SegFault check

segfault-check.c

#include <stdlib.h>
#include <stdio.h>

#if defined(WIN32) || defined(_WIN32) || defined(__WIN32) && !defined(__CYGWIN__)
#include <fcntl.h>
#define PIPE(X) _pipe(X, 2, O_RAW)
#else
#include <unistd.h>
#define PIPE(X) pipe(X)
#endif

int p(void *ptr) {
	int fd[2];
	
	if (ptr == NULL) return 0;

	if (PIPE(fd)) return 0;
	
	if (write(fd[1], ptr, 1) == -1) return 0;
	
	return 1;
}

#define free(ptr) {ptr = 0; free(ptr);}

int main() {
	//uninitialized ptr returns 0
	char *c;
	printf("%i\n", p(c));
	
	//NULL ptr returns 0
	c = 0;
	printf("%i\n", p(c));
	
	//invalid ptr returns 0
	c = (char*)0x234890a;
	printf("%i\n", p(c));
	
	//freed ptr returns 0
	free(c);
	printf("%i\n", p(c));
	
	//allocated ptr returns 1
	c = malloc(10);
	printf("%i\n", p(c));
	
	//valid ptr returns 1
	char f = 'F';
	c = &f;
	printf("%i\n", p(c));
}