DLL integration

7-Zip provides COM-based DLLs for integrating archive functionality into Windows applications.

Available DLLs

Format DLLs

DLL	Bundle Location	Formats Supported
7z.dll	`Format7zF`	All formats (7z, ZIP, TAR, RAR, ISO, etc.)
7za.dll	`Format7z`	7z format only
7zxa.dll	`Format7zExtract`	7z extraction only
7zr.dll	`Format7zR`	7z reduced version
7zxr.dll	`Format7zExtractR`	7z extraction reduced

From DOC/readme.txt (lines 270-274):

Format7zF       7z.dll:   all formats
Format7z        7za.dll:  .7z support
Format7zExtract 7zxa.dll: .7z support, extracting only
Format7zR       7zr.dll:  .7z support, reduced version
Format7zExtractR 7zxr.dll: .7z support, reduced version, extracting only

GUI DLLs

DLL	Description
7-zip.dll	Shell extension for Windows Explorer
7-zip32.dll	FAR Manager plugin (32-bit)
7-zip64.dll	FAR Manager plugin (64-bit)

DLL Architecture

COM Interface

7-Zip DLLs use COM interfaces but with a simplified creation mechanism:

// Standard function exported by all format DLLs
typedef HRESULT (WINAPI *CreateObjectFunc)(
    const GUID *clsid,
    const GUID *iid,
    void **outObject
);

From DOC/readme.txt (lines 217-228):

7-Zip consists of COM modules (DLL files). But 7-Zip doesn’t use standard COM interfaces for creating objects.

Loading DLLs

Load Format DLL

#include <windows.h>
#include "7zip/Archive/IArchive.h"
#include "7zip/IDecl.h"

// Load DLL
HMODULE lib = LoadLibrary(TEXT("7z.dll"));

if (!lib) {
    // Error handling
    return E_FAIL;
}

// Get CreateObject function
typedef HRESULT (WINAPI *CreateObjectFunc)(
    const GUID *clsid,
    const GUID *iid,
    void **outObject
);

CreateObjectFunc createObject = (CreateObjectFunc)
    GetProcAddress(lib, "CreateObject");

if (!createObject) {
    FreeLibrary(lib);
    return E_FAIL;
}

Create Archive Handler

// For 7z archives
IInArchive *archive = NULL;
HRESULT hr = createObject(
    &CLSID_CFormat7z,      // 7z format
    &IID_IInArchive,       // Read interface
    (void**)&archive
);

if (SUCCEEDED(hr)) {
    // Use archive interface
    // ...
    archive->Release();
}

FreeLibrary(lib);

Archive Interfaces

IInArchive - Reading Archives

From CPP/7zip/Archive/IArchive.h:

interface IInArchive : public IUnknown
{
    // Open archive
    STDMETHOD(Open)(
        IInStream *stream,
        const UInt64 *maxCheckStartPosition,
        IArchiveOpenCallback *openCallback
    ) = 0;
    
    // Close archive
    STDMETHOD(Close)() = 0;
    
    // Get number of items
    STDMETHOD(GetNumberOfItems)(UInt32 *numItems) = 0;
    
    // Get item property
    STDMETHOD(GetProperty)(
        UInt32 index,
        PROPID propID,
        PROPVARIANT *value
    ) = 0;
    
    // Extract files
    STDMETHOD(Extract)(
        const UInt32 *indices,
        UInt32 numItems,
        Int32 testMode,
        IArchiveExtractCallback *extractCallback
    ) = 0;
};

IOutArchive - Creating Archives

interface IOutArchive : public IUnknown
{
    // Update/create archive
    STDMETHOD(UpdateItems)(
        ISequentialOutStream *outStream,
        UInt32 numItems,
        IArchiveUpdateCallback *updateCallback
    ) = 0;
    
    // Get file time type
    STDMETHOD(GetFileTimeType)(UInt32 *type) = 0;
};

Property IDs

From CPP/7zip/PropID.h (lines 1-70):

enum PROPID
{
    kpidNoProperty = 0,
    kpidPath,              // File path (VT_BSTR)
    kpidName,              // File name (VT_BSTR)
    kpidExtension,         // Extension (VT_BSTR)
    kpidIsDir,             // Is directory (VT_BOOL)
    kpidSize,              // Uncompressed size (VT_UI8)
    kpidPackSize,          // Compressed size (VT_UI8)
    kpidAttrib,            // Attributes (VT_UI4)
    kpidCTime,             // Creation time (VT_FILETIME)
    kpidATime,             // Access time (VT_FILETIME)
    kpidMTime,             // Modification time (VT_FILETIME)
    kpidSolid,             // Is solid (VT_BOOL)
    kpidCommented,         // Has comment (VT_BOOL)
    kpidEncrypted,         // Is encrypted (VT_BOOL)
    kpidCRC,               // CRC32 (VT_UI4)
    kpidMethod,            // Compression method (VT_BSTR)
    kpidHostOS,            // Host OS (VT_BSTR)
    // ... more properties
};

Example: Reading Archive

#include "7zip/Archive/IArchive.h"
#include "Common/MyString.h"
#include <stdio.h>

void ListArchive(IInArchive *archive)
{
    UInt32 numItems = 0;
    archive->GetNumberOfItems(&numItems);
    
    printf("Files in archive: %u\n", numItems);
    
    for (UInt32 i = 0; i < numItems; i++)
    {
        // Get file name
        PROPVARIANT prop;
        PropVariantInit(&prop);
        
        archive->GetProperty(i, kpidPath, &prop);
        if (prop.vt == VT_BSTR)
        {
            wprintf(L"%s", prop.bstrVal);
        }
        PropVariantClear(&prop);
        
        // Get file size
        archive->GetProperty(i, kpidSize, &prop);
        if (prop.vt == VT_UI8)
        {
            printf(" - %llu bytes\n", prop.uhVal.QuadPart);
        }
        PropVariantClear(&prop);
    }
}

Example: Extracting Files

class CExtractCallback : public IArchiveExtractCallback
{
public:
    // IProgress
    STDMETHOD(SetTotal)(UInt64 total) { return S_OK; }
    STDMETHOD(SetCompleted)(const UInt64 *completeValue) { return S_OK; }
    
    // IArchiveExtractCallback
    STDMETHOD(GetStream)(
        UInt32 index,
        ISequentialOutStream **outStream,
        Int32 askExtractMode)
    {
        // Create output stream for file
        *outStream = CreateOutFileStream(index);
        return S_OK;
    }
    
    STDMETHOD(PrepareOperation)(Int32 askExtractMode) { return S_OK; }
    STDMETHOD(SetOperationResult)(Int32 resultEOperationResult) { return S_OK; }
};

void ExtractArchive(IInArchive *archive)
{
    CExtractCallback *callback = new CExtractCallback();
    
    // Extract all files
    HRESULT hr = archive->Extract(
        NULL,      // All files (NULL = all)
        (UInt32)-1, // Number of items
        0,         // Test mode (0 = extract)
        callback
    );
    
    callback->Release();
}

Example: Creating Archive

class CUpdateCallback : public IArchiveUpdateCallback
{
public:
    // IProgress
    STDMETHOD(SetTotal)(UInt64 total) { return S_OK; }
    STDMETHOD(SetCompleted)(const UInt64 *completeValue) { return S_OK; }
    
    // IArchiveUpdateCallback
    STDMETHOD(GetUpdateItemInfo)(
        UInt32 index,
        Int32 *newData,
        Int32 *newProperties,
        UInt32 *indexInArchive)
    {
        *newData = 1;
        *newProperties = 1;
        *indexInArchive = (UInt32)-1; // New file
        return S_OK;
    }
    
    STDMETHOD(GetProperty)(UInt32 index, PROPID propID, PROPVARIANT *value)
    {
        PropVariantInit(value);
        
        switch (propID)
        {
            case kpidPath:
                value->vt = VT_BSTR;
                value->bstrVal = SysAllocString(L"file.txt");
                break;
            case kpidIsDir:
                value->vt = VT_BOOL;
                value->boolVal = VARIANT_FALSE;
                break;
            case kpidSize:
                value->vt = VT_UI8;
                value->uhVal.QuadPart = fileSize;
                break;
        }
        return S_OK;
    }
    
    STDMETHOD(GetStream)(UInt32 index, ISequentialInStream **inStream)
    {
        // Return input stream for file
        *inStream = CreateInFileStream(index);
        return S_OK;
    }
    
    STDMETHOD(SetOperationResult)(Int32 operationResult) { return S_OK; }
};

void CreateArchive(IOutArchive *outArchive, IOutStream *outStream)
{
    CUpdateCallback *callback = new CUpdateCallback();
    
    HRESULT hr = outArchive->UpdateItems(
        outStream,
        numFiles,  // Number of files to add
        callback
    );
    
    callback->Release();
}

Format CLSIDs

From CPP/7zip/Guid.txt:

// Format GUIDs
DEFINE_GUID(CLSID_CFormat7z,
  0x23170F69, 0x40C1, 0x278A, 0x10, 0x00, 0x00, 0x01, 0x10, 0x07, 0x00, 0x00);

DEFINE_GUID(CLSID_CFormatZip,
  0x23170F69, 0x40C1, 0x278A, 0x10, 0x00, 0x00, 0x01, 0x10, 0x01, 0x00, 0x00);

DEFINE_GUID(CLSID_CFormatTar,
  0x23170F69, 0x40C1, 0x278A, 0x10, 0x00, 0x00, 0x01, 0x10, 0xEE, 0x00, 0x00);

DEFINE_GUID(CLSID_CFormatRar,
  0x23170F69, 0x40C1, 0x278A, 0x10, 0x00, 0x00, 0x01, 0x10, 0x03, 0x00, 0x00);

Building DLLs

Windows

cd CPP\7zip\Bundles\Format7zF
nmake

Result: 7z.dll

Project Files

Visual Studio project files are included:

Format7zF.dsp - Visual Studio 6.0
Can be upgraded to newer VS versions

DLL Dependencies

The format DLLs have no external dependencies:

Statically linked runtime
No MFC or ATL required
Only Windows API

From DOC/readme.txt (lines 217-228):

If you don’t like it, you must use standalone version of DLL. To compile standalone version of DLL you must include all used parts to project and define some defs.

Building from Source

SDK & Integration

Contributing

DLL integration

Available DLLs

Format DLLs

GUI DLLs

DLL Architecture

COM Interface

Loading DLLs

Load Format DLL

Create Archive Handler

Archive Interfaces

IInArchive - Reading Archives

IOutArchive - Creating Archives

Property IDs

Example: Reading Archive

Example: Extracting Files

Example: Creating Archive

Format CLSIDs

Building DLLs

Windows

Project Files

DLL Dependencies

See Also

Build docs developers (and LLMs) love

Building from Source

SDK & Integration

Contributing

​Available DLLs

​Format DLLs

​GUI DLLs

​DLL Architecture

​COM Interface

​Loading DLLs

​Load Format DLL

​Create Archive Handler

​Archive Interfaces

​IInArchive - Reading Archives

​IOutArchive - Creating Archives

​Property IDs

​Example: Reading Archive

​Example: Extracting Files

​Example: Creating Archive

​Format CLSIDs

​Building DLLs

​Windows

​Project Files

​DLL Dependencies

​See Also

Build docs developers (and LLMs) love

Available DLLs

Format DLLs

GUI DLLs

DLL Architecture

COM Interface

Loading DLLs

Load Format DLL

Create Archive Handler

Archive Interfaces

IInArchive - Reading Archives

IOutArchive - Creating Archives

Property IDs

Example: Reading Archive

Example: Extracting Files

Example: Creating Archive

Format CLSIDs

Building DLLs

Windows

Project Files

DLL Dependencies

See Also