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  1. Qt
  2. QTBUG-73688

Qt doesn't treat UNC paths and NTFS symbolic links correctly

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Details

    • Bug
    • Resolution: Done
    • P2: Important
    • 5.12.4, 5.14.0 Alpha
    • 5.9
    • Core: I/O
    • None
    • Windows, WinRT
    • 3f17029aa12eafd3f8ddd5e0b246a6bf22eabfe3 (qt/qtbase/5.12)

    Description

      This tickets ties various related bug reports together.

      The various methods in QFile/QFileInfo/QDir that try to interpret symbolic links on NTFS in general, and links to UNC paths in particular, are buggy and inconsistent. Windows API specific file name tagging with ?\, ??\, or \\?\UNC\ (which is supposed to enable paths that exceed MAX_PATH) sometimes leaks through Qt APIs to the application code, even though it should be entirely invisible to Qt API users.

      As a general requirement for a fix, Qt APIs that interpret paths or follow links should

      • always generate paths that can be used in other QFile, QDir, etc APIs (ie c:\dir\file is ok; \\server\share\file is ok; ?\server\share\file is not ok)
      • never leak Windows API specific tagging to the API user
         

      The attached code prints

      This is what I know about c:\Users\host
 - fileInfo.isAbsolute true
 - fileInfo.absoluteFilePath C:/Users/host
 - fileInfo.canonicalPath C:/Users/UNC/VBOXSRV
 - fileInfo.canonicalFilePath C:/Users/UNC/VBOXSRV/host
 - fileInfo.isSymLink true
 - fileInfo.symLinkTarget C:/Users/UNC/VBOXSRV/host
 - fileInfo.isDir true
 - entry count: 19
 - dir.canonicalPath C:/Users/UNC/VBOXSRV/host
 - QDir::toNativeSeperators c:\Users\host
 - QDir::cleanPath c:/Users/host
 - storageInfo.rootPath C:/

      where c:\Users\host is created with

      mklink /D c:\Users\host \\VBOXSRV\host

       

      Attachments

        1. main.cpp
          2 kB
          Volker Hilsheimer
        2. qtbug73688.zip
          1 kB
          Friedemann Kleint

        Issue Links

          Is tested by

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-30401 QDir::canonicalPath produce wrong path when a symbolic link to a UNC directory is in the part

          • Not Evaluated - Not yet evaluated/prioritized
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-20791 QFileInfo.canonicalFilePath is wrong on symlink on NTFS volume

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-48048 QDir::canonicalPath() fails with NTFS symbolic link to network path

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-62665 Imports aren't properly resolved from UNC paths containing symlinks on Windows

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-63970 QFileInfo::canonicalPath() does not works right on WIndows symlinks to UNC paths

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed
          mentioned in

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              vhilshei Volker Hilsheimer
              vhilshei Volker Hilsheimer
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              Dates

                Created:
                Updated:
                Resolved: