--- /dev/null
+#include <mono/jit/jit.h>
+#include <mono/metadata/environment.h>
+#include <mono/metadata/assembly.h>
+#include <mono/metadata/debug-helpers.h>
+#include <string.h>
+#include <stdlib.h>
+
+/*
+ * Simple mono embedding example.
+ * We show how to create objects and invoke methods and set fields in them.
+ * Compile with:
+ * gcc -Wall -o test-invoke test-invoke.c `pkg-config --cflags --libs mono` -lm
+ * mcs invoke.cs
+ * Run with:
+ * ./test-invoke invoke.exe
+ */
+
+typedef struct
+{
+ MonoDomain *domain;
+ const char *file;
+ int argc;
+ char **argv;
+} MainThreadArgs;
+
+static void
+access_valuetype_field (MonoObject *obj)
+{
+ MonoClass *klass;
+ MonoClassField *field;
+ int val;
+
+ klass = mono_object_get_class (obj);
+
+ /* Now we'll change the value of the 'val' field (see invoke.cs) */
+ field = mono_class_get_field_from_name (klass, "val");
+
+ /* This time we also add a bit of error checking... */
+ if (!field) {
+ fprintf (stderr, "Can't find field val in MyType\n");
+ exit (1);
+ }
+ /* Check that val is an int (if you're paranoid or if you need to
+ * show how this API is used)
+ */
+ if (mono_type_get_type (mono_field_get_type (field)) != MONO_TYPE_I4) {
+ fprintf (stderr, "Field val is not a 32 bit integer\n");
+ exit (1);
+ }
+
+ /* Note we pass a pointer to the value */
+ mono_field_get_value (obj, field, &val);
+ printf ("Value of field is: %d\n", val);
+ val = 10;
+
+ /* Note we pass a pointer to the value here as well */
+ mono_field_set_value (obj, field, &val);
+
+}
+
+static void
+access_reference_field (MonoObject *obj)
+{
+ MonoClass *klass;
+ MonoDomain *domain;
+ MonoClassField *str;
+ MonoString *strval;
+ char *p;
+
+ klass = mono_object_get_class (obj);
+ domain = mono_object_get_domain (obj);
+
+ /* Now we'll see that a reference type is handled slightly differently.
+ * First, get the MonoClassField representing it.
+ */
+ str = mono_class_get_field_from_name (klass, "str");
+
+ /* No change here, we always pass a pointer */
+ mono_field_get_value (obj, str, &strval);
+
+ /* get the string in UTF-8 encoding to print it */
+ p = mono_string_to_utf8 (strval);
+ printf ("Value of str is: %s\n", p);
+ /* we need to free the result from mono_string_to_utf8 () */
+ g_free (p);
+
+ /* string are immutable, so we need to create a different string */
+ strval = mono_string_new (domain, "hello from the embedding API");
+
+ /* Here is the slight difference: for reference types we pass
+ * the pointer directly, instead of a pointer to the value.
+ */
+ mono_field_set_value (obj, str, strval);
+
+}
+
+/* Demostrate how to call methods */
+static void
+call_methods (MonoObject *obj)
+{
+ MonoClass *klass;
+ MonoDomain *domain;
+ MonoMethod *method = NULL, *m = NULL, *ctor = NULL, *fail = NULL, *mvalues;
+ MonoProperty *prop;
+ MonoObject *result, *exception;
+ MonoString *str;
+ char *p;
+ gpointer iter;
+ gpointer args [2];
+ int val;
+
+ klass = mono_object_get_class (obj);
+ domain = mono_object_get_domain (obj);
+
+ /* retrieve all the methods we need */
+ iter = NULL;
+ while ((m = mono_class_get_methods (klass, &iter))) {
+ if (strcmp (mono_method_get_name (m), "method") == 0) {
+ method = m;
+ } else if (strcmp (mono_method_get_name (m), "Fail") == 0) {
+ fail = m;
+ } else if (strcmp (mono_method_get_name (m), "Values") == 0) {
+ mvalues = m;
+ } else if (strcmp (mono_method_get_name (m), ".ctor") == 0) {
+ /* Check it's the ctor that takes two args:
+ * as you see a contrsuctor is a method like any other.
+ */
+ MonoMethodSignature * sig = mono_method_signature (m);
+ if (mono_signature_get_param_count (sig) == 2) {
+ ctor = m;
+ }
+ }
+ }
+ /* Now we'll call method () on obj: since it takes no arguments
+ * we can pass NULL as the third argument to mono_runtime_invoke ().
+ * The method will print the updated value.
+ */
+ mono_runtime_invoke (method, obj, NULL, NULL);
+
+ /* mono_object_new () doesn't call any constructor: this means that
+ * we'll have to invoke the constructor if needed ourselves. Note:
+ * invoking a constructor is no different than calling any other method,
+ * so we'll still call mono_runtime_invoke (). This also means that we
+ * can invoke a constructor at any time, like now.
+ * First, setup the array of arguments and their values.
+ */
+
+ /* As usual, we use the address of the data for valuetype arguments */
+ val = 7;
+ args [0] = &val;
+ /* and the pointer for reference types: mono_array_new () returns a MonoArray* */
+ args [1] = mono_array_new (domain, mono_get_byte_class (), 256);
+ mono_runtime_invoke (ctor, obj, args, NULL);
+
+ /* A property exists only as a metadata entity, so getting or setting the value
+ * is nothing more than calling mono_runtime_invoke () on the getter or setter method.
+ */
+ prop = mono_class_get_property_from_name (klass, "Value");
+ method = mono_property_get_get_method (prop);
+ result = mono_runtime_invoke (method, obj, NULL, NULL);
+ /* mono_runtime_invoke () always boxes the return value if it's a valuetype */
+ val = *(int*)mono_object_unbox (result);
+
+ printf ("Value of val from property is: %d\n", val);
+
+ /* we also have an helper method: note that reference types are returned as is */
+ prop = mono_class_get_property_from_name (klass, "Message");
+ str = (MonoString*)mono_property_get_value (prop, obj, NULL, NULL);
+ /* get the string in UTF-8 encoding to print it */
+ p = mono_string_to_utf8 (str);
+ printf ("Value of str from property is: %s\n", p);
+ /* we need to free the result from mono_string_to_utf8 () */
+ g_free (p);
+
+ /* Now we'll show two things:
+ * 1) static methods are invoked with mono_runtime_invoke () as well,
+ * we just pass NULL as the second argument.
+ * 2) we can catch exceptions thrown by the called method.
+ * Note: fail is declared as static void Fail () in invoke.cs.
+ * We first set result to NULL: if after the invocation it will have
+ * a different value, it will be the exception that was thrown from
+ * the Fail () method. Note that if an exception was thrown, the return
+ * value (if any) is undefined and can't be used in any way (yes, the above
+ * invocations don't have this type of error checking to make things simpler).
+ */
+ exception = NULL;
+ mono_runtime_invoke (fail, NULL, NULL, &exception);
+ if (exception) {
+ printf ("An exception was thrown in Fail ()\n");
+ }
+
+ /* Now let's see how to handle methods that take by ref arguments:
+ * Valuetypes continue to be passed as pointers to the data.
+ * Reference arguments passed by ref (ref or out is the same)
+ * are handled the same way: a pointer to the pointer is used
+ * (so that the result can be read back).
+ * Small note: in this case (a System.Int32 valuetype) we can just
+ * use &val where val is a C 32 bit integer. In the general case
+ * unmanaged code doesn't know the size of a valuetype, since the
+ * runtime may decide to lay it out in what it thinks is a better way
+ * (unless ExplicitLayout is set). To avoid issues, the best thing is to
+ * create an object of the valuetype's class and retrieve the pointer
+ * to the data with the mono_object_unbox () function.
+ */
+ val = 100;
+ str = mono_string_new (domain, "another string");
+ args [0] = &val;
+ args [1] = &str;
+ mono_runtime_invoke (mvalues, obj, args, NULL);
+ /* get the string in UTF-8 encoding to print it */
+ p = mono_string_to_utf8 (str);
+ printf ("Values of str/val from Values () are: %s/%d\n", p, val);
+ /* we need to free the result from mono_string_to_utf8 () */
+ g_free (p);
+}
+
+static void
+more_methods (MonoDomain *domain)
+{
+ MonoClass *klass;
+ MonoMethodDesc* mdesc;
+ MonoMethod *method, *vtmethod;
+ MonoString *str;
+ MonoObject *obj;
+ char *p;
+ int val;
+
+ /* Now let's call an instance method on a valuetype. There are two
+ * different case:
+ * 1) calling a virtual method defined in a base class, like ToString ():
+ * we need to pass the value boxed in an object
+ * 2) calling a normal instance method: in this case
+ * we pass the address to the valuetype as the second argument
+ * instead of an object.
+ * First some initialization.
+ */
+ val = 25;
+ klass = mono_get_int32_class ();
+ obj = mono_value_box (domain, klass, &val);
+
+ /* A different way to search for a method */
+ mdesc = mono_method_desc_new (":ToString()", FALSE);
+ vtmethod = mono_method_desc_search_in_class (mdesc, klass);
+
+ str = (MonoString*)mono_runtime_invoke (vtmethod, &val, NULL, NULL);
+ /* get the string in UTF-8 encoding to print it */
+ p = mono_string_to_utf8 (str);
+ printf ("25.ToString (): %s\n", p);
+ /* we need to free the result from mono_string_to_utf8 () */
+ g_free (p);
+
+ /* Now: see how the result is different if we search for the ToString ()
+ * method in System.Object: mono_runtime_invoke () doesn't do any sort of
+ * virtual method invocation: it calls the exact method that it was given
+ * to execute. If a virtual call is needed, mono_object_get_virtual_method ()
+ * can be called.
+ */
+ method = mono_method_desc_search_in_class (mdesc, mono_get_object_class ());
+ str = (MonoString*)mono_runtime_invoke (method, obj, NULL, NULL);
+ /* get the string in UTF-8 encoding to print it */
+ p = mono_string_to_utf8 (str);
+ printf ("25.ToString (), from System.Object: %s\n", p);
+ /* we need to free the result from mono_string_to_utf8 () */
+ g_free (p);
+
+ /* Now get the method that overrides ToString () in obj */
+ vtmethod = mono_object_get_virtual_method (obj, method);
+ if (mono_class_is_valuetype (mono_method_get_class (vtmethod))) {
+ printf ("Need to unbox this for call to virtual ToString () for %s\n", mono_class_get_name (klass));
+ }
+
+ mono_method_desc_free (mdesc);
+}
+
+static void
+create_object (MonoDomain *domain, MonoImage *image)
+{
+ MonoClass *klass;
+ MonoObject *obj;
+
+ klass = mono_class_from_name (image, "Embed", "MyType");
+ if (!klass) {
+ fprintf (stderr, "Can't find MyType in assembly %s\n", mono_image_get_filename (image));
+ exit (1);
+ }
+
+ obj = mono_object_new (domain, klass);
+ /* mono_object_new () only allocates the storage:
+ * it doesn't run any constructor. Tell the runtime to run
+ * the default argumentless constructor.
+ */
+ mono_runtime_object_init (obj);
+
+ access_valuetype_field (obj);
+ access_reference_field (obj);
+
+ call_methods (obj);
+ more_methods (domain);
+}
+
+static void main_thread_handler (gpointer user_data)
+{
+ MainThreadArgs *main_args=(MainThreadArgs *)user_data;
+ MonoAssembly *assembly;
+
+ /* Loading an assembly makes the runtime setup everything
+ * needed to execute it. If we're just interested in the metadata
+ * we'd use mono_image_load (), instead and we'd get a MonoImage*.
+ */
+ assembly = mono_domain_assembly_open (main_args->domain,
+ main_args->file);
+ if (!assembly)
+ exit (2);
+ /*
+ * mono_jit_exec() will run the Main() method in the assembly.
+ * The return value needs to be looked up from
+ * System.Environment.ExitCode.
+ */
+ mono_jit_exec (main_args->domain, assembly, main_args->argc,
+ main_args->argv);
+
+ create_object (main_args->domain, mono_assembly_get_image (assembly));
+}
+
+int
+main (int argc, char* argv[]) {
+ MonoDomain *domain;
+ const char *file;
+ int retval;
+ MainThreadArgs main_args;
+
+ if (argc < 2){
+ fprintf (stderr, "Please provide an assembly to load\n");
+ return 1;
+ }
+ file = argv [1];
+ /*
+ * mono_jit_init() creates a domain: each assembly is
+ * loaded and run in a MonoDomain.
+ */
+ domain = mono_jit_init (file);
+
+ main_args.domain=domain;
+ main_args.file=file;
+ main_args.argc=argc-1;
+ main_args.argv=argv+1;
+
+ mono_runtime_exec_managed_code (domain, main_thread_handler,
+ &main_args);
+
+ retval=mono_environment_exitcode_get ();
+
+ mono_jit_cleanup (domain);
+ return retval;
+}
+
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