support for writing to files in stdio

src/library.js

@@ -228,19 +228,19 @@ var Library = {
       _stdin = Pointer_make([0], null, ALLOC_STATIC);
       IHEAP[_stdin] = this.prepare('<<stdin>>');
       _stdout = Pointer_make([0], null, ALLOC_STATIC);
-      IHEAP[_stdout] = this.prepare('<<stdout>>');
+      IHEAP[_stdout] = this.prepare('<<stdout>>', null, true);
       _stderr = Pointer_make([0], null, ALLOC_STATIC);
-      IHEAP[_stderr] = this.prepare('<<stderr>>');
+      IHEAP[_stderr] = this.prepare('<<stderr>>', null, true);
     },
-    prepare: function(filename, data) {
+    prepare: function(filename, data, print_) {
       var stream = this.counter++;
       this.streams[stream] = {
         filename: filename,
-        data: data,
+        data: data ? data : [],
         position: 0,
         eof: 0,
         error: 0,
-        print: 1 // true for stdout and stderr - we print when receiving data for them
+        print: print_ // true for stdout and stderr - we print when receiving data for them
       };
       this.filenames[filename] = stream;
       return stream;
@@ -249,9 +249,19 @@ var Library = {
 
   fopen__deps: ['STDIO'],
   fopen: function(filename, mode) {
-    var str = Pointer_stringify(filename);
-    //assert(str in this._STDIO.filenames, 'No information for file: ' + str);
-    return this._STDIO.filenames[str];
+    filename = Pointer_stringify(filename);
+    mode = Pointer_stringify(mode);
+    if (mode.indexOf('r') >= 0) {
+      //assert(filename in this._STDIO.filenames, 'No information for file: ' + filename);
+      var stream = this._STDIO.filenames[filename];
+      var info = this._STDIO.streams[stream];
+      info.position = info.error = info.eof = 0;
+      return stream;
+    } else if (mode.indexOf('w') >= 0) {
+      return this._STDIO.prepare(filename);
+    } else {
+      assert(false, 'fopen with odd params: ' + mode);
+    }
   },
   __01fopen64_: 'fopen',
 
@@ -304,7 +314,13 @@ var Library = {
     var info = this._STDIO.streams[stream];
     if (info.print) {
       __print__(intArrayToString(Array_copy(ptr, count*size)));
-    } // XXX
+    } else {
+      for (var i = 0; i < size*count; i++) {
+        info.data[info.position] = HEAP[ptr];
+        info.position++;
+        ptr++;
+      }
+    }
     return count;
   },
 

src/postamble.js

@@ -38,3 +38,5 @@ Module['run'] = run;
 run(args);
 #endif
 
+// {{POST_RUN_ADDITIONS}}
+

tests/files.cpp

@@ -2,7 +2,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int main() {
+int main()
+{
+  // Reading
+
   FILE *file = fopen("somefile.binary", "rb");
   assert(file);
 
@@ -25,9 +28,24 @@ int main() {
   fclose (file);
   free (buffer);
 
+  // Standard streams
+
   fwrite("texto\n", 1, 6, stdout);
   fwrite("texte\n", 1, 6, stderr);
 
+  // Writing
+
+  char data[5] = { 10, 30, 20, 11, 88 };
+  FILE *outf = fopen("go.out", "wb");
+  fwrite(data, 1, 5, outf);
+  fclose(outf);
+
+  char data2[10];
+  FILE *inf = fopen("go.out", "rb");
+  int num = fread(data2, 1, 10, inf);
+  fclose(inf);
+  printf("%d : %d,%d,%d,%d,%d\n", num, data2[0], data2[1], data2[2], data2[3], data2[4]);
+
   return 0;
 }
 

tests/runner.py

@@ -1302,7 +1302,7 @@ if 'benchmark' not in sys.argv:
         )
         open(filename, 'w').write(src)
       src = open(path_from_root('tests', 'files.cpp'), 'r').read()
-      self.do_test(src, 'size: 7\ndata: 100,200,50,25,10,77,123\ntexto\ntexte\n', post_build=post)
+      self.do_test(src, 'size: 7\ndata: 100,200,50,25,10,77,123\ntexto\ntexte\n5 : 10,30,20,11,88\n', post_build=post)
 
     ### 'Big' tests