From 08aa1c03f2f9b783782042faf7db626237bf426e Mon Sep 17 00:00:00 2001
From: "sergey.kitov" <sergey.kitov@open-xchange.com>
Date: Mon, 14 Oct 2024 18:45:38 +0300
Subject: [PATCH] lib-imap: Introduce imap_write_capability() function.

---
 src/lib-imap/imap-util.c      | 24 ++++++++++++++++++++++++
 src/lib-imap/imap-util.h      |  5 +++++
 src/lib-imap/test-imap-util.c | 17 +++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/src/lib-imap/imap-util.c b/src/lib-imap/imap-util.c
index dc1ae24466..944f091fc2 100644
--- a/src/lib-imap/imap-util.c
+++ b/src/lib-imap/imap-util.c
@@ -200,3 +200,27 @@ const char *imap_args_to_str(const struct imap_arg *args)
 	imap_write_args(str, args);
 	return str_c(str);
 }
+
+void imap_write_capability(string_t *dest, const ARRAY_TYPE(const_string) *capabilities)
+{
+	string_t *cap_str;
+	string_t *cur_str;
+	const char *const *tmp;
+	if (array_is_empty(capabilities))
+		return;
+	cap_str = t_str_new(256);
+	for (tmp = array_front(capabilities); *tmp != NULL; tmp++) {
+		if (str_begins_with(*tmp, "IMAP4"))
+			cur_str = dest;
+		else
+			cur_str = cap_str;
+		if (str_len(cur_str) > 0)
+			str_append_c(cur_str, ' ');
+		str_append(cur_str, *tmp);
+	}
+	if (str_len(cap_str) > 0) {
+		if (str_len(dest) > 0)
+			str_append_c(dest, ' ');
+		str_append(dest, str_c(cap_str));
+	}
+}
diff --git a/src/lib-imap/imap-util.h b/src/lib-imap/imap-util.h
index 47b7d2c066..0c21406876 100644
--- a/src/lib-imap/imap-util.h
+++ b/src/lib-imap/imap-util.h
@@ -26,4 +26,9 @@ void imap_write_args_for_human(string_t *dest, const struct imap_arg *args);
 /* Like imap_write_args(), but return the string allocated from data stack. */
 const char *imap_args_to_str(const struct imap_arg *args);
 
+/* Writes capabilities from boollist to string.
+   Capabilities beginning with IMAP4 are written first
+   to avoid breaking clients that expect IMAP4rev1 to be the first. */
+void imap_write_capability(string_t *dest, const ARRAY_TYPE(const_string) *capabilities);
+
 #endif
diff --git a/src/lib-imap/test-imap-util.c b/src/lib-imap/test-imap-util.c
index 90f59a1c80..9757412d66 100644
--- a/src/lib-imap/test-imap-util.c
+++ b/src/lib-imap/test-imap-util.c
@@ -68,11 +68,28 @@ static void test_imap_write_arg(void)
 	test_end();
 }
 
+static void test_imap_write_capabilities(void)
+{
+	ARRAY_TYPE(const_string) capabilities;
+	t_array_init(&capabilities, 5);
+	const char *const unsorted_capabilities[] = {
+		"foo", "bar", "IMAP4rev1", "baz", "IMAP4rev2"
+	};
+	array_append(&capabilities, unsorted_capabilities, N_ELEMENTS(unsorted_capabilities));
+	string_t *cap_str = t_str_new(256);
+
+	test_begin("imap_write_capabilities");
+	imap_write_capability(cap_str, &capabilities);
+	test_assert_strcmp(str_c(cap_str), "IMAP4rev1 IMAP4rev2 foo bar baz");
+	test_end();
+}
+
 int main(void)
 {
 	static void (*const test_functions[])(void) = {
 		test_imap_parse_system_flag,
 		test_imap_write_arg,
+		test_imap_write_capabilities,
 		NULL
 	};
 	return test_run(test_functions);
-- 
2.47.3