Updated on 2024-04-29 GMT+08:00

Performing a Modification

If you have any questions during development, post them on the Issues page of GitHub.

The modification API modify_object applies only to buckets used as parallel file systems. This API shares the same parameters and usage as that of put_object. The only difference is that the start position of the write object is added.

Parameter Description

Field

Type

Mandatory or Optional

Description

option

The context of the bucket. For details, see Configuring option.

Mandatory

Bucket parameter

key

char *

Mandatory

Object name

content_length

uint64_t

Mandatory

Length of the object content

position

char *

Mandatory

Start position of the object to be modified

put_properties

obs_put_properties*

Mandatory

Properties of the uploaded object

encryption_params

server_side_encryption_params *

Optional

Encryption setting of the uploaded object

handler

obs_modify_object_handler *

Mandatory

Callback function

callback_data

void *

Optional

Callback data

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.