This document describes how to complete some basic operations of the OSS C-SDK.
Step 1. Initialize the runtime environment of OSS C-SDK
When using the OSS C-SDK, you must first initialize the runtime environment, and clear the runtime environment before you stop using it. The following code demonstrates the initialization of the OSS C-SDK runtime environment:
int main(int argc, char *argv[]){/* Call the aos_http_io_initialize method at the project entry. This method initializes global resources involving the network and memory */if (aos_http_io_initialize(NULL, 0) != AOSE_OK) {exit(1);}/* Call the OSS SDK interface to upload or download an object *//* ... The user logic code. Skipped. *//* Before the project ends, call the aos_http_io_deinitialize method to release the previously allocated global resources */aos_http_io_deinitialize();return 0;}
Note:
The aos_http_io_initialize method initializes the OSS C-SDK runtime environment. The first parameter can be used to customize the user agent content for statistics in the future.
The aos_http_io_deinitialize method clears the OSS C-SDK runtime environment.
Step 2. Initialize the request options
Request options for all operations of OSS C-SDK must initialized. Use the following code to initialize the request options:
/* Equivalent to apr_pool_t. It is used for the memory pool of memory management and the implementation code is in the apr library */aos_pool_t *pool;oss_request_options_t *options;/* Recreate a new memory pool. The second parameter is NULL, indicating that it does not inherit from any other memory pool */aos_pool_create(&pool, NULL);/* Create and initialize options. This parameter mainly includes endpoint, access_key_id, acces_key_secret, is_cname, and curl parameters among other global configuration information* The options memory is allocated by the pool. After the pool is released, the options memory is also released. This means you do not need to release the memory separately*/options = oss_request_options_create(pool);options->config = oss_config_create(options->pool);/* aos_str_set is to initialize the aos_string_t data type with a char* string*/aos_str_set(&options->config->endpoint, "<Your endpoint>");aos_str_set(&options->config->access_key_id, "<Your AccessKeyId>");aos_str_set(&options->config->access_key_secret, "<Your AccessKeySecret>");/* Is CNAME used? */options->config->is_cname = 0;/* Used to set network-related parameters, such as the time-out value*/options->ctl = aos_http_controller_create(options->pool, 0);
Step 3. Create a bucket
You can create a bucket with the following code:
aos_pool_t *p;oss_request_options_t *options;aos_status_t *s;aos_table_t *resp_headers;oss_acl_e oss_acl = OSS_ACL_PRIVATE;char *bucket_name = "<Name of your bucket>";aos_string_t bucket;aos_pool_create(&p, NULL);options = oss_request_options_create(p);init_options(options);/* Assign a char* to the aos_string_t bucket */aos_str_set(&bucket, bucket_name);s = oss_create_bucket(options, &bucket, oss_acl, &resp_headers);/* Identify whether the request succeeds */if (aos_status_is_ok(s)) {printf("create bucket succeeded\n");} else {printf("create bucket failed\n");}/* After a request is executed, releasing the memory pool actually releases the memory allocated to various parts used during the request process */aos_pool_destroy(p);
Note:
For more information about bucket naming conventions, see Basic OSS concepts.
The bucket name cannot be the same as the existing bucket names of other users in OSS. To create a bucket successfully, you must select a unique bucket name.
The returned value of oss_create_bucket is of the aos_status_t* type, including code(http code), error_code, error_msg and req_id. The req_id can assist in troubleshooting. Other interfaces also returns aos_status_t* values if not specified.
Step 4. Upload an object
Objects are the most basic data units in OSS. You can use the following code to upload an object:
aos_pool_t *p;oss_request_options_t *options;aos_status_t *s;aos_table_t *headers;aos_table_t *resp_headers;char *bucket_name = "<Name of your bucket>";char *object_name = "<Name of your object>";aos_string_t bucket;aos_string_t object;char *data = "object content";aos_list_t buffer;aos_buf_t *content;aos_pool_create(&p, NULL);/* Create and initialize options */options = oss_request_options_create(p);init_options(options);/* Initialize parameters */aos_str_set(&object, object_name);aos_str_set(&bucket, bucket_name);headers = aos_table_make(p, 0);/* Convert char* data to aos_list_t as required by the oss_put_object_from_buffer interface */aos_list_init(&buffer);content = aos_buf_pack(options->pool, data, strlen(data));aos_list_add_tail(&content->node, &buffer);/* Upload the object */s = oss_put_object_from_buffer(options, &bucket, &object, &buffer, headers, &resp_headers);/* Identify whether the request succeeds */if (aos_status_is_ok(s)) {printf("put file succeeded\n");} else {printf("put file failed\n");}/* Release the resources */aos_pool_destroy(p);
Note: For more information, see Upload objects.
Step 5. List all objects in the bucket
The following code checks objects in a bucket after you upload objects to the bucket:
aos_pool_t *p;oss_request_options_t *options;aos_status_t *s;aos_table_t *resp_headers;char *bucket_name = "<Name of your bucket>";aos_string_t bucket;oss_list_object_params_t *params;oss_list_object_content_t *content;int max_ret = 1000;char *key;aos_pool_create(&p, NULL);/* Create and initialize options */options = oss_request_options_create(p);init_options(options);/* Initialize parameters */aos_str_set(&bucket, bucket_name);params = oss_create_list_object_params(p);params->max_ret = max_ret;aos_str_set(¶ms->prefix, "<prefix>");aos_str_set(¶ms->delimiter, "<delimiter>");aos_str_set(¶ms->marker, "<marker>");s = oss_list_object(options, &bucket, params, &resp_headers);/* Identify whether the request succeeds */if (aos_status_is_ok(s)) {printf("list file succeeded\n");} else {printf("list file failed\n");}/* Get the name of each object */aos_list_for_each_entry(content, ¶ms->object_list, node) {key = apr_psprintf(p, "%.*s", content->key.len, content->key.data);}/* Release the resources */aos_pool_destroy(p);
Note: For more information on flexible parameter configuration, see Manage objects.
Step 6. Download a specified object
See the following code to download a specified object:
aos_pool_t *p;oss_request_options_t *options;aos_status_t *s;aos_table_t *headers;aos_table_t *resp_headers;char *bucket_name = "<Name of your bucket>";char *object_name = "<Name of your object>";aos_string_t bucket;aos_string_t object;aos_list_t buffer;aos_buf_t *content;char *buf;int64_t len = 0;int64_t size = 0;int64_t pos = 0;aos_pool_create(&p, NULL);/* Create and initialize options */options = oss_request_options_create(p);init_options(options);/* Initialize parameters */aos_str_set(&object, object_name);aos_str_set(&bucket, bucket_name);headers = aos_table_make(p, 1);/* Download the object to the buffer */aos_list_init(&buffer);s = oss_get_object_to_buffer(options, &bucket, &object, headers, &buffer, &resp_headers);/* Identify whether the request succeeds */if (aos_status_is_ok(s)) {printf("get file succeeded\n");} else {printf("get file failed\n");}/* Convert the aos_list_t in the buffer to char* and calculate the total length of the object read */len = aos_buf_list_len(&buffer);buf = aos_pcalloc(p, len + 1);buf[len] = '\0';aos_list_for_each_entry(content, &buffer, node) {size = aos_buf_size(content);memcpy(buf + pos, content->pos, size);pos += size;}/* Release the resources */aos_pool_destroy(p);
Note: For more information, see Download objects.