dj(1): fix segfault when bses are mismatched

src/dj.c

@@ -35,15 +35,15 @@ char *program_name = "dj";
  * writing ends of its jockeyed "pipe". User-configurable members are noted
  * with their relevant options. */
 struct Io{
-	int bs;			/* buffer size (-bB) */
+	int bs;       	/* buffer size (-bB) */
 	size_t bufuse;	/* buffer usage */
 	char *buf;		/* buffer */
-	int bytes;		/* bytes processed */
+	size_t bytes;	/* bytes processed */
 	int fd;			/* file descriptor */
 	int fl;			/* file opening flags */
 	char *fn;		/* file name (may be stdin_name or stdout_name) (-io) */
-	int prec;		/* partial records processed */
-	int rec;		/* records processed */
+	size_t prec;	/* partial records processed */
+	size_t rec; 	/* records processed */
 	long seek;		/* bytes to seek/skip (will be 0 after skippage) (-sS) */
 }; 
 
@@ -197,6 +197,7 @@ int main(int argc, char *argv[]){
 	noerror = 0;
 	for(i = 0; i < 2; ++i){
 		io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */
+		io[i].bufuse = 0;
 		io[i].bytes = 0;
 		io[i].fd = i == 0 ? STDIN_FILENO : STDOUT_FILENO;
 		io[i].fn = i == 0 ? stdin_name   : stdout_name;