From 3b1c108eaeec19c67cf1292d60ab43fb052526c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sa=C3=BAl=20Ibarra=20Corretg=C3=A9?= <s@saghul.net>
Date: Tue, 9 Jun 2026 17:00:59 +0200
Subject: [PATCH] Disable standalone executable support under WASM/Emscripten

---
 qjs.c | 48 +++++++++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/qjs.c b/qjs.c
index bdf8d2d45..965339102 100644
--- a/qjs.c
+++ b/qjs.c
@@ -45,16 +45,23 @@ extern const uint32_t qjsc_repl_size;
 extern const uint8_t qjsc_standalone[];
 extern const uint32_t qjsc_standalone_size;
 
+#if defined(EMSCRIPTEN) || defined(__wasi__)
+// Standalone executables (the --compile option and detecting/running an
+// executable with appended bytecode) can't work in these environments.
+#define emscripten_or_wasi 1
+#else
+#define emscripten_or_wasi 0
+#endif
+
+static int qjs__argc;
+static char **qjs__argv;
+
 // Must match standalone.js
 #define TRAILER_SIZE 12
 static const char trailer_magic[] = "quickjs2";
 static const int trailer_magic_size = sizeof(trailer_magic) - 1;
 static const int trailer_size = TRAILER_SIZE;
 
-static int qjs__argc;
-static char **qjs__argv;
-
-
 static bool is_standalone(const char *exe)
 {
     FILE *exe_f = fopen(exe, "rb");
@@ -386,13 +393,15 @@ void help(int exit_status)
            "    --std          make 'std', 'os' and 'bjson' available to script\n"
            "-T  --trace        trace memory allocation\n"
            "-d  --dump         dump the memory usage stats\n"
-           "-D  --dump-flags   flags for dumping debug data (see DUMP_* defines)\n"
-           "-c  --compile FILE compile the given JS file as a standalone executable\n"
-           "-o  --out FILE     output file for standalone executables\n"
-           "    --exe          select the executable to use as the base, defaults to the current one\n"
-           "    --memory-limit n       limit the memory usage to 'n' Kbytes\n"
+           "-D  --dump-flags   flags for dumping debug data (see DUMP_* defines)\n",
+           JS_GetVersion());
+    if (!emscripten_or_wasi)
+        printf("-c  --compile FILE compile the given JS file as a standalone executable\n"
+               "-o  --out FILE     output file for standalone executables\n"
+               "    --exe          select the executable to use as the base, defaults to the current one\n");
+    printf("    --memory-limit n       limit the memory usage to 'n' Kbytes\n"
            "    --stack-size n         limit the stack size to 'n' Kbytes\n"
-           "-q  --quit         just instantiate the interpreter and quit\n", JS_GetVersion());
+           "-q  --quit         just instantiate the interpreter and quit\n");
     exit(exit_status);
 }
 
@@ -400,18 +409,18 @@ int main(int argc, char **argv)
 {
     JSRuntime *rt;
     JSContext *ctx;
-    JSValue ret = JS_UNDEFINED;
     struct trace_malloc_data trace_data = { NULL };
     int r = 0;
     int optind = 1;
+    JSValue ret = JS_UNDEFINED;
     char exebuf[JS__PATH_MAX];
     size_t exebuf_size = sizeof(exebuf);
     char *compile_file = NULL;
     char *exe = NULL;
-    char *expr = NULL;
-    char *dump_flags_str = NULL;
     char *out = NULL;
     int standalone = 0;
+    char *expr = NULL;
+    char *dump_flags_str = NULL;
     int interactive = 0;
     int dump_memory = 0;
     int dump_flags = 0;
@@ -429,8 +438,8 @@ int main(int argc, char **argv)
     qjs__argv = argv;
 
     /* check if this is a standalone executable */
-
-    if (!js_exepath(exebuf, &exebuf_size) && is_standalone(exebuf)) {
+    if (!emscripten_or_wasi &&
+            !js_exepath(exebuf, &exebuf_size) && is_standalone(exebuf)) {
         standalone = 1;
         goto start;
     }
@@ -549,7 +558,8 @@ int main(int argc, char **argv)
                 stack_size = parse_limit(optarg);
                 break;
             }
-            if (opt == 'c' || !strcmp(longopt, "compile")) {
+            if (!emscripten_or_wasi &&
+                    (opt == 'c' || !strcmp(longopt, "compile"))) {
                 if (!optarg) {
                     if (optind >= argc) {
                         fprintf(stderr, "qjs: missing file for -c\n");
@@ -560,7 +570,7 @@ int main(int argc, char **argv)
                 compile_file = optarg;
                 break;
             }
-            if (opt == 'o' || !strcmp(longopt, "out")) {
+            if (!emscripten_or_wasi && (opt == 'o' || !strcmp(longopt, "out"))) {
                 if (!optarg) {
                     if (optind >= argc) {
                         fprintf(stderr, "qjs: missing file for -o\n");
@@ -571,7 +581,7 @@ int main(int argc, char **argv)
                 out = optarg;
                 break;
             }
-            if (!strcmp(longopt, "exe")) {
+            if (!emscripten_or_wasi && !strcmp(longopt, "exe")) {
                 if (!optarg) {
                     if (optind >= argc) {
                         fprintf(stderr, "qjs: missing file for --exe\n");
@@ -591,7 +601,7 @@ int main(int argc, char **argv)
         }
     }
 
-    if (compile_file && !out)
+    if (!emscripten_or_wasi && compile_file && !out)
         help(1);
 
 start: