modem: chat: Add runtime API to modem chat matches

Add APIs for changing the contents of modem chat matches
safely at runtime.

This allows for reusing a single modem_chat_match at the cost
of placing the match and its buffers in RAM.

Signed-off-by: Bjarki Arge Andreasen <bjarki@arge-andreasen.me>

include/zephyr/modem/chat.h

@@ -45,9 +45,9 @@ struct modem_chat_match {
 	/** Size of separators array */
 	uint8_t separators_size;
 	/** Set if modem chat instance shall use wildcards when matching */
-	uint8_t wildcards : 1;
+	bool wildcards;
 	/** Set if script shall not continue to next step in case of match */
-	uint8_t partial : 1;
+	bool partial;
 	/** Type of modem chat instance */
 	modem_chat_match_callback callback;
 };
@@ -376,6 +376,56 @@ void modem_chat_script_abort(struct modem_chat *chat);
  */
 void modem_chat_release(struct modem_chat *chat);
 
+/**
+ * @brief Initialize modem chat match
+ * @param chat_match Modem chat match instance
+ */
+void modem_chat_match_init(struct modem_chat_match *chat_match);
+
+/**
+ * @brief Set match of modem chat match instance
+ * @param chat_match Modem chat match instance
+ * @param match Match to set
+ * @note The lifetime of match must match or exceed the lifetime of chat_match
+ * @warning Always call this API after match is modified
+ *
+ * @retval 0 if successful, negative errno code otherwise
+ */
+int modem_chat_match_set_match(struct modem_chat_match *chat_match, const char *match);
+
+/**
+ * @brief Set separators of modem chat match instance
+ * @param chat_match Modem chat match instance
+ * @param separators Separators to set
+ * @note The lifetime of separators must match or exceed the lifetime of chat_match
+ * @warning Always call this API after separators are modified
+ *
+ * @retval 0 if successful, negative errno code otherwise
+ */
+int modem_chat_match_set_separators(struct modem_chat_match *chat_match, const char *separators);
+
+/**
+ * @brief Set modem chat match callback
+ * @param chat_match Modem chat match instance
+ * @param callback Callback to set
+ */
+void modem_chat_match_set_callback(struct modem_chat_match *chat_match,
+				   modem_chat_match_callback callback);
+
+/**
+ * @brief Set modem chat match partial flag
+ * @param chat_match Modem chat match instance
+ * @param partial Partial flag to set
+ */
+void modem_chat_match_set_partial(struct modem_chat_match *chat_match, bool partial);
+
+/**
+ * @brief Set modem chat match wildcards flag
+ * @param chat_match Modem chat match instance
+ * @param enable Enable/disable Wildcards
+ */
+void modem_chat_match_enable_wildcards(struct modem_chat_match *chat_match, bool enable);
+
 #ifdef __cplusplus
 }
 #endif

subsys/modem/modem_chat.c

@@ -4,6 +4,9 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#undef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L
+
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(modem_chat, CONFIG_MODEM_MODULES_LOG_LEVEL);
 
@@ -929,3 +932,54 @@ void modem_chat_release(struct modem_chat *chat)
 	chat->matches[MODEM_CHAT_MATCHES_INDEX_RESPONSE] = NULL;
 	chat->matches_size[MODEM_CHAT_MATCHES_INDEX_RESPONSE] = 0;
 }
+
+void modem_chat_match_init(struct modem_chat_match *chat_match)
+{
+	memset(chat_match, 0, sizeof(struct modem_chat_match));
+}
+
+int modem_chat_match_set_match(struct modem_chat_match *chat_match, const char *match)
+{
+	size_t size;
+
+	size = strnlen(match, UINT8_MAX + 1);
+
+	if (size == (UINT8_MAX + 1)) {
+		return -ENOMEM;
+	}
+
+	chat_match->match = match;
+	chat_match->match_size = (uint8_t)size;
+	return 0;
+}
+
+int modem_chat_match_set_separators(struct modem_chat_match *chat_match, const char *separators)
+{
+	size_t size;
+
+	size = strnlen(separators, UINT8_MAX + 1);
+
+	if (size == (UINT8_MAX + 1)) {
+		return -ENOMEM;
+	}
+
+	chat_match->separators = separators;
+	chat_match->separators_size = (uint8_t)size;
+	return 0;
+}
+
+void modem_chat_match_set_callback(struct modem_chat_match *match,
+				   modem_chat_match_callback callback)
+{
+	match->callback = callback;
+}
+
+void modem_chat_match_set_partial(struct modem_chat_match *match, bool partial)
+{
+	match->partial = partial;
+}
+
+void modem_chat_match_enable_wildcards(struct modem_chat_match *match, bool enable)
+{
+	match->wildcards = enable;
+}

tests/subsys/modem/modem_chat/src/main.c

@@ -676,6 +676,34 @@ ZTEST(modem_chat, test_script_chat_timeout_cmd)
 		      "Script sent too many requests");
 }
 
+ZTEST(modem_chat, test_runtime_match)
+{
+	int ret;
+	struct modem_chat_match test_match;
+
+	modem_chat_match_init(&test_match);
+
+	ret = modem_chat_match_set_match(&test_match, "AT345");
+	zassert_ok(ret, "Failed to set match");
+	zassert_ok(strcmp(test_match.match, "AT345"), "Failed to set match");
+	zassert_equal(test_match.match_size, 5, "Failed to set size of match");
+
+	ret = modem_chat_match_set_separators(&test_match, ",*");
+	zassert_ok(ret, "Failed to set match");
+	zassert_ok(strcmp(test_match.separators, ",*"), "Failed to set separators");
+	zassert_equal(test_match.separators_size, 2, "Failed to set size of separators");
+
+	modem_chat_match_set_partial(&test_match, true);
+	zassert_equal(test_match.partial, true);
+	modem_chat_match_set_partial(&test_match, false);
+	zassert_equal(test_match.partial, false);
+
+	modem_chat_match_enable_wildcards(&test_match, true);
+	zassert_equal(test_match.wildcards, true);
+	modem_chat_match_enable_wildcards(&test_match, false);
+	zassert_equal(test_match.wildcards, false);
+}
+
 /*************************************************************************************************/
 /*                                         Test suite                                            */
 /*************************************************************************************************/