Added basic support for dynamic module loading.

5 files changed, 163 insertions, 5 deletions

diff --git a/src/jsifier.js b/src/jsifier.js
index 71797daa..27b27252 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -261,7 +261,12 @@ function JSify(data, functionsOnly, givenFunctions, givenGlobalVariables) {
           } else {
             ident = '_' + ident;
           }
-          return (deps ? '\n' + deps.map(addFromLibrary).join('\n') : '') + 'var ' + ident + '=' + snippet + ';';
+          var depsString =  deps ? '\n' + deps.map(addFromLibrary).join('\n') : '';
+          var defString = 'var ' + ident + '=' + snippet + ';';
+          if (BUILD_AS_SHARED_LIB) {
+            defString = 'if (typeof ' + ident + ' == "undefined") {\n  ' + defString + '\n}';
+          }
+          return depsString + defString;
         }
         item.JS = addFromLibrary(shortident);
       } else {
@@ -764,14 +769,18 @@ function JSify(data, functionsOnly, givenFunctions, givenGlobalVariables) {
     //        postamble
     //          global_vars
 
-    var shellParts = read('shell.js').split('{{BODY}}');
+    var shellFile = BUILD_AS_SHARED_LIB ? 'shell_sharedlib.js' : 'shell.js';
+    var shellParts = read(shellFile).split('{{BODY}}');
     print(shellParts[0]);
-      var pre = processMacros(preprocess(read('preamble.js').replace('{{RUNTIME}}', getRuntime()), CONSTANTS));
-      print(pre);
+      if (!BUILD_AS_SHARED_LIB) {
+        var pre = processMacros(preprocess(read('preamble.js').replace('{{RUNTIME}}', getRuntime()), CONSTANTS));
+        print(pre);
+      }
       generated.forEach(function(item) { print(indentify(item.JS || '', 2)); });
       print(Functions.generateIndexing());
 
-      var postParts = processMacros(preprocess(read('postamble.js'), CONSTANTS)).split('{{GLOBAL_VARS}}');
+      var postFile = BUILD_AS_SHARED_LIB ? 'postamble_sharedlib.js' : 'postamble.js';
+      var postParts = processMacros(preprocess(read(postFile), CONSTANTS)).split('{{GLOBAL_VARS}}');
       print(postParts[0]);
         itemsDict.GlobalVariable.forEach(function(item) { print(indentify(item.JS, 4)); });
         itemsDict.GlobalVariablePostSet.forEach(function(item) { print(indentify(item.JS, 4)); });
diff --git a/src/library.js b/src/library.js
index c73b94ad..d2b05764 100644
--- a/src/library.js
+++ b/src/library.js
@@ -1194,6 +1194,123 @@ var Library = {
     return Math.pow(2, x);
   },
 
+  
+  // ==========================================================================
+  // dlfcn.h
+  // ==========================================================================
+
+  // Data for dlfcn.h.
+  $DLFCN_DATA: {
+    error: null,
+    is_error: false,
+    loaded_libs: {}, // handle -> [refcount, name, lib_object]
+    loaded_lib_names: {}, // name -> handle
+  },
+  // void* dlopen(const char* filename, int flag);
+  dlopen__deps: ['$DLFCN_DATA'],
+  dlopen: function(filename, flag) {
+    filename = Pointer_stringify(filename);
+    filename += '.js';
+
+    if (DLFCN_DATA.loaded_lib_names[filename]) {
+      // Already loaded; increment ref count and return.
+      var handle = DLFCN_DATA.loaded_lib_names[filename];
+      DLFCN_DATA.loaded_libs[handle][0]++;
+      return handle;
+    }
+
+    try {
+      var lib_data = read(filename);
+    } catch (e) {
+      DLFCN_DATA.is_error = true;
+      return 0;
+    }
+
+    try {
+      var lib_module = eval(lib_data)();
+    } catch (e) {
+      DLFCN_DATA.is_error = true;
+      return 0;
+    }
+
+    // Not all browsers support Object.keys().
+    var handle = 1;
+    for (var key in DLFCN_DATA.loaded_libs) {
+      if (DLFCN_DATA.loaded_libs.hasOwnProperty(key)) handle++;
+    }
+
+    DLFCN_DATA.loaded_libs[handle] = [1, filename, lib_module];
+    DLFCN_DATA.loaded_lib_names[filename] = handle;
+
+    // We don't care about RTLD_NOW and RTLD_LAZY.
+    if (flag & 256) { // RTLD_GLOBAL
+      for (var ident in lib_module) {
+        if (lib_module.hasOwnProperty(ident)) {
+          // TODO: Check if we need to unmangle here.
+          Module[ident] = lib_module[ident];
+        }
+      }
+    }
+
+    return handle;
+  },
+  // int dlclose(void* handle);
+  dlclose__deps: ['$DLFCN_DATA'],
+  dlclose: function(handle) {
+    if (!DLFCN_DATA.loaded_libs[handle]) {
+      DLFCN_DATA.is_error = true;
+      return 1;
+    } else {
+      var lib_record = DLFCN_DATA.loaded_libs[handle];
+      if (lib_record[0]-- == 0) {
+        delete DLFCN_DATA.loaded_lib_names[lib_record[1]];
+        delete DLFCN_DATA.loaded_libs[handle];
+      }
+      return 0;
+    }
+  },
+  // void* dlsym(void* handle, const char* symbol);
+  dlsym__deps: ['$DLFCN_DATA'],
+  dlsym: function(handle, symbol) {
+    symbol = Pointer_stringify(symbol);
+    // TODO: Properly mangle.
+    symbol = '_' + symbol;
+
+    if (!DLFCN_DATA.loaded_libs[handle]) {
+      DLFCN_DATA.is_error = true;
+      return 0;
+    } else {
+      var lib_module = DLFCN_DATA.loaded_libs[handle][2];
+      if (!lib_module[symbol]) {
+        DLFCN_DATA.is_error = true;
+        return 0;
+      } else {
+        var result = lib_module[symbol];
+        if (typeof result == 'function') {
+          FUNCTION_TABLE.push(result);
+          result = FUNCTION_TABLE.length - 1;
+        }
+        return result;
+      }
+    }
+  },
+  // char* dlerror(void);
+  dlerror__deps: ['$DLFCN_DATA'],
+  dlerror: function() {
+    if (DLFCN_DATA.is_error) {
+      return 0;
+    } else {
+      // TODO: Return non-generic error messages.
+      if (DLFCN_DATA.error === null) {
+        var msg = 'An error occurred while loading dynamic library.';
+        var arr = Module.intArrayFromString(msg)
+        DLFCN_DATA.error = Pointer_make(arr, 0, 2, 'i8');
+      }
+      DLFCN_DATA.is_error = false;
+      return DLFCN_DATA.error;
+    }
+  },
+
   // ==========================================================================
   // unistd.h
   // ==========================================================================
diff --git a/src/postamble_sharedlib.js b/src/postamble_sharedlib.js
new file mode 100644
index 00000000..1fd78f23
--- /dev/null
+++ b/src/postamble_sharedlib.js
@@ -0,0 +1,15 @@
+
+// === Auto-generated postamble setup entry stuff ===
+
+function run(args) {
+  {{GLOBAL_VARS}}
+  __globalConstructor__();
+}
+Module['run'] = run;
+
+// {{PRE_RUN_ADDITIONS}}
+
+run();
+
+// {{POST_RUN_ADDITIONS}}
+
diff --git a/src/settings.js b/src/settings.js
index f3ed4d06..b756822c 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -107,6 +107,9 @@ EXPORTED_GLOBALS = []; // Global non-function variables that are explicitly
 
 SHOW_LABELS = 0; // Show labels in the generated code
 
+BUILD_AS_SHARED_LIB = 1; // Whether to build the code as a shared library, which
+                         // must be loaded dynamically using dlopen().
+
 // Compiler debugging options
 DEBUG_TAGS_SHOWING = [];
   // Some useful items:
diff --git a/src/shell_sharedlib.js b/src/shell_sharedlib.js
new file mode 100644
index 00000000..d7af23fc
--- /dev/null
+++ b/src/shell_sharedlib.js
@@ -0,0 +1,14 @@
+"use strict";
+
+// Capture the output of this into a variable, if you want
+(function() {
+  var Module = {};
+  var args = [];
+  Module.arguments = [];
+
+  {{BODY}}
+
+  // {{MODULE_ADDITIONS}}
+
+  return Module;
+});