Add utf8_fprintf helper that returns correct number of columns

Since command usages can be translated, they may include utf-8
encoded strings, and the output in console may not align well any
more. This is because strlen() is different from strwidth() on utf-8
strings.

A wrapper utf8_fprintf() can help to return the correct number of
columns required.

Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 25 insertions, 2 deletions

diff --git a/parse-options.c b/parse-options.c
index c1c66bd408..670bf09b45 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -3,6 +3,7 @@
 #include "cache.h"
 #include "commit.h"
 #include "color.h"
+#include "utf8.h"
 
 static int parse_options_usage(struct parse_opt_ctx_t *ctx,
 			       const char * const *usagestr,
@@ -491,7 +492,7 @@ static int usage_argh(const struct option *opts, FILE *outfile)
 			s = literal ? "[%s]" : "[<%s>]";
 	else
 		s = literal ? " %s" : " <%s>";
-	return fprintf(outfile, s, opts->argh ? _(opts->argh) : _("..."));
+	return utf8_fprintf(outfile, s, opts->argh ? _(opts->argh) : _("..."));
 }
 
 #define USAGE_OPTS_WIDTH 24
@@ -550,7 +551,7 @@ static int usage_with_options_internal(struct parse_opt_ctx_t *ctx,
 		if (opts->long_name)
 			pos += fprintf(outfile, "--%s", opts->long_name);
 		if (opts->type == OPTION_NUMBER)
-			pos += fprintf(outfile, "-NUM");
+			pos += utf8_fprintf(outfile, _("-NUM"));
 
 		if ((opts->flags & PARSE_OPT_LITERAL_ARGHELP) ||
 		    !(opts->flags & PARSE_OPT_NOARG))
diff --git a/utf8.c b/utf8.c
index 5c61bbe113..c7bda66e38 100644
--- a/utf8.c
+++ b/utf8.c
@@ -431,6 +431,27 @@ int same_encoding(const char *src, const char *dst)
 }
 
 /*
+ * Wrapper for fprintf and returns the total number of columns required
+ * for the printed string, assuming that the string is utf8.
+ */
+int utf8_fprintf(FILE *stream, const char *format, ...)
+{
+	struct strbuf buf = STRBUF_INIT;
+	va_list arg;
+	int columns;
+
+	va_start(arg, format);
+	strbuf_vaddf(&buf, format, arg);
+	va_end(arg);
+
+	columns = fputs(buf.buf, stream);
+	if (0 <= columns) /* keep the error from the I/O */
+		columns = utf8_strwidth(buf.buf);
+	strbuf_release(&buf);
+	return columns;
+}
+
+/*
  * Given a buffer and its encoding, return it re-encoded
  * with iconv.  If the conversion fails, returns NULL.
  */
diff --git a/utf8.h b/utf8.h
index 93ef60042c..3ca85c7737 100644
--- a/utf8.h
+++ b/utf8.h
@@ -8,6 +8,7 @@ int utf8_strwidth(const char *string);
 int is_utf8(const char *text);
 int is_encoding_utf8(const char *name);
 int same_encoding(const char *, const char *);
+int utf8_fprintf(FILE *, const char *, ...);
 
 int strbuf_add_wrapped_text(struct strbuf *buf,
 		const char *text, int indent, int indent2, int width);