[PATCH v2 1/3] shared/gatt-client: Support pending GATT helper requests

[Kyle Pepper <cochcoder@proton.me>]

Allow pending requests to own a cancellable GATT helper request, so
multi-PDU operations can use the existing cancellation queue. Expose a
request-returning read-by-type helper and keep the boolean interface for
callers that do not retain requests.

Assisted-by: Codex:gpt-6
---
 src/shared/gatt-client.c  | 10 ++++++++++
 src/shared/gatt-helpers.c | 26 ++++++++++++++++++++++----
 src/shared/gatt-helpers.h |  7 +++++++
 3 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/src/shared/gatt-client.c b/src/shared/gatt-client.c
index 7bebc50dc..f301a105b 100644
--- a/src/shared/gatt-client.c
+++ b/src/shared/gatt-client.c
@@ -120,6 +120,7 @@ struct request {
 	int ref_count;
 	unsigned int id;
 	unsigned int att_id;
+	struct bt_gatt_request *gatt_req;
 	void *data;
 	void (*destroy)(void *);
 };
@@ -2811,6 +2812,15 @@ static bool cancel_request(struct request *req)
 {
 	req->removed = true;
 
+	if (req->gatt_req) {
+		struct bt_gatt_request *gatt_req = req->gatt_req;
+
+		req->gatt_req = NULL;
+		bt_gatt_request_cancel(gatt_req);
+		bt_gatt_request_unref(gatt_req);
+		return true;
+	}
+
 	if (req->long_write)
 		return cancel_long_write_req(req->client, req);
 
diff --git a/src/shared/gatt-helpers.c b/src/shared/gatt-helpers.c
index ea77a41ef..6d307e893 100644
--- a/src/shared/gatt-helpers.c
+++ b/src/shared/gatt-helpers.c
@@ -1484,7 +1484,8 @@ done:
 	discovery_op_complete(op, success, att_ecode);
 }
 
-bool bt_gatt_read_by_type(struct bt_att *att, uint16_t start, uint16_t end,
+struct bt_gatt_request *bt_gatt_read_by_type_request(struct bt_att *att,
+					uint16_t start, uint16_t end,
 					const bt_uuid_t *uuid,
 					bt_gatt_request_callback_t callback,
 					void *user_data,
@@ -1495,7 +1496,7 @@ bool bt_gatt_read_by_type(struct bt_att *att, uint16_t start, uint16_t end,
 	struct iovec req = { pdu, 0 };
 
 	if (!att || !uuid || uuid->type == BT_UUID_UNSPEC)
-		return false;
+		return NULL;
 
 	op = new0(struct bt_gatt_request, 1);
 	op->att = att;
@@ -1516,10 +1517,27 @@ bool bt_gatt_read_by_type(struct bt_att *att, uint16_t start, uint16_t end,
 						bt_gatt_request_ref(op),
 						async_req_unref);
 	if (op->id)
-		return true;
+		return bt_gatt_request_ref(op);
 
 	free(op);
-	return false;
+	return NULL;
+}
+
+bool bt_gatt_read_by_type(struct bt_att *att, uint16_t start, uint16_t end,
+					const bt_uuid_t *uuid,
+					bt_gatt_request_callback_t callback,
+					void *user_data,
+					bt_gatt_destroy_func_t destroy)
+{
+	struct bt_gatt_request *req;
+
+	req = bt_gatt_read_by_type_request(att, start, end, uuid, callback,
+							user_data, destroy);
+	if (!req)
+		return false;
+
+	bt_gatt_request_unref(req);
+	return true;
 }
 
 static void discover_descs_cb(uint8_t opcode, const void *pdu,
diff --git a/src/shared/gatt-helpers.h b/src/shared/gatt-helpers.h
index 2bf5aad46..528ef2196 100644
--- a/src/shared/gatt-helpers.h
+++ b/src/shared/gatt-helpers.h
@@ -102,5 +102,12 @@ bool bt_gatt_read_by_type(struct bt_att *att, uint16_t start, uint16_t end,
 					void *user_data,
 					bt_gatt_destroy_func_t destroy);
 
+struct bt_gatt_request *bt_gatt_read_by_type_request(struct bt_att *att,
+					uint16_t start, uint16_t end,
+					const bt_uuid_t *uuid,
+					bt_gatt_request_callback_t callback,
+					void *user_data,
+					bt_gatt_destroy_func_t destroy);
+
 uint16_t bt_gatt_req_get_end_handle(struct bt_gatt_request *req);
 uint16_t bt_gatt_req_get_start_handle(struct bt_gatt_request *req);
-- 
2.56.0