Performing a Modification

Parameter Description

Sample Code

static void test_modify_object_from_buffer()
{
    // Buffer to be uploaded
    char *buffer = "abcdefg";
    // Length of the buffer to be uploaded
    int buffer_size = strlen(buffer);
    // Name of an object to be uploaded
    char *key = "put_buffer_test";
    char * position = "0";
    // Initialize option.
    obs_options option;
    init_obs_options(&option);
    option.bucket_options.host_name = "<your-endpoint>";
    option.bucket_options.bucket_name = "<Your bucketname>";

    // Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables ACCESS_KEY_ID and SECRET_ACCESS_KEY.
    // Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/intl/en-us/usermanual-ca/ca_01_0003.html.
    option.bucket_options.access_key = getenv("ACCESS_KEY_ID");
    option.bucket_options.secret_access_key = getenv("SECRET_ACCESS_KEY");
    option.bucket_options.certificate_info = "<Your certificate>";
    // Initialize the properties of an object to be uploaded.
    obs_put_properties put_properties;
    init_put_properties(&put_properties);
    // Initialize the structure for storing uploaded data.
    put_buffer_object_callback_data data;
    memset(&data, 0, sizeof(put_buffer_object_callback_data));
    // Assign the buffer value to the structure.
    data.put_buffer = buffer;
    // Set buffersize.
    data.buffer_size = buffer_size;
    // Set callback function.
    obs_modify_object_handler modify0bjectHandler =
    { 
        { &response_properties_callback, &put_buffer_complete_callback },
          &put_buffer_data_callback
    };
    modify_object(&option, key, buffer_size, position, &put_properties,
    0, &modify0bjectHandler, &data);
    if (OBS_STATUS_OK == data.ret_status) {
        printf("modify object from buffer successfully. \n");
    }
    else
    {
        printf("modify object from buffer failed(%s).\n", obs_get_status_name(data.ret_status));
    }
}

• modify_object applies only to buckets used as parallel file systems.
• When you call modify_object for the first time, if the object to be modified does not exist, an error (HTTP status code: 404) will be reported.
• The sixth parameter in modify_object is used to provide the server-side encryption. For details, see section Server-Side Encryption.