From 4655485eb7dc1d137595149b9bd58eb73e11bb19 Mon Sep 17 00:00:00 2001 From: Aaron Ballman Date: Wed, 19 Jun 2013 21:03:50 +0000 Subject: Modified the implementation of fs::GetUniqueID on Windows such that it actually finds a unique identifier for a file. Also adds unit tests for GetUniqueID. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184351 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Support/Windows/PathV2.inc | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) (limited to 'lib/Support') diff --git a/lib/Support/Windows/PathV2.inc b/lib/Support/Windows/PathV2.inc index bec95e36cc..e6888f93e6 100644 --- a/lib/Support/Windows/PathV2.inc +++ b/lib/Support/Windows/PathV2.inc @@ -426,15 +426,20 @@ error_code file_size(const Twine &path, uint64_t &result) { } error_code GetUniqueID(const Twine Path, uint64_t &Result) { - // FIXME: this is only unique if the file is accessed by the same file path. - // How do we do this for C:\dir\file and ..\dir\file ? Unix has inode - // numbers, but the concept doesn't exist in Windows. - SmallString<128> Storage; - StringRef P = Path.toStringRef(Storage); - uint64_t UniqueID = 0; - for (StringRef::iterator I = P.begin(), E = P.end(); I != E; ++I) - UniqueID += *I; - Result = UniqueID; + file_status Status; + if (error_code E = status(Path, Status)) + return E; + + // The file is uniquely identified by the volume serial number along + // with the 64-bit file identifier. + Result = (static_cast(Status.FileIndexHigh) << 32ULL) | + static_cast(Status.FileIndexLow); + + // Because the serial number is 32-bits, but we've already used up all 64 + // bits for the file index, XOR the serial number into the high 32 bits of + // the resulting value. We could potentially get collisons from this, but + // the likelihood is low. + Result ^= (static_cast(Status.VolumeSerialNumber) << 32ULL); return error_code::success(); } -- cgit v1.2.3