strcpy_test3.c

#include <string.h>
#include <stdio.h>

void* xmalloc(size_t s);

int main(void)
{
  char *str = "12345";
	char *buf = xmalloc(5);

	strcpy(buf, str);

	return 0;
}

xmalloc.c

#include <stdlib.h>

void* xmalloc(size_t s)
{
  return malloc(s);
}