diff --git a/test/zdtm/lib/streamutil.c b/test/zdtm/lib/streamutil.c
index ba6645872..90305c02a 100644
--- a/test/zdtm/lib/streamutil.c
+++ b/test/zdtm/lib/streamutil.c
@@ -40,3 +40,36 @@ int pipe_in2out(int infd, int outfd, uint8_t *buffer, int length)
 		}
 	}
 }
+
+int read_data(int fd, unsigned char *buf, int size)
+{
+	int cur = 0;
+	int ret;
+	while (cur != size) {
+		ret = read(fd, buf + cur, size - cur);
+		if (ret <= 0) {
+			pr_perror("read(%d) = %d", size - cur, ret);
+			return -1;
+		}
+		cur += ret;
+	}
+
+	return 0;
+}
+
+int write_data(int fd, const unsigned char *buf, int size)
+{
+	int cur = 0;
+	int ret;
+
+	while (cur != size) {
+		ret = write(fd, buf + cur, size - cur);
+		if (ret <= 0) {
+			pr_perror("write(%d) = %d", size - cur, ret);
+			return -1;
+		}
+		cur += ret;
+	}
+
+	return 0;
+}
diff --git a/test/zdtm/lib/zdtmtst.h b/test/zdtm/lib/zdtmtst.h
index cd513b9c9..737ac77cf 100644
--- a/test/zdtm/lib/zdtmtst.h
+++ b/test/zdtm/lib/zdtmtst.h
@@ -55,6 +55,8 @@ extern int datasum(const uint8_t *buffer, unsigned length, uint32_t *crc);
 /* streaming helpers */
 extern int set_nonblock(int fd, int on);
 extern int pipe_in2out(int infd, int outfd, uint8_t *buffer, int length);
+extern int read_data(int fd, unsigned char *buf, int len);
+extern int write_data(int fd, const unsigned char *buf, int len);
 
 /* command line args */
 struct long_opt {