Method create

Bcore/src/main/cpp/utils/FileMap.cpp:129–220

Create a new mapping on an open file. Closing the file descriptor does not unmap the pages, so we don't claim ownership of the fd. Returns "false" on failure.

//
// Returns "false" on failure.
bool FileMap::create(const char* origFileName, int fd, off64_t offset, size_t length,
        bool readOnly)
{
#if defined(__MINGW32__)
    int     adjust;
    off64_t adjOffset;
    size_t  adjLength;

    if (mPageSize == -1) {
        SYSTEM_INFO  si;

        GetSystemInfo( &si );
        mPageSize = si.dwAllocationGranularity;
    }

    DWORD  protect = readOnly ? PAGE_READONLY : PAGE_READWRITE;

    mFileHandle  = (HANDLE) _get_osfhandle(fd);
    mFileMapping = CreateFileMapping( mFileHandle, NULL, protect, 0, 0, NULL);
    if (mFileMapping == NULL) {
        ALOGE("CreateFileMapping(%p, %lx) failed with error %lu\n",
              mFileHandle, protect, GetLastError() );
        return false;
    }

    adjust    = offset % mPageSize;
    adjOffset = offset - adjust;
    adjLength = length + adjust;

    mBasePtr = MapViewOfFile( mFileMapping,
                              readOnly ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
                              0,
                              (DWORD)(adjOffset),
                              adjLength );
    if (mBasePtr == NULL) {
        ALOGE("MapViewOfFile(%" PRId64 ", %zu) failed with error %lu\n",
              adjOffset, adjLength, GetLastError() );
        CloseHandle(mFileMapping);
        mFileMapping = NULL;
        return false;
    }
#else // !defined(__MINGW32__)
    int     prot, flags, adjust;
    off64_t adjOffset;
    size_t  adjLength;

    void* ptr;

    assert(fd >= 0);
    assert(offset >= 0);
    assert(length > 0);

    // init on first use
    if (mPageSize == -1) {
        mPageSize = sysconf(_SC_PAGESIZE);
        if (mPageSize == -1) {
            //chensenhua   ALOGE("could not get _SC_PAGESIZE\n");
            return false;