+/*
+ * Add/update, if necessary, the message C-T-E, based on the least restrictive
+ * of the part C-T-E's.
+ */
+static void
+update_cte (CT ct) {
+ const int least_restrictive_enc = least_restrictive_encoding (ct);
+
+ if (least_restrictive_enc != CE_UNKNOWN &&
+ least_restrictive_enc != CE_7BIT) {
+ char *cte = concat (" ", ce_str (least_restrictive_enc), "\n", NULL);
+ HF hf;
+ int found_cte = 0;
+
+ /* Update/add Content-Transfer-Encoding header field. */
+ for (hf = ct->c_first_hf; hf; hf = hf->next) {
+ if (! strcasecmp (ENCODING_FIELD, hf->name)) {
+ found_cte = 1;
+ free (hf->value);
+ hf->value = cte;
+ }
+ }
+ if (! found_cte) {
+ add_header (ct, add (ENCODING_FIELD, NULL), cte);
+ }
+ }
+}
+
+
+/*
+ * Find the least restrictive encoding (7bit, 8bit, binary) of the parts
+ * within a message.
+ */
+static int
+least_restrictive_encoding (CT ct) {
+ int encoding = CE_UNKNOWN;
+
+ switch (ct->c_type) {
+ case CT_MULTIPART: {
+ struct multipart *m = (struct multipart *) ct->c_ctparams;
+ struct part *part;
+
+ for (part = m->mp_parts; part; part = part->mp_next) {
+ const int part_encoding =
+ least_restrictive_encoding (part->mp_part);
+
+ if (less_restrictive (encoding, part_encoding)) {
+ encoding = part_encoding;
+ }
+ }
+ break;
+ }
+
+ case CT_MESSAGE:
+ if (ct->c_subtype == MESSAGE_EXTERNAL) {
+ struct exbody *e = (struct exbody *) ct->c_ctparams;
+ const int part_encoding =
+ least_restrictive_encoding (e->eb_content);
+
+ if (less_restrictive (encoding, part_encoding)) {
+ encoding = part_encoding;
+ }
+ }
+ break;
+
+ default: {
+ if (less_restrictive (encoding, ct->c_encoding)) {
+ encoding = ct->c_encoding;
+ }
+ }}
+
+ return encoding;
+}
+
+
+/*
+ * Return whether the second encoding is less restrictive than the first, where
+ * "less restrictive" is in the sense used by RFC 2045 Secs. 6.1 and 6.4. So,
+ * CE_BINARY is less restrictive than CE_8BIT and
+ * CE_8BIT is less restrictive than CE_7BIT.
+ */
+static int
+less_restrictive (int encoding, int second_encoding) {
+ switch (second_encoding) {
+ case CE_BINARY:
+ return encoding != CE_BINARY;
+ case CE_8BIT:
+ return encoding != CE_BINARY && encoding != CE_8BIT;
+ case CE_7BIT:
+ return encoding != CE_BINARY && encoding != CE_8BIT &&
+ encoding != CE_7BIT;
+ default :
+ return 0;
+ }
+}
+
+
projects / nmh / blobdiff