Description of error types and repairing

This page contains information about error types as CheckImage detects them.

These error names use CheckImage in the "Error" column.

  • Crosslinked

    Description:

    Each file (and directory) consists of several clusters (the whole image is divided into clusters, their size is fixed by formatting), that aren't in the image always one after another. Each cluster of such a file has its unique index and in the FAT there is for this cluster a reference to the next cluster, where that file continues (for the last cluster there is a mark that the file ends here). Clusters of a file create this way a chain.

    But when the FAT goes wrong and a reference from one link of a chain points to a completly different file, the previous continuing of this chain gets lost and the chain (= the file) joins a foreign chain. So now two different files have joint ends. This situation can also simply happen to more than two files at once (they create a crosslinked group). It's almost impossible to make out to which file belonged the joint end before.

    One clue to this problem is the file length information in the parent directory entry that logically hasn't been affected by an error in FAT. When a file "stoles" its end from another file, it's possible that this new end hasn't the same chain lenght as the former end had. In this case the file length doesn't consist with the real length of the file chain. On the other hand if the file length and the length of the chain have the same value, it is most likely that this file has its own end that other chains joined.

    Solution:

    If the crosslinked item is a directory, there is no way to repair it and it has to be deleted.

    A crosslinked file is by default set to be deleted . Only if there is just one file in a crosslinked group that has correct chain size, in this case this file is set to be corrected . You can't select do nothing option for a crosslinked file.

    You can repair more files from one crosslinked group. The repairing then proceeds according to specified priority. The file with the highest priority occupies its whole chain including the joint part, the others take in sequence as much of their chains as possible (until they run into a part of the chain that has occupied some file before). This applies to methods Repair it and Repair it (extend) . For method Repair it (shorten) a file occupies its chain until it reaches its size specified in parent directory.

  • Too long

    Description:

    The chain of this file (see first paragraph in the description of "Crosslinked") is too long. Its size is bigger than the size of this file recorded in the file's parent directory. The length of the chain is in the parentheses next to this error.

    Solution:

    There are two possibilities how to repair this error:

    Repair it (shorten) : this method shotens the file chain so it fits the size specified in the parent directory.

    Repair it (extend) : on the other side if you choose this method, the file size in the parent directory will be increased to the chain size.

  • Too short

    Description:

    The chain of this file (see first paragraph in the description of "Crosslinked") is too short. Its size is smaller than the size of this file recorded in the file's parent directory. The length of the chain is in the parentheses next to this error.

    Solution:

    The only way to repair it is to correct the size entry in the parent directory in agreement with the chain size, so the file gets smaller. You can't enlarge the chain, because you don't know where should it continue. For the last cluster in the chain there is no reference to the next cluster.

  • Too-long-path

    Description:

    The complete path to this file (or directory) is longer than 255 letters, which is illegal in Windows. There are two ways how this can happen:
    1. This is an error in some parent directory, which implicates that that direcory contains many nested files and directories with unreadable names and enormous sizes. These files (including the one with "Too-long-name" error) haven't most likely ever existed, this is just an error in that directory.
    2. This file (or directory) is really valid, but the path to this file has been extended over the limit after that this file was created. Maybe some parent directory has been renamed or moved into a directory with longer path.

    Solution:

    1. case: There's no reason to repair this item. You should either delete the whole wrong directory, or all it's invalid content if it contains some additional valid files.
    2. case: If you want to save this file you must change the method to Do nothing (otherwise it would be deleted by repairing). After the repair you must shorten the path to this file manually (but you can't rename this file directly). If this is a directory, all its opportune content will be deleted although you set its action as "Do nothing", when you repair it. You must shorten the path to this directory before you repair this image.

  • Self LFName

    Description:

    In the FAT filesystem (used in TDisk images) has each file since the MS-DOS its name in the format 8.3 (8 letters for the filename and 3 letters for the file extension). The Windows operating system added to the filesystem longer names. But these longer names are stored separately because of holding compatibility with the old system. So it is possible that a long name is corrupted while the corresponding short name is all right. That's the case of this error. What CheckImage managed to read from the corrupted filename is that filename which you can see in the errors list.

    Solution:

    You can of course delete the whole file. You can also do nothing with this error but it's possible that you won't be able to read or modify this file later in normal usage. If you choose to repair this error, the long filename will be deleted so just the short name will remain. You can, after you mounted the image, rename the file back to its whole long name manually.

  • Invalid FAT index

    Description:

    One cluster from this file's chain has an invalid reference to the next cluster where this file should continue. That reference pointed to a nonexistent cluster. For further explanation of file chain see the first paragraph in the description of "Crosslinked". This error is most likely combined with the "Too short" error.

    Solution:

    It is impossible to correct the invalid reference in terms of finding the cluster where the file originally continued. You can just trim the file on position of the invalid reference. Additional repairing progress depends on other errors that this file contains (e.g. the length of a file with a "Too short" chain will be shortened to fit the chain length).

    A directory with this error has to be deleted .

  • Loop error

    Description:

    This error is very similar to the "Invalid FAT index" error. But in this case a bad reference points from one cluster to another cluster that is already somewhere earlier in the chain of this file. So the file has in its chain an endless loop.

    Solution:

    The file has to be trimmed on the position of the bad reference. The repair methods also depends on other errors in this file.

    A directory with this error has to be deleted .

  • Duplicate name

    Description:

    Path to each file must be unique. This implies that a directory can't contain more files with the same name.

    Solution:

    You can save only one file from such a group of files with the same name. You must delete all other files from this group. If you don't do this, you won't be able to accede to these files except for one (except for the file that is in the parent directory as the first from this group).

  • LFName

    Description:

    Long filenames (see the description of "Self LFName") are stored in the parent directory of corresponding files. This error indicates that there are some long filenames in this directory that don't belong to any files.

    Solution:

    If you choose to repair this error, these redundant long filenames are simply deleted.

  • Dots error

    Description:

    Each directory (except for the root directory) contains two special items. One item (with the name "..") that points to the parent directory and the other (".") that points to itself. This error means that these items are somehow corrupted.

    Solution:

    To repair this error is rather simple (if the item doesn't contain any more serious error). These two directory items are plainly repaired.

  • Invalid size

    Description:

    This directory has too much allocated space. Either there are many redundant deleted items at the end of this directory (that's no weighty error) or is this directory also "Crosslinked".

    Solution:

    If the directory is "Crosslinked", it must be deleted . Else it's easy to repair it by deleting the unnecessary end of the directory.

Related references

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