Use the correct memory for host func

Instead of assuming memory index 0,
look up an export with the name "memory".

lib/cconv.c

@@ -3,6 +3,7 @@
  * a part of core wasm.
  */
 
+#include "cconv.h"
 #include "exec.h"
 #include "instance.h"
 #include "module.h"
@@ -11,6 +12,18 @@
 static const struct name name_func_table =
         NAME_FROM_CSTR_LITERAL("__indirect_function_table");
 
+/*
+ * the export name "memory" is defined by wasi.
+ * https://github.com/WebAssembly/WASI/blob/main/legacy/README.md
+ * it's widely used for non-wasi interfaces as well.
+ *
+ * Note: some runtimes, including old versions of toywasm, assume
+ * the memidx 0 even for wasi. it would end up with some
+ * incompatibilities with multi-memory proposal.
+ */
+static const struct name name_default_memory =
+        NAME_FROM_CSTR_LITERAL("memory");
+
 /*
  * dereference a C function pointer.
  * that is, get the func inst pointed by the pointer.
@@ -48,3 +61,20 @@ cconv_deref_func_ptr(struct exec_context *ctx, const struct instance *inst,
         *fip = func;
         return 0;
 }
+
+int
+cconv_default_memory(struct exec_context *ctx, uint32_t *memidxp)
+{
+        const struct module *m = ctx->instance->module;
+        int ret;
+        /*
+         * XXX searching exports on each call can be too slow.
+         */
+        ret = module_find_export(m, &name_default_memory, EXTERNTYPE_MEMORY,
+                                 memidxp);
+        if (ret != 0) {
+                return trap_with_id(ctx, TRAP_DEFAULT_MEMORY_NOT_FOUND,
+                                    "default memory not found");
+        }
+        return 0;
+}

lib/cconv.h

@@ -13,4 +13,6 @@ int cconv_deref_func_ptr(struct exec_context *ctx, const struct instance *inst,
                          uint32_t wasmfuncptr, const struct functype *ft,
                          const struct funcinst **fip);
 
+int cconv_default_memory(struct exec_context *ctx, uint32_t *memidxp);
+
 __END_EXTERN_C

lib/exec_context.h

@@ -92,7 +92,7 @@ enum trapid {
         TRAP_UNCAUGHT_EXCEPTION,
         TRAP_THROW_REF_NULL,
         TRAP_UNRESOLVED_IMPORTED_FUNC,
-        TRAP_INVALID_MEMORY,
+        TRAP_DEFAULT_MEMORY_NOT_FOUND,
 };
 
 enum exec_event {

lib/host_instance.c

@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "cconv.h"
 #include "exec.h"
 #include "host_instance.h"
 #include "instance.h"
@@ -159,13 +160,18 @@ int
 host_func_copyin(struct exec_context *ctx, void *hostaddr, uint32_t wasmaddr,
                  size_t len, size_t align)
 {
+        uint32_t memidx;
         void *p;
         int ret;
+        ret = cconv_default_memory(ctx, &memidx);
+        if (ret != 0) {
+                return ret;
+        }
         ret = host_func_check_align(ctx, wasmaddr, align);
         if (ret != 0) {
                 return ret;
         }
-        ret = memory_getptr(ctx, 0, wasmaddr, 0, len, &p);
+        ret = memory_getptr(ctx, memidx, wasmaddr, 0, len, &p);
         if (ret != 0) {
                 return ret;
         }
@@ -177,50 +183,43 @@ int
 host_func_copyout(struct exec_context *ctx, const void *hostaddr,
                   uint32_t wasmaddr, size_t len, size_t align)
 {
+        uint32_t memidx;
         void *p;
         int ret;
+        ret = cconv_default_memory(ctx, &memidx);
+        if (ret != 0) {
+                return ret;
+        }
         ret = host_func_check_align(ctx, wasmaddr, align);
         if (ret != 0) {
                 return ret;
         }
-        ret = memory_getptr(ctx, 0, wasmaddr, 0, len, &p);
+        ret = memory_getptr(ctx, memidx, wasmaddr, 0, len, &p);
         if (ret != 0) {
                 return ret;
         }
         memcpy(p, hostaddr, len);
         return 0;
 }
 
-static int
-check_memidx(struct exec_context *ctx, uint32_t memidx)
-{
-        const struct module *m = ctx->instance->module;
-        if (memidx < m->nmems + m->nimportedmems) {
-                return 0;
-        }
-        return trap_with_id(
-                ctx, TRAP_INVALID_MEMORY,
-                "access to invalid memidx %" PRIx32 " in a host call", memidx);
-}
-
 int
-host_func_memory_getptr(struct exec_context *ctx, uint32_t memidx,
-                        uint32_t ptr, uint32_t offset, uint32_t size,
-                        void **pp)
+host_func_getptr(struct exec_context *ctx, uint32_t ptr, uint32_t offset,
+                 uint32_t size, void **pp)
 {
-        int ret = check_memidx(ctx, memidx);
+        uint32_t memidx;
+        int ret = cconv_default_memory(ctx, &memidx);
         if (ret != 0) {
                 return ret;
         }
         return memory_getptr(ctx, memidx, ptr, offset, size, pp);
 }
 
 int
-host_func_memory_getptr2(struct exec_context *ctx, uint32_t memidx,
-                         uint32_t ptr, uint32_t offset, uint32_t size,
-                         void **pp, bool *movedp)
+host_func_getptr2(struct exec_context *ctx, uint32_t ptr, uint32_t offset,
+                  uint32_t size, void **pp, bool *movedp)
 {
-        int ret = check_memidx(ctx, memidx);
+        uint32_t memidx;
+        int ret = cconv_default_memory(ctx, &memidx);
         if (ret != 0) {
                 return ret;
         }

lib/host_instance.h

@@ -89,12 +89,10 @@ int host_func_copyout(struct exec_context *ctx, const void *hostaddr,
                       uint32_t wasmaddr, size_t len, size_t align);
 int host_func_copyin(struct exec_context *ctx, void *hostaddr,
                      uint32_t wasmaddr, size_t len, size_t align);
-int host_func_memory_getptr(struct exec_context *ctx, uint32_t memidx,
-                            uint32_t ptr, uint32_t offset, uint32_t size,
-                            void **pp);
-int host_func_memory_getptr2(struct exec_context *ctx, uint32_t memidx,
-                             uint32_t ptr, uint32_t offset, uint32_t size,
-                             void **pp, bool *movedp);
+int host_func_getptr(struct exec_context *ctx, uint32_t ptr, uint32_t offset,
+                     uint32_t size, void **pp);
+int host_func_getptr2(struct exec_context *ctx, uint32_t ptr, uint32_t offset,
+                      uint32_t size, void **pp, bool *movedp);
 int host_func_trap(struct exec_context *ctx, const char *fmt, ...)
         __attribute__((__format__(__printf__, 2, 3)));
 struct restart_info;

libdyld/dyld_dlfcn.c

@@ -75,7 +75,7 @@ dyld_dlfcn_load_object(struct exec_context *ctx, struct host_instance *hi,
         }
 
         void *vp;
-        ret = host_func_memory_getptr(ctx, 0, namep, 0, namelen, &vp);
+        ret = host_func_getptr(ctx, namep, 0, namelen, &vp);
         if (ret != 0) {
                 user_ret = 1;
                 goto fail;
@@ -169,7 +169,7 @@ dyld_dlfcn_resolve_symbol(struct exec_context *ctx, struct host_instance *hi,
         const struct dyld_dynamic_object *dobj = &VEC_ELEM(d->dynobjs, idx);
 
         void *vp;
-        ret = host_func_memory_getptr(ctx, 0, namep, 0, namelen, &vp);
+        ret = host_func_getptr(ctx, namep, 0, namelen, &vp);
         if (ret != 0) {
                 user_ret = 1;
                 goto fail;

libwasi/wasi_abi_path.c

@@ -267,7 +267,7 @@ wasi_path_readlink(struct exec_context *ctx, struct host_instance *hi,
          * https://github.com/bytecodealliance/wasmtime/commit/24b607cf751930c51f2b6449cdfbf2e81dce1c31
          */
         void *p;
-        host_ret = host_func_memory_getptr(ctx, 0, buf, 0, buflen, &p);
+        host_ret = host_func_getptr(ctx, buf, 0, buflen, &p);
         if (host_ret != 0) {
                 goto fail;
         }

libwasi/wasi_abi_poll.c

@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "cconv.h"
 #include "endian.h"
 #include "exec_context.h"
 #include "restart.h"
@@ -51,7 +52,7 @@ wasi_poll_oneoff(struct exec_context *ctx, struct host_instance *hi,
         if (host_ret != 0) {
                 goto fail;
         }
-        host_ret = host_func_memory_getptr(ctx, 0, in, 0, insize, &p);
+        host_ret = host_func_getptr(ctx, in, 0, insize, &p);
         if (host_ret != 0) {
                 goto fail;
         }
@@ -62,8 +63,7 @@ wasi_poll_oneoff(struct exec_context *ctx, struct host_instance *hi,
         if (host_ret != 0) {
                 goto fail;
         }
-        host_ret =
-                host_func_memory_getptr2(ctx, 0, out, 0, outsize, &p, &moved);
+        host_ret = host_func_getptr2(ctx, out, 0, outsize, &p, &moved);
         if (host_ret != 0) {
                 goto fail;
         }

libwasi/wasi_abi_random.c

@@ -29,7 +29,7 @@ wasi_random_get(struct exec_context *ctx, struct host_instance *hi,
         uint32_t buflen = HOST_FUNC_PARAM(ft, params, 1, i32);
         int ret = 0;
         void *p;
-        int host_ret = host_func_memory_getptr(ctx, 0, buf, 0, buflen, &p);
+        int host_ret = host_func_getptr(ctx, buf, 0, buflen, &p);
         if (host_ret != 0) {
                 goto fail;
         }

libwasi/wasi_subr.c

@@ -80,8 +80,8 @@ wasi_copyin_iovec(struct exec_context *ctx, uint32_t iov_uaddr,
         if (host_ret != 0) {
                 goto fail;
         }
-        host_ret = host_func_memory_getptr(
-                ctx, 0, iov_uaddr, 0, iov_count * sizeof(struct wasi_iov), &p);
+        host_ret = host_func_getptr(ctx, iov_uaddr, 0,
+                                    iov_count * sizeof(struct wasi_iov), &p);
         if (host_ret != 0) {
                 goto fail;
         }
@@ -93,8 +93,8 @@ wasi_copyin_iovec(struct exec_context *ctx, uint32_t iov_uaddr,
                 uint32_t iov_len = le32_decode(&iov_in_module[i].iov_len);
                 xlog_trace("iov [%" PRIu32 "] base %" PRIx32 " len %" PRIu32,
                            i, iov_base, iov_len);
-                host_ret = host_func_memory_getptr2(ctx, 0, iov_base, 0,
-                                                    iov_len, &p, &moved);
+                host_ret = host_func_getptr2(ctx, iov_base, 0, iov_len, &p,
+                                             &moved);
                 if (host_ret != 0) {
                         goto fail;
                 }