#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>
#include "elf.h"

int main(int argc, const char **argv)
{
	if (argc < 2) {
		fprintf(stderr, "no elf file specified.\n");
		return -1;
	}

	unsigned long pagesz = sysconf(_SC_PAGESIZE);

	FILE *fp = fopen(argv[1], "r+b");
	if (!fp) {
		perror(argv[1]);
		return -1;
	}

	void *p = mmap(NULL, pagesz, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(fp), 0);
	if (p == MAP_FAILED) {
		perror("mmap");
		fclose(fp);
		return -1;
	}

	elf_ehdr_t *elf = p;
	elf->e_machine = EM_386;

	munmap(p, pagesz);
	fclose(fp);

	printf("patched %s e_machine to EM_386\n", argv[1]);
	
	return 0;
}