Re: [boost] [filesystem] resize_file_api leaks a HANDLE

Subject: Re: [boost] [filesystem] resize_file_api leaks a HANDLE
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2015-01-02 06:34:58

On 30 Dec 2014 at 15:40, Peter Dimov wrote:

> ... when SetFilePointerEx or SetEndOfFile fails.
> 
> BOOL resize_file_api(const wchar_t* p, boost::uintmax_t size)
> {
>   HANDLE handle = CreateFileW(p, GENERIC_WRITE, 0, 0, OPEN_EXISTING,
>                               FILE_ATTRIBUTE_NORMAL, 0);
>   LARGE_INTEGER sz;
>   sz.QuadPart = size;
>   return handle != INVALID_HANDLE_VALUE
>     && ::SetFilePointerEx(handle, sz, 0, FILE_BEGIN)
>     && ::SetEndOfFile(handle)
>     && ::CloseHandle(handle);
> }

Additionally, that code is racy. Better is this:

// WinVista and later have the SetFileInformationByHandle() function, 
but for WinXP
// compatibility we use the kernel syscall directly
static inline bool wintruncate(HANDLE h, off_t newsize)
{
    windows_nt_kernel::init();
    using namespace windows_nt_kernel;
    IO_STATUS_BLOCK isb={ 0 };
    BOOST_AFIO_ERRHNT(NtSetInformationFile(h, &isb, &newsize, 
sizeof(newsize), FileEndOfFileInformation));
    return true;
}

Niall

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