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Mohammad Mahhouk
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#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include "wasm_export.h"
void my_printf(wasm_exec_env_t exec_env, char *text)
{
printf(text);
}
void my_nprintf(wasm_exec_env_t exec_env, char *text, size_t len)
{
printf("message: '%.*s'\n", len, text);
}
void hello_world(wasm_exec_env_t exec_env)
{
printf("simple hello world is here \n");
}
char *read_wasm_binary_to_buffer(char *path, uint32_t *size)
{
FILE *fd = fopen(path, "rb");
if(!fd)
{
perror("fopen failed!\n");
return NULL;
}
if (fseek(fd, 0, SEEK_END) != 0)
{
perror("fseek failed\n");
return NULL;
}
long fsize = ftell(fd);
if(fseek(fd, 0, SEEK_SET) != 0) // rewind(fd); can be used here too
{
perror("fseek failed\n");
return NULL;
}
char *buffer = malloc(fsize + 1);
if (!buffer)
{
perror("malloc for file buffer failed!\n");
return NULL;
}
size_t read_bytes = fread(buffer, 1, fsize, fd);
if(read_bytes != fsize)
{
fprintf(stderr, "file read didnt read the whole file size and returned only %zu instead of %zu \n", read_bytes, fsize);
exit(EXIT_FAILURE);
}
fclose(fd);
*size = fsize + 1;
buffer[fsize] = 0;
return buffer;
}
int main(int argc, char *argv[])
{
static NativeSymbol native_symbols[] =
{
{
"my_printf", // the name of WASM function name
my_printf, // the native function pointer
"($)" // the function prototype signature
},
{
"my_nprintf", // the name of WASM function name
my_nprintf, // the native function pointer
"(*~)" // the function prototype signature
},
{
"hello_world", // the name of WASM function name
hello_world, // the native function pointer
"()" // the function prototype signature
}
};
char *buffer, error_buf[128];
wasm_module_t module;
wasm_module_inst_t module_inst;
wasm_function_inst_t func;
wasm_exec_env_t exec_env;
uint32_t size, stack_size = 8092, heap_size = 8092;
/* initialize the wasm runtime by default configurations */
if(!wasm_runtime_init())
{
fprintf(stderr,"wasm runtime initialisation failed\n");
exit(EXIT_FAILURE);
}
/* read WASM file into a memory buffer */
buffer = read_wasm_binary_to_buffer(argv[1], &size);
if(buffer == NULL)
{
fprintf(stderr, "the returned buffer for reading the wasm module is null\n");
exit(EXIT_FAILURE);
}
/* add line below if we want to export native functions to WASM app */
int n_native_symbols = sizeof(native_symbols) / sizeof(NativeSymbol);
if (!wasm_runtime_register_natives("env", native_symbols, n_native_symbols))
{
free(buffer);
exit(EXIT_FAILURE);
}
/* parse the WASM file from buffer and create a WASM module */
module = wasm_runtime_load(buffer, size, error_buf, sizeof(error_buf));
/* create an instance of the WASM module (WASM linear memory is ready) */
module_inst = wasm_runtime_instantiate(module, stack_size, heap_size,
error_buf, sizeof(error_buf));
if(module_inst == NULL)
{
fprintf(stderr, "module instantiation failed!\n");
exit(EXIT_FAILURE);
}
/* lookup a WASM function by its name
The function signature can NULL here */
func = wasm_runtime_lookup_function(module_inst, "main", NULL);
if (func == NULL) {
printf("main function not found\n");
return -1;
}
/* creat an execution environment to execute the WASM functions */
exec_env = wasm_runtime_create_exec_env(module_inst, stack_size);
if (exec_env == NULL) {
printf("execution environmnet creation failed\n");
return -1;
}
uint32_t args[1] = {0};
if (wasm_runtime_call_wasm(exec_env, func, 0, args) ) {
/* the return value is stored in argv[0] */
printf("main function returned\n");
}
else {
/* exception is thrown if call fails */
printf("%s\n", wasm_runtime_get_exception(module_inst));
}
wasm_runtime_destroy();
return 0;
}