diff -r e79a60b3a7cb -r 7c3ff86ee9d4 ucx/cx/utils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ucx/cx/utils.h	Tue May 23 11:11:28 2023 +0200
@@ -0,0 +1,196 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file utils.h
+ *
+ * \brief General purpose utility functions.
+ *
+ * \author Mike Becker
+ * \author Olaf Wintermann
+ * \version 3.0
+ * \copyright 2-Clause BSD License
+ */
+
+#ifndef UCX_UTILS_H
+#define UCX_UTILS_H
+
+#include "common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Convenience macro for a for loop that counts from zero to n-1.
+ */
+#define cx_for_n(varname, n) for (size_t varname = 0 ; (varname) < (n) ; (varname)++)
+
+/**
+ * Convenience macro for swapping two pointers.
+ */
+#ifdef __cplusplus
+#define cx_swap_ptr(left, right) do {auto cx_tmp_swap_var = left; left = right; right = cx_tmp_swap_var;} while(0)
+#else
+#define cx_swap_ptr(left, right) do {void *cx_tmp_swap_var = left; left = right; right = cx_tmp_swap_var;} while(0)
+#endif
+
+// cx_szmul() definition
+
+#if (__GNUC__ >= 5 || defined(__clang__)) && !defined(CX_NO_SZMUL_BUILTIN)
+#define CX_SZMUL_BUILTIN
+
+/**
+ * Alias for \c __builtin_mul_overflow.
+ *
+ * Performs a multiplication of size_t values and checks for overflow.
+ *
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define cx_szmul(a, b, result) __builtin_mul_overflow(a, b, result)
+
+#else // no GNUC or clang bultin
+
+/**
+ * Performs a multiplication of size_t values and checks for overflow.
+  *
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define cx_szmul(a, b, result) cx_szmul_impl(a, b, result)
+
+/**
+ * Performs a multiplication of size_t values and checks for overflow.
+ *
+ * This is a custom implementation in case there is no compiler builtin
+ * available.
+ *
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t where the result should be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+int cx_szmul_impl(size_t a, size_t b, size_t *result);
+
+#endif // cx_szmul
+
+
+/**
+ * Reads data from a stream and writes it to another stream.
+ *
+ * @param src the source stream
+ * @param dest the destination stream
+ * @param rfnc the read function
+ * @param wfnc the write function
+ * @param buf a pointer to the copy buffer or \c NULL if a buffer
+ * shall be implicitly created on the heap
+ * @param bufsize the size of the copy buffer - if \p buf is \c NULL you can
+ * set this to zero to let the implementation decide
+ * @param n the maximum number of bytes that shall be copied.
+ * If this is larger than \p bufsize, the content is copied over multiple
+ * iterations.
+ * @return the total number of bytes copied
+ */
+__attribute__((__nonnull__(1, 2, 3, 4)))
+size_t cx_stream_bncopy(
+        void *src,
+        void *dest,
+        cx_read_func rfnc,
+        cx_write_func wfnc,
+        char *buf,
+        size_t bufsize,
+        size_t n
+);
+
+/**
+ * Reads data from a stream and writes it to another stream.
+ *
+ * @param src the source stream
+ * @param dest the destination stream
+ * @param rfnc the read function
+ * @param wfnc the write function
+ * @param buf a pointer to the copy buffer or \c NULL if a buffer
+ * shall be implicitly created on the heap
+ * @param bufsize the size of the copy buffer - if \p buf is \c NULL you can
+ * set this to zero to let the implementation decide
+ * @return total number of bytes copied
+ */
+#define cx_stream_bcopy(src, dest, rfnc, wfnc, buf, bufsize) \
+    cx_stream_bncopy(src, dest, rfnc, wfnc, buf, bufsize, SIZE_MAX)
+
+/**
+ * Reads data from a stream and writes it to another stream.
+ *
+ * The data is temporarily stored in a stack allocated buffer.
+ *
+ * @param src the source stream
+ * @param dest the destination stream
+ * @param rfnc the read function
+ * @param wfnc the write function
+ * @param n the maximum number of bytes that shall be copied.
+ * @return total number of bytes copied
+ */
+__attribute__((__nonnull__))
+size_t cx_stream_ncopy(
+        void *src,
+        void *dest,
+        cx_read_func rfnc,
+        cx_write_func wfnc,
+        size_t n
+);
+
+/**
+ * Reads data from a stream and writes it to another stream.
+ *
+ * The data is temporarily stored in a stack allocated buffer.
+ *
+ * @param src the source stream
+ * @param dest the destination stream
+ * @param rfnc the read function
+ * @param wfnc the write function
+ * @param n the maximum number of bytes that shall be copied.
+ * @return total number of bytes copied
+ */
+#define cx_stream_copy(src, dest, rfnc, wfnc) \
+    cx_stream_ncopy(src, dest, rfnc, wfnc, SIZE_MAX)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // UCX_UTILS_H