Fix ES module deserialization

api-test.c

@@ -3,6 +3,7 @@
 #endif
 #include <assert.h>
 #include <stdlib.h>
+#include <string.h>
 #include "quickjs.h"
 
 #define MAX_TIME 10
@@ -180,12 +181,66 @@ static void is_array(void)
     JS_FreeRuntime(rt);
 }
 
+static int loader_calls;
+
+static JSModuleDef *loader(JSContext *ctx, const char *name, void *opaque)
+{
+    loader_calls++;
+    assert(!strcmp(name, "b"));
+    static const char code[] = "export function f(x){}";
+    JSValue ret = JS_Eval(ctx, code, strlen(code), "b",
+                          JS_EVAL_TYPE_MODULE|JS_EVAL_FLAG_COMPILE_ONLY);
+    assert(!JS_IsException(ret));
+    JSModuleDef *m = JS_VALUE_GET_PTR(ret);
+    assert(m);
+    JS_FreeValue(ctx, ret);
+    return m;
+}
+
+static void module_serde(void)
+{
+    JSRuntime *rt = JS_NewRuntime();
+    JS_SetDumpFlags(rt, JS_DUMP_MODULE_RESOLVE);
+    JS_SetModuleLoaderFunc(rt, NULL, loader, NULL);
+    JSContext *ctx = JS_NewContext(rt);
+    static const char code[] = "import {f} from 'b'; f()";
+    assert(loader_calls == 0);
+    JSValue mod = JS_Eval(ctx, code, strlen(code), "a",
+                          JS_EVAL_TYPE_MODULE|JS_EVAL_FLAG_COMPILE_ONLY);
+    assert(loader_calls == 1);
+    assert(!JS_IsException(mod));
+    assert(JS_IsModule(mod));
+    size_t len = 0;
+    uint8_t *buf = JS_WriteObject(ctx, &len, mod,
+                                  JS_WRITE_OBJ_BYTECODE|JS_WRITE_OBJ_REFERENCE);
+    assert(buf);
+    assert(len > 0);
+    JS_FreeValue(ctx, mod);
+    assert(loader_calls == 1);
+    mod = JS_ReadObject(ctx, buf, len, JS_READ_OBJ_BYTECODE);
+    free(buf);
+    assert(loader_calls == 1); // 'b' is returned from cache
+    assert(!JS_IsException(mod));
+    JSValue ret = JS_EvalFunction(ctx, mod);
+    assert(!JS_IsException(ret));
+    assert(JS_IsPromise(ret));
+    JSValue result = JS_PromiseResult(ctx, ret);
+    assert(!JS_IsException(result));
+    assert(JS_IsUndefined(result));
+    JS_FreeValue(ctx, result);
+    JS_FreeValue(ctx, ret);
+    JS_FreeValue(ctx, mod);
+    JS_FreeContext(ctx);
+    JS_FreeRuntime(rt);
+}
+
 int main(void)
 {
     sync_call();
     async_call();
     async_call_stack_overflow();
     raw_context_global_var();
     is_array();
+    module_serde();
     return 0;
 }

quickjs.c

@@ -35150,8 +35150,21 @@ static JSValue JS_ReadModule(BCReaderState *s)
             goto fail;
         for(i = 0; i < m->req_module_entries_count; i++) {
             JSReqModuleEntry *rme = &m->req_module_entries[i];
+            JSModuleDef **pm = &rme->module;
             if (bc_get_atom(s, &rme->module_name))
                 goto fail;
+            // Resolves a module either from the cache or by requesting
+            // it from the module loader. From cache is not ideal because
+            // the module may not be the one it was a time of serialization
+            // but directly petitioning the module loader is not correct
+            // either because then the same module can get loaded twice.
+            // JS_WriteModule() does not serialize modules transitively
+            // because that doesn't work for C modules and is also prone
+            // to loading the same JS module twice.
+            *pm = js_host_resolve_imported_module_atom(s->ctx, m->module_name,
+                                                       rme->module_name);
+            if (!*pm)
+                goto fail;
         }
     }
 

quickjs.h

@@ -662,6 +662,11 @@ static inline bool JS_IsObject(JSValue v)
     return JS_VALUE_GET_TAG(v) == JS_TAG_OBJECT;
 }
 
+static inline bool JS_IsModule(JSValue v)
+{
+    return JS_VALUE_GET_TAG(v) == JS_TAG_MODULE;
+}
+
 JS_EXTERN JSValue JS_Throw(JSContext *ctx, JSValue obj);
 JS_EXTERN JSValue JS_GetException(JSContext *ctx);
 JS_EXTERN bool JS_HasException(JSContext *ctx);