do preRun and postRun only if we actually run

2 files changed, 32 insertions, 8 deletions

diff --git a/src/postamble.js b/src/postamble.js
index 4a2fbf60..c42d6794 100644
--- a/src/postamble.js
+++ b/src/postamble.js
@@ -34,6 +34,10 @@ function run(args) {
 
   initRuntime();
 
+  if (Module['preRun']) {
+    Module['preRun']();
+  }
+
   var ret = null;
   if (Module['_main']) {
     ret = Module.callMain(args);
@@ -41,16 +45,17 @@ function run(args) {
       exitRuntime();
     }
   }
+
+  if (Module['postRun']) {
+    Module['postRun']();
+  }
+
   return ret;
 }
 Module['run'] = run;
 
 // {{PRE_RUN_ADDITIONS}}
 
-if (Module['preRun']) {
-  Module['preRun']();
-}
-
 #if INVOKE_RUN
 #else
 addRunDependency();
@@ -65,7 +70,3 @@ if (runDependencies == 0) {
 
 // {{POST_RUN_ADDITIONS}}
 
-if (Module['postRun']) {
-  Module['postRun']();
-}
-
diff --git a/tests/runner.py b/tests/runner.py
index fddcf1df..00c78a35 100755
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -6539,6 +6539,29 @@ f.close()
       Popen(['python', EMCC, os.path.join(self.get_dir(), 'main.cpp'), '--pre-js', 'before.js', '--post-js', 'after.js']).communicate()
       self.assertContained('hello from main\nhello from js\n', run_js(os.path.join(self.get_dir(), 'a.out.js')))
 
+    def test_prepost(self):
+      open(os.path.join(self.get_dir(), 'main.cpp'), 'w').write('''
+        #include <stdio.h>
+        int main() {
+          printf("hello from main\\n");
+          return 0;
+        }
+      ''')
+      open(os.path.join(self.get_dir(), 'pre.js'), 'w').write('''
+        var Module = {
+          preRun: function() { Module.print('pre-run') },
+          postRun: function() { Module.print('post-run') }
+        };
+      ''')
+
+      Popen(['python', EMCC, os.path.join(self.get_dir(), 'main.cpp'), '--pre-js', 'pre.js']).communicate()
+      self.assertContained('pre-run\nhello from main\npost-run\n', run_js(os.path.join(self.get_dir(), 'a.out.js')))
+
+      # never run, so no preRun or postRun
+      src = open(os.path.join(self.get_dir(), 'a.out.js')).read().replace('// {{PRE_RUN_ADDITIONS}}', 'addRunDependency()')
+      open(os.path.join(self.get_dir(), 'a.out.js'), 'w').write(src)
+      self.assertNotContained('pre-run\nhello from main\npost-run\n', run_js(os.path.join(self.get_dir(), 'a.out.js')))
+
     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()