'])
+    shutil.copyfile('test.html', 'first.html')
+    self.btest('file_db.cpp', secret)
+    shutil.copyfile('test.html', 'second.html')
+    open('moar.txt', 'w').write('aliantha')
+    self.btest('file_db.cpp', secret, args=['--preload-file', 'moar.txt']) # even with a file there, we load over it
+    shutil.move('test.html', 'third.html')
+
   def test_sdl_pumpevents(self):
     # key events should be detected using SDL_PumpEvents
     open(os.path.join(self.get_dir(), 'pre.js'), 'w').write('''