An example of running bytecode from within a C program

calling-bytecode.c

#include <string.h>
#include <sys/mman.h>

int main(void) {
    char rawr[] = "Rawr!\n";
    char bytecode[] = {
            0x60,					// pusha
            0xb8, 0x04, 0x00, 0x00, 0x00,		// mov eax, 4
            0xbb, 0x01, 0x00, 0x00, 0x00,		// mov ebx, 1
            0xb9, /* for rawr */ 0,0,0,0,		// mov ecx, 0
            0xba, sizeof(rawr), 0x00, 0x00, 0x00,	// mov edx, sizeof(rawr) [6 or 7]
            0xcd, 0x80,					// int 0x80
            0x61,					// popa
            0xc3					// ret
    };

	// Add the address of rawr to bytecode
    *((int*)(bytecode + 12)) = rawr; 

    void* mmbytecode = mmap(0,
                            sizeof(bytecode),
                            PROT_READ|PROT_WRITE|PROT_EXEC,
                            MAP_ANONYMOUS|MAP_PRIVATE,
                            -1, 0);

    /* Store the bytecode in the newly mapped area */
    memcpy(mmbytecode, bytecode, sizeof(bytecode));

    /* Execute the bytecode */
    ((void(*)(void))mmbytecode)();

    munmap(mmbytecode, sizeof(bytecode));
	return 0;
}