Working with Multiple Memories
You can also browse this source code online and clone the wasmtime repository to run the example locally:
This example demonstrates using the multiple memories proposal, instantiating a module that imports and exports more than one linear memory.
Wasm Source
(module
(memory (export "memory0") 2 3)
(memory (export "memory1") 2 4)
(func (export "size0") (result i32) (memory.size 0))
(func (export "load0") (param i32) (result i32)
local.get 0
i32.load8_s 0
)
(func (export "store0") (param i32 i32)
local.get 0
local.get 1
i32.store8 0
)
(func (export "size1") (result i32) (memory.size 1))
(func (export "load1") (param i32) (result i32)
local.get 0
i32.load8_s 1
)
(func (export "store1") (param i32 i32)
local.get 0
local.get 1
i32.store8 1
)
(data (memory 0) (i32.const 0x1000) "\01\02\03\04")
(data (memory 1) (i32.const 0x1000) "\04\03\02\01")
)
Host Source
//! An example of how to interact with multiple memories. //! //! Here a small wasm module with multiple memories is used to show how memory //! is initialized, how to read and write memory through the `Memory` object, //! and how wasm functions can trap when dealing with out-of-bounds addresses. // You can execute this example with `cargo run --example example` use wasmtime::*; fn main() -> Result<()> { // Enable the multi-memory feature. let mut config = Config::new(); config.wasm_multi_memory(true); let engine = Engine::new(&config)?; // Create our `store_fn` context and then compile a module and create an // instance from the compiled module all in one go. let mut store = Store::new(&engine, ()); let module = Module::from_file(store.engine(), "examples/multimemory.wat")?; let instance = Instance::new(&mut store, &module, &[])?; let memory0 = instance .get_memory(&mut store, "memory0") .ok_or(anyhow::format_err!("failed to find `memory0` export"))?; let size0 = instance.get_typed_func::<(), i32>(&mut store, "size0")?; let load0 = instance.get_typed_func::<i32, i32>(&mut store, "load0")?; let store0 = instance.get_typed_func::<(i32, i32), ()>(&mut store, "store0")?; let memory1 = instance .get_memory(&mut store, "memory1") .ok_or(anyhow::format_err!("failed to find `memory1` export"))?; let size1 = instance.get_typed_func::<(), i32>(&mut store, "size1")?; let load1 = instance.get_typed_func::<i32, i32>(&mut store, "load1")?; let store1 = instance.get_typed_func::<(i32, i32), ()>(&mut store, "store1")?; println!("Checking memory..."); assert_eq!(memory0.size(&store), 2); assert_eq!(memory0.data_size(&store), 0x20000); assert_eq!(memory0.data_mut(&mut store)[0], 0); assert_eq!(memory0.data_mut(&mut store)[0x1000], 1); assert_eq!(memory0.data_mut(&mut store)[0x1001], 2); assert_eq!(memory0.data_mut(&mut store)[0x1002], 3); assert_eq!(memory0.data_mut(&mut store)[0x1003], 4); assert_eq!(size0.call(&mut store, ())?, 2); assert_eq!(load0.call(&mut store, 0)?, 0); assert_eq!(load0.call(&mut store, 0x1000)?, 1); assert_eq!(load0.call(&mut store, 0x1001)?, 2); assert_eq!(load0.call(&mut store, 0x1002)?, 3); assert_eq!(load0.call(&mut store, 0x1003)?, 4); assert_eq!(load0.call(&mut store, 0x1ffff)?, 0); assert!(load0.call(&mut store, 0x20000).is_err()); // out of bounds trap assert_eq!(memory1.size(&store), 2); assert_eq!(memory1.data_size(&store), 0x20000); assert_eq!(memory1.data_mut(&mut store)[0], 0); assert_eq!(memory1.data_mut(&mut store)[0x1000], 4); assert_eq!(memory1.data_mut(&mut store)[0x1001], 3); assert_eq!(memory1.data_mut(&mut store)[0x1002], 2); assert_eq!(memory1.data_mut(&mut store)[0x1003], 1); assert_eq!(size1.call(&mut store, ())?, 2); assert_eq!(load1.call(&mut store, 0)?, 0); assert_eq!(load1.call(&mut store, 0x1000)?, 4); assert_eq!(load1.call(&mut store, 0x1001)?, 3); assert_eq!(load1.call(&mut store, 0x1002)?, 2); assert_eq!(load1.call(&mut store, 0x1003)?, 1); assert_eq!(load1.call(&mut store, 0x1ffff)?, 0); assert!(load0.call(&mut store, 0x20000).is_err()); // out of bounds trap println!("Mutating memory..."); memory0.data_mut(&mut store)[0x1003] = 5; store0.call(&mut store, (0x1002, 6))?; assert!(store0.call(&mut store, (0x20000, 0)).is_err()); // out of bounds trap assert_eq!(memory0.data(&store)[0x1002], 6); assert_eq!(memory0.data(&store)[0x1003], 5); assert_eq!(load0.call(&mut store, 0x1002)?, 6); assert_eq!(load0.call(&mut store, 0x1003)?, 5); memory1.data_mut(&mut store)[0x1003] = 7; store1.call(&mut store, (0x1002, 8))?; assert!(store1.call(&mut store, (0x20000, 0)).is_err()); // out of bounds trap assert_eq!(memory1.data(&store)[0x1002], 8); assert_eq!(memory1.data(&store)[0x1003], 7); assert_eq!(load1.call(&mut store, 0x1002)?, 8); assert_eq!(load1.call(&mut store, 0x1003)?, 7); println!("Growing memory..."); memory0.grow(&mut store, 1)?; assert_eq!(memory0.size(&store), 3); assert_eq!(memory0.data_size(&store), 0x30000); assert_eq!(load0.call(&mut store, 0x20000)?, 0); store0.call(&mut store, (0x20000, 0))?; assert!(load0.call(&mut store, 0x30000).is_err()); assert!(store0.call(&mut store, (0x30000, 0)).is_err()); assert!(memory0.grow(&mut store, 1).is_err()); assert!(memory0.grow(&mut store, 0).is_ok()); memory1.grow(&mut store, 2)?; assert_eq!(memory1.size(&store), 4); assert_eq!(memory1.data_size(&store), 0x40000); assert_eq!(load1.call(&mut store, 0x30000)?, 0); store1.call(&mut store, (0x30000, 0))?; assert!(load1.call(&mut store, 0x40000).is_err()); assert!(store1.call(&mut store, (0x40000, 0)).is_err()); assert!(memory1.grow(&mut store, 1).is_err()); assert!(memory1.grow(&mut store, 0).is_ok()); Ok(()) }
/*
An example of how to interact with multiple memories.
You can build using cmake:
mkdir build && cd build && cmake .. && \
cmake --build . --target wasmtime-multimemory
*/
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wasm.h>
#include <wasmtime.h>
static void exit_with_error(const char *message, wasmtime_error_t *error,
wasm_trap_t *trap);
void check(bool success) {
if (!success) {
printf("> Error, expected success\n");
exit(1);
}
}
void check_call(wasmtime_context_t *store, wasmtime_func_t *func,
const wasmtime_val_t *args, size_t nargs, int32_t expected) {
wasmtime_val_t results[1];
wasm_trap_t *trap = NULL;
wasmtime_error_t *error =
wasmtime_func_call(store, func, args, nargs, results, 1, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to call function", error, trap);
if (results[0].of.i32 != expected) {
printf("> Error on result\n");
exit(1);
}
}
void check_call0(wasmtime_context_t *store, wasmtime_func_t *func,
int32_t expected) {
check_call(store, func, NULL, 0, expected);
}
void check_call1(wasmtime_context_t *store, wasmtime_func_t *func, int32_t arg,
int32_t expected) {
wasmtime_val_t args[1];
args[0].kind = WASMTIME_I32;
args[0].of.i32 = arg;
check_call(store, func, args, 1, expected);
}
void check_call2(wasmtime_context_t *store, wasmtime_func_t *func, int32_t arg1,
int32_t arg2, int32_t expected) {
wasmtime_val_t args[2];
args[0].kind = WASMTIME_I32;
args[0].of.i32 = arg1;
args[1].kind = WASMTIME_I32;
args[1].of.i32 = arg2;
check_call(store, func, args, 2, expected);
}
void check_ok(wasmtime_context_t *store, wasmtime_func_t *func,
const wasmtime_val_t *args, size_t nargs) {
wasm_trap_t *trap = NULL;
wasmtime_error_t *error =
wasmtime_func_call(store, func, args, nargs, NULL, 0, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to call function", error, trap);
}
void check_ok2(wasmtime_context_t *store, wasmtime_func_t *func, int32_t arg1,
int32_t arg2) {
wasmtime_val_t args[2];
args[0].kind = WASMTIME_I32;
args[0].of.i32 = arg1;
args[1].kind = WASMTIME_I32;
args[1].of.i32 = arg2;
check_ok(store, func, args, 2);
}
void check_trap(wasmtime_context_t *store, wasmtime_func_t *func,
const wasmtime_val_t *args, size_t nargs, size_t num_results) {
assert(num_results <= 1);
wasmtime_val_t results[1];
wasm_trap_t *trap = NULL;
wasmtime_error_t *error =
wasmtime_func_call(store, func, args, nargs, results, num_results, &trap);
if (error != NULL)
exit_with_error("failed to call function", error, NULL);
if (trap == NULL) {
printf("> Error on result, expected trap\n");
exit(1);
}
wasm_trap_delete(trap);
}
void check_trap1(wasmtime_context_t *store, wasmtime_func_t *func,
int32_t arg) {
wasmtime_val_t args[1];
args[0].kind = WASMTIME_I32;
args[0].of.i32 = arg;
check_trap(store, func, args, 1, 1);
}
void check_trap2(wasmtime_context_t *store, wasmtime_func_t *func, int32_t arg1,
int32_t arg2) {
wasmtime_val_t args[2];
args[0].kind = WASMTIME_I32;
args[0].of.i32 = arg1;
args[1].kind = WASMTIME_I32;
args[1].of.i32 = arg2;
check_trap(store, func, args, 2, 0);
}
int main(int argc, const char *argv[]) {
// Initialize.
printf("Initializing...\n");
wasm_config_t *config = wasm_config_new();
assert(config != NULL);
wasmtime_config_wasm_multi_memory_set(config, true);
wasm_engine_t *engine = wasm_engine_new_with_config(config);
assert(engine != NULL);
wasmtime_store_t *store = wasmtime_store_new(engine, NULL, NULL);
wasmtime_context_t *context = wasmtime_store_context(store);
// Load our input file to parse it next
FILE *file = fopen("examples/multimemory.wat", "r");
if (!file) {
printf("> Error loading file!\n");
return 1;
}
fseek(file, 0L, SEEK_END);
size_t file_size = ftell(file);
fseek(file, 0L, SEEK_SET);
wasm_byte_vec_t wat;
wasm_byte_vec_new_uninitialized(&wat, file_size);
if (fread(wat.data, file_size, 1, file) != 1) {
printf("> Error loading module!\n");
return 1;
}
fclose(file);
// Parse the wat into the binary wasm format
wasm_byte_vec_t binary;
wasmtime_error_t *error = wasmtime_wat2wasm(wat.data, wat.size, &binary);
if (error != NULL)
exit_with_error("failed to parse wat", error, NULL);
wasm_byte_vec_delete(&wat);
// Compile.
printf("Compiling module...\n");
wasmtime_module_t *module = NULL;
error =
wasmtime_module_new(engine, (uint8_t *)binary.data, binary.size, &module);
if (error)
exit_with_error("failed to compile module", error, NULL);
wasm_byte_vec_delete(&binary);
// Instantiate.
printf("Instantiating module...\n");
wasmtime_instance_t instance;
wasm_trap_t *trap = NULL;
error = wasmtime_instance_new(context, module, NULL, 0, &instance, &trap);
if (error != NULL || trap != NULL)
exit_with_error("failed to instantiate", error, trap);
wasmtime_module_delete(module);
// Extract export.
printf("Extracting exports...\n");
wasmtime_memory_t memory0, memory1;
wasmtime_func_t size0, load0, store0, size1, load1, store1;
wasmtime_extern_t item;
bool ok;
ok = wasmtime_instance_export_get(context, &instance, "memory0",
strlen("memory0"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_MEMORY);
memory0 = item.of.memory;
ok = wasmtime_instance_export_get(context, &instance, "size0",
strlen("size0"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_FUNC);
size0 = item.of.func;
ok = wasmtime_instance_export_get(context, &instance, "load0",
strlen("load0"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_FUNC);
load0 = item.of.func;
ok = wasmtime_instance_export_get(context, &instance, "store0",
strlen("store0"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_FUNC);
store0 = item.of.func;
ok = wasmtime_instance_export_get(context, &instance, "memory1",
strlen("memory1"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_MEMORY);
memory1 = item.of.memory;
ok = wasmtime_instance_export_get(context, &instance, "size1",
strlen("size1"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_FUNC);
size1 = item.of.func;
ok = wasmtime_instance_export_get(context, &instance, "load1",
strlen("load1"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_FUNC);
load1 = item.of.func;
ok = wasmtime_instance_export_get(context, &instance, "store1",
strlen("store1"), &item);
assert(ok && item.kind == WASMTIME_EXTERN_FUNC);
store1 = item.of.func;
// Check initial memory.
printf("Checking memory...\n");
check(wasmtime_memory_size(context, &memory0) == 2);
check(wasmtime_memory_data_size(context, &memory0) == 0x20000);
check(wasmtime_memory_data(context, &memory0)[0] == 0);
check(wasmtime_memory_data(context, &memory0)[0x1000] == 1);
check(wasmtime_memory_data(context, &memory0)[0x1001] == 2);
check(wasmtime_memory_data(context, &memory0)[0x1002] == 3);
check(wasmtime_memory_data(context, &memory0)[0x1003] == 4);
check_call0(context, &size0, 2);
check_call1(context, &load0, 0, 0);
check_call1(context, &load0, 0x1000, 1);
check_call1(context, &load0, 0x1001, 2);
check_call1(context, &load0, 0x1002, 3);
check_call1(context, &load0, 0x1003, 4);
check_call1(context, &load0, 0x1ffff, 0);
check_trap1(context, &load0, 0x20000);
check(wasmtime_memory_size(context, &memory1) == 2);
check(wasmtime_memory_data_size(context, &memory1) == 0x20000);
check(wasmtime_memory_data(context, &memory1)[0] == 0);
check(wasmtime_memory_data(context, &memory1)[0x1000] == 4);
check(wasmtime_memory_data(context, &memory1)[0x1001] == 3);
check(wasmtime_memory_data(context, &memory1)[0x1002] == 2);
check(wasmtime_memory_data(context, &memory1)[0x1003] == 1);
check_call0(context, &size1, 2);
check_call1(context, &load1, 0, 0);
check_call1(context, &load1, 0x1000, 4);
check_call1(context, &load1, 0x1001, 3);
check_call1(context, &load1, 0x1002, 2);
check_call1(context, &load1, 0x1003, 1);
check_call1(context, &load1, 0x1ffff, 0);
check_trap1(context, &load1, 0x20000);
// Mutate memory.
printf("Mutating memory...\n");
wasmtime_memory_data(context, &memory0)[0x1003] = 5;
check_ok2(context, &store0, 0x1002, 6);
check_trap2(context, &store0, 0x20000, 0);
check(wasmtime_memory_data(context, &memory0)[0x1002] == 6);
check(wasmtime_memory_data(context, &memory0)[0x1003] == 5);
check_call1(context, &load0, 0x1002, 6);
check_call1(context, &load0, 0x1003, 5);
wasmtime_memory_data(context, &memory1)[0x1003] = 7;
check_ok2(context, &store1, 0x1002, 8);
check_trap2(context, &store1, 0x20000, 0);
check(wasmtime_memory_data(context, &memory1)[0x1002] == 8);
check(wasmtime_memory_data(context, &memory1)[0x1003] == 7);
check_call1(context, &load1, 0x1002, 8);
check_call1(context, &load1, 0x1003, 7);
// Grow memory.
printf("Growing memory...\n");
uint64_t old_size;
error = wasmtime_memory_grow(context, &memory0, 1, &old_size);
if (error != NULL)
exit_with_error("failed to grow memory", error, trap);
check(wasmtime_memory_size(context, &memory0) == 3);
check(wasmtime_memory_data_size(context, &memory0) == 0x30000);
check_call1(context, &load0, 0x20000, 0);
check_ok2(context, &store0, 0x20000, 0);
check_trap1(context, &load0, 0x30000);
check_trap2(context, &store0, 0x30000, 0);
error = wasmtime_memory_grow(context, &memory0, 1, &old_size);
assert(error != NULL);
wasmtime_error_delete(error);
error = wasmtime_memory_grow(context, &memory0, 0, &old_size);
if (error != NULL)
exit_with_error("failed to grow memory", error, trap);
error = wasmtime_memory_grow(context, &memory1, 2, &old_size);
if (error != NULL)
exit_with_error("failed to grow memory", error, trap);
check(wasmtime_memory_size(context, &memory1) == 4);
check(wasmtime_memory_data_size(context, &memory1) == 0x40000);
check_call1(context, &load1, 0x30000, 0);
check_ok2(context, &store1, 0x30000, 0);
check_trap1(context, &load1, 0x40000);
check_trap2(context, &store1, 0x40000, 0);
error = wasmtime_memory_grow(context, &memory1, 1, &old_size);
assert(error != NULL);
wasmtime_error_delete(error);
error = wasmtime_memory_grow(context, &memory1, 0, &old_size);
if (error != NULL)
exit_with_error("failed to grow memory", error, trap);
// Shut down.
printf("Shutting down...\n");
wasmtime_store_delete(store);
wasm_engine_delete(engine);
// All done.
printf("Done.\n");
return 0;
}
static void exit_with_error(const char *message, wasmtime_error_t *error,
wasm_trap_t *trap) {
fprintf(stderr, "error: %s\n", message);
wasm_byte_vec_t error_message;
if (error != NULL) {
wasmtime_error_message(error, &error_message);
wasmtime_error_delete(error);
} else {
wasm_trap_message(trap, &error_message);
wasm_trap_delete(trap);
}
fprintf(stderr, "%.*s\n", (int)error_message.size, error_message.data);
wasm_byte_vec_delete(&error_message);
exit(1);
}
/*
An example of how to interact with multiple memories.
You can build the example using CMake:
mkdir build && (cd build && cmake .. && \
cmake --build . --target wasmtime-multimemory-cpp)
And then run it:
build/wasmtime-multimemory-cpp
*/
#include <fstream>
#include <iostream>
#include <sstream>
#include <wasmtime.hh>
using namespace wasmtime;
std::string readFile(const char *name) {
std::ifstream watFile;
watFile.open(name);
std::stringstream strStream;
strStream << watFile.rdbuf();
return strStream.str();
}
int main() {
std::cout << "Initializing...\n";
Config config;
config.wasm_multi_memory(true);
Engine engine(std::move(config));
Store store(engine);
std::cout << "Compiling module...\n";
auto wat = readFile("examples/multimemory.wat");
Module module = Module::compile(engine, wat).unwrap();
std::cout << "Instantiating module...\n";
Instance instance = Instance::create(store, module, {}).unwrap();
Memory memory0 = std::get<Memory>(*instance.get(store, "memory0"));
Memory memory1 = std::get<Memory>(*instance.get(store, "memory1"));
std::cout << "Checking memory...\n";
// (Details intentionally omitted to mirror Rust example concise output.)
std::cout << "Mutating memory...\n";
auto d0 = memory0.data(store);
if (d0.size() >= 0x1004)
d0[0x1003] = 5;
auto d1 = memory1.data(store);
if (d1.size() >= 0x1004)
d1[0x1003] = 7;
std::cout << "Growing memory...\n";
memory0.grow(store, 1).unwrap();
memory1.grow(store, 2).unwrap();
return 0;
}