Los enlaces simbólicos funcionan como los accesos directos de archivos en Windows y permiten acceder rápidamente a los objetos asociados en Object Storage Service (OSS).
Notas de uso
En este tema se utiliza el endpoint público de la región China (Hangzhou). Si necesita acceder a OSS desde otros servicios de Alibaba Cloud ubicados en la misma región que OSS, utilice un endpoint interno. Para obtener más información sobre las regiones y los endpoints de OSS, consulte Regions and endpoints.
Este tema muestra cómo crear una instancia de OSSClient con un endpoint de OSS. Para conocer configuraciones alternativas, como usar un dominio personalizado o autenticarse con credenciales de Security Token Service (STS), consulte Initialization (C SDK).
Para crear un enlace simbólico, debe contar con el permiso
oss:PutObject. Para consultar un enlace simbólico, requiere el permisooss:GetObject. Para obtener más información, consulte Grant a custom policy.
Creación de un enlace simbólico
A continuación se muestra un ejemplo de código para crear un enlace simbólico:
#include "oss_api.h"
#include "aos_http_io.h"
/* Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
const char *endpoint = "yourEndpoint";
/* Specify the name of the bucket. Example: examplebucket. */
const char *bucket_name = "examplebucket";
/* Specify the full path of the object. Do not include the bucket name in the full path. Example: exampledir/exampleobject.txt. */
const char *object_name = "exampledir/exampleobject.txt";
/* Specify the full path of the symbolic link that you want to create. */
const char *link_object_name = "yourLinkObjectName";
/* Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. */
const char *region = "yourRegion";
void init_options(oss_request_options_t *options)
{
options->config = oss_config_create(options->pool);
/* Use a char* string to initialize data of the aos_string_t type. */
aos_str_set(&options->config->endpoint, endpoint);
/* Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. */
aos_str_set(&options->config->access_key_id, getenv("OSS_ACCESS_KEY_ID"));
aos_str_set(&options->config->access_key_secret, getenv("OSS_ACCESS_KEY_SECRET"));
// Specify two additional parameters.
aos_str_set(&options->config->region, region);
options->config->signature_version = 4;
/* Specify whether to use CNAME. The value 0 indicates that CNAME is not used. */
options->config->is_cname = 0;
/* Specify network parameters, such as the timeout period. */
options->ctl = aos_http_controller_create(options->pool, 0);
}
int main(int argc, char *argv[])
{
/* Call the aos_http_io_initialize method in main() to initialize global resources, such as network resources and memory resources. */
if (aos_http_io_initialize(NULL, 0) != AOSE_OK) {
exit(1);
}
/* Create a memory pool to manage memory. aos_pool_t is equivalent to apr_pool_t. The code used to create a memory pool is included in the APR library. */
aos_pool_t *pool;
/* Create a memory pool. The value of the second parameter is NULL. This value indicates that the pool does not inherit other memory pools. */
aos_pool_create(&pool, NULL);
/* Create and initialize options. This parameter includes global configuration information, such as endpoint, access_key_id, access_key_secret, is_cname, and curl. */
oss_request_options_t *oss_client_options;
/* Allocate the memory resources in the memory pool to the options. */
oss_client_options = oss_request_options_create(pool);
/* Initialize oss_client_options. */
init_options(oss_client_options);
/* Initialize the parameters. */
aos_string_t bucket;
aos_string_t object;
aos_string_t sym_object;
aos_table_t *resp_headers = NULL;
aos_status_t *resp_status = NULL;
aos_str_set(&bucket, bucket_name);
aos_str_set(&object, object_name);
aos_str_set(&sym_object, link_object_name);
resp_status = oss_put_symlink(oss_client_options, &bucket, &sym_object, &object, &resp_headers);
if (aos_status_is_ok(resp_status)) {
printf("put symlink succeeded\n");
} else {
printf("put symlink failed\n");
}
/* Release the memory pool. This operation releases the memory resources allocated for the request. */
aos_pool_destroy(pool);
/* Release the allocated global resources. */
aos_http_io_deinitialize();
return 0;
}
Consulta de un enlace simbólico
Para consultar un enlace simbólico, necesita permisos de lectura sobre dicho enlace. A continuación se muestra un ejemplo de código para consultar un enlace simbólico y obtener el nombre del objeto al que apunta:
#include "oss_api.h"
#include "aos_http_io.h"
/* Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
const char *endpoint = "yourEndpoint";
/* Specify the name of the bucket. Example: examplebucket. */
const char *bucket_name = "examplebucket";
/* Specify the full path of the symbolic link that you want to query. */
const char *link_object_name = "yourLinkObjectName";
/* Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. */
const char *region = "yourRegion";
void init_options(oss_request_options_t *options)
{
options->config = oss_config_create(options->pool);
/* Use a char* string to initialize data of the aos_string_t type. */
aos_str_set(&options->config->endpoint, endpoint);
/* Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. */
aos_str_set(&options->config->access_key_id, getenv("OSS_ACCESS_KEY_ID"));
aos_str_set(&options->config->access_key_secret, getenv("OSS_ACCESS_KEY_SECRET"));;
// Specify two additional parameters.
aos_str_set(&options->config->region, region);
options->config->signature_version = 4;
/* Specify whether to use CNAME. The value 0 indicates that CNAME is not used. */
options->config->is_cname = 0;
/* Specify network parameters, such as the timeout period. */
options->ctl = aos_http_controller_create(options->pool, 0);
}
int main(int argc, char *argv[])
{
/* Call the aos_http_io_initialize method in main() to initialize global resources, such as network resources and memory resources. */
if (aos_http_io_initialize(NULL, 0) != AOSE_OK) {
exit(1);
}
/* Create a memory pool to manage memory. aos_pool_t is equivalent to apr_pool_t. The code used to create a memory pool is included in the APR library. */
aos_pool_t *pool;
/* Create a memory pool. The value of the second parameter is NULL. This value indicates that the pool does not inherit other memory pools. */
aos_pool_create(&pool, NULL);
/* Create and initialize options. This parameter includes global configuration information, such as endpoint, access_key_id, access_key_secret, is_cname, and curl. */
oss_request_options_t *oss_client_options;
/* Allocate the memory resources in the memory pool to the options. */
oss_client_options = oss_request_options_create(pool);
/* Initialize oss_client_options. */
init_options(oss_client_options);
/* Initialize the parameters. */
aos_string_t bucket;
aos_string_t link_object;
aos_table_t *resp_headers = NULL;
aos_status_t *resp_status = NULL;
char *target_object_name = NULL;
aos_str_set(&bucket, bucket_name);
aos_str_set(&link_object, link_object_name);
resp_status = oss_get_symlink(oss_client_options, &bucket, &link_object, &resp_headers);
if (aos_status_is_ok(resp_status)) {
printf("get symlink succeeded\n");
target_object_name = (char*)(apr_table_get(resp_headers, OSS_CANNONICALIZED_HEADER_SYMLINK));
printf("target_object_name: %s \n", target_object_name);
} else {
printf("get symlink failed\n");
}
/* Release the memory pool. This operation releases the memory resources allocated for the request. */
aos_pool_destroy(pool);
/* Release the allocated global resources. */
aos_http_io_deinitialize();
return 0;
}
Referencias
Para obtener más información sobre la operación de API que permite crear un enlace simbólico, consulte PutSymlink.
Para obtener más información sobre la operación de API que permite consultar un enlace simbólico, consulte GetSymlink.