[PATCH] mailinfo.c::convert_to_utf8: reuse strlen info

["Đoàn Trần Công Danh" <congdanhqx@gmail.com>]

We're passing buffer from strbuf to reencode_string,
which will call strlen(3) on that buffer,
and discard the length of newly created buffer.

Then, we compute the length of the return buffer to attach to strbuf.

We can do better by reusing all the available information,
and call the underlying lower level function that will be called
indirectly by reencode_string.

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 mailinfo.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mailinfo.c b/mailinfo.c
index 742fa376ab..0e9911df6d 100644
--- a/mailinfo.c
+++ b/mailinfo.c
@@ -447,19 +447,21 @@ static int convert_to_utf8(struct mailinfo *mi,
 			   struct strbuf *line, const char *charset)
 {
 	char *out;
+	size_t out_len;
 
 	if (!mi->metainfo_charset || !charset || !*charset)
 		return 0;
 
 	if (same_encoding(mi->metainfo_charset, charset))
 		return 0;
-	out = reencode_string(line->buf, mi->metainfo_charset, charset);
+	out = reencode_string_len(line->buf, line->len,
+				  mi->metainfo_charset, charset, &out_len);
 	if (!out) {
 		mi->input_error = -1;
 		return error("cannot convert from %s to %s",
 			     charset, mi->metainfo_charset);
 	}
-	strbuf_attach(line, out, strlen(out), strlen(out));
+	strbuf_attach(line, out, out_len, out_len);
 	return 0;
 }
 
-- 
2.26.1.301.g55bc3eb7cb