Implementation for emscripten_async_wget

src/library_browser.js

@@ -142,24 +142,59 @@ mergeInto(LibraryManager.library, {
              0;
     },
 
-    asyncLoad: function(url, callback) {
+    xhrLoad: function(url, onload, onerror) {
       var xhr = new XMLHttpRequest();
       xhr.open('GET', url, true);
       xhr.responseType = 'arraybuffer';
       xhr.onload = function() {
-        var arrayBuffer = xhr.response;
-        assert(arrayBuffer, 'Loading data file "' + url + '" failed (no arrayBuffer).');
-        callback(new Uint8Array(arrayBuffer));
-        removeRunDependency();
-      };
-      xhr.onerror = function(event) {
-        assert(arrayBuffer, 'Loading data file "' + url + '" failed.');
+          if (xhr.status == 200) {
+            onload(xhr.response);
+          } else {
+            onerror();
+          }
       };
+      xhr.onerror = onerror;
       xhr.send(null);
+    },
+
+    asyncLoad: function(url, callback) {
+      Browser.xhrLoad(url, 
+        function(arrayBuffer) {
+          assert(arrayBuffer, 'Loading data file "' + url + '" failed (no arrayBuffer).');
+          callback(new Uint8Array(arrayBuffer));
+          removeRunDependency();
+        },
+        function(event) {
+          assert(arrayBuffer, 'Loading data file "' + url + '" failed.');
+        });
       addRunDependency();
     }
   },
 
+  emscripten_async_wget: function(url, file, onload, onerror) {
+    url = Pointer_stringify(url);
+
+    Browser.xhrLoad(url,
+      function (response) {
+        var absolute = Pointer_stringify(file);
+        var index = absolute.lastIndexOf('/');
+        FS.createDataFile(
+          absolute.substr(0, index),
+          absolute.substr(index +1), 
+          new Uint8Array(response), 
+          true, true);
+
+        if (onload) {
+          FUNCTION_TABLE[onload](file);
+        }
+      },
+      function (event) {
+       if (onerror) {
+          FUNCTION_TABLE[onerror](file);
+        }
+      });
+  },
+
   emscripten_async_run_script__deps: ['emscripten_run_script'],
   emscripten_async_run_script: function(script, millis) {
     Module['noExitRuntime'] = true;

system/include/emscripten/emscripten.h

@@ -102,6 +102,18 @@ float emscripten_random();
  */
 //extern void EMSCRIPTEN_COMMENT(const char *text);
 
+/*
+ * Emscripten file system api
+ */
+
+/*
+ * Load file from url in asynchronous way. 
+ * When file is loaded then 'onload' callback will called.
+ * If any error occurred 'onerror' will called.
+ * The callbacks are called with the file as their argument.
+ */ 
+void emscripten_async_wget(const char* url, const char* file, void (*onload)(const char*), void (*onerror)(const char*));
+
 /*
  * Profiling tools.
  * INIT must be called first, with the maximum identifier that

tests/emscripten_fs_api_browser.cpp

@@ -0,0 +1,69 @@
+#include<stdio.h>
+#include<emscripten.h>
+#include<assert.h>
+#include <string.h>
+
+extern "C" {
+
+int result = 1;
+int get_count = 0;
+
+void wait_wgets() {
+  if (get_count == 2) {
+    emscripten_cancel_main_loop();
+    REPORT_RESULT();
+  }
+}
+
+void onLoaded(const char* file) {
+  if (strcmp(file, "/tmp/test.html")) {
+    result = 0;
+  }
+
+  printf("loaded: %s\n", file);
+
+  if (FILE * f = fopen(file, "r")) {
+      printf("exists: %s\n", file);
+      int c = fgetc (f);
+      if (c == EOF) {
+        printf("file empty: %s\n", file);
+        result = 0;
+      }
+      fclose(f);
+  } else {
+    result = 0;
+    printf("!exists: %s\n", file);
+  }
+  
+  get_count++;
+}
+
+void onError(const char* file) {
+  if (strcmp(file, "/tmp/null")) {
+    result = 0;
+  }
+
+  printf("error: %s\n", file);
+  get_count++;
+}
+
+int main() {
+  emscripten_async_wget(
+    "http://localhost:8888/this_is_not_a_file", 
+    "/tmp/null",
+    onLoaded,
+    onError);
+
+  emscripten_async_wget(
+    "http://localhost:8888/test.html", 
+    "/tmp/test.html",
+    onLoaded,
+    onError);
+
+  emscripten_set_main_loop(wait_wgets, 0);
+
+  return 0;
+}
+
+}
+

tests/runner.py

@@ -7747,6 +7747,9 @@ elif 'browser' in str(sys.argv):
     def test_emscripten_api(self):
       self.btest('emscripten_api_browser.cpp', '1')
 
+    def test_emscripten_fs_api(self):
+      self.btest('emscripten_fs_api_browser.cpp', '1')
+
     def test_gc(self):
       self.btest('browser_gc.cpp', '1')