--- a/src/lib-imap/imap-quote.c	Sat Jun 21 09:21:38 2008 +0300
+++ b/src/lib-imap/imap-quote.c	Sat Jun 21 09:21:51 2008 +0300
@@ -108,3 +108,26 @@
 		t_pop();
 	return ret;
 }
+
+void imap_dquote_append(string_t *dest, const char *src)
+{
+	str_append_c(dest, '"');
+	for (; *src != '\0'; src++) {
+		switch (*src) {
+		case '"':
+		case '\\':
+			str_append_c(dest, '\\');
+			str_append_c(dest, *src);
+			break;
+		default:
+			if ((unsigned char)*src >= 0x80) {
+				/* 8bit input not allowed in dquotes */
+				break;
+			}
+
+			str_append_c(dest, *src);
+			break;
+		}
+	}
+	str_append_c(dest, '"');
+}

--- a/src/lib-imap/imap-quote.h	Sat Jun 21 09:21:38 2008 +0300
+++ b/src/lib-imap/imap-quote.h	Sat Jun 21 09:21:51 2008 +0300
@@ -15,4 +15,7 @@
 	imap_quote_append(str, (const unsigned char *)(value), \
 			  (size_t)-1, compress_lwsp)
 
+/* Append data to destination string quoted using "". */
+void imap_dquote_append(string_t *dest, const char *src);
+
 #endif