DArc

Distended Arc - Based on FreeArc

Overview

DArc is a command-line archiver based on FreeArc. It supports solid compression, strong encryption, recovery records, SFX archives, and a wide variety of compression algorithms.

The console binary is named `darc` (`darc.exe` on Windows).
Archives produced by DArc are largely format-compatible with DArc86 — but compatibility is not a design requirement, and where it conflicts with being correct or corruption-resilient, DArc takes the better behaviour and marks the divergence. Encrypted archives are already not compatible: they carry `:h1`, because the old key/IV hex decoding was broken and weakened the key.

Building

Build System Overview: DArc is two Rust binaries built with cargo: the archiver darc and the extractor unarc, which doubles as the SFX module. Nothing else is required — no Haskell (mhs, cpphs and GHC are all unnecessary), and no C or C++ at all. There is no C source in the repository; the differential harnesses fetch what they compile from pinned commits in git history.

Every platform

cargo build --release --manifest-path rust/Cargo.toml -p darc-arc --bin darc

That is the whole archiver, at rust/target/release/darc. It needs nothing outside the Rust toolchain — no ncurses, no libcurl, no system TLS.

--original http://… fetches a remote copy by byte range and is on by default; --no-default-features removes it and its entire dependency subtree.

For Windows, cross-compile rather than building on Windows:

cargo build --release --manifest-path rust/Cargo.toml \
  --target x86_64-pc-windows-gnu      -p darc-arc --bin darc   # needs mingw-w64
cargo build --release --manifest-path rust/Cargo.toml \
  --target aarch64-pc-windows-gnullvm -p darc-arc --bin darc   # needs llvm-mingw

Both targets are listed in rust-toolchain.toml, so rustup installs them on demand.

`unarc`, the extractor and SFX module

cargo build --release --manifest-path rust/Cargo.toml -p darc-unarc

One binary does both jobs. Run as unarc it extracts an archive you name; used as an SFX module (darc a -sfx<path-to-unarc> out.arc files…) it is prepended to the archive, and on startup it asks whether an archive is appended to its own executable and extracts that instead. There is no separate stub and no compile-time SFX flag. The archive is made executable when it is written, so ./out runs.

Adding --autorun'CMD' makes it an installer: the stub extracts itself into a scratch directory, shows you CMD, and runs it there only if you answer y (or passed -y), then deletes the directory and exits with the command's own status. CMD must name a file the archive itself contains — a path leading out of the extracted tree is refused when the archive is written, and again before anything is run.

Without --autorun an SFX archive executes nothing, and it never executes anything under darc l, darc t or darc x, nor when you give unarc an explicit command. Receiving an SFX file from someone else is still receiving an executable: the risk is the megabyte of program at the front, not the archive at the back, and darc x opens one without running any of it.

Unarc/ — the C++ extractor, the Windows GUI SFX, the installer stub and the FAR Manager plugin — was deleted once this replaced it. Its ArcStructure.h was a second implementation of the archive format that disagreed with the writer about the width of one field, which is the kind of drift a single reader cannot have. There is also no longer a tiered arc-mini / arc-tiny: those linked progressively fewer C decoders, and one Rust binary carries every codec, so the tiers could only have been identical copies under three names.

Where the C went

There is none in the repository. Compression/ — the codec wrappers and the vendored engines — was deleted once nothing in the tree compiled it: the archiver and unarc are cargo binaries, and the only remaining consumer was the differential test suite, which now fetches what it compiles from two pinned commits in git history (DARC_C_REF_SHA for the original C, and DARC_WRAPPER_REF_SHA for the thin forwarders that replaced its engines). A test is not a reason to keep source in the tree when git already holds it.

Four headers remain, all under rust/: rust/include/{Compression,Common}.h are the C ABI contract that bindgen reads at build time, with a wrapper.h per crate. rust/difftest/c-header-check.sh requires them to stay byte-identical to the pinned copies.

Troubleshooting

An editor reports "You must define OS!" in rust/include/Common.h: expected. It requires an OS and a byte-order define; the build scripts and harnesses pass them, a bare clangd invocation does not.
cargo cannot reach crates.io: the archiver has real dependencies now (rayon, and ureq/rustls for --original). --no-default-features drops the HTTP half but not the rest.

macOS specifics. Covered by CI (macos-latest) and needs only the Xcode command line tools beyond cargo. Handled automatically by the C build:

Apple's clang ships no OpenMP, so -fopenmp/-lgomp are dropped on Darwin. Nothing is lost — libbsc's OpenMP paths are compiled out regardless.
objcopy does not exist; the 7z codec uses ld -r -exported_symbols_list to achieve the same symbol localization.
There is no /proc, so physical-memory queries go through sysctl.

What the archiver cannot do yet

Every compression method is supported for both reading and writing, and Tests/run-tests.sh scores the same 24/24 as the pre-port reference.

-mm (multimedia mode), -ma (file-type autodetection level) and -mc (disable an algorithm) are implemented and gated by rust/difftest/arc-multimedia-check.sh; so are the memory limits -lc/-ld, including their -lc-/-ld- "no limit" forms. An earlier version of this section said all five were refused, which stopped being true in #129/#130.

A limit that cannot physically be met is now reported rather than quietly missed — -ld1m on LZMA warns, because LZMA needs its dictionary plus a fixed ~2 MB and no dictionary satisfies 1 MB.

CLI Usage

darc <command> [options...] <archive> [files... @listfiles...]

<command> — one of the commands listed below.
[options...] — zero or more options (each prefixed with -).
<archive> — path to the archive file. The default extension .arc is added automatically unless --noarcext is used.
[files...] — files or directories to process. Wildcards are supported. If omitted, all files are processed (*).
[@listfiles...] — text files containing lists of filenames to process, one per line.

Multiple commands can be chained with ; as a separator, for example:

darc "a archive -r ; t archive ; x archive"

Commands

Command	Description
`a`	Add files to archive
`c`	Add comment to archive
`ch`	Modify archive (recompress, encrypt, etc.)
`create`	Create new archive
`cw`	Write archive comment to file
`d`	Delete files from archive
`e`	Extract files from archive, ignoring pathnames
`f`	Freshen archive (update files that are newer on disk)
`j`	Join archives
`k`	Lock archive
`l`	List files in archive
`lb`	Bare list of files in archive (filenames only)
`lt`	Technical archive listing
`m`	Move files and directories to archive
`mf`	Move only files to archive
`r`	Recover archive using recovery record
`rr`	Add recovery record to archive
`s`	Convert archive to SFX (self-extracting)
`t`	Test archive integrity
`u`	Update files in archive
`v`	Verbosely list files in archive
`x`	Extract files from archive (preserving paths)

Command Examples

# Add all files in the current directory recursively
darc a archive.arc -r .

# Extract all files from an archive
darc x archive.arc

# Extract, ignoring directory paths
darc e archive.arc

# Test archive integrity
darc t archive.arc

# List archive contents
darc l archive.arc

# Delete a file from an archive
darc d archive.arc unwanted.txt

# Add a recovery record (5% of archive size)
darc rr archive.arc -rr5%

# Recover a damaged archive
darc r archive.arc

# Convert to self-extracting archive
darc s archive.arc

# Join multiple archives
darc j output.arc part1.arc part2.arc

# Lock archive (prevent modifications)
darc k archive.arc

Options

Options use the short form -<opt> or long form --<option>.
Options that take a parameter use -<opt><value> or --<option>=<value>.

General

Short	Long	Description
`-y`	`--yes`	Answer Yes to all queries
`--`		Stop processing options
`-cfg FILE`	`--config=FILE`	Use config FILE (default: `darc.toml`)
`-env VAR`		Read default options from environment variable VAR (default: `DARC`)

File Selection

Short	Long	Description
`-r`	`--recursive`	Recursively collect files from subdirectories
`-x FILESPECS`	`--exclude=FILESPECS`	Exclude matching files from operation
`-n FILESPECS`	`--include=FILESPECS`	Include only files matching FILESPECS
`-ep MODE`	`--ExcludePath=MODE`	Exclude/expand path (1, 2, or 3)
`-fn`	`--fullnames`	Match filespecs against full file paths
`-sm SIZE`	`--SizeMore=SIZE`	Select files larger than SIZE
`-sl SIZE`	`--SizeLess=SIZE`	Select files smaller than SIZE
`-tb TIME`	`--TimeBefore=TIME`	Select files modified before TIME
`-ta TIME`	`--TimeAfter=TIME`	Select files modified after TIME
`-tn PERIOD`	`--TimeNewer=PERIOD`	Select files newer than PERIOD
`-to PERIOD`	`--TimeOlder=PERIOD`	Select files older than PERIOD

Paths

Short	Long	Description
`-ap DIR`	`--arcpath=DIR`	Base directory inside archive
`-dp DIR`	`--diskpath=DIR`	Base directory on disk
`-ad`	`--adddir`	Add archive name to extraction path
`-w DIR`	`--workdir=DIR`	Directory for temporary files

Compression

Short	Long	Description
`-m METHOD`	`--method=METHOD`	Compression method (`-m0`–`-m9`, `-m1x`–`-m9x`)
`-dm METHOD`	`--dirmethod=METHOD`	Compression method for archive directory
`-md N`	`--dictionary=N`	Set compression dictionary to N MB
`-ms`	`--StoreCompressed`	Store already-compressed files without recompression
`-mt N`	`--MultiThreaded=N`	Number of compression threads
`-mc`		Disable specific compression algorithms (e.g., `-mcd-`, `-mc-rep`)
`-mm MODE`	`--multimedia=MODE`	Multimedia compression mode
`-ma LEVEL`		File-type auto-detection level (0–9, `+`, `-`)
`-mx`		Maximum internal compression mode
`-max`		Maximum compression (uses external tools: precomp, ecm, ppmonstr)
`-s GROUPING`	`--solid=GROUPING`	Solid compression grouping
`-ds ORDER`	`--sort=ORDER`	Sort files in ORDER before compressing
`--groups=FILE`		Name of file-groups definition file
`-lc N`	`--LimitCompMem=N`	Limit memory for compression to N MB
`-ld N`	`--LimitDecompMem=N`	Limit memory for decompression to N MB

Compression Levels

Option	Description
`-m0`	No compression (store only)
`-m1`–`-m9`	Compression levels 1–9 (increasing compression/time)
`-m1x`–`-m9x`	Extra-mode compression at levels 1–9
`-mx` or `-max`	Maximum compression

Solid Grouping Values (`-s`)

Value	Description
(empty)	All files in one solid block
`-`	No solid compression
`e`	Group by file extension
`s<size>`	Group by block size

Encryption

Short	Long	Description
`-p PASSWORD`	`--password=PASSWORD`	Encrypt/decrypt data with PASSWORD
`-hp PASSWORD`	`--HeadersPassword=PASSWORD`	Encrypt/decrypt archive headers and data
`-ae ALGO`	`--encryption=ALGO`	Encryption algorithm: `aes` (default), `blowfish`, `serpent`, `twofish`
`-kf FILE`	`--keyfile=FILE`	Encrypt/decrypt using KEYFILE
`-op PASSWORD`	`--OldPassword=PASSWORD`	Old password used only for decryption
`-okf FILE`	`--OldKeyfile=FILE`	Old keyfile used only for decryption

Archive Management

Short	Long	Description
`-f`	`--freshen`	Update only files that are newer on disk
`-u`	`--update`	Update only files not present or newer on disk
`--sync`		Synchronize archive and disk contents
`-o MODE`	`--overwrite=MODE`	Overwrite mode: `+` (always), `-` (never), `p` (prompt)
`-k`	`--lock`	Lock archive to prevent modifications
`-rr SIZE`	`--recovery=SIZE`	Add recovery information of SIZE to archive (`-rr`/`-rr+` reuse the archive's own setting, or a recommended amount if it had none)
`-sfx MODULE`		Add SFX module (`freearc.sfx` by default)
	`--autorun=CMD`	Have the SFX module offer to run CMD from the extracted files; `--autorun-` clears it
`--noarcext`		Do not add the default `.arc` extension to archive name
`-ag FMT`	`--autogenerate=FMT`	Autogenerate archive name using a time format string
`--recompress`		Force recompression of all files
`--append`		Add new files to the end of archive only
`-z FILE`	`--arccmt=FILE`	Read archive comment from FILE or stdin
`--archive-comment=TEXT`		Specify archive comment directly on the command line
`-t`	`--test`	Test archive integrity after archiving
`-tp MODE`	`--pretest=MODE`	Test archive before operation (0=none, 1=recovery only, 2=recovery or full, 3=full)
`-d`	`--delete`	Delete files and directories after successful archiving
`-df`	`--delfiles`	Delete only files after successful archiving
`-kb`	`--keepbroken`	Keep broken extracted files
`-ba MODE`	`--BrokenArchive=MODE`	Handle badly broken archives (`-`, `0`, or `1`)
`-tk`	`--keeptime`	Keep original archive modification time
`-tl`	`--timetolast`	Set archive time to the latest file's modification time
`--dirs`		Add empty directories to archive
`-ed`	`--nodirs`	Do not add empty directories to archive

Windows-Only Options

Short	Long	Description
`-ac`	`--ClearArchiveBit`	Clear Archive attribute on successfully (de)archived files
`-ao`	`--SelectArchiveBit`	Select only files with Archive attribute set

Display and Logging

Short	Long	Description
`-i TYPE`	`--indicator=TYPE`	Progress indicator type: `0` (none), `1` (default), `2` (per-file)
`-di AMOUNT`	`--display=AMOUNT`	Control amount of information displayed
`--logfile=FILE`		Duplicate all output to FILE
`--print-config`		Display built-in compression method definitions

Network/URL Options

Long	Description
`--proxy=PROXY`	Set proxy server(s) for URL access
`--bypass=LIST`	Set proxy bypass list for URL access
`--original=URL`	Re-download broken archive parts from URL — a local path, an `http(s)://` URL fetched by byte range, `?CMD` to run `CMD <archive>` for the URL, or empty to read it from `files.bbs`/`descript.ion`
`--save-bad-ranges=FILE`	Save list of broken archive parts to FILE
`--cache=N`	Use N MB for read-ahead cache

Reproducibility and Advanced

Short	Long	Description
	`--nodates`	Don't store file timestamps in the archive. Makes archive bytes reproducible for a given input
	`--create-in-workdir`	Create the archive in the work directory, then move it to its final location
	`--queue`	Serialize operations across multiple concurrent DArc processes
`-ioff`	`--shutdown`	Shut the computer down when the operation completes
	`--pause-before-exit`	Pause just before closing the program window
	`--nodata`	Don't store file data in the archive (directory only)
	`--crconly`	Save and check CRCs, but don't store file data

Charset

Short	Long	Description
`-sc CHARSETS`	`--charset=CHARSETS`	Character sets for list files and comment files
`--language=FILE`		Load localization strings from FILE

Configuration File (`darc.toml`)

By default, DArc reads options from darc.toml beside the executable. You can override the config file with -cfg <file> or disable it with -cfg-.

Default options are set per-command under [defaults]. A key may name several commands, and all applies to every one:

[defaults]
all = "-mx"
a   = "--display"
ch  = "-m4x -ms"

Compression methods are defined under [methods], and external compressors under [external.NAME] — that is how -msrep is wired up.

The DARC environment variable is also read for default options (override with -env <VAR> or disable with -env-).

arc.ini and $FREEARC are gone, and a leftover one is refused rather than ignored. They were FreeArc's names; DArc uses darc.toml and $DARC. If an arc.ini is found beside the executable the run stops and names the replacement, because a config that is silently skipped changes the archive you get — -cfg-/-env- silence it deliberately. The old [Default options] / [Compression methods] INI sections have no equivalent spelling; use the TOML above.

List Files

You can pass a file containing a list of filenames (one per line) to any command by prefixing the filename with @:

darc a archive.arc @myfiles.txt

Blank lines are ignored, the file may use LF, CRLF or CR endings, and the names are read in the l charset (-sc). A name is a filespec like any other, so it may hold wildcards, and it is resolved relative to --diskpath when that is given:

# test.lst holds  0007/0.paz  and  bin64/prog.exe
darc a --diskpath="/games/Crimson Desert" ExternalData.arc @test.lst

On Windows the names may be spelled with either separator — 0007\0.paz and 0007/0.paz both work, and produce the same archive. On Unix only / is a separator, because \ is a legal character in a file name there.

@ also applies to the values of -n and -x, as -n@list.txt.

If no filespec matches anything, no archive is written and darc reports WARNING: no files, erasing empty archive and exits non-zero. An empty archive is never left behind.

Examples

# Create archive with maximum compression
darc a -mx myarchive.arc documents/

# Create encrypted archive
darc a -p"my secret" secure.arc private/

# Extract archive to a specific directory
darc x archive.arc -dp /home/user/extracted/

# Add recovery record (10% of archive size)
darc ch myarchive.arc -rr10%

# List archive contents verbosely
darc v myarchive.arc

# Update archive with changed files
darc u myarchive.arc documents/

# Create self-extracting archive
darc s myarchive.arc

# Freshen archive, then test it
darc a archive.arc -r src/ -t

# Compress with specific algorithm and dictionary size
darc a -m4 -md128m myarchive.arc bigfiles/

# Exclude certain file types
darc a myarchive.arc docs/ -x"*.tmp" -x"*.log"

License

DArc is distributed under the GNU General Public License, version 3 or later — see LICENSE.

It was GPLv2 until the .7z reader moved to the sevenz-rust2 crate, which is Apache-2.0; Apache-2.0 is compatible with GPLv3 and not with GPLv2. Bundled and depended-on components carry their own terms — see THIRD-PARTY.md.

Name		Name	Last commit message	Last commit date
.cargo		.cargo
.github		.github
LICENSES		LICENSES
Tests		Tests
docs		docs
rust		rust
.gitattributes		.gitattributes
.gitignore		.gitignore
CLAUDE.md		CLAUDE.md
LICENSE		LICENSE
README.md		README.md
THIRD-PARTY.md		THIRD-PARTY.md
rust-toolchain.toml		rust-toolchain.toml

Navigation Menu

Repository files navigation

DArc

Overview

Building

Every platform

`unarc`, the extractor and SFX module

Where the C went

Troubleshooting

What the archiver cannot do yet

CLI Usage

Commands

Command Examples

Options

General

File Selection

Paths

Compression

Compression Levels

Solid Grouping Values (`-s`)

Encryption

Archive Management

Windows-Only Options

Display and Logging

Network/URL Options

Reproducibility and Advanced

Charset

Configuration File (`darc.toml`)

List Files

Examples

License

About

Releases

Packages

Used by

Contributors

Languages

Latest commit

History

Folders and files

Repository files navigation

DArc

Overview

Building

Every platform

unarc, the extractor and SFX module

Where the C went

Troubleshooting

What the archiver cannot do yet

CLI Usage

Commands

Command Examples

Options

General

File Selection

Paths

Compression

Compression Levels

Solid Grouping Values (-s)

Encryption

Archive Management

Windows-Only Options

Display and Logging

Network/URL Options

Reproducibility and Advanced

Charset

Configuration File (darc.toml)

List Files

Examples

License

About

Topics

Resources

Stars

Watchers

Forks

Releases

Packages

Used by

Contributors

Languages

`unarc`, the extractor and SFX module

Solid Grouping Values (`-s`)

Configuration File (`darc.toml`)