lib-mail: Make message_header_strdup() public

Also move it to a better file.

src/lib-mail/message-header-parser.c

@@ -4,6 +4,7 @@
 #include "buffer.h"
 #include "istream.h"
 #include "str.h"
+#include "unichar.h"
 #include "message-size.h"
 #include "message-header-parser.h"
 
@@ -411,3 +412,25 @@ void message_header_line_write(buffer_t *output,
 		buffer_append_c(output, '\n');
 	}
 }
+
+const char *
+message_header_strdup(pool_t pool, const unsigned char *data, size_t size)
+{
+	if (memchr(data, '\0', size) == NULL) {
+		/* fast path */
+		char *dest = p_malloc(pool, size+1);
+		memcpy(dest, data, size);
+		return dest;
+	}
+
+	/* slow path - this could be made faster, but it should be
+	   rare so keep it simple */
+	string_t *str = str_new(pool, size+2);
+	for (size_t i = 0; i < size; i++) {
+		if (data[i] != '\0')
+			str_append_c(str, data[i]);
+		else
+			str_append(str, UNICODE_REPLACEMENT_CHAR_UTF8);
+	}
+	return str_c(str);
+}

src/lib-mail/message-header-parser.h

@@ -74,4 +74,9 @@ void message_parse_header(struct istream *input, struct message_size *hdr_size,
 void message_header_line_write(buffer_t *output,
 			       const struct message_header_line *hdr);
 
+/* Duplicate the given header value data and return it. Replaces any NULs with
+   UNICODE_REPLACEMENT_CHAR_UTF8. */
+const char *
+message_header_strdup(pool_t pool, const unsigned char *data, size_t size);
+
 #endif

src/lib-mail/message-part-data.c

@@ -170,28 +170,6 @@ envelope_get_field(const char *name)
 	return ENVELOPE_FIELD_UNKNOWN;
 }
 
-static const char *
-message_header_strdup(pool_t pool, const unsigned char *data, size_t size)
-{
-	if (memchr(data, '\0', size) == NULL) {
-		/* fast path */
-		char *dest = p_malloc(pool, size+1);
-		memcpy(dest, data, size);
-		return dest;
-	}
-
-	/* slow path - this could be made faster, but it should be
-	   rare so keep it simple */
-	string_t *str = str_new(pool, size+2);
-	for (size_t i = 0; i < size; i++) {
-		if (data[i] != '\0')
-			str_append_c(str, data[i]);
-		else
-			str_append(str, UNICODE_REPLACEMENT_CHAR_UTF8);
-	}
-	return str_c(str);
-}
-
 void message_part_envelope_parse_from_header(pool_t pool,
 	struct message_part_envelope **data,
 	struct message_header_line *hdr)