Bug 1746052, don't allow Windows reserved filenames when sanitizing filenames. Move MangleTextToValidFileName to nsLocalFileWin and rename it to CheckForReservedFileName, r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D138737

netwerk/mime/nsIMIMEService.idl

@@ -168,6 +168,8 @@ interface nsIMIMEService : nsISupports {
      *    character, either ' ' or an ideographic space 0x3000 if present.
      *  - Unless VALIDATE_DONT_TRUNCATE is specified, the filename is truncated
      *    to a maximum length, preserving the extension if possible.
+     *  - Some filenames are invalid on certain platforms. These are replaced if
+     *    possible.
      *
      * If the VALIDATE_NO_DEFAULT_FILENAME flag is not specified, and after the
      * rules above are applied, the resulting filename is empty, a default

uriloader/exthandler/nsExternalHelperAppService.cpp

@@ -105,6 +105,7 @@
 
 #ifdef XP_WIN
 #  include "nsWindowsHelpers.h"
+#  include "nsLocalFile.h"
 #endif
 
 #include "mozilla/Components.h"
@@ -3451,6 +3452,10 @@ nsExternalHelperAppService::ValidateFileNameForSaving(
     }
   }
 
+#ifdef XP_WIN
+  nsLocalFile::CheckForReservedFileName(fileName);
+#endif
+
   // If no filename is present, use a default filename.
   if (!(aFlags & VALIDATE_NO_DEFAULT_FILENAME) &&
       (fileName.Length() == 0 || fileName.RFind(".") == 0)) {

widget/windows/nsDataObj.cpp

@@ -44,6 +44,7 @@
 #include "imgIEncoder.h"
 #include "imgITools.h"
 #include "WinUtils.h"
+#include "nsLocalFile.h"
 
 #include "mozilla/LazyIdleThread.h"
 #include <algorithm>
@@ -1087,36 +1088,6 @@ nsDataObj ::GetFileContents(FORMATETC& aFE, STGMEDIUM& aSTG) {
 
 }  // GetFileContents
 
-//
-// Given a unicode string, we ensure that it contains only characters which are
-// valid within the file system. Remove all forbidden characters from the name,
-// and completely disallow any title that starts with a forbidden name and
-// extension (e.g. "nul" is invalid, but "nul." and "nul.txt" are also invalid
-// and will cause problems).
-//
-// It would seem that this is more functionality suited to being in nsIFile.
-//
-static void MangleTextToValidFilename(nsString& aText) {
-  static const char* forbiddenNames[] = {
-      "COM1", "COM2", "COM3", "COM4", "COM5", "COM6", "COM7",  "COM8",
-      "COM9", "LPT1", "LPT2", "LPT3", "LPT4", "LPT5", "LPT6",  "LPT7",
-      "LPT8", "LPT9", "CON",  "PRN",  "AUX",  "NUL",  "CLOCK$"};
-
-  aText.StripChars(FILE_PATH_SEPARATOR FILE_ILLEGAL_CHARACTERS);
-  aText.CompressWhitespace(true, true);
-  uint32_t nameLen;
-  for (size_t n = 0; n < ArrayLength(forbiddenNames); ++n) {
-    nameLen = (uint32_t)strlen(forbiddenNames[n]);
-    if (aText.EqualsIgnoreCase(forbiddenNames[n], nameLen)) {
-      // invalid name is either the entire string, or a prefix with a period
-      if (aText.Length() == nameLen || aText.CharAt(nameLen) == char16_t('.')) {
-        aText.Truncate();
-        break;
-      }
-    }
-  }
-}
-
 //
 // Given a unicode string, convert it down to a valid local charset filename
 // with the supplied extension. This ensures that we do not cut MBCS characters
@@ -1129,7 +1100,7 @@ static bool CreateFilenameFromTextA(nsString& aText, const char* aExtension,
   // ensure that the supplied name doesn't have invalid characters. If
   // a valid mangled filename couldn't be created then it will leave the
   // text empty.
-  MangleTextToValidFilename(aText);
+  nsLocalFile::CheckForReservedFileName(aText);
   if (aText.IsEmpty()) return false;
 
   // repeatably call WideCharToMultiByte as long as the title doesn't fit in the
@@ -1161,7 +1132,7 @@ static bool CreateFilenameFromTextW(nsString& aText, const wchar_t* aExtension,
   // ensure that the supplied name doesn't have invalid characters. If
   // a valid mangled filename couldn't be created then it will leave the
   // text empty.
-  MangleTextToValidFilename(aText);
+  nsLocalFile::CheckForReservedFileName(aText);
   if (aText.IsEmpty()) return false;
 
   const int extensionLen = wcslen(aExtension);
@@ -2183,7 +2154,7 @@ HRESULT nsDataObj::GetDownloadDetails(nsIURI** aSourceURI,
   if (srcFileName.IsEmpty()) return E_FAIL;
 
   // make the name safe for the filesystem
-  MangleTextToValidFilename(srcFileName);
+  nsLocalFile::CheckForReservedFileName(srcFileName);
 
   sourceURI.swap(*aSourceURI);
   aFilename = srcFileName;

xpcom/io/nsLocalFileWin.cpp

@@ -191,6 +191,26 @@ nsresult nsLocalFile::RevealFile(const nsString& aResolvedPath) {
   return SUCCEEDED(hr) ? NS_OK : NS_ERROR_FAILURE;
 }
 
+// static
+void nsLocalFile::CheckForReservedFileName(nsString& aFileName) {
+  static const char* forbiddenNames[] = {
+      "COM1", "COM2", "COM3", "COM4", "COM5", "COM6", "COM7",  "COM8",
+      "COM9", "LPT1", "LPT2", "LPT3", "LPT4", "LPT5", "LPT6",  "LPT7",
+      "LPT8", "LPT9", "CON",  "PRN",  "AUX",  "NUL",  "CLOCK$"};
+
+  uint32_t nameLen;
+  for (size_t n = 0; n < ArrayLength(forbiddenNames); ++n) {
+    nameLen = (uint32_t)strlen(forbiddenNames[n]);
+    if (aFileName.EqualsIgnoreCase(forbiddenNames[n], nameLen)) {
+      // invalid name is either the entire string, or a prefix with a period
+      if (aFileName.Length() == nameLen ||
+          aFileName.CharAt(nameLen) == char16_t('.')) {
+        aFileName.Truncate();
+      }
+    }
+  }
+}
+
 class nsDriveEnumerator : public nsSimpleEnumerator,
                           public nsIDirectoryEnumerator {
  public:

xpcom/io/nsLocalFileWin.h

@@ -49,6 +49,10 @@ class nsLocalFile final : public nsILocalFileWin {
   // Called off the main thread to open the window revealing the file
   static nsresult RevealFile(const nsString& aResolvedPath);
 
+  // Checks if the filename is one of the windows reserved filenames
+  // (com1, com2, etc...) and truncates the string if so.
+  static void CheckForReservedFileName(nsString& aFileName);
+
  private:
   // CopyMove and CopySingleFile constants for |options| parameter:
   enum CopyFileOption {