hook mono实现Assembly.Load从指定路径读取文件

mono-unity github: https://github.com/Unity-Technologies/mono/blob/unity-staging/mono/metadata/assembly.c

此方案需要assemblyname已在GAC中，若不在可以用反射方式读取

mini/main.c: main()
    mono_main_with_options()
        mono_main()    --mini/driver.c
            mini_init()    --mini/mini.c
            mono_assembly_open()    --metadata/assembly.c
            --mono_assembly_load_from_full() --
            ----对文件名进行判断 是否已 file://开头
            ----mono_assembly_is_in_gac --判断是否在gac当中
            ----mono_assembly_open_from_bundle()
            ------mono_image_open_from_data_with_name()  --image.c
            --------do_mono_image_load()
            main_thread_handler() // assembly（也就是bytecode）的编译执行
            mini_cleanup()

mono_image_open_from_data_with_name方法中需要用到file的数据指针，和size，

所以需要在其上一层Hook，从指定的路径读取file到内存获得指针和size。

Hook的方法：mono_assembly_open_from_bundle(...)

原型：（源文件：/mono/metadata/assembly.c）

MonoImage *
mono_assembly_open_from_bundle (const char *filename, MonoImageOpenStatus *status, gboolean refonly)
{}

完整代码

/** 
 * mono_assembly_open_from_bundle:
 * @filename: Filename requested
 * @status: return value
 *
 * This routine tries to open the assembly specified by `filename' from the
 * defined bundles, if found, returns the MonoImage for it, if not found
 * returns NULL
 */
MonoImage *
mono_assembly_open_from_bundle (const char *filename, MonoImageOpenStatus *status, gboolean refonly)
{
	int i;
	char *name;
	MonoImage *image = NULL;

	/*
	 * we do a very simple search for bundled assemblies: it's not a general 
	 * purpose assembly loading mechanism.
	 */

	if (!bundles)
		return NULL;

	name = g_path_get_basename (filename);

	mono_assemblies_lock ();
	for (i = 0; !image && bundles [i]; ++i) {
		if (strcmp (bundles [i]->name, name) == 0) {
			image = mono_image_open_from_data_with_name ((char*)bundles [i]->data, bundles [i]->size, FALSE, status, refonly, name);
			break;
		}
	}
	mono_assemblies_unlock ();
	g_free (name);
	if (image) {
		mono_image_addref (image);
		return image;
	}
	return NULL;
}