Include st_dev to make the result of getUniqueID actually unique.

This will let us use getUniqueID instead of st_dev directly on clang.

llvm-svn: 187378

include/llvm/Support/FileSystem.h

@@ -125,8 +125,19 @@ inline perms operator~(perms x) {
   return static_cast<perms>(~static_cast<unsigned short>(x));
 }
 
+class UniqueID {
+  uint64_t A;
+  uint64_t B;
+
+public:
+  UniqueID() {}
+  UniqueID(uint64_t A, uint64_t B) : A(A), B(B) {}
+  bool operator==(const UniqueID &Other) const {
+    return A == Other.A && B == Other.B;
+  }
+  bool operator!=(const UniqueID &Other) const { return !(*this == Other); }
+};
 
- 
 /// file_status - Represents the result of a call to stat and friends. It has
 ///               a platform specific member to store the result.
 class file_status
@@ -148,7 +159,6 @@ class file_status
   uint32_t FileIndexLow;
   #endif
   friend bool equivalent(file_status A, file_status B);
-  friend error_code getUniqueID(const Twine Path, uint64_t &Result);
   file_type Type;
   perms Perms;
 public:
@@ -176,6 +186,7 @@ public:
   file_type type() const { return Type; }
   perms permissions() const { return Perms; }
   TimeValue getLastModificationTime() const;
+  UniqueID getUniqueID();
 
   #if defined(LLVM_ON_UNIX)
   uint32_t getUser() const { return fs_st_uid; }
@@ -664,7 +675,7 @@ file_magic identify_magic(StringRef magic);
 ///          platform specific error_code.
 error_code identify_magic(const Twine &path, file_magic &result);
 
-error_code getUniqueID(const Twine Path, uint64_t &Result);
+error_code getUniqueID(const Twine Path, UniqueID &Result);
 
 /// This class represents a memory mapped file. It is based on
 /// boost::iostreams::mapped_file.

lib/Support/Path.cpp

@@ -638,6 +638,15 @@ bool is_relative(const Twine &path) {
 
 namespace fs {
 
+error_code getUniqueID(const Twine Path, UniqueID &Result) {
+  file_status Status;
+  error_code EC = status(Path, Status);
+  if (EC)
+    return EC;
+  Result = Status.getUniqueID();
+  return error_code::success();
+}
+
 error_code createUniqueFile(const Twine &Model, int &ResultFd,
                             SmallVectorImpl<char> &ResultPath, unsigned Mode) {
   return createUniqueEntity(Model, ResultFd, ResultPath, false, Mode, FS_File);

lib/Support/Unix/Path.inc

@@ -293,6 +293,10 @@ TimeValue file_status::getLastModificationTime() const {
   return Ret;
 }
 
+UniqueID file_status::getUniqueID() {
+  return UniqueID(fs_st_dev, fs_st_ino);
+}
+
 error_code current_path(SmallVectorImpl<char> &result) {
 #ifdef MAXPATHLEN
   result.reserve(MAXPATHLEN);
@@ -457,18 +461,6 @@ error_code equivalent(const Twine &A, const Twine &B, bool &result) {
   return error_code::success();
 }
 
-error_code getUniqueID(const Twine Path, uint64_t &Result) {
-  SmallString<128> Storage;
-  StringRef P = Path.toNullTerminatedStringRef(Storage);
-
-  struct stat Status;
-  if (::stat(P.begin(), &Status) != 0)
-    return error_code(errno, system_category());
-
-  Result = Status.st_ino;
-  return error_code::success();
-}
-
 static error_code fillStatus(int StatRet, const struct stat &Status,
                              file_status &Result) {
   if (StatRet != 0) {

lib/Support/Windows/Path.inc

@@ -269,6 +269,14 @@ std::string getMainExecutable(const char *argv0, void *MainExecAddr) {
   return ret != MAX_PATH ? pathname : "";
 }
 
+UniqueID file_status::getUniqueID() {
+  // The file is uniquely identified by the volume serial number along
+  // with the 64-bit file identifier.
+  uint64_t FileID = (static_cast<uint64_t>(FileIndexHigh) << 32ULL) |
+                    static_cast<uint64_t>(FileIndexLow);
+
+  return UniqueID(VolumeSerialNumber, FileID);
+}
 
 TimeValue file_status::getLastModificationTime() const {
   ULARGE_INTEGER UI;
@@ -533,25 +541,6 @@ error_code equivalent(const Twine &A, const Twine &B, bool &result) {
   return error_code::success();
 }
 
-error_code getUniqueID(const Twine Path, uint64_t &Result) {
-  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<uint64_t>(Status.FileIndexHigh) << 32ULL) |
-           static_cast<uint64_t>(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<uint64_t>(Status.VolumeSerialNumber) << 32ULL);
-
-  return error_code::success();
-}
-
 static bool isReservedName(StringRef path) {
   // This list of reserved names comes from MSDN, at:
   // http://msdn.microsoft.com/en-us/library/aa365247%28v=vs.85%29.aspx

unittests/Support/Path.cpp

@@ -169,7 +169,7 @@ TEST_F(FileSystemTest, Unique) {
       fs::createTemporaryFile("prefix", "temp", FileDescriptor, TempPath));
 
   // The same file should return an identical unique id.
-  uint64_t F1, F2;
+  fs::UniqueID F1, F2;
   ASSERT_NO_ERROR(fs::getUniqueID(Twine(TempPath), F1));
   ASSERT_NO_ERROR(fs::getUniqueID(Twine(TempPath), F2));
   ASSERT_EQ(F1, F2);
@@ -180,7 +180,7 @@ TEST_F(FileSystemTest, Unique) {
   ASSERT_NO_ERROR(
       fs::createTemporaryFile("prefix", "temp", FileDescriptor2, TempPath2));
 
-  uint64_t D;
+  fs::UniqueID D;
   ASSERT_NO_ERROR(fs::getUniqueID(Twine(TempPath2), D));
   ASSERT_NE(D, F1);
   ::close(FileDescriptor2);
@@ -190,7 +190,7 @@ TEST_F(FileSystemTest, Unique) {
   // Two paths representing the same file on disk should still provide the
   // same unique id.  We can test this by making a hard link.
   ASSERT_NO_ERROR(fs::create_hard_link(Twine(TempPath), Twine(TempPath2)));
-  uint64_t D2;
+  fs::UniqueID D2;
   ASSERT_NO_ERROR(fs::getUniqueID(Twine(TempPath2), D2));
   ASSERT_EQ(D2, F1);