拷贝对象

对象是存储数据的基本单元。对象由元信息（Object Meta），用户数据（Data）和文件名（Key）组成。对象由桶内部唯一的Key来标识。本文介绍如何拷贝对象。

接口定义：

void S3_copy_object(const S3BucketContext *bucketContext,
                    const char *key, const char *destinationBucket,
                    const char *destinationKey,
                    const S3PutProperties *putProperties,
                    int64_t *lastModifiedReturn, int eTagReturnSize,
                    char *eTagReturn, S3RequestContext *requestContext,
                    int timeoutMs,
                    const S3ResponseHandler *handler, void *callbackData);

参数：

参数名	类型	说明
bucketContext	const S3BucketContext *	源bucket及请求参数
key	const char *	源对象名
destinationBucket	const char *	目的bucket
destinationKey	const char *	目的对象名
putProperties	const S3PutProperties *	请求消息头
lastModifiedReturn	int64_t *	对象上次修改时间
eTagReturnSize	int	eTag缓存区大小
eTagReturn	char *	eTag缓存区
requestContext	S3RequestContext *	请求参数，如果为NULL，则立即同步执行请求
timeoutMs	int	如果非0，则是以毫秒为单位的请求超时时间
handler	const S3ResponseHandler *	回调函数
callbackData	void *	回调数据

代码示例：

#include <time.h>
#include <unistd.h>

void copy_object(const char *sourceBucketName, const char *sourceKey,
                        const char *destinationBucketName, const char *destinationKey)
{

    const char *cacheControl = 0, *contentType = 0;
    const char *contentDispositionFilename = 0, *contentEncoding = 0;
    int64_t expires = -1;
    S3CannedAcl cannedAcl = S3CannedAclPrivate;
    int metaPropertiesCount = 0;
    S3NameValue metaProperties[S3_MAX_METADATA_COUNT];
    int anyPropertiesSet = 0;

    S3PutProperties putProperties =
        {
            contentType,
            0,
            cacheControl,
            contentDispositionFilename,
            contentEncoding,
            expires,
            cannedAcl,
            metaPropertiesCount,
            metaProperties};

    S3ResponseHandler responseHandler =
        {
            &responsePropertiesCallback,
            &responseCompleteCallback};

    S3BucketContext bucketContext2 =
    {
        hostname,
        sourceBucketName,
        S3ProtocolHTTP,
        S3UriStylePath,
        accessKeyG,
        secretKeyG,
        NULL,
        NULL};

    int64_t lastModified;
    char eTag[256];

    do
    {
        S3_copy_object(&bucketContext2, sourceKey, destinationBucketName,
                       destinationKey, anyPropertiesSet ? &putProperties : 0,
                       &lastModified, sizeof(eTag), eTag, 0, 0,
                       &responseHandler, 0);
    } while (S3_status_is_retryable(statusG) && should_retry());

    if (statusG == S3StatusOK)
    {
        if (lastModified >= 0)
        {
            char timebuf[256];
            time_t t = (time_t)lastModified;
            strftime(timebuf, sizeof(timebuf), "%Y-%m-%dT%H:%M:%SZ",
                     gmtime(&t));
            printf("Last-Modified: %s\n", timebuf);
        }
        if (eTag[0])
        {
            printf("ETag: %s\n", eTag);
        }
    }
    else
    {
        printError();
    }
}