Quickstart: Extract app package contents

Learn how to extract files from the app package for a Windows Store app using the packaging API.

Create a package reader

To create a package reader, call the IAppxFactory::CreatePackageReader method. The first parameter is an input stream for the package (.appx file). The second parameter is an output parameter that receives a pointer to an IAppxPackageReader pointer.


#include <windows.h>
#include <shlwapi.h>
#include <AppxPackaging.h>

int wmain(
    _In_ int argc,
    _In_count_(argc) wchar_t** argv)
{
    HRESULT hr = S_OK;

    if (argc != 3)
    {
        wprintf(L"Usage:  ExtractAppx.exe inputFile outputPath\n");
        wprintf(L"    inputFile: Path to the appx package\n");
        wprintf(L"    outputPath: Path to the folder for the extracted package contents\n");
        return 2;
    }

    // Specify the appropriate COM threading model
    hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);

    if (SUCCEEDED(hr))
    {
        // Create a package reader using the file name in argv[1] 
        IAppxPackageReader* packageReader = NULL;
        hr = GetPackageReader(argv[1], &packageReader);

        // Print information about all footprint files, and extract them to disk
        if (SUCCEEDED(hr))
        {
            hr = ExtractFootprintFiles(packageReader, argv[2]);
        }

        // Print information about all payload files, and extract them to disk
        if (SUCCEEDED(hr))
        {
            hr = ExtractPayloadFiles(packageReader, argv[2]);
        }
    }
}

//
// Creates an app package reader.
//
// Parameters:
//   inputFileName  
//     The fully-qualified name of the app package (.appx file) to be opened.
//   reader 
//     On success, receives the created instance of IAppxPackageReader.
//
HRESULT GetPackageReader(
    _In_ LPCWSTR inputFileName,
    _Outptr_ IAppxPackageReader** reader)
{
    HRESULT hr = S_OK;
    IAppxFactory* appxFactory = NULL;
    IStream* inputStream = NULL;

    // Create a new factory
    hr = CoCreateInstance(
            __uuidof(AppxFactory),
            NULL,
            CLSCTX_INPROC_SERVER,
            __uuidof(IAppxFactory),
            (LPVOID*)(&appxFactory));

    // Create a stream over the input app package
    if (SUCCEEDED(hr))
    {
        hr = SHCreateStreamOnFileEx(
                inputFileName,
                STGM_READ | STGM_SHARE_EXCLUSIVE,
                0, // default file attributes
                FALSE, // do not create new file
                NULL, // no template
                &inputStream);
    }

    // Create a new package reader using the factory.  For 
    // simplicity, we don't verify the digital signature of the package.
    if (SUCCEEDED(hr))
    {
        hr = appxFactory->CreatePackageReader(
                inputStream,
                reader);
    }

    // Clean up allocated resources
    if (inputStream != NULL)
    {
        inputStream->Release();
        inputStream = NULL;
    }
    if (appxFactory != NULL)
    {
        appxFactory->Release();
        appxFactory = NULL;
    }
    return hr;
}

Extract footprint files

Call the IAppxPackageReader::GetFootprintFile method to get each footprint file. Each footprint file is represented by an IAppxFile interface. The ExtractFile function in this sample uses the GetName, GetContentType, and GetSize methods of IAppxFile to display basic information about the footprint file.



//
// Extracts all footprint files from a package.
//
// Parameters:
//   packageReader 
//      The package reader for the app package.
//   outputPath 
//      The path of the folder for the extracted footprint files.
//
// Types of footprint files in an app package
const int FootprintFilesCount = 4;
const APPX_FOOTPRINT_FILE_TYPE FootprintFilesType[FootprintFilesCount] = {
APPX_FOOTPRINT_FILE_TYPE_MANIFEST,
APPX_FOOTPRINT_FILE_TYPE_BLOCKMAP,
APPX_FOOTPRINT_FILE_TYPE_SIGNATURE,
APPX_FOOTPRINT_FILE_TYPE_CODEINTEGRITY
};
const LPCWSTR FootprintFilesName[FootprintFilesCount] = {
L"manifest",
L"block map",
L"digital signature",
L"CI catalog"
}; 
//

HRESULT ExtractFootprintFiles(
    _In_ IAppxPackageReader* packageReader,
    _In_ LPCWSTR outputPath)
{
    HRESULT hr = S_OK;
    wprintf(L"\nExtracting footprint files from the package...\n");

    for (int i = 0; SUCCEEDED(hr) && (i < FootprintFilesCount); i++)
    {
        IAppxFile* footprintFile = NULL;

        hr = packageReader->GetFootprintFile(FootprintFilesType[i], &footprintFile);

        if (hr == HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND))
        {
            // Some footprint files are optional. It is normal for the GetFootprintFile
            // call to fail when there is no file.
            wprintf(L"\nThe package does not contain a %s.\n", FootprintFilesName[i]);
            hr = S_OK;
        }
        else if (SUCCEEDED(hr))
        {
            hr = ExtractFile(footprintFile, outputPath);
        }

        if (footprintFile != NULL)
        {
            footprintFile->Release();
            footprintFile = NULL;
        }
    }
    return hr;
}

//
// Prints basic info about a footprint or payload file and writes the file to disk.
//
// Parameters:
//   file 
//      The IAppxFile interface that represents a footprint or payload file in the package.
//   outputPath 
//      The path of the folder for the extracted files.
//
HRESULT ExtractFile(
    _In_ IAppxFile* file,
    _In_ LPCWSTR outputPath)
{
    HRESULT hr = S_OK;
    LPWSTR fileName = NULL;
    LPWSTR contentType = NULL;
    UINT64 fileSize = 0;
    IStream* fileStream = NULL;
    IStream* outputStream = NULL;
    ULARGE_INTEGER fileSizeLargeInteger = {0};

    // Get basic info about the file
    hr = file->GetName(&fileName);

    if (SUCCEEDED(hr))
    {
        hr = file->GetContentType(&contentType);
    }
    if (SUCCEEDED(hr))
    {
        hr = file->GetSize(&fileSize);
        fileSizeLargeInteger.QuadPart = fileSize;
    }
    if (SUCCEEDED(hr))
    {
        wprintf(L"\nFile name: %s\n", fileName);
        wprintf(L"Content type: %s\n", contentType);
        wprintf(L"Size: %llu bytes\n", fileSize);
    }

    // Write the file to disk
    if (SUCCEEDED(hr))
    {
        hr = file->GetStream(&fileStream);
    }
    if (SUCCEEDED(hr))
    {
        hr = GetOutputStream(outputPath, fileName, &outputStream);
    }
    if (SUCCEEDED(hr))
    {
        hr = fileStream->CopyTo(outputStream, fileSizeLargeInteger, NULL, NULL);
    }

    // You must free string buffers obtained from the packaging APIs
    CoTaskMemFree(fileName);
    CoTaskMemFree(contentType);

    // Clean up other allocated resources
    if (outputStream != NULL)
    {
        outputStream->Release();
        outputStream = NULL;
    }
    if (fileStream != NULL)
    {
        fileStream->Release();
        fileStream = NULL;
    }
    return hr;
}

The previous code uses these variable definitions and GetOutputStream helper function.



// Creates a writable IStream for a file with the specified name under the specified path.  
// This function also creates intermediate subdirectories if necessary. For simplicity, 
// we keep file names including path to 200 characters or less. Make sure your appl 
// handles longer names. Allocate the necessary buffer dynamically.
//
// Parameters:
//    path 
//       The path of the folder containing the file to be opened. Make sure this does not end
//       with a '\' character.
//    fileName 
//       The name of the file to be opened, without the path.
//    stream 
//       On success, receives the created instance of IStream.
//
HRESULT GetOutputStream(
    _In_ LPCWSTR path,
    _In_ LPCWSTR fileName,
    _Outptr_ IStream** stream)
{
    HRESULT hr = S_OK;
    const int MaxFileNameLength = 200;
    WCHAR fullFileName[MaxFileNameLength + 1];

    // Create full file name by concatenating path and fileName
    hr = StringCchCopyW(fullFileName, MaxFileNameLength, path);

    if (SUCCEEDED(hr))
    {
        hr = StringCchCat(fullFileName, MaxFileNameLength, L"\\");
    }
    if (SUCCEEDED(hr))
    {
        hr = StringCchCat(fullFileName, MaxFileNameLength, fileName);
    }

    // Search through fullFileName for the '\' character which denotes
    // subdirectory and create each subdirectory in order of depth.
    for (int i = 0; SUCCEEDED(hr) && (i < MaxFileNameLength); i++)
    {
        if (fullFileName[i] == L'\0')
        {
            break;
        }
        else if (fullFileName[i] == L'\\')
        {
            // Temporarily set string to terminate at the '\' character
            // to obtain name of the subdirectory to create
            fullFileName[i] = L'\0';

            if (!CreateDirectory(fullFileName, NULL))
            {
                DWORD lastError = GetLastError();

                // It is normal for CreateDirectory to fail if the subdirectory
                // already exists.  Don't ignore other errors.
                if (lastError != ERROR_ALREADY_EXISTS)
                {
                    hr = HRESULT_FROM_WIN32(lastError);
                }
            }

            // Restore original string
            fullFileName[i] = L'\\';
        }
    }

    // Create stream for writing the file
    if (SUCCEEDED(hr))
    {
        hr = SHCreateStreamOnFileEx(
                fullFileName,
                STGM_CREATE | STGM_WRITE | STGM_SHARE_EXCLUSIVE,
                0, // default file attributes
                TRUE, // create new file if it does not exist
                NULL, // no template
                stream);
    }
    return hr;
}

Extract payload files

Call the IAppxPackageReader::GetPayloadFiles method to enumerate the payload files. Each payload file is represented by an IAppxFile interface. The ExtractFile function in this sample uses the GetName, GetContentType, and GetSize methods of IAppxFile to display basic info about the payload file.

This code uses the ExtractFile helper function shown in the previous step to create the stream for the package manifest.


//
// Extracts all payload files from a package.
//
// Parameters:
//   packageReader 
//      The package reader for the app package.
//   outputPath 
//      The path of the folder for the extracted payload files.
//
HRESULT ExtractPayloadFiles(
    _In_ IAppxPackageReader* packageReader,
    _In_ LPCWSTR outputPath)
{
    HRESULT hr = S_OK;
    IAppxFilesEnumerator* payloadFiles = NULL;
    wprintf(L"\nExtracting payload files from the package...\n");

    // Get an enumerator of all payload files from the package reader and iterate
    // through all files.
    hr = packageReader->GetPayloadFiles(&payloadFiles);

    if (SUCCEEDED(hr))
    {
        BOOL hasCurrent = FALSE;
        hr = payloadFiles->GetHasCurrent(&hasCurrent);

        while (SUCCEEDED(hr) && hasCurrent)
        {
            IAppxFile* payloadFile = NULL;

            hr = payloadFiles->GetCurrent(&payloadFile);

            if (SUCCEEDED(hr))
            {
                hr = ExtractFile(payloadFile, outputPath);
            }
            if (SUCCEEDED(hr))
            {
                hr = payloadFiles->MoveNext(&hasCurrent);
            }

            if (payloadFile != NULL)
            {
                payloadFile->Release();
                payloadFile = NULL;
            }
        }
    }

    if (payloadFiles != NULL)
    {
        payloadFiles->Release();
        payloadFiles = NULL;
    }
    return hr;
}

Clean up the package reader

Before returning from the wmain function, call the Release method to clean up the package reader and call the CoUninitialize function.


// Clean up allocated resources
if (packageReader != NULL)
{
    packageReader->Release();
    packageReader = NULL;
}

CoUninitialize();

Related topics

Samples
Extract app package contents sample
Concepts
App packages and deployment
Reference
IAppxPackageReader

 

 

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