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| author | Mounir IDRASSI <mounir.idrassi@idrix.fr> | 2019-10-20 21:50:41 +0200 |
|---|---|---|
| committer | Mounir IDRASSI <mounir.idrassi@idrix.fr> | 2019-10-20 22:17:12 +0200 |
| commit | 9b394ddc49c54765c4a0abf75472221963c108d2 (patch) | |
| tree | c87ef65132fbac903b0500b9caf2861afe35e603 /src/Common/BootEncryption.cpp | |
| parent | 31a87c2e5ff2d6a66d72dea662bb2beb7a7de6f1 (diff) | |
| download | VeraCrypt-9b394ddc49c54765c4a0abf75472221963c108d2.tar.gz VeraCrypt-9b394ddc49c54765c4a0abf75472221963c108d2.zip | |
Windows: Avoid unnecessary write operations when copying/modifying EFI bootloader files in order to avoid leaking modification timestamp
Diffstat (limited to 'src/Common/BootEncryption.cpp')
| -rw-r--r-- | src/Common/BootEncryption.cpp | 130 |
1 files changed, 124 insertions, 6 deletions
diff --git a/src/Common/BootEncryption.cpp b/src/Common/BootEncryption.cpp index 50fd23d2..6131ede5 100644 --- a/src/Common/BootEncryption.cpp +++ b/src/Common/BootEncryption.cpp @@ -2829,14 +2829,120 @@ namespace VeraCrypt } + bool EfiBoot::CompareFiles (const wchar_t* fileName1, const wchar_t* fileName2) + { + bool bRet = false; + File f1 (fileName1, true); + File f2 (fileName2, true); + + if (f1.IsOpened() && f2.IsOpened()) + { + try + { + DWORD size1, size2; + f1.GetFileSize (size1); + f2.GetFileSize (size2); + + if (size1 == size2) + { + // same size, so now we compare content + std::vector<byte> file1Buf (8096); + std::vector<byte> file2Buf (8096); + DWORD remainingBytes = size1, dataToRead; + + while (remainingBytes) + { + dataToRead = VC_MIN (remainingBytes, (DWORD) file1Buf.size()); + DWORD f1Bytes = f1.Read (file1Buf.data(), dataToRead); + DWORD f2Bytes = f2.Read (file2Buf.data(), dataToRead); + + if ((f1Bytes != f2Bytes) || memcmp (file1Buf.data(), file2Buf.data(), (size_t) f1Bytes)) + { + break; + } + else + { + remainingBytes -= f1Bytes; + } + } + + if (0 == remainingBytes) + { + // content is the same + bRet = true; + } + } + } + catch (...) {} + } + + f1.Close(); + f2.Close(); + + return bRet; + } + + bool EfiBoot::CompareFileData (const wchar_t* fileName, const byte* data, DWORD size) + { + bool bRet = false; + + File f(fileName, true); + if (f.IsOpened ()) + { + try + { + // check if the file has the same content + // if yes, don't perform any write operation to avoid changing its timestamp + DWORD existingSize = 0; + + f.GetFileSize(existingSize); + + if (existingSize == size) + { + std::vector<byte> fileBuf (8096); + DWORD remainingBytes = size, dataOffset = 0, dataToRead; + + while (remainingBytes) + { + dataToRead = VC_MIN (remainingBytes, (DWORD) fileBuf.size()); + dataToRead = f.Read (fileBuf.data(), dataToRead); + + if (memcmp (data + dataOffset, fileBuf.data(), (size_t) dataToRead)) + { + break; + } + else + { + dataOffset += dataToRead; + remainingBytes -= dataToRead; + } + } + + if (0 == remainingBytes) + { + // content is the same + bRet = true; + } + } + } + catch (...){} + } + + f.Close(); + + return bRet; + } + void EfiBoot::SaveFile(const wchar_t* name, byte* data, DWORD size) { wstring path = EfiBootPartPath; path += name; - File f(path, false, true); - f.Write(data, size); - f.Close(); - + if (!CompareFileData (path.c_str(), data, size)) + { + File f(path, false, true); + f.Write(data, size); + f.Close(); + } } bool EfiBoot::FileExists(const wchar_t* name) { @@ -2875,7 +2981,10 @@ namespace VeraCrypt } else targetPath = targetName; - throw_sys_if (!::CopyFileW (path.c_str(), targetPath.c_str(), FALSE)); + + // if both files are the same, we don't perform copy operation + if (!CompareFiles (path.c_str(), targetPath.c_str())) + throw_sys_if (!::CopyFileW (path.c_str(), targetPath.c_str(), FALSE)); } BOOL EfiBoot::RenameFile(const wchar_t* name, const wchar_t* nameNew, BOOL bForce) { @@ -2883,7 +2992,16 @@ namespace VeraCrypt path += name; wstring pathNew = EfiBootPartPath; pathNew += nameNew; - return MoveFileExW(path.c_str(), pathNew.c_str(), bForce? MOVEFILE_REPLACE_EXISTING : 0); + + BOOL bRet; + if (CompareFiles (path.c_str(), pathNew.c_str())) + { + // files identical. Delete source file only + bRet = DeleteFile (path.c_str()); + } + else + bRet = MoveFileExW(path.c_str(), pathNew.c_str(), bForce? MOVEFILE_REPLACE_EXISTING : 0); + return bRet; } BOOL EfiBoot::DelFile(const wchar_t* name) { |