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// **************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: http://www.gnu.org/licenses/gpl.html *
// * Copyright (C) 2008-2011 ZenJu (zhnmju123 AT gmx.de) *
// **************************************************************************
//
#ifndef SYMLINK_WIN_H_INCLUDED
#define SYMLINK_WIN_H_INCLUDED
#include "loki/ScopeGuard.h"
#include "last_error.h"
#include "string_conv.h"
#include "file_error.h"
#include "i18n.h"
#ifdef FFS_WIN
#include <wx/msw/wrapwin.h> //includes "windows.h"
#include "WinIoCtl.h"
#include "privilege.h"
#include "long_path_prefix.h"
#elif defined FFS_LINUX
#include <unistd.h>
#endif
#ifdef _MSC_VER //I don't have Windows Driver Kit at hands right now, so unfortunately we need to redefine this structures and cross fingers...
typedef struct _REPARSE_DATA_BUFFER
{
ULONG ReparseTag;
USHORT ReparseDataLength;
USHORT Reserved;
union
{
struct
{
USHORT SubstituteNameOffset;
USHORT SubstituteNameLength;
USHORT PrintNameOffset;
USHORT PrintNameLength;
ULONG Flags;
WCHAR PathBuffer[1];
} SymbolicLinkReparseBuffer;
struct
{
USHORT SubstituteNameOffset;
USHORT SubstituteNameLength;
USHORT PrintNameOffset;
USHORT PrintNameLength;
WCHAR PathBuffer[1];
} MountPointReparseBuffer;
struct
{
UCHAR DataBuffer[1];
} GenericReparseBuffer;
};
} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER;
#define REPARSE_DATA_BUFFER_HEADER_SIZE FIELD_OFFSET(REPARSE_DATA_BUFFER, GenericReparseBuffer)
#endif
namespace
{
//retrieve raw target data of symlink or junction
Zstring getSymlinkRawTargetString(const Zstring& linkPath) //throw (FileError)
{
using zen::zToWx;
using zen::FileError;
#ifdef FFS_WIN
//FSCTL_GET_REPARSE_POINT: http://msdn.microsoft.com/en-us/library/aa364571(VS.85).aspx
try //reading certain symlinks requires admin rights! This shall not cause an error in user mode!
{
//allow access to certain symbolic links/junctions
zen::Privileges::getInstance().ensureActive(SE_BACKUP_NAME); //throw (FileError)
}
catch (...) {}
const HANDLE hLink = ::CreateFile(zen::applyLongPathPrefix(linkPath).c_str(),
GENERIC_READ,
FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
NULL,
OPEN_EXISTING,
FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT,
NULL);
if (hLink == INVALID_HANDLE_VALUE)
{
wxString errorMessage = wxString(_("Error resolving symbolic link:")) + wxT("\n\"") + zen::zToWx(linkPath) + wxT("\"");
throw FileError(errorMessage + wxT("\n\n") + zen::getLastErrorFormatted());
}
Loki::ScopeGuard dummy = Loki::MakeGuard(::CloseHandle, hLink);
(void)dummy; //silence warning "unused variable"
//respect alignment issues...
std::vector<char> buffer(REPARSE_DATA_BUFFER_HEADER_SIZE + MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
DWORD bytesReturned; //dummy value required by FSCTL_GET_REPARSE_POINT!
if (!::DeviceIoControl(hLink, //__in HANDLE hDevice,
FSCTL_GET_REPARSE_POINT, //__in DWORD dwIoControlCode,
NULL, //__in_opt LPVOID lpInBuffer,
0, //__in DWORD nInBufferSize,
&buffer[0], //__out_opt LPVOID lpOutBuffer,
static_cast<DWORD>(buffer.size()), //__in DWORD nOutBufferSize,
&bytesReturned, //__out_opt LPDWORD lpBytesReturned,
NULL)) //__inout_opt LPOVERLAPPED lpOverlapped
{
wxString errorMessage = wxString(_("Error resolving symbolic link:")) + wxT("\n\"") + zen::zToWx(linkPath) + wxT("\"");
throw FileError(errorMessage + wxT("\n\n") + zen::getLastErrorFormatted());
}
REPARSE_DATA_BUFFER& reparseData = *reinterpret_cast<REPARSE_DATA_BUFFER*>(&buffer[0]); //REPARSE_DATA_BUFFER needs to be artificially enlarged!
Zstring output;
if (reparseData.ReparseTag == IO_REPARSE_TAG_SYMLINK)
{
output = Zstring(reparseData.SymbolicLinkReparseBuffer.PathBuffer + reparseData.SymbolicLinkReparseBuffer.SubstituteNameOffset / sizeof(WCHAR),
reparseData.SymbolicLinkReparseBuffer.SubstituteNameLength / sizeof(WCHAR));
}
else if (reparseData.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT)
{
output = Zstring(reparseData.MountPointReparseBuffer.PathBuffer + reparseData.MountPointReparseBuffer.SubstituteNameOffset / sizeof(WCHAR),
reparseData.MountPointReparseBuffer.SubstituteNameLength / sizeof(WCHAR));
}
else
{
wxString errorMessage = wxString(_("Error resolving symbolic link:")) + wxT("\n\"") + zen::zToWx(linkPath) + wxT("\"");
throw FileError(errorMessage + wxT("\n\n") + wxT("Not a symbolic link or junction!"));
}
//absolute symlinks and junctions technically start with \??\ while relative ones do not
if (output.StartsWith(Zstr("\\??\\")))
output = Zstring(output.c_str() + 4, output.length() - 4);
return output;
#elif defined FFS_LINUX
const int BUFFER_SIZE = 10000;
char buffer[BUFFER_SIZE];
const int bytesWritten = ::readlink(linkPath.c_str(), buffer, BUFFER_SIZE);
if (bytesWritten < 0 || bytesWritten >= BUFFER_SIZE)
{
wxString errorMessage = wxString(_("Error resolving symbolic link:")) + wxT("\n\"") + zToWx(linkPath) + wxT("\"");
if (bytesWritten < 0) errorMessage += wxString(wxT("\n\n")) + zen::getLastErrorFormatted();
throw FileError(errorMessage);
}
buffer[bytesWritten] = 0; //set null-terminating char
return buffer;
#endif
}
}
#endif // SYMLINK_WIN_H_INCLUDED
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