4.1

1 files changed, 140 insertions, 0 deletions

diff --git a/zen/symlink_target.h b/zen/symlink_target.h
new file mode 100644
index 00000000..3704eebe
--- /dev/null
+++ b/zen/symlink_target.h
@@ -0,0 +1,140 @@
+// **************************************************************************
+// * 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 "scope_guard.h"
+#include "file_error.h"
+
+#ifdef FFS_WIN
+#include "win.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 //from ntifs.h
+{
+    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 namespace zen;
+#ifdef FFS_WIN
+    //FSCTL_GET_REPARSE_POINT: http://msdn.microsoft.com/en-us/library/aa364571(VS.85).aspx
+
+    try //reading certain symlinks/junctions requires admin rights! This shall not cause an error in user mode!
+    {
+        Privileges::getInstance().ensureActive(SE_BACKUP_NAME); //throw FileError
+    }
+    catch (...) {}
+
+    const HANDLE hLink = ::CreateFile(applyLongPathPrefix(linkPath).c_str(),
+                                      GENERIC_READ,
+                                      FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                                      0,
+                                      OPEN_EXISTING,
+                                      FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT,
+                                      NULL);
+    if (hLink == INVALID_HANDLE_VALUE)
+        throw FileError(_("Error resolving symbolic link:") + "\n\"" + linkPath + "\"" + "\n\n" + getLastErrorFormatted());
+    ZEN_ON_BLOCK_EXIT(::CloseHandle(hLink));
+
+    //respect alignment issues...
+    const DWORD bufferSize = REPARSE_DATA_BUFFER_HEADER_SIZE + MAXIMUM_REPARSE_DATA_BUFFER_SIZE;
+    std::vector<char> buffer(bufferSize);
+
+    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,
+                           bufferSize,              //__in         DWORD nOutBufferSize,
+                           &bytesReturned,          //__out_opt    LPDWORD lpBytesReturned,
+                           NULL))                   //__inout_opt  LPOVERLAPPED lpOverlapped
+        throw FileError(_("Error resolving symbolic link:") + "\n\"" + linkPath + "\"" + "\n\n" + 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
+        throw FileError(_("Error resolving symbolic link:") + "\n\"" + linkPath + "\"" + "\n\n" + "Not a symbolic link or junction!");
+
+    //absolute symlinks and junctions technically start with \??\ while relative ones do not
+    if (startsWith(output, Zstr("\\??\\")))
+        output = Zstring(output.c_str() + 4, output.length() - 4);
+
+    return output;
+
+#elif defined FFS_LINUX
+    const int BUFFER_SIZE = 10000;
+    std::vector<char> buffer(BUFFER_SIZE);
+
+    const int bytesWritten = ::readlink(linkPath.c_str(), &buffer[0], BUFFER_SIZE);
+    if (bytesWritten < 0 || bytesWritten >= BUFFER_SIZE)
+    {
+        std::wstring errorMessage = _("Error resolving symbolic link:") + "\n\"" + linkPath + "\"";
+        if (bytesWritten < 0)
+            errorMessage += L"\n\n" + getLastErrorFormatted();
+        throw FileError(errorMessage);
+    }
+    buffer[bytesWritten] = 0; //set null-terminating char
+
+    return Zstring(&buffer[0], bytesWritten);
+#endif
+}
+}
+
+#endif // SYMLINK_WIN_H_INCLUDED