From 82c4576a9d226343973147ffa591ac282dedb29b Mon Sep 17 00:00:00 2001
From: KWSys Upstream <kwrobot@kitware.com>
Date: Thu, 30 May 2024 10:30:12 -0400
Subject: [PATCH] KWSys 2024-05-30 (cb379374)

Code extracted from:

    https://gitlab.kitware.com/utils/kwsys.git

at commit cb3793745292850727dfcdb32ac200132961041e (master).

Upstream Shortlog
-----------------

Jochem van Boxtel (1):
      510b13b4 SystemTools: Add FileId class and GetFileId function
---
 SystemTools.cxx    | 69 ++++++++++++++++++++++++++++++++++++++++++++++
 SystemTools.hxx.in | 46 +++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+)

diff --git a/SystemTools.cxx b/SystemTools.cxx
index 11018a6bef..63566160fa 100644
--- a/SystemTools.cxx
+++ b/SystemTools.cxx
@@ -1356,6 +1356,75 @@ bool SystemTools::DeleteRegistryValue(const std::string&, KeyWOW64)
 }
 #endif
 
+#ifdef _WIN32
+SystemTools::WindowsFileId::WindowsFileId(unsigned long volumeSerialNumber,
+                                          unsigned long fileIndexHigh,
+                                          unsigned long fileIndexLow)
+  : m_volumeSerialNumber(volumeSerialNumber)
+  , m_fileIndexHigh(fileIndexHigh)
+  , m_fileIndexLow(fileIndexLow)
+{
+}
+
+bool SystemTools::WindowsFileId::operator==(const WindowsFileId& o) const
+{
+  return (m_volumeSerialNumber == o.m_volumeSerialNumber &&
+          m_fileIndexHigh == o.m_fileIndexHigh &&
+          m_fileIndexLow == o.m_fileIndexLow);
+}
+
+bool SystemTools::WindowsFileId::operator!=(const WindowsFileId& o) const
+{
+  return !(*this == o);
+}
+#else
+SystemTools::UnixFileId::UnixFileId(dev_t volumeSerialNumber,
+                                    ino_t fileSerialNumber, off_t fileSize)
+  : m_volumeSerialNumber(volumeSerialNumber)
+  , m_fileSerialNumber(fileSerialNumber)
+  , m_fileSize(fileSize)
+{
+}
+
+bool SystemTools::UnixFileId::operator==(const UnixFileId& o) const
+{
+  return (m_volumeSerialNumber == o.m_volumeSerialNumber &&
+          m_fileSerialNumber == o.m_fileSerialNumber &&
+          m_fileSize == o.m_fileSize);
+}
+
+bool SystemTools::UnixFileId::operator!=(const UnixFileId& o) const
+{
+  return !(*this == o);
+}
+#endif
+
+bool SystemTools::GetFileId(const std::string& file, FileId& id)
+{
+#ifdef _WIN32
+  HANDLE hFile =
+    CreateFileW(Encoding::ToWide(file).c_str(), GENERIC_READ, FILE_SHARE_READ,
+                nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
+  if (hFile != INVALID_HANDLE_VALUE) {
+    BY_HANDLE_FILE_INFORMATION fiBuf;
+    GetFileInformationByHandle(hFile, &fiBuf);
+    CloseHandle(hFile);
+    id = FileId(fiBuf.dwVolumeSerialNumber, fiBuf.nFileIndexHigh,
+                fiBuf.nFileIndexLow);
+    return true;
+  } else {
+    return false;
+  }
+#else
+  struct stat fileStat;
+  if (stat(file.c_str(), &fileStat) == 0) {
+    id = FileId(fileStat.st_dev, fileStat.st_ino, fileStat.st_size);
+    return true;
+  }
+  return false;
+#endif
+}
+
 bool SystemTools::SameFile(const std::string& file1, const std::string& file2)
 {
 #ifdef _WIN32
diff --git a/SystemTools.hxx.in b/SystemTools.hxx.in
index 729928e6f3..294ffca326 100644
--- a/SystemTools.hxx.in
+++ b/SystemTools.hxx.in
@@ -616,6 +616,52 @@ public:
   static CopyStatus CloneFileContent(std::string const& source,
                                      std::string const& destination);
 
+  /**
+   * Object encapsulating a unique identifier for a file
+   * or directory
+   */
+#ifdef _WIN32
+  class WindowsFileId
+  {
+  public:
+    WindowsFileId() = default;
+    WindowsFileId(unsigned long volumeSerialNumber,
+                  unsigned long fileIndexHigh, unsigned long fileIndexLow);
+
+    bool operator==(const WindowsFileId& o) const;
+    bool operator!=(const WindowsFileId& o) const;
+
+  private:
+    unsigned long m_volumeSerialNumber;
+    unsigned long m_fileIndexHigh;
+    unsigned long m_fileIndexLow;
+  };
+  using FileId = WindowsFileId;
+#else
+  class UnixFileId
+  {
+  public:
+    UnixFileId() = default;
+    UnixFileId(dev_t volumeSerialNumber, ino_t fileSerialNumber,
+               off_t fileSize);
+
+    bool operator==(const UnixFileId& o) const;
+    bool operator!=(const UnixFileId& o) const;
+
+  private:
+    dev_t m_volumeSerialNumber;
+    ino_t m_fileSerialNumber;
+    off_t m_fileSize;
+  };
+  using FileId = UnixFileId;
+#endif
+
+  /**
+   * Outputs a FileId for the given file or directory.
+   * Returns true on success, false on failure
+   */
+  static bool GetFileId(const std::string& file, FileId& id);
+
   /**
    * Return true if the two files are the same file
    */