1 files changed, 103 insertions, 0 deletions
diff --git a/src/lib-mail/message-part.c b/src/lib-mail/message-part.c
new file mode 100644
index 0000000..340dbbb
--- /dev/null
+++ b/src/lib-mail/message-part.c
@@ -0,0 +1,103 @@
+/* Copyright (c) 2014-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "message-part.h"
+
+static const struct message_part *
+message_part_root(const struct message_part *part)
+{
+	while (part->parent != NULL)
+		part = part->parent;
+	return part;
+}
+
+static bool message_part_find(const struct message_part *siblings,
+			      const struct message_part *part,
+			      unsigned int *n)
+{
+	const struct message_part *p;
+
+	for (p = siblings; p != NULL; p = p->next) {
+		if (p == part)
+			return TRUE;
+		*n += 1;
+		if (message_part_find(p->children, part, n))
+			return TRUE;
+	}
+	return FALSE;
+}
+
+unsigned int message_part_to_idx(const struct message_part *part)
+{
+	const struct message_part *root;
+	unsigned int n = 0;
+
+	root = message_part_root(part);
+	if (!message_part_find(root, part, &n))
+		i_unreached();
+	return n;
+}
+
+static struct message_part *
+message_sub_part_by_idx(struct message_part *parts,
+			unsigned int idx)
+{
+	struct message_part *part = parts;
+
+	for (; part != NULL && idx > 0; part = part->next) {
+		if (part->children_count >= idx)
+			return message_sub_part_by_idx(part->children, idx-1);
+		idx -= part->children_count + 1;
+	}
+	return part;
+}
+
+struct message_part *
+message_part_by_idx(struct message_part *parts, unsigned int idx)
+{
+	i_assert(parts->parent == NULL);
+
+	return message_sub_part_by_idx(parts, idx);
+}
+
+bool message_part_is_equal(const struct message_part *p1,
+			   const struct message_part *p2)
+{
+	/* This cannot be p1 && p2, because then we would return
+	   TRUE when either part is NULL, and we should return FALSE */
+	while (p1 != NULL || p2 != NULL) {
+		/* If either part is NULL, return false */
+		if ((p1 != NULL) != (p2 != NULL))
+			return FALSE;
+
+		/* Expect that both either have children, or both
+		   do not have children */
+		if ((p1->children != NULL) != (p2->children != NULL))
+			return FALSE;
+
+		/* If there are children, ensure they are equal */
+		if (p1->children != NULL) {
+			if (!message_part_is_equal(p1->children, p2->children))
+				return FALSE;
+		}
+
+		/* If any of these properties differ, then parts are not equal */
+		if (p1->physical_pos != p2->physical_pos ||
+		    p1->header_size.physical_size != p2->header_size.physical_size ||
+		    p1->header_size.virtual_size != p2->header_size.virtual_size ||
+		    p1->header_size.lines != p2->header_size.lines ||
+		    p1->body_size.physical_size != p2->body_size.physical_size ||
+		    p1->body_size.virtual_size != p2->body_size.virtual_size ||
+		    p1->body_size.lines != p2->body_size.lines ||
+		    p1->children_count != p2->children_count ||
+		    p1->flags != p2->flags)
+			return FALSE;
+
+		/* Move forward */
+		p1 = p1->next;
+		p2 = p2->next;
+	}
+
+	/* Parts are equal */
+	return TRUE;
+}