Hi Łukasz,
On Thu, Mar 31, 2016 at 12:01 AM, Łukasz Rymanowski
<lukasz.rymanowski@xxxxxxxxxxx> wrote:
> With this patch long write and nested long write reliable is supported.
> GATT server is responsible now to do aggregation of prep write data
> for long write session.
> Note: We consider long write as the consequtive prepare writes with
> continues offsets.
>
> E.g. 1
>
> prep_write: handle 1, offset 0, value_len 10
> prep_write: handle 1, offset 10, value_len 10
> prep_write: handle 2, offset 0, value_len 10
> prep_write: handle 2, offset 10, value_len 10
>
> Will result with following calles to app:
>
> exec_write: handle 1: offset 0, value_len 20
> exec_write: handle 2: offset 0, value_len 20
>
> E.g. 2
>
> prep_write: handle 1, offset 0, value_len 10
> prep_write: handle 1, offset 2, value_len 5
> prep_write: handle 2, offset 0, value_len 10
> prep_write: handle 2, offset 4, value_len 5
>
> Will result with following calles to app:
>
> exec_write: handle 1: offset 0, value_len 10
> exec_write: handle 1: offset 2, value_len 5
> exec_write: handle 2: offset 0, value_len 10
> exec_write: handle 2: offset 4, value_len 5
>
> E.g. 3
> prep_write: handle 1, offset 0, value_len 10
> prep_write: handle 1, offset 5, value_len 5
> prep_write: handle 1, offset 10, value_len 6
>
> will result with following calles to app:
>
> exec_write: handle 1, offset 0, value 10
> exec_write: handle 1, offset 5, value 11
> ---
> src/shared/gatt-server.c | 79 +++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 65 insertions(+), 14 deletions(-)
>
> diff --git a/src/shared/gatt-server.c b/src/shared/gatt-server.c
> index c41273a..ae079b1 100644
> --- a/src/shared/gatt-server.c
> +++ b/src/shared/gatt-server.c
> @@ -1088,6 +1088,56 @@ error:
> bt_att_send_error_rsp(server->att, opcode, 0, ecode);
> }
>
> +static bool create_and_store_prep_data(struct bt_gatt_server *server,
> + uint16_t handle, uint16_t offset,
> + uint16_t length, uint8_t *value)
> +{
> + struct prep_write_data *prep_data;
> +
> + prep_data = new0(struct prep_write_data, 1);
> + prep_data->length = length;
> + if (prep_data->length) {
> + prep_data->value = malloc(prep_data->length);
> + if (!prep_data->value) {
> + return false;
> + }
> +
> + memcpy(prep_data->value, value, prep_data->length);
> + }
> +
> + prep_data->server = server;
> + prep_data->handle = handle;
> + prep_data->offset = offset;
> +
> + queue_push_tail(server->prep_queue, prep_data);
> +
> + return true;
> +}
> +
> +static bool make_aggregation_of_long_write_data(struct bt_gatt_server *server,
> + struct prep_write_data *prep_data,
> + uint16_t handle, uint16_t length,
> + uint8_t *value)
> +{
> + uint8_t *buf;
> + uint16_t new_len;
> +
> + new_len = prep_data->length + length;
> +
> + buf = malloc(new_len);
> + if (!buf)
> + return false;
> +
> + memcpy(buf, prep_data->value, prep_data->length);
> + memcpy(buf + prep_data->length, value, length);
I think we could use realloc here instead of copying like this.
> +
> + free(prep_data->value);
> + prep_data->value = buf;
> + prep_data->length = new_len;
> +
> + return true;
> +}
> +
> static void prep_write_cb(uint8_t opcode, const void *pdu,
> uint16_t length, void *user_data)
> {
> @@ -1097,6 +1147,7 @@ static void prep_write_cb(uint8_t opcode, const void *pdu,
> uint16_t offset;
> struct gatt_db_attribute *attr;
> uint8_t ecode;
> + bool success;
>
> if (length < 4) {
> ecode = BT_ATT_ERROR_INVALID_PDU;
> @@ -1126,22 +1177,22 @@ static void prep_write_cb(uint8_t opcode, const void *pdu,
> if (ecode)
> goto error;
>
> - prep_data = new0(struct prep_write_data, 1);
> - prep_data->length = length - 4;
> - if (prep_data->length) {
> - prep_data->value = malloc(prep_data->length);
> - if (!prep_data->value) {
> - ecode = BT_ATT_ERROR_INSUFFICIENT_RESOURCES;
> - goto error;
> - }
> - }
> + /* Now lets check if prep write is a continuation of long write */
> + prep_data = queue_peek_tail(server->prep_queue);
>
> - prep_data->server = server;
> - prep_data->handle = handle;
> - prep_data->offset = offset;
> - memcpy(prep_data->value, pdu + 4, prep_data->length);
> + if (prep_data && (prep_data->handle == handle) &&
> + (offset == prep_data->length + prep_data->offset))
> + success = make_aggregation_of_long_write_data(server, prep_data,
> + handle, length - 4,
> + &((uint8_t *) pdu)[4]);
> + else
> + success = create_and_store_prep_data(server, handle, offset,
> + length - 4, &((uint8_t *) pdu)[4]);
I would prefer if this would actually be done in a separate function,
store_prep_data which should be able to detect if the data shall be
appended or if a new item should be created.
>
> - queue_push_tail(server->prep_queue, prep_data);
> + if (!success) {
> + ecode = BT_ATT_ERROR_INSUFFICIENT_RESOURCES;
> + goto error;
> + }
>
> bt_att_send(server->att, BT_ATT_OP_PREP_WRITE_RSP, pdu, length, NULL,
> NULL, NULL);
> --
> 2.5.0
>
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--
Luiz Augusto von Dentz
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