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/*-
* Public Domain 2014-present MongoDB, Inc.
* Public Domain 2008-2014 WiredTiger, Inc.
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "gcp_connection.h"
#include <fstream>
namespace gcs = google::cloud::storage;
using namespace gcs;
gcp_connection::gcp_connection(const std::string &bucket_name, const std::string &prefix)
: _gcp_client(gcs::Client()), _bucket_name(bucket_name), _bucket_prefix(prefix)
{
// StatusOr either contains a usable BucketMetadata value or a Status object explaining why the
// value is not present. The value's validity is checked by StatusOr::ok().
google::cloud::StatusOr<gcs::BucketMetadata> metadata =
_gcp_client.GetBucketMetadata(_bucket_name);
// Check if bucket exists and is accessible.
if (!metadata.ok())
throw std::invalid_argument(_bucket_name + ": " + metadata.status().message());
}
// Builds a list of object names from the bucket.
int
gcp_connection::list_objects(
std::string search_prefix, std::vector<std::string> &objects, bool list_single)
{
// Fetch the objects from the given bucket that match with the prefix given.
for (auto &&object_metadata :
_gcp_client.ListObjects(_bucket_name, gcs::Prefix(_bucket_prefix + search_prefix))) {
// Check if the current object is accessible (object exists but the user does not have
// permissions to access)
if (!object_metadata) {
// This is an error, but is non-fatal. We call handle_error to print the error message
// and then continue listing objects.
handle_error(object_metadata.status(),
"List of '" + object_metadata->name() +
"' failed: " + object_metadata.status().message());
}
objects.push_back(object_metadata->name());
if (list_single)
break;
}
return 0;
}
// Puts an object into a google cloud bucket.
int
gcp_connection::put_object(const std::string &object_key, const std::string &file_path)
{
// Client library automatically computes a hash on the client-side to
// verify data integrity.
google::cloud::StatusOr<gcs::ObjectMetadata> metadata =
_gcp_client.UploadFile(file_path, _bucket_name, _bucket_prefix + object_key);
// Check if file has been successfully uploaded.
if (!metadata)
return handle_error(metadata.status(),
"Upload of '" + _bucket_prefix + object_key + "' failed: " + metadata.status().message());
return 0;
}
// Deletes an object from google cloud bucket.
int
gcp_connection::delete_object(const std::string &object_key)
{
auto status = _gcp_client.DeleteObject(_bucket_name, _bucket_prefix + object_key);
if (!status.ok())
return handle_error(
status, "Delete '" + _bucket_prefix + object_key + "' failed: " + status.message());
return 0;
}
// Retrieves an object from the google cloud bucket.
int
gcp_connection::read_object(const std::string &object_key, int64_t offset, size_t len, void *buf)
{
bool exists = false;
size_t object_size;
// The object_exists function will check if the given object exists and print out any error
// messages.
int ret = object_exists(object_key, exists, object_size);
if (ret != 0)
return ret;
if (!exists) {
std::cerr << "Object '" << object_key << "' does not exist." << std::endl;
return ENOENT;
}
if (offset < 0) {
std::cerr << "Offset " << offset << " is invalid. The offset cannot be less than zero."
<< std::endl;
return EINVAL;
}
if (offset + len > object_size) {
std::cerr << "Length " << len << " plus offset " << offset
<< " must not exceed the object size " << object_size << "." << std::endl;
return EINVAL;
}
gcs::ObjectReadStream stream = _gcp_client.ReadObject(
_bucket_name, _bucket_prefix + object_key, gcs::ReadFromOffset(offset));
if (stream.bad())
return handle_error(stream.status(),
"Read '" + _bucket_prefix + object_key + "' failed: " + stream.status().message());
std::istreambuf_iterator<char> begin{stream}, end;
std::string buffer{begin, end};
memcpy(static_cast<char *>(buf), buffer.c_str(), len);
return 0;
}
// Checks whether an object with the given key exists in the google cloud bucket and also retrieves
// size of the object.
int
gcp_connection::object_exists(const std::string &object_key, bool &exists, size_t &object_size)
{
object_size = 0;
google::cloud::StatusOr<gcs::ObjectMetadata> metadata =
_gcp_client.GetObjectMetadata(_bucket_name, _bucket_prefix + object_key);
// Check if object exists and is accessible.
if (metadata.ok()) {
exists = true;
object_size = metadata.value().size();
return 0;
}
// Check if object doesn't exist.
if (metadata.status().code() == google::cloud::StatusCode::kNotFound) {
exists = false;
// This is an expected response so do not fail.
return 0;
}
return handle_error(metadata.status(),
"Object exists check for '" + _bucket_prefix + object_key +
"' failed: " + metadata.status().message());
}
// Maps Google Cloud Status code to a system error number which is returned.
// If a mapping cannot be found the Google Cloud Status code is printed and -1 is returned.
int
gcp_connection::handle_error(
const google::cloud::Status status, const std::string &error_message) const
{
std::cerr << error_message << std::endl;
if (toErrno.find(status.code()) != toErrno.end())
return (toErrno.at(status.code()));
return -1;
}
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