1 files changed, 146 insertions, 0 deletions
diff --git a/xpcom/io/FileUtilsWin.h b/xpcom/io/FileUtilsWin.h
new file mode 100644
index 0000000000..548aed6dd7
--- /dev/null
+++ b/xpcom/io/FileUtilsWin.h
@@ -0,0 +1,146 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_FileUtilsWin_h
+#define mozilla_FileUtilsWin_h
+
+#include <windows.h>
+
+#include "nsString.h"
+
+namespace mozilla {
+
+inline bool EnsureLongPath(nsAString& aDosPath) {
+  nsAutoString inputPath(aDosPath);
+  while (true) {
+    DWORD requiredLength = GetLongPathNameW(
+        inputPath.get(), reinterpret_cast<wchar_t*>(aDosPath.BeginWriting()),
+        aDosPath.Length());
+    if (!requiredLength) {
+      return false;
+    }
+    if (requiredLength < aDosPath.Length()) {
+      // When GetLongPathNameW deems the last argument too small,
+      // it returns a value, but when you pass that value back, it's
+      // satisfied and returns a number that's one smaller. If the above
+      // check was == instead of <, the loop would go on forever with
+      // GetLongPathNameW returning oscillating values!
+      aDosPath.Truncate(requiredLength);
+      return true;
+    }
+    aDosPath.SetLength(requiredLength);
+  }
+}
+
+inline bool NtPathToDosPath(const nsAString& aNtPath, nsAString& aDosPath) {
+  aDosPath.Truncate();
+  if (aNtPath.IsEmpty()) {
+    return true;
+  }
+  constexpr auto symLinkPrefix = u"\\??\\"_ns;
+  uint32_t ntPathLen = aNtPath.Length();
+  uint32_t symLinkPrefixLen = symLinkPrefix.Length();
+  if (ntPathLen >= 6 && aNtPath.CharAt(5) == L':' &&
+      ntPathLen >= symLinkPrefixLen &&
+      Substring(aNtPath, 0, symLinkPrefixLen).Equals(symLinkPrefix)) {
+    // Symbolic link for DOS device. Just strip off the prefix.
+    aDosPath = aNtPath;
+    aDosPath.Cut(0, 4);
+    return true;
+  }
+  nsAutoString logicalDrives;
+  while (true) {
+    DWORD requiredLength = GetLogicalDriveStringsW(
+        logicalDrives.Length(),
+        reinterpret_cast<wchar_t*>(logicalDrives.BeginWriting()));
+    if (!requiredLength) {
+      return false;
+    }
+    if (requiredLength < logicalDrives.Length()) {
+      // When GetLogicalDriveStringsW deems the first argument too small,
+      // it returns a value, but when you pass that value back, it's
+      // satisfied and returns a number that's one smaller. If the above
+      // check was == instead of <, the loop would go on forever with
+      // GetLogicalDriveStringsW returning oscillating values!
+      logicalDrives.Truncate(requiredLength);
+      // logicalDrives now has the format "C:\\\0D:\\\0Z:\\\0". That is,
+      // the sequence drive letter, colon, backslash, U+0000 repeats.
+      break;
+    }
+    logicalDrives.SetLength(requiredLength);
+  }
+
+  const char16_t* cur = logicalDrives.BeginReading();
+  const char16_t* end = logicalDrives.EndReading();
+  nsString targetPath;
+  targetPath.SetLength(MAX_PATH);
+  wchar_t driveTemplate[] = L" :";
+  while (cur < end) {
+    // Unfortunately QueryDosDevice doesn't support the idiom for querying the
+    // output buffer size, so it may require retries.
+    driveTemplate[0] = *cur;
+    DWORD targetPathLen = 0;
+    SetLastError(ERROR_SUCCESS);
+    while (true) {
+      targetPathLen = QueryDosDeviceW(
+          driveTemplate, reinterpret_cast<wchar_t*>(targetPath.BeginWriting()),
+          targetPath.Length());
+      if (targetPathLen || GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+        break;
+      }
+      targetPath.SetLength(targetPath.Length() * 2);
+    }
+    if (targetPathLen) {
+      // Need to use wcslen here because targetPath contains embedded NULL chars
+      size_t firstTargetPathLen = wcslen(targetPath.get());
+      const char16_t* pathComponent =
+          aNtPath.BeginReading() + firstTargetPathLen;
+      bool found = _wcsnicmp(char16ptr_t(aNtPath.BeginReading()),
+                             targetPath.get(), firstTargetPathLen) == 0 &&
+                   *pathComponent == L'\\';
+      if (found) {
+        aDosPath = driveTemplate;
+        aDosPath += pathComponent;
+        return EnsureLongPath(aDosPath);
+      }
+    }
+    // Find the next U+0000 within the logical string
+    while (*cur) {
+      // This loop skips the drive letter, the colon
+      // and the backslash.
+      cur++;
+    }
+    // Skip over the U+0000 that ends a drive entry
+    // within the logical string
+    cur++;
+  }
+  // Try to handle UNC paths. NB: This must happen after we've checked drive
+  // mappings in case a UNC path is mapped to a drive!
+  constexpr auto uncPrefix = u"\\\\"_ns;
+  constexpr auto deviceMupPrefix = u"\\Device\\Mup\\"_ns;
+  if (StringBeginsWith(aNtPath, deviceMupPrefix)) {
+    aDosPath = uncPrefix;
+    aDosPath += Substring(aNtPath, deviceMupPrefix.Length());
+    return true;
+  }
+  constexpr auto deviceLanmanRedirectorPrefix =
+      u"\\Device\\LanmanRedirector\\"_ns;
+  if (StringBeginsWith(aNtPath, deviceLanmanRedirectorPrefix)) {
+    aDosPath = uncPrefix;
+    aDosPath += Substring(aNtPath, deviceLanmanRedirectorPrefix.Length());
+    return true;
+  }
+  return false;
+}
+
+bool HandleToFilename(HANDLE aHandle, const LARGE_INTEGER& aOffset,
+                      nsAString& aFilename);
+
+uint32_t GetExecutableArchitecture(const wchar_t* aPath);
+
+}  // namespace mozilla
+
+#endif  // mozilla_FileUtilsWin_h