fiz - analyze damaged zoo archive for data recovery

fiz archive[.zoo]

Fiz is used to analyze damaged zoo archives and locate directory entries and file data in them. The current version of fiz is 2.0 and it is meant to be used in conjunction with zoo version 2.0. Fiz makes no assumptions about archive structure. Instead, it simply searches the entire subject archive for tag values that mark the locations of directory entries and file data. In a zoo archive, a directory entry contains information about a stored file such as its name, whether compressed or not, and its timestamp. The file data are the actual data for the archived file, and may be either the original data, or the result of compressing the file.

For each directory entry found, fiz prints where in the archive it is located, the directory path and filename(s) found in it, whether the directory entry appears to be corrupted (indicated by [*CRC Error*]), and the value of the pointer to the file data that is found in the directory entry. For each block of file data found in the archive, fiz prints where in the archive the block begins. In the case of an undamaged archive, the pointer to file data found in a directory entry will correspond to where fiz actually locates the data. Here is some sample output from fiz:

****************
    2526: DIR  [changes] ==>   95
    2587: DATA
****************
    3909: DIR  [copyrite] ==> 1478
    3970: DATA
    4769: DATA
****************

Once the locations of directory entries and file data are found, the @ modifier to zoo's archive list and extract commands can be used and the archive contents selectively listed or extracted, skipping the damaged portion. This is further described in the documentation for zoo(1).

In the above case, commands to try giving to zoo might be x@2526,2587 (extract beginning at position 2526, and get file data from position 2587), x@3090,3970 (extract at 3090, get data from 3970) and x@3909,4769 (extract at 3909, get data from 4769). Once a correctly-matched directory entry/file data pair is found, zoo will in most cases synchronize with and correctly extract all files subsequently found in the archive. Trial and error should allow all undamaged files to be extracted. Also note that self-extracting archives created using sez (the Self-Extracting Zoo utility for MS-DOS), which are normally executed on an MS-DOS system for extraction, can be extracted on non-MSDOS systems in a similar way.

zoo(1)

Random byte patterns can occasionally be incorrectly recognized as tag values. This occurs very rarely, however, and trial and error will usually permit all undamaged data to be extracted.

Fiz always exits with a status code of 0.

Automation of data recovery from a damaged archive is potentially achievable. However, since damaged archives occur only rarely, fiz as it currently stands is unlikely to change much in the near future.

Rahul Dhesi