Adding upstream version 6.0.4-dfsg.upstream/6.0.4-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 535 insertions, 0 deletions

diff --git a/include/VBox/com/ErrorInfo.h b/include/VBox/com/ErrorInfo.h
new file mode 100644
index 00000000..eaaec190
--- /dev/null
+++ b/include/VBox/com/ErrorInfo.h
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+/** @file
+ * MS COM / XPCOM Abstraction Layer - ErrorInfo class declaration.
+ */
+
+/*
+ * Copyright (C) 2006-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef VBOX_INCLUDED_com_ErrorInfo_h
+#define VBOX_INCLUDED_com_ErrorInfo_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include "VBox/com/ptr.h"
+#include "VBox/com/string.h"
+#include "VBox/com/Guid.h"
+#include "VBox/com/assert.h"
+
+
+/** @defgroup grp_com_errinfo   ErrorInfo Classes
+ * @ingroup grp_com
+ * @{
+ */
+
+COM_STRUCT_OR_CLASS(IProgress);
+COM_STRUCT_OR_CLASS(IVirtualBoxErrorInfo);
+
+namespace com
+{
+
+/**
+ * General discussion:
+ *
+ * In COM all errors are stored on a per thread basis. In general this means
+ * only _one_ active error is possible per thread. A new error will overwrite
+ * the previous one. To prevent this use MultiResult or ErrorInfoKeeper (see
+ * below). The implementations in MSCOM/XPCOM differ slightly, but the details
+ * are handled by this glue code.
+ *
+ * We have different classes which are involved in the error management. I try
+ * to describe them separately to make clear what they are there for.
+ *
+ * ErrorInfo:
+ *
+ *  This class is able to retrieve the per thread error and store it into its
+ *  member variables. This class can also handle non-VirtualBox errors (like
+ *  standard COM errors).
+ *
+ * ProgressErrorInfo:
+ *
+ *  This is just a simple wrapper class to get the ErrorInfo stored within an
+ *  IProgress object. That is the error which was stored when the progress
+ *  object was in use and not an error produced by IProgress itself.
+ *
+ * IVirtualBoxErrorInfo:
+ *
+ *  The VirtualBox interface class for accessing error information from Main
+ *  clients. This class is also used for storing the error information in the
+ *  thread context.
+ *
+ * ErrorInfoKeeper:
+ *
+ *  A helper class which stores the current per thread info internally. After
+ *  calling methods which may produce other errors it is possible to restore
+ *  the previous error and therefore restore the situation before calling the
+ *  other methods.
+ *
+ * MultiResult:
+ *
+ *  Creating an instance of MultiResult turns error chain saving on. All errors
+ *  which follow will be saved in a chain for later access.
+ *
+ * COMErrorInfo (Qt/Gui only):
+ *
+ *  The Qt GUI does some additional work for saving errors. Because we create
+ *  wrappers for _every_ COM call, it is possible to automatically save the
+ *  error info after the execution. This allow some additional info like saving
+ *  the callee. Please note that this error info is saved on the client side
+ *  and therefore locally to the object instance. See COMBaseWithEI,
+ *  COMErrorInfo and the generated COMWrappers.cpp in the GUI.
+ *
+ * Errors itself are set in VirtualBoxBase::setErrorInternal. First a
+ * IVirtualBoxErrorInfo object is created and the given error is saved within.
+ * If MultiResult is active the current per thread error is fetched and
+ * attached to the new created IVirtualBoxErrorInfo object. Next this object is
+ * set as the new per thread error.
+ *
+ * Some general hints:
+ *
+ * - Always use setError, especially when you are working in an asynchronous thread
+ *   to indicate an error. Otherwise the error information itself will not make
+ *   it into the client.
+ *
+ */
+
+/**
+ *  The ErrorInfo class provides a convenient way to retrieve error
+ *  information set by the most recent interface method, that was invoked on
+ *  the current thread and returned an unsuccessful result code.
+ *
+ *  Once the instance of this class is created, the error information for
+ *  the current thread is cleared.
+ *
+ *  There is no sense to use instances of this class after the last
+ *  invoked interface method returns a success.
+ *
+ *  The class usage pattern is as follows:
+ *  <code>
+ *      IFoo *foo;
+ *      ...
+ *      HRESULT rc = foo->SomeMethod();
+ *      if (FAILED(rc)) {
+ *          ErrorInfo info(foo);
+ *          if (info.isFullAvailable()) {
+ *              printf("error message = %ls\n", info.getText().raw());
+ *          }
+ *      }
+ *  </code>
+ *
+ *  This class fetches error information using the IErrorInfo interface on
+ *  Win32 (MS COM) or the nsIException interface on other platforms (XPCOM),
+ *  or the extended IVirtualBoxErrorInfo interface when when it is available
+ *  (i.e. a given IErrorInfo or nsIException instance implements it).
+ *  Currently, IVirtualBoxErrorInfo is only available for VirtualBox components.
+ *
+ *  ErrorInfo::isFullAvailable() and ErrorInfo::isBasicAvailable() determine
+ *  what level of error information is available. If #isBasicAvailable()
+ *  returns true, it means that only IErrorInfo or nsIException is available as
+ *  the source of information (depending on the platform), but not
+ *  IVirtualBoxErrorInfo. If #isFullAvailable() returns true, it means that all
+ *  three interfaces are available. If both methods return false, no error info
+ *  is available at all.
+ *
+ *  Here is a table of correspondence between this class methods and
+ *  and IErrorInfo/nsIException/IVirtualBoxErrorInfo attributes/methods:
+ *
+ *  ErrorInfo       IErrorInfo      nsIException    IVirtualBoxErrorInfo
+ *  --------------------------------------------------------------------
+ *  getResultCode   --              result          resultCode
+ *  getIID          GetGUID         --              interfaceID
+ *  getComponent    GetSource       --              component
+ *  getText         GetDescription  message         text
+ *
+ *  '--' means that this interface does not provide the corresponding portion
+ *  of information, therefore it is useless to query it if only
+ *  #isBasicAvailable() returns true. As it can be seen, the amount of
+ *  information provided at the basic level, depends on the platform
+ *  (MS COM or XPCOM).
+ */
+class ErrorInfo
+{
+public:
+
+    /**
+     *  Constructs a new, "interfaceless" ErrorInfo instance that takes
+     *  the error information possibly set on the current thread by an
+     *  interface method of some COM component or by the COM subsystem.
+     *
+     *  This constructor is useful, for example, after an unsuccessful attempt
+     *  to instantiate (create) a component, so there is no any valid interface
+     *  pointer available.
+     */
+    explicit ErrorInfo()
+        : mIsBasicAvailable(false),
+          mIsFullAvailable(false),
+          mResultCode(S_OK),
+          mResultDetail(0),
+          m_pNext(NULL)
+    {
+        init();
+    }
+
+    ErrorInfo(IUnknown *pObj, const GUID &aIID)
+        : mIsBasicAvailable(false),
+          mIsFullAvailable(false),
+          mResultCode(S_OK),
+          mResultDetail(0),
+          m_pNext(NULL)
+    {
+        init(pObj, aIID);
+    }
+
+    /** Specialization for the IVirtualBoxErrorInfo smart pointer */
+    ErrorInfo(const ComPtr<IVirtualBoxErrorInfo> &aPtr)
+        : mIsBasicAvailable(false), mIsFullAvailable(false)
+        , mResultCode(S_OK), mResultDetail(0)
+        { init(aPtr); }
+
+    /**
+     *  Constructs a new ErrorInfo instance from the IVirtualBoxErrorInfo
+     *  interface pointer. If this pointer is not NULL, both #isFullAvailable()
+     *  and #isBasicAvailable() will return |true|.
+     *
+     *  @param aInfo    pointer to the IVirtualBoxErrorInfo interface that
+     *                  holds error info to be fetched by this instance
+     */
+    ErrorInfo(IVirtualBoxErrorInfo *aInfo)
+        : mIsBasicAvailable(false), mIsFullAvailable(false)
+        , mResultCode(S_OK), mResultDetail(0)
+        { init(aInfo); }
+
+    ErrorInfo(const ErrorInfo &x)
+    {
+        copyFrom(x);
+    }
+
+    virtual ~ErrorInfo()
+    {
+        cleanup();
+    }
+
+    ErrorInfo& operator=(const ErrorInfo& x)
+    {
+        cleanup();
+        copyFrom(x);
+        return *this;
+    }
+
+    /**
+     *  Returns whether basic error info is actually available for the current
+     *  thread. If the instance was created from an interface pointer that
+     *  supports basic error info and successfully provided it, or if it is an
+     *  "interfaceless" instance and there is some error info for the current
+     *  thread, the returned value will be true.
+     *
+     *  See the class description for details about the basic error info level.
+     *
+     *  The appropriate methods of this class provide meaningful info only when
+     *  this method returns true (otherwise they simply return NULL-like values).
+     */
+    bool isBasicAvailable() const
+    {
+        return mIsBasicAvailable;
+    }
+
+    /**
+     *  Returns whether full error info is actually available for the current
+     *  thread. If the instance was created from an interface pointer that
+     *  supports full error info and successfully provided it, or if it is an
+     *  "interfaceless" instance and there is some error info for the current
+     *  thread, the returned value will be true.
+     *
+     *  See the class description for details about the full error info level.
+     *
+     *  The appropriate methods of this class provide meaningful info only when
+     *  this method returns true (otherwise they simply return NULL-like values).
+     */
+    bool isFullAvailable() const
+    {
+        return mIsFullAvailable;
+    }
+
+    /**
+     *  Returns the COM result code of the failed operation.
+     */
+    HRESULT getResultCode() const
+    {
+        return mResultCode;
+    }
+
+    /**
+     *  Returns the (optional) result detail code of the failed operation.
+     */
+    LONG getResultDetail() const
+    {
+        return mResultDetail;
+    }
+
+    /**
+     *  Returns the IID of the interface that defined the error.
+     */
+    const Guid& getInterfaceID() const
+    {
+        return mInterfaceID;
+    }
+
+    /**
+     *  Returns the name of the component that generated the error.
+     */
+    const Bstr& getComponent() const
+    {
+        return mComponent;
+    }
+
+    /**
+     *  Returns the textual description of the error.
+     */
+    const Bstr& getText() const
+    {
+        return mText;
+    }
+
+    /**
+     *  Returns the next error information object or @c NULL if there is none.
+     */
+    const ErrorInfo* getNext() const
+    {
+        return m_pNext;
+    }
+
+    /**
+     *  Returns the name of the interface that defined the error
+     */
+    const Bstr& getInterfaceName() const
+    {
+        return mInterfaceName;
+    }
+
+    /**
+     *  Returns the IID of the interface that returned the error.
+     *
+     *  This method returns a non-null IID only if the instance was created
+     *  using template \<class I\> ErrorInfo(I *i) or
+     *  template \<class I\> ErrorInfo(const ComPtr<I> &i) constructor.
+     *
+     *  @todo broken ErrorInfo documentation links, possibly misleading.
+     */
+    const Guid& getCalleeIID() const
+    {
+        return mCalleeIID;
+    }
+
+    /**
+     *  Returns the name of the interface that returned the error
+     *
+     *  This method returns a non-null name only if the instance was created
+     *  using template \<class I\> ErrorInfo(I *i) or
+     *  template \<class I\> ErrorInfo(const ComPtr<I> &i) constructor.
+     *
+     *  @todo broken ErrorInfo documentation links, possibly misleading.
+     */
+    const Bstr& getCalleeName() const
+    {
+        return mCalleeName;
+    }
+
+    HRESULT getVirtualBoxErrorInfo(ComPtr<IVirtualBoxErrorInfo> &pVirtualBoxErrorInfo);
+
+    /**
+     *  Resets all collected error information. #isBasicAvailable() and
+     *  #isFullAvailable will return @c true after this method is called.
+     */
+    void setNull()
+    {
+        cleanup();
+    }
+
+protected:
+
+    ErrorInfo(bool /* aDummy */)
+        : mIsBasicAvailable(false),
+          mIsFullAvailable(false),
+          mResultCode(S_OK),
+          m_pNext(NULL)
+    { }
+
+    void copyFrom(const ErrorInfo &x);
+    void cleanup();
+
+    void init(bool aKeepObj = false);
+    void init(IUnknown *aUnk, const GUID &aIID, bool aKeepObj = false);
+    void init(IVirtualBoxErrorInfo *aInfo);
+
+    bool mIsBasicAvailable : 1;
+    bool mIsFullAvailable : 1;
+
+    HRESULT mResultCode;
+    LONG    mResultDetail;
+    Guid    mInterfaceID;
+    Bstr    mComponent;
+    Bstr    mText;
+
+    ErrorInfo *m_pNext;
+
+    Bstr mInterfaceName;
+    Guid mCalleeIID;
+    Bstr mCalleeName;
+
+    ComPtr<IUnknown> mErrorInfo;
+};
+
+/**
+ *  A convenience subclass of ErrorInfo that, given an IProgress interface
+ *  pointer, reads its errorInfo attribute and uses the returned
+ *  IVirtualBoxErrorInfo instance to construct itself.
+ */
+class ProgressErrorInfo : public ErrorInfo
+{
+public:
+
+    /**
+     *  Constructs a new instance by fetching error information from the
+     *  IProgress interface pointer. If the progress object is not NULL,
+     *  its completed attribute is true, resultCode represents a failure,
+     *  and the errorInfo attribute returns a valid IVirtualBoxErrorInfo pointer,
+     *  both #isFullAvailable() and #isBasicAvailable() will return true.
+     *
+     *  @param  progress    the progress object representing a failed operation
+     */
+    ProgressErrorInfo(IProgress *progress);
+};
+
+/**
+ *  A convenience subclass of ErrorInfo that allows to preserve the current
+ *  error info. Instances of this class fetch an error info object set on the
+ *  current thread and keep a reference to it, which allows to restore it
+ *  later using the #restore() method. This is useful to preserve error
+ *  information returned by some method for the duration of making another COM
+ *  call that may set its own error info and overwrite the existing
+ *  one. Preserving and restoring error information makes sense when some
+ *  method wants to return error information set by other call as its own
+ *  error information while it still needs to make another call before return.
+ *
+ *  Instead of calling #restore() explicitly you may let the object destructor
+ *  do it for you, if you correctly limit the object's lifetime.
+ *
+ *  The usage pattern is:
+ *  <code>
+ *      rc = foo->method();
+ *      if (FAILED(rc))
+ *      {
+ *           ErrorInfoKeeper eik;
+ *           ...
+ *           // bar may return error info as well
+ *           bar->method();
+ *           ...
+ *           // no need to call #restore() explicitly here because the eik's
+ *           // destructor will restore error info fetched after the failed
+ *           // call to foo before returning to the caller
+ *           return rc;
+ *      }
+ *  </code>
+ */
+class ErrorInfoKeeper : public ErrorInfo
+{
+public:
+
+    /**
+     *  Constructs a new instance that will fetch the current error info if
+     *  @a aIsNull is @c false (by default) or remain uninitialized (null)
+     *  otherwise.
+     *
+     *  @param aIsNull  @c true to prevent fetching error info and leave
+     *                  the instance uninitialized.
+     */
+    ErrorInfoKeeper(bool aIsNull = false)
+        : ErrorInfo(false), mForgot(aIsNull)
+    {
+        if (!aIsNull)
+            init(true /* aKeepObj */);
+    }
+
+    /**
+     *  Constructs a new instance from an ErrorInfo object, to inject a full
+     *  error info created elsewhere.
+     *
+     *  @param aInfo    @c true to prevent fetching error info and leave
+     *                  the instance uninitialized.
+     */
+    ErrorInfoKeeper(const ErrorInfo &aInfo)
+        : ErrorInfo(false), mForgot(false)
+    {
+        copyFrom(aInfo);
+    }
+
+    /**
+     *  Destroys this instance and automatically calls #restore() which will
+     *  either restore error info fetched by the constructor or do nothing
+     *  if #forget() was called before destruction.
+     */
+    ~ErrorInfoKeeper() { if (!mForgot) restore(); }
+
+    /**
+     *  Tries to (re-)fetch error info set on the current thread.  On success,
+     *  the previous error information, if any, will be overwritten with the
+     *  new error information. On failure, or if there is no error information
+     *  available, this instance will be reset to null.
+     */
+    void fetch()
+    {
+        setNull();
+        mForgot = false;
+        init(true /* aKeepObj */);
+    }
+
+    /**
+     *  Restores error info fetched by the constructor and forgets it
+     *  afterwards. Does nothing if the error info was forgotten by #forget().
+     *
+     *  @return COM result of the restore operation.
+     */
+    HRESULT restore();
+
+    /**
+     *  Forgets error info fetched by the constructor to prevent it from
+     *  being restored by #restore() or by the destructor.
+     */
+    void forget() { mForgot = true; }
+
+    /**
+     *  Forgets error info fetched by the constructor to prevent it from
+     *  being restored by #restore() or by the destructor, and returns the
+     *  stored error info object to the caller.
+     */
+    ComPtr<IUnknown> takeError() { mForgot = true; return mErrorInfo; }
+
+private:
+
+    bool mForgot : 1;
+};
+
+} /* namespace com */
+
+/** @} */
+
+#endif /* !VBOX_INCLUDED_com_ErrorInfo_h */
+