[PATCH v2 2/4] mailinfo: refactor to support utf8 decode attempts

From

JTJonathan Tan <jonathantanmy@google.com>

Date

Sep 19, 2016, 21:08 UTC

Message-ID

<e882f6395d1079037843e6e5b632c0010e1f4cdf.1474319086.git.jonathantanmy@google.com>

In-Reply-To

<cover.1474319086.git.jonathantanmy@google.com>

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
---
 mailinfo.c | 42 +++++++++++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/mailinfo.c b/mailinfo.c
index 0c4738a..aadad09 100644
--- a/mailinfo.c
+++ b/mailinfo.c
@@ -340,23 +340,47 @@ static struct strbuf *decode_b_segment(const struct strbuf *b_seg)
 	return out;
 }
 
+/*
+ * Attempts to convert line into UTF-8.
+ *
+ * This differs from convert_to_utf8 in that no inputs are overridden, and that
+ * conversion non-success is not considered an error case - mi->input_error is
+ * not set, and no error message is printed.
+ *
+ * If the conversion is unnecessary, returns 1 and stores NULL in result.
+ *
+ * If the conversion is successful, returns 1 and stores the converted string
+ * in result.
+ *
+ * If the conversion is unsuccessful, returns 0 and stores NULL in result.
+ */
+static int try_convert_to_utf8(const struct mailinfo *mi, const char *line,
+			       const char *charset, char **result)
+{
+	if (!mi->metainfo_charset || !charset || !*charset ||
+	    same_encoding(mi->metainfo_charset, charset)) {
+		*result = NULL;
+		return 1;
+	}
+
+	*result = reencode_string(line, mi->metainfo_charset, charset);
+	return !!*result;
+}
+
+/*
+ * Converts line into UTF-8, setting mi->input_error to -1 upon failure.
+ */
 static int convert_to_utf8(struct mailinfo *mi,
 			   struct strbuf *line, const char *charset)
 {
 	char *out;
-
-	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);
-	if (!out) {
+	if (!try_convert_to_utf8(mi, line->buf, charset, &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));
+	if (out)
+		strbuf_attach(line, out, strlen(out), strlen(out));
 	return 0;
 }
 

-- 
2.10.0.rc2.20.g5b18e70