Deark
Deark is a command-line utility that can decode certain types of files, and either:
- convert them to a more-modern or more-readable format; or
- extract embedded files from them
The files it writes are usually named "output.*".
This program is still being developed, and its features are subject to change without notice.
For additional information, see the technical.md file.
Usage
deark [options] [-file] <input-file> [options]
deark <-h|-version|-modules>
Command-line options:
-m <module>
The "module" to use to process the input file. The default is to autodetect.
A module may represent one file format, or a group of related formats, or
may have some special purpose.
See formats.txt for a list of modules. You usually don't need to use -m,
unless the format can't be detected, or you want to use a special-purpose
module such as "copy". See also the -onlydetect option.
-l
Don't extract, but list the files that would be extracted.
This option is not necessarily very efficient. Deark will still go through
all the motions of extracting the files, but will not actually write them.
-main
Extract only "primary" files (e.g. not thumbnail images).
-aux
Extract only "auxiliary" files, such as thumbnail images.
-a, -extractall
Extract more data than usual, including things that are rarely of interest,
such as comments. See also the "-opt extract..." options.
Note that, as a general rule, Deark doesn't extract the same data twice.
In rare cases, the -a option can actually *prevent* it from extracting
certain data, because it may now, for example, extract a block of Exif
data, instead of drilling down and extracting the thumbnail image within
it.
-o <name>
Output filenames begin with this string. This can include a directory
path. Default is "output", except in some cases when using -zip.
-k, -k2, -k3
"Keep" the input filename, and use it as the initial part of the output
filename(s).
-k: Use only the base filename.
-k2: Use the full path, but not as an actual path.
-k3: Use the full path, as-is.
-n
Do not overwrite existing output files.
-file <input-file>
This is an alternate syntax for specifying the primary input file. It works
even if the filename begins with "-".
-file2 <file>
Some formats are composed of more than one file. In some cases, you can
use the -file2 option to specify the secondary file. Refer to the
formats.txt file for details.
-zip
Write output files to a .zip file, instead of to individual files.
If the input format is an "archive" format (e.g. "ar" or "graspgl"), then
by default, the filenames in the ZIP archive might not include the usual
"output.NNN" prefix.
-arcfn <filename>
When using -zip, use this name for the .zip file. Default="output.zip".
-extrlist <filename>
Also create a text file containing a list of the names of the extracted
files. Format is UTF-8, no BOM, LF terminators. To append to the file
instead of overwriting, use with "-opt extrlist:append".
-tostdout
Write the output file(s) to the standard output stream (stdout).
It is recommended to put -tostdout early on the command line. The
-msgstostderr option is enabled automatically.
If used with -zip: Write the ZIP file to standard output. This option
might be inefficient, or have file size limitations.
Otherwise: The "-maxfiles 1" option is enabled automatically. Including the
-main option is recommended.
-fromstdin
Read the input file from the standard input stream (stdin).
If you use -fromstdin, supplying an input filename is optional. If it is
supplied, the file will not be read (and need not exist), but the name
might be used to help guess the file format.
This option might not be very efficient, and might not work with extremely
large files.
-start <n>
Pretend that the input file starts at byte offset <n>.
-size <n>
Pretend that the input file contains only (up to) <n> bytes.
-firstfile <n>
Don't extract the first <n> files found.
-maxfiles <n>
Extract at most <n> files.
-get <n>
Extract only the file identifed by <n>. The first file is 0.
Equivalent to "-firstfile <n> -maxfiles 1".
-maxdim <n>
Allow image dimensions up to <n> pixels.
By default, Deark refuses to generate images with a dimension larger than
10000 pixels. You can use -maxdim to decrease or increase the limit.
Increase the limit at your own risk. Deark does not generate large images
efficiently. In practice, a large dimension will only work if the other
dimension is very small.
-nobom
Do not add a BOM to UTF-8 output files generated or converted by Deark. Note
that if a BOM already exists in the source data, it will not necessarily be
removed.
-nodens
Do not try to record the original aspect ratio and pixel density in output
image files.
-asciihtml
When generating an HTML document, use ASCII encoding instead of UTF-8. This
does not change how a browser will render the file; it just makes it larger
and very slightly more portable.
-nonames
Make Deark less likely to try to improve output filenames by using names
from the contents of the input file. The output filenames will be more
predictable, but less informative.
-modtime
-nomodtime
Do / Do not try to preserve the modification timestamp of extracted files.
On by default, but not relevant to most formats. It's used with archive
formats where files are extracted as-is, and where each member file has a
last-modified timestamp.
-opt <module:option>=<value>
Module-specific and feature-specific options. See formats.txt.
Caution: Unrecognized or misspelled options will be silently ignored.
Options not specific to one format:
-opt font:charsperrow=<n>
The number of characters per row, when rendering a font to a bitmap
-opt font:tounicode=<0|1>
[Don't] Try to translate a font's codepoints to Unicode codepoints.
-opt char:output=<html|image>
The output format for character graphics (such as ANSI Art).
-opt char:charwidth=<8|9>
The VGA character cell width for character graphics, when the output
format is "image".
-opt archive:subdirs
When using -zip, allow subdirectories (the "/" character) in member
filenames. Warning: This option is experimental. It is not as robust as
it could be, and it may produce a ZIP file that is unsafe to unzip with
some unzip software.
-opt archive:timestamp=<n>
-opt archive:repro
Make the -zip output reproducible, by not including modification times
that are not contained in the source file. (That is, don't use the
current time, or the source file's timestamp.) If you use "repro", the
times will be set to some arbitrary value. If you use "timestamp", the
times will be set to the value you supply, in Unix time format (the
number of seconds since the beginning of 1970).
-opt extrlist:append
Affects the -extrlist option.
-opt extractexif[=0]
-opt extract8bim
-opt extractiptc[=0]
-opt extractplist
Extract the specified type of data to a file, instead of decoding it.
For more about the ".8bimtiff" and ".iptctiff" formats, see the
technical.md file.
-opt atari:palbits=<9|12|15>
For some Atari image formats, the number of significant bits per
palette color. The default is to autodetect.
-h, -?, -help:
Print the help message.
Use with -m to get help for a specific module. Use with a filename to get
help for the detected format of that file. Note that most modules have no
module-specific help to speak of.
-version
Print the version number, and other version information.
-modules
Print the names of the available modules.
With -a, list all modules, including internal modules, and modules that
don't work.
-noinfo
Suppress informational messages.
-nowarn
Suppress warning messages.
-q
Suppress informational and warning messages.
-d, -d2, -d3
Print technical and debugging information. -d2 and -d3 are more verbose.
-dprefix <msg>
Start each line printed by -d with this prefix. Default is "DEBUG: ".
-color
Allow the use of color and similar features in the debug output. This is
done using ANSI escape sequences, or Windows console commands.
This feature is experimental. Currently, it is limited to highlighting
unprintable characters, and previewing most color palettes (usually
requires -d2). The latter does not work on a Windows console.
-enc <ascii|oem>
Set the encoding of the messages that are printed to the console. This does
not affect the extracted data files.
The default is to use Unicode (UTF-8, when the encoding is relevant).
ascii: Use ASCII characters only.
oem: [Windows only; has no effect on other platforms] Use the "OEM"
character set. This may be useful when paging the output with "|more".
-inenc <ascii|utf8|latin1|cp437|windows1250|windows1251|windows1252|
macroman>
Supply a hint as to the encoding of the text contained in the input file.
This option is incompletely implemented, and will be ignored if the encoding
can be reliably determined by other means. Admittedly, Deark does not yet
know enough encodings for this option to be really useful.
-intz <offset>
Supply a hint as to the time zone used by timestamps contained in the input
file.
Many file formats unfortunately contain timestamps in "local time", with no
information about their time zone. In such cases, the supplied -intz offset
will be used to convert the timestamp to UTC.
The "offset" parameter is in hours east of UTC. For example, New York City
is -5.0, or -4.0 when Daylight Saving Time is in effect.
This option does not respect Daylight Saving Time. It cannot deal with the
case where some of the timestamps in a file are in DST, and others are not.
-msgstostderr
Print all messages to stderr, instead of stdout. This option should be
placed early on the command line, as it might not affect messages
related to options that appear before it.
-nodetect <module1,module2,...>
-onlydetect <module1,module2,...>
Disable autodetection of the formats in the list (or for -onlydetect, the
formats *not* in the list).
-disablemods <module1,module2,...>
-onlymods <module1,module2,...>
Completely disable the main functionality, and the autodetection
functionality, of the modules in the list (or for -onlymods, the modules
*not* in the list). This can have unexpected side effects, because modules
often use other modules internally. These options exist mainly to help
address potential security-related concerns in some workflows.
-modcodes <codes>
Run the module in a non-default "mode".
The existence of this option (though not its details) is documented in the
interest of transparency, but it is mainly for developers, and to make it
possible to do things whose usefulness was not anticipated.
Terms of use
Starting with version 1.4.x, Deark is distributed under an MIT-style license. See the COPYING file for the license text.
The main Deark license does not necessarily apply to the code in the "foreign" subdirectory. Each file there may have its own licensing terms. In particular:
uncompface.h: Copyright (c) James Ashton - Sydney University - June 1990 (See the file foreign/readme-compface.txt for details.)
By necessity, Deark contains knowledge about how to decode various third-party file formats. This knowledge includes data structures, algorithms, tables, color palettes, etc. The author(s) of Deark make no intellectual property claims to this essential knowledge, but they cannot guarantee that no one else will attempt to do so.
Deark contains VGA and CGA bitmapped fonts, which have no known copyright claims.
Be particularly wary of relying on Deark to decode archive and compression formats (tar, ar, gzip, cpio, ...). For example, to decode tar format, you really should use a battle-hardened application like GNU Tar, not Deark. Deark's support for such formats is often incomplete, and it does not always do integrity checking.
How to build
See the technical.md file.
Acknowledgements
Thanks to Rich Geldreich for the miniz library.
Thanks to Mike Frysinger, and the authors of compress/ncompress, for liblzw.
Thanks to Rahul Dhesi and Martin Schoenert for much of the code used by the ZOO format decoder.
Thanks to James Ashton for much of the code used by the X-Face format decoder.
Thanks to Allan G. Weber for the Huffman decompression code used by the StuffIt format decoder.
Thanks to countless others who have documented the supported file formats.
Authors
Written by Jason Summers, 2014-2019.
Copyright © 2016-2019 Jason Summers
https://entropymine.com/deark/
https://github.com/jsummers/deark