EMailParserExtension: Collect EMailParts in a GQueue.

Collect EMailParts in a GQueue provided to the EMailParserExtension,
and change the return type of parse() to gboolean to indicate whether
the given CamelMimePart was handled (even if no parts were added to
the output GQueue).

This avoids the awkward corner case of a parser extension returning a
linked list node with a NULL data member to indicate the CamelMimePart
was handled but no EMailParts produced, and then having to watch out
for that NULL data member corner case throughout the application.

Also, remove the GCancellable parameter from e_mail_parser_error() and
e_mail_parser_wrap_as_attachment() since neither function blocks.

1 files changed, 86 insertions, 93 deletions

diff --git a/modules/prefer-plain/e-mail-parser-prefer-plain.c b/modules/prefer-plain/e-mail-parser-prefer-plain.c
index 66ff32106c..296369ed32 100644
--- a/modules/prefer-plain/e-mail-parser-prefer-plain.c
+++ b/modules/prefer-plain/e-mail-parser-prefer-plain.c
@@ -99,18 +99,19 @@ enum {
 	PROP_SHOW_SUPPRESSED
 };
 
-static GSList *
+static void
 make_part_attachment (EMailParser *parser,
                       CamelMimePart *part,
                       GString *part_id,
                       gboolean force_html,
-                      GCancellable *cancellable)
+                      GCancellable *cancellable,
+                      GQueue *out_mail_parts)
 {
-	GSList *parts;
-
 	if (camel_content_type_is (camel_mime_part_get_content_type (part), "text", "html")) {
+		GQueue work_queue = G_QUEUE_INIT;
 		EMailPart *mail_part;
 		gint len;
+
 		/* always show HTML as attachments and not inline */
 		camel_mime_part_set_disposition (part, "attachment");
 
@@ -126,9 +127,12 @@ make_part_attachment (EMailParser *parser,
 		mail_part->mime_type = g_strdup ("text/html");
 		g_string_truncate (part_id, len);
 
-		parts = e_mail_parser_wrap_as_attachment (
-				parser, part, g_slist_append (NULL, mail_part),
-				part_id, cancellable);
+		g_queue_push_tail (&work_queue, mail_part);
+
+		e_mail_parser_wrap_as_attachment (
+			parser, part, part_id, &work_queue);
+
+		e_queue_transfer (&work_queue, out_mail_parts);
 
 	} else if (force_html && CAMEL_IS_MIME_MESSAGE (part)) {
 		/* message was asked to be formatted as text/html;
@@ -137,52 +141,51 @@ make_part_attachment (EMailParser *parser,
 		CamelDataWrapper *content;
 
 		content = camel_medium_get_content (CAMEL_MEDIUM (part));
-		g_return_val_if_fail (content != NULL, NULL);
+		g_return_if_fail (content != NULL);
 
 		new_part = camel_mime_part_new ();
 		camel_medium_set_content (CAMEL_MEDIUM (new_part), content);
 
-		parts = e_mail_parser_parse_part (
-				parser, new_part, part_id, cancellable);
+		e_mail_parser_parse_part (
+			parser, new_part, part_id,
+			cancellable, out_mail_parts);
 
 		g_object_unref (new_part);
 	} else {
-		parts = e_mail_parser_parse_part (
-				parser, part, part_id, cancellable);
+		e_mail_parser_parse_part (
+			parser, part, part_id, cancellable, out_mail_parts);
 	}
-
-	return parts;
 }
 
 static void
-hide_parts (GSList *parts)
+hide_parts (GQueue *work_queue)
 {
-	GSList *iter;
+	GList *head, *link;
 
-	for (iter = parts; iter; iter = g_slist_next (iter)) {
-		EMailPart *p = iter->data;
+	head = g_queue_peek_head_link (work_queue);
 
-		if (!p)
-			continue;
+	for (link = head; link != NULL; link = g_list_next (link)) {
+		EMailPart *mail_part = link->data;
 
-		p->is_hidden = TRUE;
+		mail_part->is_hidden = TRUE;
 	}
 }
 
-static GSList *
+static gboolean
 empe_prefer_plain_parse (EMailParserExtension *extension,
                          EMailParser *parser,
                          CamelMimePart *part,
                          GString *part_id,
-                         GCancellable *cancellable)
+                         GCancellable *cancellable,
+                         GQueue *out_mail_parts)
 {
 	EMailParserPreferPlain *emp_pp;
 	CamelMultipart *mp;
 	gint i, nparts, partidlen;
-	GSList *parts;
 	CamelContentType *ct;
 	gboolean has_calendar = FALSE;
-	GSList *plain_text_parts = NULL;
+	GQueue plain_text_parts = G_QUEUE_INIT;
+	GQueue work_queue = G_QUEUE_INIT;
 
 	emp_pp = (EMailParserPreferPlain *) extension;
 
@@ -194,36 +197,35 @@ empe_prefer_plain_parse (EMailParserExtension *extension,
 
 		/* Prevent recursion, fall back to next (real text/html) parser */
 		if (strstr (part_id->str, ".alternative-prefer-plain.") != NULL)
-			return NULL;
+			return FALSE;
 
 		/* Not enforcing text/plain, so use real parser */
 		if (emp_pp->mode != ONLY_PLAIN)
-			return NULL;
+			return FALSE;
 
 		/* Enforcing text/plain, but got only HTML part, so add it
 		 * as attachment, to not show empty message preview, which
 		 * is confusing. */
-		return make_part_attachment (
-			parser, part, part_id,
-			FALSE, cancellable);
+		make_part_attachment (
+			parser, part, part_id, FALSE,
+			cancellable, out_mail_parts);
+
+		return TRUE;
 	}
 
-	parts = NULL;
 	partidlen = part_id->len;
 
 	mp = (CamelMultipart *) camel_medium_get_content (CAMEL_MEDIUM (part));
 
-	if (!CAMEL_IS_MULTIPART (mp)) {
+	if (!CAMEL_IS_MULTIPART (mp))
 		return e_mail_parser_parse_part_as (
 			parser, part, part_id,
-			"application/vnd.evolution.source", cancellable);
-	}
+			"application/vnd.evolution.source",
+			cancellable, out_mail_parts);
 
 	nparts = camel_multipart_get_number (mp);
 	for (i = 0; i < nparts; i++) {
-
 		CamelMimePart *sp;
-		GSList *sparts = NULL;
 
 		sp = camel_multipart_get_part (mp, i);
 		ct = camel_mime_part_get_content_type (sp);
@@ -232,61 +234,52 @@ empe_prefer_plain_parse (EMailParserExtension *extension,
 		g_string_append_printf (part_id, ".alternative-prefer-plain.%d", i);
 
 		if (camel_content_type_is (ct, "text", "html")) {
-
 			if (emp_pp->mode != PREFER_HTML) {
 				if (emp_pp->show_suppressed) {
-					sparts = make_part_attachment (
-						parser, sp, part_id,
-						FALSE, cancellable);
+					make_part_attachment (
+						parser, sp, part_id, FALSE,
+						cancellable, &work_queue);
 				}
 			} else {
-				sparts = e_mail_parser_parse_part (
-					parser, sp, part_id, cancellable);
+				e_mail_parser_parse_part (
+					parser, sp, part_id,
+					cancellable, &work_queue);
 			}
 
-			parts = g_slist_concat (parts, sparts);
-			continue;
-		}
-
-		if (camel_content_type_is (ct, "text", "plain")) {
-
-			sparts = e_mail_parser_parse_part (
-					parser, sp, part_id, cancellable);
-
-			plain_text_parts = g_slist_concat (plain_text_parts, sparts);
-			continue;
-		}
+		} else if (camel_content_type_is (ct, "text", "plain")) {
+			e_mail_parser_parse_part (
+				parser, sp, part_id,
+				cancellable, &plain_text_parts);
 
 		/* Always show calendar part! */
-		if (camel_content_type_is (ct, "text", "calendar") ||
+		} else if (camel_content_type_is (ct, "text", "calendar") ||
 		    camel_content_type_is (ct, "text", "x-calendar")) {
 
-			/* Hide everything else, displaying native calendar part only */
-			hide_parts (parts);
+			/* Hide everything else, displaying
+			 * native calendar part only. */
+			hide_parts (&work_queue);
 
-			sparts = e_mail_parser_parse_part (
-					parser, sp, part_id, cancellable);
+			e_mail_parser_parse_part (
+				parser, sp, part_id, cancellable, &work_queue);
 
-			parts = g_slist_concat (parts, sparts);
 			has_calendar = TRUE;
-			continue;
-		}
 
 		/* Multiparts can represent a text/html with inline images or so */
-		if (camel_content_type_is (ct, "multipart", "*")) {
-			GSList *iter;
+		} else if (camel_content_type_is (ct, "multipart", "*")) {
+			GQueue inner_queue = G_QUEUE_INIT;
+			GList *head, *link;
 			gboolean has_html = FALSE;
 
-			sparts = e_mail_parser_parse_part (
-					parser, sp, part_id, cancellable);
+			e_mail_parser_parse_part (
+				parser, sp, part_id, cancellable, &inner_queue);
+
+			head = g_queue_peek_head_link (&inner_queue);
 
 			/* Check whether the multipart contains a text/html part */
-			for (iter = sparts; iter; iter = g_slist_next (iter)) {
-				EMailPart *p = iter->data;
-				if (!p)
-					continue;
+			for (link = head; link != NULL; link = g_list_next (link)) {
+				EMailPart *mail_part = link->data;
 
-				if (strstr (p->id, ".text_html") != NULL) {
+				if (strstr (mail_part->id, ".text_html") != NULL) {
 					has_html = TRUE;
 					break;
 				}
@@ -294,41 +287,41 @@ empe_prefer_plain_parse (EMailParserExtension *extension,
 
 			if (has_html && (emp_pp->mode != PREFER_HTML)) {
 				if (emp_pp->show_suppressed) {
-					sparts =  e_mail_parser_wrap_as_attachment (
-							parser, sp, sparts, part_id,
-							cancellable);
+					e_mail_parser_wrap_as_attachment (
+						parser, sp, part_id,
+						&inner_queue);
 				} else {
-					hide_parts (sparts);
+					hide_parts (&inner_queue);
 				}
 			}
 
-			parts = g_slist_concat (parts, sparts);
-			continue;
-		}
+			e_queue_transfer (&inner_queue, &work_queue);
 
 		/* Parse everything else as an attachment */
-		sparts = e_mail_parser_parse_part (
-				parser, sp, part_id, cancellable);
-		parts = g_slist_concat (
-				parts,
-				e_mail_parser_wrap_as_attachment (
-					parser, sp, sparts, part_id,
-					cancellable));
+		} else {
+			GQueue inner_queue = G_QUEUE_INIT;
+
+			e_mail_parser_parse_part (
+				parser, sp, part_id,
+				cancellable, &inner_queue);
+			e_mail_parser_wrap_as_attachment (
+				parser, sp, part_id, &inner_queue);
+
+			e_queue_transfer (&inner_queue, &work_queue);
+		}
 	}
 
 	/* Don't hide the plain text if there's nothing else to display */
-	if (has_calendar || (nparts > 1 && emp_pp->mode == PREFER_HTML)) {
-		hide_parts (plain_text_parts);
-	}
+	if (has_calendar || (nparts > 1 && emp_pp->mode == PREFER_HTML))
+		hide_parts (&plain_text_parts);
 
-	if (plain_text_parts) {
-		/* plain_text parts should be always first */
-		parts = g_slist_concat (plain_text_parts, parts);
-	}
+	/* plain_text parts should be always first */
+	e_queue_transfer (&plain_text_parts, out_mail_parts);
+	e_queue_transfer (&work_queue, out_mail_parts);
 
 	g_string_truncate (part_id, partidlen);
 
-	return parts;
+	return TRUE;
 }
 
 static const gchar **