path: root/src/corelib/global/qglobal.cpp

// Copyright (C) 2021 The Qt Company Ltd.
// Copyright (C) 2017 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qplatformdefs.h"
#include "qstring.h"
#include "qbytearrayview.h"
#include "qlist.h"
#include "qdir.h"
#include "qdatetime.h"
#include <private/qlocale_tools_p.h>
#include "qnativeinterface.h"
#include "qnativeinterface_p.h"

#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

#include <errno.h>
#if defined(Q_CC_MSVC)
#  include <crtdbg.h>
#endif

#ifdef Q_OS_WIN
#  include <qt_windows.h>
#endif

#if defined(Q_OS_VXWORKS) && defined(_WRS_KERNEL)
#  include <envLib.h>
#endif

#if defined(Q_OS_INTEGRITY)
extern "C" {
    // Function mmap resides in libshm_client.a. To be able to link with it one needs
    // to define symbols 'shm_area_password' and 'shm_area_name', because the library
    // is meant to allow the application that links to it to use POSIX shared memory
    // without full system POSIX.
#  pragma weak shm_area_password
#  pragma weak shm_area_name
    char shm_area_password[] = "dummy";
    char shm_area_name[] = "dummy";
}
#endif

#ifdef qFatal
// the qFatal in this file are just redirections from elsewhere, so
// don't capture any context again
#  undef qFatal
#endif

QT_BEGIN_NAMESPACE

using namespace Qt::StringLiterals;

/*!
    \headerfile <QtGlobal>
    \inmodule QtCore
    \title Global Qt Declarations
    \ingroup funclists

    \brief The <QtGlobal> header file includes an assortment of other headers.

    Up to Qt 6.5, most Qt header files included <QtGlobal>. Before Qt 6.5,
    <QtGlobal> defined an assortment of global declarations. Most of these
    have moved, at Qt 6.5, to separate headers, so that source code can
    include only what it needs, rather than the whole assortment. For now,
    <QtGlobal> includes those other headers (see next section), but future
    releases of Qt may remove some of these headers from <QtGlobal> or
    condition their inclusion on a version check. Likewise, in future
    releases, some Qt headers that currently include <QtGlobal> may stop
    doing so. The hope is that this will improve compilation times by
    avoiding global declarations when they are not used.

    \section1 List of Headers Extracted from <QtGlobal>

    \table
    \header \li Header                      \li Summary
    \row    \li <QFlags>                    \li Type-safe way of combining enum values
    \row    \li \l <QForeach>               \li Qt's implementation of foreach and forever loops
    \row    \li \l <QFunctionPointer>       \li Typedef for a pointer-to-function type
    \row    \li <QGlobalStatic>             \li Thread-safe initialization of global static objects
    \row    \li \l <QOverload>              \li Helpers for resolving member function overloads
    \row    \li <QSysInfo>                  \li A helper class to get system information
    \row    \li \l <QTypeInfo>              \li Helpers to get type information
    \row    \li \l <QtAssert>               \li Q_ASSERT and other runtime checks
    \row    \li \l <QtClassHelperMacros>    \li Qt class helper macros
    \row    \li \l <QtCompilerDetection>    \li Compiler-specific macro definitions
    \row    \li \l <QtDeprecationMarkers>   \li Deprecation helper macros
    \row    \li \l <QtEnvironmentVariables> \li Helpers for working with environment variables
    \row    \li <QtExceptionHandling>       \li Helpers for exception handling
    \row    \li \l <QtLogging>              \li Qt logging helpers
    \row    \li <QtMalloc>                  \li Memory allocation helpers
    \row    \li \l <QtMinMax>               \li Helpers for comparing values
    \row    \li \l <QtNumeric>              \li Various numeric functions
    \row    \li \l <QtPreprocessorSupport>  \li Helper preprocessor macros
    \row    \li \l <QtProcessorDetection>   \li Architecture-specific macro definitions
    \row    \li \l <QtResource>             \li Helpers for initializing and cleaning resources
    \row    \li \l <QtSwap>                 \li Implementation of qSwap()
    \row    \li \l <QtSystemDetection>      \li Platform-specific macro definitions
    \row    \li \l <QtTranslation>          \li Qt translation helpers
    \row    \li \l <QtTypeTraits>           \li Qt type traits
    \row    \li \l <QtTypes>                \li Qt fundamental type declarations
    \row    \li \l <QtVersionChecks>        \li Qt Version related checks
    \endtable
*/

/*
    Dijkstra's bisection algorithm to find the square root of an integer.
    Deliberately not exported as part of the Qt API, but used in both
    qsimplerichtext.cpp and qgfxraster_qws.cpp
*/
Q_CORE_EXPORT Q_DECL_CONST_FUNCTION unsigned int qt_int_sqrt(unsigned int n)
{
    // n must be in the range 0...UINT_MAX/2-1
    if (n >= (UINT_MAX >> 2)) {
        unsigned int r = 2 * qt_int_sqrt(n / 4);
        unsigned int r2 = r + 1;
        return (n >= r2 * r2) ? r2 : r;
    }
    uint h, p = 0, q = 1, r = n;
    while (q <= n)
        q <<= 2;
    while (q != 1) {
        q >>= 2;
        h = p + q;
        p >>= 1;
        if (r >= h) {
            p += q;
            r -= h;
        }
    }
    return p;
}

void qAbort()
{
#ifdef Q_OS_WIN
    // std::abort() in the MSVC runtime will call _exit(3) if the abort
    // behavior is _WRITE_ABORT_MSG - see also _set_abort_behavior(). This is
    // the default for a debug-mode build of the runtime. Worse, MinGW's
    // std::abort() implementation (in msvcrt.dll) is basically a call to
    // _exit(3) too. Unfortunately, _exit() and _Exit() *do* run the static
    // destructors of objects in DLLs, a violation of the C++ standard (see
    // [support.start.term]). So we bypass std::abort() and directly
    // terminate the application.

#  if defined(Q_CC_MSVC)
    if (IsProcessorFeaturePresent(PF_FASTFAIL_AVAILABLE))
        __fastfail(FAST_FAIL_FATAL_APP_EXIT);
#  else
    RaiseFailFastException(nullptr, nullptr, 0);
#  endif

    // Fallback
    TerminateProcess(GetCurrentProcess(), STATUS_FATAL_APP_EXIT);

    // Tell the compiler the application has stopped.
    Q_UNREACHABLE_IMPL();
#else // !Q_OS_WIN
    std::abort();
#endif
}

// Also specified to behave as if they call tzset():
// localtime() -- but not localtime_r(), which we use when threaded
// strftime() -- not used (except in tests)

struct QInternal_CallBackTable
{
    QList<QList<qInternalCallback>> callbacks;
};

Q_GLOBAL_STATIC(QInternal_CallBackTable, global_callback_table)

bool QInternal::registerCallback(Callback cb, qInternalCallback callback)
{
    if (unsigned(cb) < unsigned(QInternal::LastCallback)) {
        QInternal_CallBackTable *cbt = global_callback_table();
        cbt->callbacks.resize(cb + 1);
        cbt->callbacks[cb].append(callback);
        return true;
    }
    return false;
}

bool QInternal::unregisterCallback(Callback cb, qInternalCallback callback)
{
    if (unsigned(cb) < unsigned(QInternal::LastCallback)) {
        if (global_callback_table.exists()) {
            QInternal_CallBackTable *cbt = global_callback_table();
            return cbt->callbacks[cb].removeAll(callback) > 0;
        }
    }
    return false;
}

bool QInternal::activateCallbacks(Callback cb, void **parameters)
{
    Q_ASSERT_X(cb >= 0, "QInternal::activateCallback()", "Callback id must be a valid id");

    if (!global_callback_table.exists())
        return false;

    QInternal_CallBackTable *cbt = &(*global_callback_table);
    if (cbt && cb < cbt->callbacks.size()) {
        QList<qInternalCallback> callbacks = cbt->callbacks[cb];
        bool ret = false;
        for (int i = 0; i < callbacks.size(); ++i)
            ret |= (callbacks.at(i))(parameters);
        return ret;
    }
    return false;
}

/*!
    \macro QT_NAMESPACE
    \internal

    If this macro is defined to \c ns all Qt classes are put in a namespace
    called \c ns. Also, moc will output code putting metaobjects etc.
    into namespace \c ns.

    \sa QT_BEGIN_NAMESPACE, QT_END_NAMESPACE,
    QT_PREPEND_NAMESPACE, QT_USE_NAMESPACE,
    QT_BEGIN_INCLUDE_NAMESPACE, QT_END_INCLUDE_NAMESPACE,
    QT_BEGIN_MOC_NAMESPACE, QT_END_MOC_NAMESPACE,
*/

/*!
    \macro QT_PREPEND_NAMESPACE(identifier)
    \internal

    This macro qualifies \a identifier with the full namespace.
    It expands to \c{::QT_NAMESPACE::identifier} if \c QT_NAMESPACE is defined
    and only \a identifier otherwise.

    \sa QT_NAMESPACE
*/

/*!
    \macro QT_USE_NAMESPACE
    \internal

    This macro expands to using QT_NAMESPACE if QT_NAMESPACE is defined
    and nothing otherwise.

    \sa QT_NAMESPACE
*/

/*!
    \macro QT_BEGIN_NAMESPACE
    \internal

    This macro expands to

    \snippet code/src_corelib_global_qglobal.cpp begin namespace macro

    if \c QT_NAMESPACE is defined and nothing otherwise. If should always
    appear in the file-level scope and be followed by \c QT_END_NAMESPACE
    at the same logical level with respect to preprocessor conditionals
    in the same file.

    As a rule of thumb, \c QT_BEGIN_NAMESPACE should appear in all Qt header
    and Qt source files after the last \c{#include} line and before the first
    declaration.

    If that rule can't be followed because, e.g., \c{#include} lines and
    declarations are wildly mixed, place \c QT_BEGIN_NAMESPACE before
    the first declaration and wrap the \c{#include} lines in
    \c QT_BEGIN_INCLUDE_NAMESPACE and \c QT_END_INCLUDE_NAMESPACE.

    When using the \c QT_NAMESPACE feature in user code
    (e.g., when building plugins statically linked to Qt) where
    the user code is not intended to go into the \c QT_NAMESPACE
    namespace, all forward declarations of Qt classes need to
    be wrapped in \c QT_BEGIN_NAMESPACE and \c QT_END_NAMESPACE.
    After that, a \c QT_USE_NAMESPACE should follow.
    No further changes should be needed.

    \sa QT_NAMESPACE
*/

/*!
    \macro QT_END_NAMESPACE
    \internal

    This macro expands to

    \snippet code/src_corelib_global_qglobal.cpp end namespace macro

    if \c QT_NAMESPACE is defined and nothing otherwise. It is used to cancel
    the effect of \c QT_BEGIN_NAMESPACE.

    If a source file ends with a \c{#include} directive that includes a moc file,
    \c QT_END_NAMESPACE should be placed before that \c{#include}.

    \sa QT_NAMESPACE
*/

/*!
    \macro QT_BEGIN_INCLUDE_NAMESPACE
    \internal

    This macro is equivalent to \c QT_END_NAMESPACE.
    It only serves as syntactic sugar and is intended
    to be used before #include lines within a
    \c QT_BEGIN_NAMESPACE ... \c QT_END_NAMESPACE block.

    \sa QT_NAMESPACE
*/

/*!
    \macro QT_END_INCLUDE_NAMESPACE
    \internal

    This macro is equivalent to \c QT_BEGIN_NAMESPACE.
    It only serves as syntactic sugar and is intended
    to be used after #include lines within a
    \c QT_BEGIN_NAMESPACE ... \c QT_END_NAMESPACE block.

    \sa QT_NAMESPACE
*/

/*!
    \macro QT_BEGIN_MOC_NAMESPACE
    \internal

    This macro is output by moc at the beginning of
    moc files. It is equivalent to \c QT_USE_NAMESPACE.

    \sa QT_NAMESPACE
*/

/*!
    \macro QT_END_MOC_NAMESPACE
    \internal

    This macro is output by moc at the beginning of
    moc files. It expands to nothing.

    \sa QT_NAMESPACE
*/

/*!
    \macro qMove(x)
    \relates <QtGlobal>
    \deprecated

    Use \c std::move instead.

    It expands to "std::move".

    qMove takes an rvalue reference to its parameter \a x, and converts it to an xvalue.
*/

/*!
    \macro QT_TERMINATE_ON_EXCEPTION(expr)
    \relates <QtGlobal>
    \internal

    In general, use of the Q_DECL_NOEXCEPT macro is preferred over
    Q_DECL_NOTHROW, because it exhibits well-defined behavior and
    supports the more powerful Q_DECL_NOEXCEPT_EXPR variant. However,
    use of Q_DECL_NOTHROW has the advantage that Windows builds
    benefit on a wide range or compiler versions that do not yet
    support the C++11 noexcept feature.

    It may therefore be beneficial to use Q_DECL_NOTHROW and emulate
    the C++11 behavior manually with an embedded try/catch.

    Qt provides the QT_TERMINATE_ON_EXCEPTION(expr) macro for this
    purpose. It either expands to \c expr (if Qt is compiled without
    exception support or the compiler supports C++11 noexcept
    semantics) or to
    \snippet code/src_corelib_global_qglobal.cpp qterminate
    otherwise.

    Since this macro expands to just \c expr if the compiler supports
    C++11 noexcept, expecting the compiler to take over responsibility
    of calling std::terminate() in that case, it should not be used
    outside Q_DECL_NOTHROW functions.

    \sa Q_DECL_NOEXCEPT, Q_DECL_NOTHROW, qTerminate()
*/

namespace QtPrivate {
Q_LOGGING_CATEGORY(lcNativeInterface, "qt.nativeinterface")
}

QT_END_NAMESPACE