Thread: mmap assertion failing

Hi, I'm using mmap for the first time in a program where I'm trying to benchmark different data structures. I'm checking the return value, through a assert, and its failing. I dont know why

Heres the assert

skipLists: skipLists.c:266: main: Assertion `buffer != ((void *) -1)' failed.

Heres the code with the line commented

Code:

int main(int argc, char *argv[]) {
   	int i, inc;
    	int device_fd;
    	int *buffer;
	time_t start, end;

	int tmp;
	list l; 
	init();
	l = newList();

	/* 
	 * Check arguments(file, fileSize, searchFile, searchSize) 
	 */
	assert(argc != 4);

	/*
	 * Load in dataset
	 */
	fprintf(stderr, "* Loading file %s\n", argv[1]);
	device_fd = open(argv[1], O_RDONLY);
	assert(device_fd != -1);
	buffer = mmap(0, atoi(argv[2]), PROT_READ, MAP_FILE, device_fd, 0);
	assert(buffer != MAP_FAILED);

	inc = 2;
	fprintf(stderr, "* Starting insert\n");
	time(&start);
		for(i = 0; i < atoi(argv[2])/4 - 1; ++i) {
			if(i == inc) {
				time(&end);
				fprintf(stderr, "\t* %i in %f seconds\n", i, difftime(end, start));
				inc <<= 2;
			}

			insert(l, buffer[i], buffer[i]);
		}
	time(&end);
	fprintf(stderr, "\t* Done in %f seconds\n", difftime(end, start));
	close(device_fd);

	/*
	 * Start random searches
	 */
	fprintf(stderr, "* Loading file %s\n", argv[3]);
	device_fd = open(argv[3], O_RDONLY);
	assert(device_fd != -1);
	buffer = mmap(0, atoi(argv[4]), PROT_READ, MAP_FILE, device_fd, 0);
	assert(buffer != MAP_FAILED);	// THIS LINE HERE

	inc = 2;
	fprintf(stderr, "* Starting search\n");
	time(&start);
		for(i = 0; i < atoi(argv[4])/4 - 1; ++i) {
			if(i == inc) {
				time(&end);
				fprintf(stderr, "\t* %i in %f seconds\n", i, difftime(end, start));
				inc <<= 2;
			}

			search(l, buffer[i], &tmp);
		}
	time(&end);
	fprintf(stderr, "\t* Done in %f seconds\n", difftime(end, start));

	/*
	 * Start deleting (with same file)
	 */
	inc = 2;
	fprintf(stderr, "* Starting delete\n");
	time(&start);
		for(i = 0; i < atoi(argv[4])/4 - 1; ++i) {
			if(i == inc) {
				time(&end);
				fprintf(stderr, "\t* %i in %f seconds\n", i, difftime(end, start));
				inc <<= 2;
			}

			delete(l, buffer[i]);
		}
	time(&end);
	fprintf(stderr, "\t* Done in %f seconds\n", difftime(end, start));
	close(device_fd);

	freeList(l);
	return 0;
}

Thanks for any help