XGameSaveReadBlobData

Article
06/22/2023

Reads the blob data for a container.

Syntax

HRESULT XGameSaveReadBlobData(  
         XGameSaveContainerHandle container,  
         const char** blobNames,  
         uint32_t* countOfBlobs,  
         size_t blobsSize,  
         XGameSaveBlob* blobData  
)

Parameters

container _In_
Type: XGameSaveContainerHandle

Handle to the XGameSaveContainer containing the XGameSaveBlob data.

blobNames _In_opt_z_count_(countOfBlobs)
Type: char*

Pointer to an array of strings representing the XGameSaveBlob names.

countOfBlobs _Inout_
Type: uint32_t*

Number of blobs to read.

blobsSize _In_
Type: size_t

Size of the allocated blob data, can be inferred from reading the blob metadata.

blobData _Out_writes_bytes_(blobsSize)
Type: XGameSaveBlob*

XGameSaveBlob pointer to contain the blob data. Must have memory allocated to store all of the blobs requested from the container.

Return value

Type: HRESULT

Function result.

Common errors

E_GS_INVALID_CONTAINER_NAME
E_GS_PROVIDED_BUFFER_TOO_SMALL
E_GS_BLOB_NOT_FOUND
E_GS_CONTAINER_NOT_IN_SYNC
E_GS_CONTAINER_SYNC_FAILED
E_GS_HANDLE_EXPIRED

Remarks

Note

This function isn't safe to call on a time-sensitive thread. For more information, see Time-sensitive threads.

Use this function to read the data in a game save blob. The function will return the number of blobs and the data inside of a blob container. You can use these in order to iterate over the blobs in a container to read the appropriate information. There is an asynchronous version of this function called XGameSaveReadBlobDataAsync.

// SYNC Read - should not be called on time sensitive thread 
//             as this will block until the operation is complete 
void Sample::_ReadContainerBlobsSync(const XGameSaveContainerInfo* container) 
{ 
    const char* blobNames[] = { 
        "WorldState", 
        "PlayerState", 
        "PlayerInventory" 
    }; 
  
    XGameSaveContainerHandle containerContext = nullptr; 
    size_t allocSize; 
    uint32_t countOfBlobs = _countof(blobNames); 
    XGameSaveBlob* blobs = nullptr; 
    HRESULT hr = XGameSaveCreateContainer(_provider, container->name, &containerContext); 
  
    if (SUCCEEDED(hr)) 
    { 
        // this method finds the size for only the blobs in the container 
        // that we are requesting to read right now 
        hr = _GetContainerBlobsDataSize(container, blobNames, _countof(blobNames), &allocSize); 
    } 
    if (SUCCEEDED(hr)) 
    { 
        blobs = reinterpret_cast<XGameSaveBlob*>(malloc(allocSize)); 
        if (blobs == nullptr) 
        { 
            hr = E_OUTOFMEMORY; 
        } 
    } 
    if (SUCCEEDED(hr)) 
    { 
        hr = XGameSaveReadBlobData(containerContext, blobNames, &countOfBlobs, allocSize, blobs); 
    } 
    if (SUCCEEDED(hr)) 
    { 
        if (countOfBlobs == _countof(blobNames)) 
        { 
            for (uint32_t i = 0; i < countOfBlobs; i++) 
            { 
                XGameSaveBlob* currentBlob = blobs + i; 
                if (strcmp(currentBlob->info.name, "WorldState") == 0) 
                { 
                    hr = _LoadSaveBlob(currentBlob, _worldState); 
                } 
                else if (strcmp(currentBlob->info.name, "PlayerState") == 0) 
                { 
                    hr = _LoadSaveBlob(currentBlob, _playerState); 
                } 
                else if (strcmp(currentBlob->info.name, "PlayerInventory") == 0) 
                { 
                    hr = _LoadSaveBlob(currentBlob, _playerInventory); 
                } 
                if (FAILED(hr)) 
                { 
                    break; 
                } 
            } 
        } 
        else 
        { 
            hr = E_UNEXPECTED; 
        } 
    } 
  
    _HandleContainerBlobErrors(hr); 
  
    if (blobs != nullptr) 
    { 
        free(blobs); 
    } 
    if (containerContext != nullptr) 
    { 
        XGameSaveCloseContainer(containerContext); 
    } 
} 
  
  
void Sample::_HandleContainerBlobErrors(HRESULT hr) 
{ 
    // set some state 
    switch (hr) 
    { 
    case E_GS_INVALID_CONTAINER_NAME: 
        // tried to access a container with an invalid name 
        break; 
    case E_GS_PROVIDED_BUFFER_TOO_SMALL: 
        // shouldn't ever happen unless our math is wrong!! 
        break; 
    case E_GS_BLOB_NOT_FOUND: 
        // we asked for a blob that isn't in the container 
        break; 
    case E_GS_CONTAINER_NOT_IN_SYNC: 
    case E_GS_CONTAINER_SYNC_FAILED: 
        // need to sync and we are offline ? 
        break; 
    case E_GS_HANDLE_EXPIRED: 
        // need to re-initialize since another device has taken 
        // ownership while we were suspended and/or busy  
        break; 
    } 
}

Requirements

Header: XGameSave.h

Library: xgameruntime.lib

Supported platforms: Windows, Xbox One family consoles and Xbox Series consoles

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