Add piping API to buffered writer

test/unit/buf_writer.c

@@ -119,10 +119,78 @@ TEST_BEGIN(test_buf_write_oom) {
 }
 TEST_END
 
+static int test_read_count;
+static size_t test_read_len;
+static uint64_t arg_sum;
+
+ssize_t
+test_read_cb(void *cbopaque, void *buf, size_t limit) {
+	static uint64_t rand = 4;
+
+	arg_sum += *(uint64_t *)cbopaque;
+	assert_zu_gt(limit, 0, "Limit for read_cb must be positive");
+	--test_read_count;
+	if (test_read_count == 0) {
+		return -1;
+	} else {
+		size_t read_len = limit;
+		if (limit > 1) {
+			rand = prng_range_u64(&rand, (uint64_t)limit);
+			read_len -= (size_t)rand;
+		}
+		assert(read_len > 0);
+		memset(buf, 'a', read_len);
+		size_t prev_test_read_len = test_read_len;
+		test_read_len += read_len;
+		assert_zu_le(prev_test_read_len, test_read_len,
+		    "Test read overflowed");
+		return read_len;
+	}
+}
+
+static void
+test_buf_writer_pipe_body(tsdn_t *tsdn, buf_writer_t *buf_writer) {
+	arg = 4; /* Starting value of random argument. */
+	for (int count = 5; count > 0; --count) {
+		arg = prng_lg_range_u64(&arg, 64);
+		arg_sum = 0;
+		test_read_count = count;
+		test_read_len = 0;
+		test_write_len = 0;
+		buf_writer_pipe(buf_writer, test_read_cb, &arg);
+		assert(test_read_count == 0);
+		expect_u64_eq(arg_sum, arg * count, "");
+		expect_zu_eq(test_write_len, test_read_len,
+		    "Write length should be equal to read length");
+	}
+	buf_writer_terminate(tsdn, buf_writer);
+}
+
+TEST_BEGIN(test_buf_write_pipe) {
+	buf_writer_t buf_writer;
+	tsdn_t *tsdn = tsdn_fetch();
+	assert_false(buf_writer_init(tsdn, &buf_writer, test_write_cb, &arg,
+	    test_buf, TEST_BUF_SIZE),
+	    "buf_writer_init() should not encounter error on static buffer");
+	test_buf_writer_pipe_body(tsdn, &buf_writer);
+}
+TEST_END
+
+TEST_BEGIN(test_buf_write_pipe_oom) {
+	buf_writer_t buf_writer;
+	tsdn_t *tsdn = tsdn_fetch();
+	assert_true(buf_writer_init(tsdn, &buf_writer, test_write_cb, &arg,
+	    NULL, SC_LARGE_MAXCLASS + 1), "buf_writer_init() should OOM");
+	test_buf_writer_pipe_body(tsdn, &buf_writer);
+}
+TEST_END
+
 int
 main(void) {
 	return test(
 	    test_buf_write_static,
 	    test_buf_write_dynamic,
-	    test_buf_write_oom);
+	    test_buf_write_oom,
+	    test_buf_write_pipe,
+	    test_buf_write_pipe_oom);
 }