3 files changed, 161 insertions, 0 deletions
diff --git a/src/common/tuklib_mbstr.h b/src/common/tuklib_mbstr.h
new file mode 100644
index 00000000..9f358355
--- /dev/null
+++ b/src/common/tuklib_mbstr.h
@@ -0,0 +1,66 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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
diff --git a/src/common/tuklib_mbstr_fw.c b/src/common/tuklib_mbstr_fw.c
new file mode 100644
index 00000000..978a3fe1
--- /dev/null
+++ b/src/common/tuklib_mbstr_fw.c
@@ -0,0 +1,31 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       tuklib_mstr_fw.c
+/// \brief      Get the field width for printf() e.g. to align table columns
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "tuklib_mbstr.h"
+
+
+extern int
+tuklib_mbstr_fw(const char *str, int columns_min)
+{
+	size_t len;
+	const size_t width = tuklib_mbstr_width(str, &len);
+	if (width == (size_t)-1)
+		return -1;
+
+	if (width > (size_t)columns_min)
+		return 0;
+
+	if (width < (size_t)columns_min)
+		len += (size_t)columns_min - width;
+
+	return len;
+}
diff --git a/src/common/tuklib_mbstr_width.c b/src/common/tuklib_mbstr_width.c
new file mode 100644
index 00000000..3c38990f
--- /dev/null
+++ b/src/common/tuklib_mbstr_width.c
@@ -0,0 +1,64 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       tuklib_mstr_width.c
+/// \brief      Calculate width of a multibyte string
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "tuklib_mbstr.h"
+
+#if defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH)
+#	include <wchar.h>
+#endif
+
+
+extern size_t
+tuklib_mbstr_width(const char *str, size_t *bytes)
+{
+	const size_t len = strlen(str);
+	if (bytes != NULL)
+		*bytes = len;
+
+#if !(defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH))
+	// In single-byte mode, the width of the string is the same
+	// as its length.
+	return len;
+
+#else
+	mbstate_t state;
+	memset(&state, 0, sizeof(state));
+
+	size_t width = 0;
+	size_t i = 0;
+
+	// Convert one multibyte character at a time to wchar_t
+	// and get its width using wcwidth().
+	while (i < len) {
+		wchar_t wc;
+		const size_t ret = mbrtowc(&wc, str + i, len - i, &state);
+		if (ret < 1 || ret > len)
+			return (size_t)-1;
+
+		i += ret;
+
+		const int wc_width = wcwidth(wc);
+		if (wc_width < 0)
+			return (size_t)-1;
+
+		width += wc_width;
+	}
+
+	// Require that the string ends in the initial shift state.
+	// This way the caller can be combine the string with other
+	// strings without needing to worry about the shift states.
+	if (!mbsinit(&state))
+		return (size_t)-1;
+
+	return width;
+#endif
+}