init runtime immediately, so that even with noInitialRun we can still call filesystem-using functions and they will work

4 files changed, 17 insertions, 5 deletions

diff --git a/src/library.js b/src/library.js
index 56583c76..19b8e90f 100644
--- a/src/library.js
+++ b/src/library.js
@@ -26,7 +26,8 @@ LibraryManager.library = {
   _impure_ptr: 0,
 
   $FS__deps: ['$ERRNO_CODES', '__setErrNo', 'stdin', 'stdout', 'stderr', '_impure_ptr'],
-  $FS__postset: '__ATINIT__.unshift({ func: function() { FS.ignorePermissions = false; if (!FS.init.initialized) FS.init() } });' +
+  $FS__postset: '__ATINIT__.unshift({ func: function() { if (!Module["noFSInit"] && !FS.init.initialized) FS.init() } });' +
+                '__ATMAIN__.push({ func: function() { FS.ignorePermissions = false } });' +
                 '__ATEXIT__.push({ func: function() { FS.quit() } });',
   $FS: {
     // The path to the current folder.
diff --git a/src/postamble.js b/src/postamble.js
index 1f4c9c04..cf863669 100644
--- a/src/postamble.js
+++ b/src/postamble.js
@@ -40,10 +40,9 @@ function run(args) {
     Module['preRun']();
   }
 
-  initRuntime();
-
   var ret = null;
   if (Module['_main']) {
+    preMain();
     ret = Module.callMain(args);
     if (!Module['noExitRuntime']) {
       exitRuntime();
@@ -60,6 +59,8 @@ Module['run'] = run;
 
 // {{PRE_RUN_ADDITIONS}}
 
+initRuntime();
+
 #if INVOKE_RUN
 #else
 addRunDependency();
diff --git a/src/preamble.js b/src/preamble.js
index 39412bc3..968571a0 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -697,12 +697,15 @@ function callRuntimeCallbacks(callbacks) {
 }
 
 var __ATINIT__ = []; // functions called during startup
+var __ATMAIN__ = []; // functions called when main() is to be run
 var __ATEXIT__ = []; // functions called during shutdown
 
 function initRuntime() {
   callRuntimeCallbacks(__ATINIT__);
 }
-
+function preMain() {
+  callRuntimeCallbacks(__ATMAIN__);
+}
 function exitRuntime() {
   callRuntimeCallbacks(__ATEXIT__);
 
diff --git a/tests/runner.py b/tests/runner.py
index 477cd29c..3baf91fd 100755
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -3825,6 +3825,7 @@ Pass: 0.000012 0.000012''')
 def process(filename):
   src = \'\'\'
     var Module = {
+      'noFSInit': true,
       'preRun': function() {
         FS.createDataFile('/', 'somefile.binary', [100, 200, 50, 25, 10, 77, 123], true, false);  // 200 becomes -56, since signed chars are used in memory
         FS.createLazyFile('/', 'test.file', 'test.file', true, false);
@@ -6551,10 +6552,16 @@ f.close()
       # noInitialRun prevents run
       for no_initial_run in [0, 1]:
         Popen(['python', EMCC, os.path.join(self.get_dir(), 'main.cpp')]).communicate()
-        src = 'var Module = { noInitialRun: %d };\n' % no_initial_run + open(os.path.join(self.get_dir(), 'a.out.js')).read();
+        src = 'var Module = { noInitialRun: %d };\n' % no_initial_run + open(os.path.join(self.get_dir(), 'a.out.js')).read()
         open(os.path.join(self.get_dir(), 'a.out.js'), 'w').write(src)
         assert ('hello from main' in run_js(os.path.join(self.get_dir(), 'a.out.js'))) != no_initial_run, 'only run if no noInitialRun'
 
+        if no_initial_run:
+          # Calling main later should still work, filesystem etc. must be set up.
+          src = open(os.path.join(self.get_dir(), 'a.out.js')).read() + '\n_main();\n';
+          open(os.path.join(self.get_dir(), 'a.out.js'), 'w').write(src)
+          assert 'hello from main' in run_js(os.path.join(self.get_dir(), 'a.out.js')), 'main should print when called manually'
+
     def test_eliminator(self):
       input = open(path_from_root('tools', 'eliminator', 'eliminator-test.js')).read()
       expected = open(path_from_root('tools', 'eliminator', 'eliminator-test-output.js')).read()