mman.cpp

/*
 * NOLINT(legal/copyright) - the original authors did not slap a (C) notice in here,
 * for whatever reason, and I'm in no position to do that for them.
 *
 * This file has been included as a part of IsoSpec project, under a MIT licence. It
 * comes from the repository:
 *
 * https://github.com/witwall/mman-win32
 *
 * which itself is a mirror of:
 *
 * https://code.google.com/archive/p/mman-win32/
 */
 
#include "platform.h"
#if ISOSPEC_GOT_MMAN && !ISOSPEC_GOT_SYSTEM_MMAN
 
#define NOMINMAX
#include <windows.h>
#include <errno.h>
#include <io.h>
 
#include "mman.h"
 
#ifndef FILE_MAP_EXECUTE
#define FILE_MAP_EXECUTE    0x0020
#endif /* FILE_MAP_EXECUTE */
 
 
static int __map_mman_error(const DWORD err, const int /* deferr */)
{
    if (err == 0)
        return 0;
    // TODO: implement       NOLINT(readability/todo) - well, should be assigned to the original authors
    return err;
}
 
static DWORD __map_mmap_prot_page(const int prot)
{
    DWORD protect = 0;
 
    if (prot == PROT_NONE)
        return protect;
 
    if ((prot & PROT_EXEC) != 0)
    {
        protect = ((prot & PROT_WRITE) != 0) ?
                    PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ;
    }
    else
    {
        protect = ((prot & PROT_WRITE) != 0) ?
                    PAGE_READWRITE : PAGE_READONLY;
    }
 
    return protect;
}
 
static DWORD __map_mmap_prot_file(const int prot)
{
    DWORD desiredAccess = 0;
 
    if (prot == PROT_NONE)
        return desiredAccess;
 
    if ((prot & PROT_READ) != 0)
        desiredAccess |= FILE_MAP_READ;
    if ((prot & PROT_WRITE) != 0)
        desiredAccess |= FILE_MAP_WRITE;
    if ((prot & PROT_EXEC) != 0)
        desiredAccess |= FILE_MAP_EXECUTE;
 
    return desiredAccess;
}
 
void* mmap(void * /* addr */, size_t len, int prot, int flags, int fildes, OffsetType off)
{
    HANDLE fm, h;
 
    void * map = MAP_FAILED;
 
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable: 4293)
#endif
 
    const DWORD dwFileOffsetLow = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                    (DWORD)off : (DWORD)(off & 0xFFFFFFFFL);
    const DWORD dwFileOffsetHigh = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                    (DWORD)0 : (DWORD)((off >> 32) & 0xFFFFFFFFL);
    const DWORD protect = __map_mmap_prot_page(prot);
    const DWORD desiredAccess = __map_mmap_prot_file(prot);
 
    const OffsetType maxSize = off + (OffsetType)len;
 
    const DWORD dwMaxSizeLow = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                    (DWORD)maxSize : (DWORD)(maxSize & 0xFFFFFFFFL);
    const DWORD dwMaxSizeHigh = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                    (DWORD)0 : (DWORD)((maxSize >> 32) & 0xFFFFFFFFL);
 
#ifdef _MSC_VER
#pragma warning(pop)
#endif
 
    errno = 0;
 
    if (len == 0
        /* Unsupported flag combinations */
        || (flags & MAP_FIXED) != 0
        /* Usupported protection combinations */
        || prot == PROT_EXEC)
    {
        errno = EINVAL;
        return MAP_FAILED;
    }
 
    h = ((flags & MAP_ANONYMOUS) == 0) ?
                    (HANDLE)_get_osfhandle(fildes) : INVALID_HANDLE_VALUE;
 
    if ((flags & MAP_ANONYMOUS) == 0 && h == INVALID_HANDLE_VALUE)
    {
        errno = EBADF;
        return MAP_FAILED;
    }
 
    fm = CreateFileMapping(h, NULL, protect, dwMaxSizeHigh, dwMaxSizeLow, NULL);
 
    if (fm == NULL)
    {
        errno = __map_mman_error(GetLastError(), EPERM);
        return MAP_FAILED;
    }
 
    map = MapViewOfFile(fm, desiredAccess, dwFileOffsetHigh, dwFileOffsetLow, len);
 
    CloseHandle(fm);
 
    if (map == NULL)
    {
        errno = __map_mman_error(GetLastError(), EPERM);
        return MAP_FAILED;
    }
 
    return map;
}
 
int munmap(void *addr, size_t /* len */)
{
    if (UnmapViewOfFile(addr))
        return 0;
 
    errno =  __map_mman_error(GetLastError(), EPERM);
 
    return -1;
}
 
#if 0
// Unused by IsoSpec
 
 
int _mprotect(void *addr, size_t len, int prot)
{
    DWORD newProtect = __map_mmap_prot_page(prot);
    DWORD oldProtect = 0;
 
    if (VirtualProtect(addr, len, newProtect, &oldProtect))
        return 0;
 
    errno =  __map_mman_error(GetLastError(), EPERM);
 
    return -1;
}
 
int msync(void *addr, size_t len, int /* flags */)
{
    if (FlushViewOfFile(addr, len))
        return 0;
 
    errno =  __map_mman_error(GetLastError(), EPERM);
 
    return -1;
}
 
int mlock(const void *addr, size_t len)
{
    if (VirtualLock((LPVOID)addr, len))
        return 0;
 
    errno =  __map_mman_error(GetLastError(), EPERM);
 
    return -1;
}
 
int munlock(const void *addr, size_t len)
{
    if (VirtualUnlock((LPVOID)addr, len))
        return 0;
 
    errno =  __map_mman_error(GetLastError(), EPERM);
 
    return -1;
}
#endif
 
#endif