// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef MASM_EXECUTABLEALLOCATOR_H
#define MASM_EXECUTABLEALLOCATOR_H

#include <RefPtr.h>
#include <RefCounted.h>
#include <wtf/PageBlock.h>

#include <private/qv4executableallocator_p.h>

#if OS(INTEGRITY)
#include "OSAllocator.h"
#endif

#if OS(WINDOWS)
#include <qt_windows.h>
#else
#include <sys/mman.h>
#include <unistd.h>
#endif

#ifdef __QNXNTO__
using std::perror;
#endif

namespace JSC {

class JSGlobalData;

struct ExecutableMemoryHandle : public RefCounted<ExecutableMemoryHandle> {
    ExecutableMemoryHandle(QV4::ExecutableAllocator *allocator, size_t size)
        : m_allocator(allocator)
        , m_size(size)
    {
        m_allocation = allocator->allocate(size);
    }
    ~ExecutableMemoryHandle()
    {
        m_allocation->deallocate(m_allocator);
    }

    inline void shrink(size_t) {
        // ### TODO.
    }

    inline bool isManaged() const { return true; }

    void *memoryStart() { return m_allocation->memoryStart(); }
    size_t memorySize() { return m_allocation->memorySize(); }

    void *exceptionHandlerStart() { return m_allocation->exceptionHandlerStart(); }
    size_t exceptionHandlerSize() { return m_allocation->exceptionHandlerSize(); }

    void *codeStart() { return m_allocation->codeStart(); }
    size_t codeSize() { return m_size; }

    QV4::ExecutableAllocator::ChunkOfPages *chunk() const
    { return m_allocator->chunkForAllocation(m_allocation); }

    QV4::ExecutableAllocator *m_allocator;
    QV4::ExecutableAllocator::Allocation *m_allocation;
    size_t m_size;
};

struct ExecutableAllocator {
    ExecutableAllocator(QV4::ExecutableAllocator *alloc)
        : realAllocator(alloc)
    {}

    Ref<ExecutableMemoryHandle> allocate(JSGlobalData&, size_t size, void*, int)
    {
        return adoptRef(new ExecutableMemoryHandle(realAllocator, size));
    }

    static bool makeWritable(void* addr, size_t size)
    {
        quintptr pageSize = WTF::pageSize();
        quintptr iaddr = reinterpret_cast<quintptr>(addr);
        quintptr roundAddr = iaddr & ~(pageSize - 1);
        size = size + (iaddr - roundAddr);
        addr = reinterpret_cast<void*>(roundAddr);

#if ENABLE(ASSEMBLER_WX_EXCLUSIVE) && !defined(V4_BOOTSTRAP)
#  if OS(WINDOWS)
        DWORD oldProtect;
#    if !OS(WINRT)
        VirtualProtect(addr, size, PAGE_READWRITE, &oldProtect);
#    else
        bool hr = VirtualProtectFromApp(addr, size, PAGE_READWRITE, &oldProtect);
        if (!hr) {
            return false;
        }
#    endif
#  elif OS(INTEGRITY)
         OSAllocator::setMemoryAttributes(addr, size, /*writable*/ true, /*executable*/ false);
#  else
        int mode = PROT_READ | PROT_WRITE;
        if (mprotect(addr, size, mode) != 0) {
            perror("mprotect failed in ExecutableAllocator::makeWritable");
            return false;
        }
#  endif
#else
        // We assume we already have RWX
        (void)addr; // suppress unused parameter warning
        (void)size; // suppress unused parameter warning
#endif
        return true;
    }

    static bool makeExecutable(void* addr, size_t size)
    {
        quintptr pageSize = WTF::pageSize();
        quintptr iaddr = reinterpret_cast<quintptr>(addr);
        quintptr roundAddr = iaddr & ~(pageSize - 1);
        size = size + (iaddr - roundAddr);
        addr = reinterpret_cast<void*>(roundAddr);

#if !defined(V4_BOOTSTRAP)
#if ENABLE(ASSEMBLER_WX_EXCLUSIVE)
#  if OS(WINDOWS)
        DWORD oldProtect;
#    if !OS(WINRT)
        VirtualProtect(addr, size, PAGE_EXECUTE_READ, &oldProtect);
#    else
        bool hr = VirtualProtectFromApp(addr, size, PAGE_EXECUTE_READ, &oldProtect);
        if (!hr) {
            return false;
        }
#    endif
#  elif OS(INTEGRITY)
        OSAllocator::setMemoryAttributes(addr, size, /*writable*/ false, /*executable*/ true);
#  else
        int mode = PROT_READ | PROT_EXEC;
        if (mprotect(addr, size, mode) != 0) {
            perror("mprotect failed in ExecutableAllocator::makeExecutable");
            return false;
        }
#  endif
#else
#  error "Only W^X is supported"
#endif
#else
        (void)addr; // suppress unused parameter warning
        (void)size; // suppress unused parameter warning
#endif
        return true;
    }

    QV4::ExecutableAllocator *realAllocator;
};

}

#endif // MASM_EXECUTABLEALLOCATOR_H