io: fix few error path leaks

src/gunzip.c

@@ -149,12 +149,10 @@ struct apk_istream *apk_bstream_gunzip_mpart(struct apk_bstream *bs,
 {
 	struct apk_gzip_istream *gis;
 
-	if (bs == NULL)
-		return NULL;
+	if (!bs) return NULL;
 
 	gis = malloc(sizeof(struct apk_gzip_istream));
-	if (gis == NULL)
-		goto err;
+	if (!gis) goto err;
 
 	*gis = (struct apk_gzip_istream) {
 		.is.read = gzi_read,

src/io.c

@@ -427,14 +427,19 @@ struct apk_bstream *apk_bstream_tee(struct apk_bstream *from, int atfd, const ch
 	struct apk_tee_bstream *tbs;
 	int fd;
 
+	if (!from) return NULL;
+
 	fd = openat(atfd, to, O_CREAT | O_RDWR | O_TRUNC | O_CLOEXEC,
 		    S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
-	if (fd < 0)
+	if (fd < 0) {
+		from->close(from, NULL);
 		return NULL;
+	}
 
 	tbs = malloc(sizeof(struct apk_tee_bstream));
-	if (tbs == NULL) {
+	if (!tbs) {
 		close(fd);
+		from->close(from, NULL);
 		return NULL;
 	}