mirror of
https://github.com/fluencelabs/wasmer
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3fea07dc8a
`imports` contains `func_import`, `global_import`, `memory_import` and `table_import`, so 4 items. This patch updates the length of `imports` when calling the `wasmer_instantiate` function.
156 lines
5.6 KiB
C
156 lines
5.6 KiB
C
#include <stdio.h>
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#include "../wasmer.h"
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#include <assert.h>
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#include <stdint.h>
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#include <string.h>
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bool static print_str_called = false;
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// Host function that will be imported into the Web Assembly Instance
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void print_str(const wasmer_instance_context_t *ctx, int32_t ptr, int32_t len)
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{
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print_str_called = true;
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const wasmer_memory_t *memory = wasmer_instance_context_memory(ctx, 0);
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uint32_t mem_len = wasmer_memory_length(memory);
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uint8_t *mem_bytes = wasmer_memory_data(memory);
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printf("%.*s", len, mem_bytes + ptr);
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}
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// Use the last_error API to retrieve error messages
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void print_wasmer_error()
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{
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int error_len = wasmer_last_error_length();
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printf("Error len: `%d`\n", error_len);
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char *error_str = malloc(error_len);
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wasmer_last_error_message(error_str, error_len);
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printf("Error str: `%s`\n", error_str);
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}
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int main()
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{
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// Create a new func to hold the parameter and signature
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// of our `print_str` host function
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wasmer_value_tag params_sig[] = {WASM_I32, WASM_I32};
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wasmer_value_tag returns_sig[] = {};
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wasmer_import_func_t *func = wasmer_import_func_new((void (*)(void *)) print_str, params_sig, 2, returns_sig, 0);
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// Create module name for our imports
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// represented in bytes for UTF-8 compatability
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const char *module_name = "env";
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wasmer_byte_array module_name_bytes;
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module_name_bytes.bytes = (const uint8_t *) module_name;
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module_name_bytes.bytes_len = strlen(module_name);
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// Define a function import
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const char *import_name = "_print_str";
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wasmer_byte_array import_name_bytes;
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import_name_bytes.bytes = (const uint8_t *) import_name;
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import_name_bytes.bytes_len = strlen(import_name);
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wasmer_import_t func_import;
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func_import.module_name = module_name_bytes;
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func_import.import_name = import_name_bytes;
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func_import.tag = WASM_FUNCTION;
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func_import.value.func = func;
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// Define a memory import
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const char *import_memory_name = "memory";
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wasmer_byte_array import_memory_name_bytes;
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import_memory_name_bytes.bytes = (const uint8_t *) import_memory_name;
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import_memory_name_bytes.bytes_len = strlen(import_memory_name);
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wasmer_import_t memory_import;
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memory_import.module_name = module_name_bytes;
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memory_import.import_name = import_memory_name_bytes;
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memory_import.tag = WASM_MEMORY;
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wasmer_memory_t *memory = NULL;
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wasmer_limits_t descriptor;
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descriptor.min = 256;
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wasmer_limit_option_t max;
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max.has_some = true;
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max.some = 256;
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descriptor.max = max;
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wasmer_result_t memory_result = wasmer_memory_new(&memory, descriptor);
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if (memory_result != WASMER_OK)
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{
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print_wasmer_error();
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}
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memory_import.value.memory = memory;
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// Define a global import
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const char *import_global_name = "__memory_base";
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wasmer_byte_array import_global_name_bytes;
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import_global_name_bytes.bytes = (const uint8_t *) import_global_name;
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import_global_name_bytes.bytes_len = strlen(import_global_name);
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wasmer_import_t global_import;
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global_import.module_name = module_name_bytes;
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global_import.import_name = import_global_name_bytes;
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global_import.tag = WASM_GLOBAL;
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wasmer_value_t val;
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val.tag = WASM_I32;
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val.value.I32 = 1024;
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wasmer_global_t *global = wasmer_global_new(val, false);
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global_import.value.global = global;
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// Define a table import
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const char *import_table_name = "table";
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wasmer_byte_array import_table_name_bytes;
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import_table_name_bytes.bytes = (const uint8_t *) import_table_name;
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import_table_name_bytes.bytes_len = strlen(import_table_name);
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wasmer_import_t table_import;
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table_import.module_name = module_name_bytes;
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table_import.import_name = import_table_name_bytes;
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table_import.tag = WASM_TABLE;
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wasmer_table_t *table = NULL;
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wasmer_limits_t table_descriptor;
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table_descriptor.min = 256;
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wasmer_limit_option_t table_max;
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table_max.has_some = true;
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table_max.some = 256;
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table_descriptor.max = table_max;
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wasmer_result_t table_result = wasmer_table_new(&table, table_descriptor);
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if (table_result != WASMER_OK)
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{
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print_wasmer_error();
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}
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table_import.value.table = table;
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// Define an array containing our imports
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wasmer_import_t imports[] = {func_import, global_import, memory_import, table_import};
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// Read the wasm file bytes
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FILE *file = fopen("hello_wasm.wasm", "r");
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fseek(file, 0, SEEK_END);
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long len = ftell(file);
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uint8_t *bytes = malloc(len);
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fseek(file, 0, SEEK_SET);
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fread(bytes, 1, len, file);
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fclose(file);
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// Creates a WebAssembly Instance from wasm bytes and imports
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wasmer_instance_t *instance = NULL;
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wasmer_result_t compile_result = wasmer_instantiate(&instance, bytes, len, imports, 4);
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printf("Compile result: %d\n", compile_result);
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if (compile_result != WASMER_OK)
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{
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print_wasmer_error();
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}
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assert(compile_result == WASMER_OK);
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// Call the exported "hello_wasm" function of our instance
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wasmer_value_t params[] = {};
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wasmer_value_t result_one;
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wasmer_value_t results[] = {result_one};
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wasmer_result_t call_result = wasmer_instance_call(instance, "_hello_wasm", params, 0, results, 1);
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printf("Call result: %d\n", call_result);
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assert(call_result == WASMER_OK);
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assert(print_str_called);
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// Use *_destroy methods to cleanup as specified in the header documentation
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wasmer_import_func_destroy(func);
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wasmer_global_destroy(global);
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wasmer_memory_destroy(memory);
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wasmer_table_destroy(table);
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wasmer_instance_destroy(instance);
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return 0;
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}
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