fcup-smsend[mult]: fix buglet in K&R C NULL pointer passing The only 100% safe way to pass a NULL pointer as a function argument in K&R C is to cast 0 to a pointer type; failing to do so may cause mysterious bugs (invalid stack frames or garbage in argument registers) on 64-bit machines. This issue has already been fixed in most of FC host tools, but I just found some missed spots: passing of NULL UDH to PDU encoding functions in fcup-smsend[mult] in the case of single (not concatenated) SMS.

/*
 * Both arguments to fc-cal2text must name directories that already exist.
 * Here we implement the check for this requirement.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

check_directory_exists(pathname)
	char *pathname;
{
	struct stat st;

	if (stat(pathname, &st) < 0) {
		perror(pathname);
		exit(1);
	}
	if (!S_ISDIR(st.st_mode)) {
		fprintf(stderr, "error: %s is not a directory\n", pathname);
		exit(1);
	}
	return(0);
}