[jira] [Closed] (IO-452) FileUtils.isSymlink returns false for broken symlinks.

["Kristian Rosenvold (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IO-452?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kristian Rosenvold closed IO-452.
---------------------------------
       Resolution: Fixed
    Fix Version/s: 2.5
         Assignee: Kristian Rosenvold

> FileUtils.isSymlink returns false for broken symlinks.
> ------------------------------------------------------
>
>                 Key: IO-452
>                 URL: https://issues.apache.org/jira/browse/IO-452
>             Project: Commons IO
>          Issue Type: Improvement
>          Components: Utilities
>    Affects Versions: 2.5
>         Environment: java version "1.7.0_55"
> OpenJDK Runtime Environment (IcedTea 2.4.7) (7u55-2.4.7-1ubuntu1)
> OpenJDK Server VM (build 24.51-b03, mixed mode)
> Linux weeble 3.13.0-30-generic #55-Ubuntu SMP Fri Jul 4 21:43:42 UTC 2014 i686 i686 i686 GNU/Linux
>            Reporter: David Standish
>            Assignee: Kristian Rosenvold
>            Priority: Minor
>             Fix For: 2.5
>
>
> FileUtils.isSymlink returns false for broken symlinks.
> In contrast, java 7 java.nio.file.Files.isSymbolicLink() returns true for broken symlink.
> One possible work around for java 6 and below is to use the fact that File.exists() returns false for a broken symlink and the fact that the file is found in its parents directory listing.
> I don't have a compelling argument for fixing this, here is a candidate patch.
> {code}
> someguy@weeble:~/prog/java/commons-io/commons-io$ svn diff src/main/java/org/apache/commons/io/FileUtils.java 
> Index: src/main/java/org/apache/commons/io/FileUtils.java
> ===================================================================
> --- src/main/java/org/apache/commons/io/FileUtils.java  (revision 1609743)
> +++ src/main/java/org/apache/commons/io/FileUtils.java  (working copy)
> @@ -3068,10 +3068,41 @@
>          }
>  
>          if (fileInCanonicalDir.getCanonicalFile().equals(fileInCanonicalDir.getAbsoluteFile())) {
> -            return false;
> +            return isBrokenSymlink(file);
>          } else {
>              return true;
>          }
>      }
>  
> +    /**
> +     * Determines if the specified file is possibly a broken symbolic link.
> +     * 
> +     * @param file the file to check
> +     * @return true if the file is a Symbolic Link
> +     * @throws IOException if an IO error occurs while checking the file
> +     */
> +    private static boolean isBrokenSymlink(final File file) throws IOException {
> +        // if file exists then if it is a symlink it's not broken   
> +        if ( file.exists() ) {
> +            return false;
> +        }
> +        // a broken symlink will show up in the list of files of its parent directory
> +        final File canon = file.getCanonicalFile();
> +        File parentDir = canon.getParentFile();
> +        if ( parentDir == null || ! parentDir.exists() ) {
> +            return false;
> +        }
> +        
> +        // is it worthwhile to create a FileFilterUtil method for this?
> +        // is it worthwhile to create an "identity"  IOFileFilter for this?
> +        File[] fileInDir = parentDir.listFiles(
> +            new FileFilter() {
> +                public boolean accept( File aFile ) {
> +                    return aFile.equals(canon);
> +                }
> +                }
> +            );
> +        return fileInDir.length > 0;
> +    }
> +
>  }
> {code}
> {code}
> someguy@weeble:~/prog/java/commons-io/commons-io$ svn diff src/test/java/org/apache/commons/io/FileUtilsCleanSymlinksTestCase.java 
> Index: src/test/java/org/apache/commons/io/FileUtilsCleanSymlinksTestCase.java
> ===================================================================
> --- src/test/java/org/apache/commons/io/FileUtilsCleanSymlinksTestCase.java     (revision 1609743)
> +++ src/test/java/org/apache/commons/io/FileUtilsCleanSymlinksTestCase.java     (working copy)
> @@ -203,6 +203,25 @@
>          assertFalse(FileUtils.isSymlink(randomFile));
>      }
>  
> +    public void testIdentifiesBrokenSymlinkFile() throws Exception {
> +        if (System.getProperty("os.name").startsWith("Win")) {
> +            // cant create symlinks in windows.
> +            return;
> +        }
> +
> +        final File noexistFile = new File(top, "noexist");
> +        final File symlinkFile = new File(top, "fakeinner");
> +        final File badSymlinkInPathFile = new File(symlinkFile, "fakeinner");
> +        final File noexistParentFile = new File("noexist", "file");
> +        
> +        setupSymlink(noexistFile, symlinkFile);
> +
> +        assertTrue(FileUtils.isSymlink(symlinkFile));
> +        assertFalse(FileUtils.isSymlink(noexistFile));
> +        assertFalse(FileUtils.isSymlink(noexistParentFile));
> +        assertFalse(FileUtils.isSymlink(badSymlinkInPathFile));
> +    }
> +
>      public void testCorrectlyIdentifySymlinkWithParentSymLink() throws Exception {
>          if (System.getProperty("os.name").startsWith("Win")) {
>              // cant create symlinks in windows.
> {code}



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