WASIX libc compatibility tests

.gitignore

@@ -3,3 +3,4 @@
 build
 .vscode
 dist
+test-builds

TESTING.md

@@ -0,0 +1,107 @@
+# WASIX libc tests
+
+This repo has a small WASIX-focused test suite under `test/wasix`. These tests
+compile C/C++ sources to WASI/WASIX wasm and run them with Wasmer.
+
+The key things that make the suite pass are:
+
+- **Use a non‑EH sysroot + toolchain** (no wasm exceptions). This mirrors the
+  working setup in `wasix-tests/wasmer/tests/c-wasi-tests/Makefile`.
+- **Do not force `--enable-all`** when running Wasmer. Let Wasmer detect module
+  features.
+- **Pick a Wasmer binary with WASIX support** (the wasix-tests repo build works).
+
+## Quickstart (known‑good)
+
+```bash
+export PATH="$HOME/.wasixcc/llvm/bin:$PATH"
+export CC="$HOME/.wasixcc/llvm/bin/clang"
+export CXX="$HOME/.wasixcc/llvm/bin/clang++"
+export WASIX_TRIPLE=wasm32-wasi
+
+# Non‑EH toolchain (avoids legacy-exceptions + libunwind issues)
+export TOOLCHAIN="$(pwd)/tools/clang-wasix-pic.cmake_toolchain"
+
+# Non‑EH sysroot (from wasixcc)
+export WASIX_SYSROOT_PIC="$HOME/.wasixcc/sysroot/sysroot"
+
+# Wasmer runtime + backend
+export WASMER_BACKEND_FLAG=--llvm
+# Optional: use a specific Wasmer binary (e.g. from wasix-tests)
+# export WASMER_BIN="/Users/fessguid/Projects/wasix-tests/wasmer/target/release/wasmer"
+
+./test/wasix/run_tests.sh
+```
+
+## Single test
+
+```bash
+./test/wasix/run_tests.sh cpp_executable
+```
+
+## Why this toolchain/sysroot?
+
+The tests match the c‑wasi‑tests Makefile in the `wasix-tests` repo:
+
+- uses `--target=wasm32-wasi` + `-matomics -mbulk-memory -mmutable-globals -pthread`
+- **does not enable wasm exceptions**
+- runs under Wasmer with `--enable-threads` and standard WASI caps
+
+Using the non‑EH sysroot (`~/.wasixcc/sysroot/sysroot`) avoids:
+
+- `legacy_exceptions` validation errors in Wasmer
+- missing `libunwind` when using the non‑EH sysroot
+- `__c_longjmp` tag import expectations
+
+## Common problems & fixes
+
+### 1) `legacy_exceptions feature required for try instruction`
+
+You are compiling with wasm EH enabled (or using an EH sysroot). Switch to
+`tools/clang-wasix-pic.cmake_toolchain` and `~/.wasixcc/sysroot/sysroot`.
+
+### 2) `unknown import env.__c_longjmp` / `__cpp_exception`
+
+Your module expects wasm EH tags. Either:
+
+- use the non‑EH toolchain+sysroot (preferred for these tests), or
+- ensure Wasmer supports wasm EH tags and you use an EH sysroot.
+
+### 3) `wasm-ld: unable to find library -lunwind`
+
+You are using a toolchain that links `-lunwind` with a sysroot that does not
+provide `libunwind` (the non‑EH sysroot). Use the non‑EH toolchain file or an
+EH sysroot that includes `libunwind`.
+
+### 4) CMake warning: `System is unknown to cmake, create: Platform/WASI`
+
+This is a CMake warning and can be ignored for these tests.
+
+## Updating libc for local changes
+
+If you change libc sources in this repo (e.g. `sigsetjmp`), you need those
+objects in the sysroot used by the tests.
+
+One practical path on macOS:
+
+1) Build libc (C only) in this repo:
+   - `build32.sh` builds libc into `sysroot/` but may fail later while building
+     libc++. That is OK if you only need `libc.a`.
+   - If `sed -i` fails on macOS, use GNU sed (`gsed`) or run the script with a
+     small sed wrapper.
+2) Replace the libc in the wasixcc sysroot:
+   - copy `sysroot/lib/wasm32-wasi/libc.a` → `$HOME/.wasixcc/sysroot/sysroot/lib/wasm32-wasi/libc.a`
+3) Re-run `test/wasix/run_tests.sh` with the same env from Quickstart.
+
+## Toolchain files
+
+- `tools/clang-wasix.cmake_toolchain` — enables wasm EH (`-fwasm-exceptions`) and
+  links `libunwind`. Use with an EH sysroot (e.g. `sysroot-eh`) if needed.
+- `tools/clang-wasix-pic.cmake_toolchain` — **non‑EH** toolchain used for tests.
+
+## Environment variables used by the test runner
+
+- `TOOLCHAIN` — CMake toolchain file used to build each test.
+- `WASIX_SYSROOT_PIC` — sysroot path passed to CMake.
+- `WASMER_BACKEND_FLAG` — e.g. `--llvm` (default in test scripts).
+- `WASMER_BIN` — optional path to a Wasmer binary (defaults to `wasmer`).

libc-top-half/musl/src/ldso/dlclose.c

@@ -2,8 +2,23 @@
 #include "dynlink.h"
 #include "wasi/api.h"
 
+extern __wasi_dl_handle_t __wasix_main_dl_handle;
+extern int __wasix_dl_release(__wasi_dl_handle_t handle, int *should_close);
+
 int dlclose(void *p)
 {
+	if (__wasix_main_dl_handle != 0 && (__wasi_dl_handle_t)p == __wasix_main_dl_handle)
+	{
+		return 0;
+	}
+
+	int should_close = 0;
+	int known = __wasix_dl_release((__wasi_dl_handle_t)p, &should_close);
+	if (known && !should_close)
+	{
+		return 0;
+	}
+
 	int err = __wasi_dl_invalid_handle((__wasi_dl_handle_t)p);
 	if (err != 0)
 	{

libc-top-half/musl/src/ldso/dlopen.c

@@ -4,6 +4,125 @@
 #include "string.h"
 #include "stdlib.h"
 
+__wasi_dl_handle_t __wasix_main_dl_handle = 0;
+
+struct __wasix_dl_entry {
+	char *name;
+	__wasi_dl_handle_t handle;
+	int flags;
+	int refcount;
+	struct __wasix_dl_entry *next;
+};
+
+static struct __wasix_dl_entry *__wasix_dl_list = NULL;
+
+static struct __wasix_dl_entry *__wasix_find_by_name(const char *name)
+{
+	struct __wasix_dl_entry *cur = __wasix_dl_list;
+	while (cur) {
+		if (cur->name && strcmp(cur->name, name) == 0) {
+			return cur;
+		}
+		cur = cur->next;
+	}
+	return NULL;
+}
+
+static struct __wasix_dl_entry *__wasix_find_by_handle(__wasi_dl_handle_t handle)
+{
+	struct __wasix_dl_entry *cur = __wasix_dl_list;
+	while (cur) {
+		if (cur->handle == handle) {
+			return cur;
+		}
+		cur = cur->next;
+	}
+	return NULL;
+}
+
+int __wasix_dl_handle_alive(__wasi_dl_handle_t handle)
+{
+	return __wasix_find_by_handle(handle) != NULL;
+}
+
+static void __wasix_add_or_update(const char *name, __wasi_dl_handle_t handle, int mode)
+{
+	struct __wasix_dl_entry *entry = __wasix_find_by_name(name);
+	if (entry) {
+		entry->handle = handle;
+		entry->flags |= mode;
+		entry->refcount += 1;
+		return;
+	}
+
+	entry = __wasix_find_by_handle(handle);
+	if (entry) {
+		entry->flags |= mode;
+		entry->refcount += 1;
+		return;
+	}
+
+	entry = (struct __wasix_dl_entry *)calloc(1, sizeof(*entry));
+	if (!entry) {
+		return;
+	}
+
+	entry->name = strdup(name);
+	if (!entry->name) {
+		free(entry);
+		return;
+	}
+
+	entry->handle = handle;
+	entry->flags = mode;
+	entry->refcount = 1;
+	entry->next = __wasix_dl_list;
+	__wasix_dl_list = entry;
+}
+
+size_t __wasix_dl_copy_global_handles(__wasi_dl_handle_t *out, size_t max)
+{
+	size_t count = 0;
+	struct __wasix_dl_entry *cur = __wasix_dl_list;
+	while (cur && count < max) {
+		if (cur->flags & RTLD_GLOBAL) {
+			out[count++] = cur->handle;
+		}
+		cur = cur->next;
+	}
+	return count;
+}
+
+int __wasix_dl_release(__wasi_dl_handle_t handle, int *should_close)
+{
+	struct __wasix_dl_entry *cur = __wasix_dl_list;
+	struct __wasix_dl_entry *prev = NULL;
+
+	while (cur) {
+		if (cur->handle == handle) {
+			if (cur->refcount > 1) {
+				cur->refcount -= 1;
+				*should_close = 0;
+				return 1;
+			}
+
+			if (prev) {
+				prev->next = cur->next;
+			} else {
+				__wasix_dl_list = cur->next;
+			}
+			free(cur->name);
+			free(cur);
+			*should_close = 1;
+			return 1;
+		}
+		prev = cur;
+		cur = cur->next;
+	}
+
+	return 0;
+}
+
 void *dlopen(const char *file, int mode)
 {
 	__wasi_dl_handle_t ret = 0;
@@ -12,6 +131,17 @@ void *dlopen(const char *file, int mode)
 
 	char *ld_library_path = getenv("LD_LIBRARY_PATH");
 
+	if (file && (mode & RTLD_NOLOAD)) {
+		struct __wasix_dl_entry *entry = __wasix_find_by_name(file);
+		if (entry) {
+			entry->flags |= mode;
+			entry->refcount += 1;
+			return (void *)entry->handle;
+		}
+		__dl_seterr("dlopen failed: library \"%s\" wasn't loaded and RTLD_NOLOAD prevented it", file);
+		return NULL;
+	}
+
 	int err = __wasi_dlopen(file, mode, (uint8_t *)err_buf, sizeof(err_buf), ld_library_path, &ret);
 
 	if (err != 0)
@@ -27,5 +157,14 @@ void *dlopen(const char *file, int mode)
 		return NULL;
 	}
 
+	if (file == NULL && ret != 0)
+	{
+		__wasix_main_dl_handle = ret;
+	}
+	else if (file != NULL && ret != 0)
+	{
+		__wasix_add_or_update(file, ret, mode);
+	}
+
 	return (void *)ret;
 }

libc-top-half/musl/src/ldso/dlsym.c

@@ -3,12 +3,71 @@
 #include "wasi/api.h"
 #include "string.h"
 
+extern __wasi_dl_handle_t __wasix_main_dl_handle;
+size_t __wasix_dl_copy_global_handles(__wasi_dl_handle_t *out, size_t max);
+int __wasix_dl_handle_alive(__wasi_dl_handle_t handle);
+
+static void *__wasix_dlsym_handle(__wasi_dl_handle_t handle, const char *s, char *err_buf, size_t err_buf_len, int *err_out, __wasi_size_t *ret_out)
+{
+	err_buf[0] = '\0';
+	int err = __wasi_dlsym(handle, s, (uint8_t *)err_buf, err_buf_len, ret_out);
+	if (err == 0) {
+		return (void *)*ret_out;
+	}
+	*err_out = err;
+	return NULL;
+}
+
 void *dlsym(void *restrict p, const char *restrict s)
 {
 	__wasi_size_t ret;
 	char err_buf[256];
 	err_buf[0] = '\0';
 
+	if (p == RTLD_DEFAULT) {
+		__wasi_dl_handle_t handles[64];
+		char last_err_buf[256];
+		int last_err = 0;
+		last_err_buf[0] = '\0';
+
+		if (__wasix_main_dl_handle) {
+			void *found = __wasix_dlsym_handle(__wasix_main_dl_handle, s, err_buf, sizeof(err_buf), &last_err, &ret);
+			if (found) {
+				return found;
+			}
+			if (err_buf[0] != '\0') {
+				strncpy(last_err_buf, err_buf, sizeof(last_err_buf));
+				last_err_buf[sizeof(last_err_buf) - 1] = '\0';
+			}
+		}
+
+		size_t count = __wasix_dl_copy_global_handles(handles, sizeof(handles) / sizeof(handles[0]));
+		for (size_t i = 0; i < count; i++) {
+			void *found = __wasix_dlsym_handle(handles[i], s, err_buf, sizeof(err_buf), &last_err, &ret);
+			if (found) {
+				return found;
+			}
+			if (err_buf[0] != '\0') {
+				strncpy(last_err_buf, err_buf, sizeof(last_err_buf));
+				last_err_buf[sizeof(last_err_buf) - 1] = '\0';
+			}
+		}
+
+		if (last_err_buf[0] != '\0') {
+			__dl_seterr("%s", last_err_buf);
+		} else if (last_err != 0) {
+			__dl_seterr("dlsym failed with error %s", strerror(last_err));
+		} else {
+			__dl_seterr("dlsym failed: symbol \"%s\" not found", s);
+		}
+		return NULL;
+	}
+
+	if (p != NULL && (__wasi_dl_handle_t)p != __wasix_main_dl_handle && !__wasix_dl_handle_alive((__wasi_dl_handle_t)p)) {
+		__dl_seterr("dlsym failed: invalid handle");
+		return NULL;
+	}
+
 	int err = __wasi_dlsym((__wasi_dl_handle_t)p, s, (uint8_t *)err_buf, sizeof(err_buf), &ret);
 
 	if (err != 0)

libc-top-half/musl/src/linux/setgroups.c

@@ -43,6 +43,11 @@ int setgroups(size_t count, const gid_t list[])
 	__synccall(do_setgroups, &c);
 	return __syscall_ret(c.ret);
 #else
+  /* WASIX does not currently support supplementary groups.
+   * Allow clearing the list as a no-op for compatibility. */
+  if (count == 0) {
+    return 0;
+  }
   errno = ENOTSUP;
   return -1;
 #endif