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diff --git a/src/common/tuklib_mbstr.h b/src/common/tuklib_mbstr.h
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       tuklib_mstr.h
+/// \brief      Utility functions for handling multibyte strings
+///
+/// If not enough multibyte string support is available in the C library,
+/// these functions keep working with the assumption that all strings
+/// are in a single-byte character set without combining characters, e.g.
+/// US-ASCII or ISO-8859-*.
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef TUKLIB_MBSTR_H
+#define TUKLIB_MBSTR_H
+
+#include "tuklib_common.h"
+TUKLIB_DECLS_BEGIN
+
+#define tuklib_mbstr_width TUKLIB_SYMBOL(tuklib_mbstr_width)
+extern size_t tuklib_mbstr_width(const char *str, size_t *bytes);
+///<
+/// \brief      Get the number of columns needed for the multibyte string
+///
+/// This is somewhat similar to wcswidth() but works on multibyte strings.
+///
+/// \param      str         String whose width is to be calculated. If the
+///                         current locale uses a multibyte character set
+///                         that has shift states, the string must begin
+///                         and end in the initial shift state.
+/// \param      bytes       If this is not NULL, *bytes is set to the
+///                         value returned by strlen(str) (even if an
+///                         error occurs when calculating the width).
+///
+/// \return     On success, the number of columns needed to display the
+///             string e.g. in a terminal emulator is returned. On error,
+///             (size_t)-1 is returned. Possible errors include invalid,
+///             partial, or non-printable multibyte character in str, or
+///             that str doesn't end in the initial shift state.
+
+#define tuklib_mbstr_fw TUKLIB_SYMBOL(tuklib_mbstr_fw)
+extern int tuklib_mbstr_fw(const char *str, int columns_min);
+///<
+/// \brief      Get the field width for printf() e.g. to align table columns
+///
+/// Printing simple tables to a terminal can be done using the field field
+/// feature in the printf() format string, but it works only with single-byte
+/// character sets. To do the same with multibyte strings, tuklib_mbstr_fw()
+/// can be used to calculate appropriate field width.
+///
+/// The behavior of this function is undefined, if
+///   - str is NULL or not terminated with '\0';
+///   - columns_min <= 0; or
+///   - the calculated field width exceeds INT_MAX.
+///
+/// \return     If tuklib_mbstr_width(str, NULL) fails, -1 is returned.
+///             If str needs more columns than columns_min, zero is returned.
+///             Otherwise a positive integer is returned, which can be
+///             used as the field width, e.g. printf("%*s", fw, str).
+
+TUKLIB_DECLS_END
+#endif