INTRODUCTION
-This is wimlib version 1.5.2 (November 2013). wimlib is a C library for
+This is wimlib version 1.8.2 (August 2015). wimlib is a C library for
creating, modifying, extracting, and mounting files in the Windows Imaging
-Format (WIM files). These files are normally created using the ImageX
-(imagex.exe) or Dism (Dism.exe) utilities on Windows, but wimlib is distributed
-with a free implementation of ImageX called "wimlib-imagex" for both UNIX-like
-systems and Windows.
+Format (WIM files). wimlib and its command-line frontend 'wimlib-imagex'
+provide a free and cross-platform alternative to Microsoft's WIMGAPI, ImageX,
+and DISM.
INSTALLATION
-To install wimlib and wimlib-imagex on Windows you simply need to download and
-extract the ZIP file containing the latest binaries from the SourceForge page
-(http://sourceforge.net/projects/wimlib/), which you may have already done.
-
-To install wimlib and wimlib-imagex on UNIX-like systems (with Linux being the
-primary supported and tested platform), you must compile the source code, which
-is also available at http://sourceforge.net/projects/wimlib/. Alternatively,
-check if a package has been prepared for your Linux distribution. Example files
+To install wimlib and wimlib-imagex on UNIX-like systems, you can compile from
+source (e.g. './configure && make && sudo make install'). Alternatively, check
+if a package has already been prepared for your operating system. Example files
for Debian and RPM packaging are in the debian/ and rpm/ directories.
- WIM FILES
+To install wimlib and wimlib-imagex on Windows, just download and extract the
+ZIP file containing the latest binaries. See README.WINDOWS for more details.
+
+All official wimlib releases are available from http://wimlib.net.
+
+ WIM FILES
A Windows Imaging (WIM) file is an archive designed primarily for archiving
Windows filesystems. However, it can be used on other platforms as well, with
some limitations. Like some other archive formats such as ZIP, files in WIM
-archives may be compressed. WIM files support two compression formats: LZX and
-XPRESS *. Both are supported by wimlib.
+archives may be compressed. WIM archives support multiple compression formats,
+including LZX, XPRESS, and LZMS. All these formats are supported by wimlib.
-A WIM file consists of one or more "images". Each image is an independent
-top-level directory structure and is logically separate from all other images in
-the WIM. Each image has a name as well as a 1-based index in the WIM file. To
-save space, WIM archives automatically combine all duplicate files across all
-images.
+A WIM archive contains one or more "images", each of which is a logically
+independent directory tree. Each image has a 1-based index and usually a name.
-A WIM file may be either stand-alone or split into multiple parts. Split WIMs
-are read-only and cannot be modified.
+WIM archives provide data deduplication at the level of full file contents. In
+other words, each unique "file contents" is only stored once in the archive,
+regardless of how many files have that contents across all images.
-* Note: The Windows 8 WIMGAPI apparently adds a third format, LZMS, but it is
- not documented and is incompatible with ImageX and Dism. It is unclear if
- this new format is actually being used for anything.
+A WIM archive may be either stand-alone or split into multiple parts.
+
+An update of the WIM format --- first added by Microsoft for Windows 8 ---
+supports solid-mode compression. This refers to files being compressed together
+(e.g. as in a .tar.xz or .7z archive) rather than separately (e.g. as in a .zip
+archive). This usually produces a much better compression ratio. Solid
+archives are sometimes called "ESD files" by Microsoft and may have the ".esd"
+file extension rather than ".wim". They are supported in wimlib since v1.6.0.
IMAGEX IMPLEMENTATION
wimlib itself is a C library, and it provides a documented public API (See:
-http://wimlib.sourceforge.net) for other programs to use. However, it is also
+http://wimlib.net/apidoc) for other programs to use. However, it is also
distributed with a command-line program called "wimlib-imagex" that uses this
library to implement an imaging tool similar to Microsoft's ImageX.
wimlib-imagex supports almost all the capabilities of Microsoft's ImageX as well
files are converted from UNIX-style "man pages", they do document
Windows-specific behavior when appropriate.
- COMPRESSION RATIO
-
-wimlib (and wimlib-imagex) can create XPRESS or LZX compressed WIM archives.
-The following tables compare the compression ratio and performance for creating
-a compressed x86_64 Windows PE image. Note: these timings were done on Windows
-so that the times would be fully comparable; however, wimlib may have even
-better performance on other operating systems such as Linux. Timings were done
-with 2 CPUs available, both of which automatically are used by wimlib for both
-XPRESS and LZX, and also by imagex.exe but apparently only for LZX.
-
- Table 1. WIM size
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.5.3): 207,444,390 bytes 188,106,091 bytes
- Microsoft imagex.exe (Windows 7): 209,960,209 bytes 188,224,481 bytes
-
- Table 2. Time to create WIM
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.5.3): 73 sec 202 sec
- Microsoft imagex.exe (Windows 7): 90 sec 149 sec
-
-The above LZX data are using explicitly specified maximum compression
-('--compress=maximum') as of wimlib v1.5.3. If `wimlib-imagex capture' or
-`wimlib-imagex capture' is instead run with no '--compress' argument, then a
-faster LZX compressor is used; it will produce results in between those given
-for XPRESS and LZX above.
-
-Note: if the absolute maximum compression ratio is desired, `wimlib-imagex
-optimize WIMFILE --recompress --compress-slow' on one of the above
-LZX-compressed WIMs produces a WIM of 187,089,943 bytes in about 400 seconds.
+ COMPRESSION RATIO
+
+wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM files.
+wimlib's compression codecs usually outperform and outcompress their Microsoft
+equivalents. Although results will vary depending on the data being compressed,
+the table below shows results for a common use case: creating an x86 Windows PE
+image ("boot.wim"). Each row shows the compression type, the size of the
+resulting WIM file in bytes, and the time it took to create the file. When
+possible, the results with the Microsoft equivalent are included.
+
+ =============================================================================
+ | Compression || wimlib (v1.8.0) | WIMGAPI (Windows 8.1) |
+ =============================================================================
+ | None [1] || 361,314,224 in 2.4s | 361,315,338 in 4.5s |
+ | XPRESS [2] || 138,218,750 in 3.0s | 140,457,436 in 6.0s |
+ | XPRESS (slow) [3] || 135,173,511 in 8.9s | N/A |
+ | LZX (quick) [4] || 130,207,195 in 3.8s | N/A |
+ | LZX (normal) [5] || 126,522,539 in 10.4s | 127,293,240 in 19.2s |
+ | LZX (slow) [6] || 126,042,313 in 17.3s | N/A |
+ | LZMS (non-solid) [7] || 116,150,682 in 25.3s | N/A |
+ | LZMS (solid) [8] || 88,107,484 in 61.7s | 88,769,830 in 102.3s |
+ | "WIMBoot" [9] || 167,023,719 in 3.5s | 169,109,211 in 10.4s |
+ | "WIMBoot" (slow) [10] || 165,027,583 in 7.9s | N/A |
+ =============================================================================
+
+Notes:
+ [1] '--compress=none' for wimlib-imagex; '/compress:none' for DISM.
+
+ [2] '--compress=XPRESS' for wimlib-imagex; '/compress:fast' for DISM.
+ Compression chunk size defaults to 32768 bytes in both cases.
+
+ [3] '--compress=XPRESS:80' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [4] '--compress=LZX:20' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [5] '--compress=LZX' or '--compress=LZX:50' or no option for wimlib-imagex;
+ '/compress:maximum' for DISM.
+ Compression chunk size defaults to 32768 bytes in both cases.
+
+ [6] '--compress=LZX:100' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [7] '--compress=LZMS' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 131072 bytes.
+
+ [8] '--solid' for wimlib-imagex. Should be '/compress:recovery' for DISM,
+ but only works for /Export-Image, not /Capture-Image. Compression chunk
+ size in solid resources defaults to 67108864 bytes in both cases.
+
+ [9] '--wimboot' for wimlib-imagex; '/wimboot' for DISM.
+ This is really XPRESS compression with 4096 byte chunks, so the same as
+ '--compress=XPRESS --chunk-size=4096'.
+
+ [10] '--wimboot --compress=XPRESS:80' for wimlib-imagex;
+ no known equivalent for DISM.
+ Same format as [9], but trying harder to get a good compression ratio.
+
+Note: wimlib-imagex's --compress option also accepts the "fast", "maximum", and
+"recovery" aliases for XPRESS, LZX, and LZMS, respectively.
+
+Testing environment:
+
+ - 64 bit binaries
+ - Windows 8.1 virtual machine running on Linux with VT-x
+ - 4 CPUs and 4 GiB memory given to virtual machine
+ - SSD-backed virtual disk
+ - All tests done with page cache warmed
+
+The compression ratio provided by wimlib is also competitive with commonly used
+archive formats. Below are file sizes that result when the Canterbury corpus is
+compressed with wimlib (v1.8.0), WIMGAPI (Windows 8.1), and some other
+formats/programs:
+
+ =====================================================
+ | Format | Size (bytes) |
+ =====================================================
+ | tar | 2,826,240 |
+ | WIM (WIMGAPI, None) | 2,814,254 |
+ | WIM (wimlib, None) | 2,814,216 |
+ | WIM (WIMGAPI, XPRESS) | 825,536 |
+ | WIM (wimlib, XPRESS) | 789,296 |
+ | tar.gz (gzip, default) | 738,796 |
+ | ZIP (Info-ZIP, default) | 735,334 |
+ | tar.gz (gzip, -9) | 733,971 |
+ | ZIP (Info-ZIP, -9) | 732,297 |
+ | WIM (wimlib, LZX quick) | 690,110 |
+ | WIM (WIMGAPI, LZX) | 651,866 |
+ | WIM (wimlib, LZX normal) | 624,634 |
+ | WIM (wimlib, LZX slow) | 620,728 |
+ | WIM (wimlib, LZMS non-solid) | 581,046 |
+ | tar.bz2 (bzip, default) | 565,008 |
+ | tar.bz2 (bzip, -9) | 565,008 |
+ | WIM (WIMGAPI, LZMS solid) | 521,366 |
+ | WIM (wimlib, LZMS solid) | 515,800 |
+ | tar.xz (xz, default) | 486,916 |
+ | tar.xz (xz, -9) | 486,904 |
+ | 7z (7-zip, default) | 484,700 |
+ | 7z (7-zip, -9) | 483,239 |
+ =====================================================
+
+Note: WIM does even better on directory trees containing duplicate files, which
+the Canterbury corpus doesn't have.
NTFS SUPPORT
For both platforms the code for NTFS capture and extraction is complete enough
that it is possible to apply an image from the "install.wim" contained in recent
-Windows installation media (Vista, Windows 7, or Windows 8) directly to a NTFS
-filesystem, and then boot Windows from it after preparing the Boot Configuration
-Data. In addition, a Windows installation can be captured (or backed up) into a
-WIM file, and then re-applied later.
+Windows installation media (Vista or later) directly to an NTFS filesystem, and
+then boot Windows from it after preparing the Boot Configuration Data. In
+addition, a Windows installation can be captured (or backed up) into a WIM file,
+and then re-applied later.
WINDOWS PE
perform maintenance. It is the operating system that runs when you boot from
the Windows installation media.
-You can find Windows PE on the installation DVD for Windows Vista, Windows 7, or
-Windows 8, in the file `sources/boot.wim'. Windows PE can also be found in the
-Windows Automated Installation Kit (WAIK), which is free to download from
-Microsoft, inside the `WinPE.cab' file, which you can extract natively on
-Windows, or on UNIX-like systems if you install either the `cabextract' or
-`p7zip' programs.
+You can find Windows PE on the installation media for Windows (Vista or later)
+as the file `sources/boot.wim'. Windows PE can also be found in the Windows
+Automated Installation Kit (WAIK), which is free to download from Microsoft,
+inside the `WinPE.cab' file, which you can extract natively on Windows, or on
+UNIX-like systems if you install either the `cabextract' or `p7zip' programs.
In addition, Windows installations and recovery partitions frequently contain a
WIM containing an image of the Windows Recovery Environment, which is similar to
dependencies were already included and this section is irrelevant.
* libxml2 (required)
- This is a commonly used free library to read and write XML files. You
- likely already have it installed as a dependency for some other program.
- For more information see http://xmlsoft.org/.
-
-* libfuse (optional but highly recommended)
- Unless configured with --without-fuse, wimlib requires a non-ancient
- version of libfuse to be installed. Most Linux distributions already
- include this, but make sure you have the libfuse package installed, and
- also libfuse-dev if your distribution distributes header files
- separately. FUSE also requires a kernel module. If the kernel module
- is available it will automatically be loaded if you try to mount a WIM
- file. For more information see http://fuse.sourceforge.net/. FUSE is
- also available for FreeBSD.
-
-* libntfs-3g (optional but highly recommended)
- Unless configured with --without-ntfs-3g, wimlib requires the library
- and headers for libntfs-3g version 2011-4-12 or later to be installed.
- Versions dated 2010-3-6 and earlier do not work because they are missing
- the header xattrs.h (and the file xattrs.c, which contains functions we
- need). libntfs-3g version 2013-1-13 is compatible only with wimlib
- 1.2.4 and later.
+ This is a commonly used free library to read and write XML documents.
+ Almost all Linux distributions should include this; however, you may
+ need to install the header files, which might be in a package named
+ "libxml2-dev" or similar. For more information see http://xmlsoft.org/.
+
+* libfuse (optional but recommended)
+ Unless configured --without-fuse, wimlib requires a non-ancient version
+ of libfuse. Most Linux distributions already include this, but make
+ sure you have the libfuse package installed, and also libfuse-dev if
+ your distribution distributes header files separately. FUSE also
+ requires a kernel module. If the kernel module is available it should
+ automatically be loaded if you try to mount a WIM image. For more
+ information see http://fuse.sourceforge.net/.
+
+* libattr (optional but recommended)
+ Unless configured --without-fuse, wimlib also requires libattr. Almost
+ all Linux distributions should include this; however, you may need to
+ install the header files, which might be in a package named "attr-dev",
+ "libattr1-dev", or similar.
+
+* libntfs-3g (optional but recommended)
+ Unless configured --without-ntfs-3g, wimlib requires the library and
+ headers for libntfs-3g version 2011-4-12 or later to be installed.
* OpenSSL / libcrypto (optional)
- wimlib can use the SHA1 message digest code from OpenSSL instead of
- compiling in yet another SHA1 implementation. (See LICENSE section.)
+ wimlib can use the SHA-1 message digest implementation from libcrypto
+ (usually provided by OpenSSL) instead of compiling in yet another SHA-1
+ implementation.
* cdrkit (optional)
* mtools (optional)
--without-ntfs-3g
If libntfs-3g is not available or is not version 2011-4-12 or later,
wimlib can be built without it, in which case it will not be possible to
- apply or capture images directly to/from NTFS volumes.
+ capture or apply WIM images directly from/to NTFS volumes.
+
+ The default is --with-ntfs-3g when building for any UNIX-like system,
+ and --without-ntfs-3g when building for Windows.
--without-fuse
- If libfuse or the FUSE kernel module is not available, wimlib can be
- compiled with --without-fuse. This will remove the ability to mount and
- unmount WIM files.
+ The --without-fuse option disables support for mounting WIM images.
+ This removes dependencies on libfuse, librt, and libattr. The wimmount,
+ wimmountrw, and wimunmount commands will not work.
+
+ The default is --with-fuse when building for Linux, and --without-fuse
+ otherwise.
--without-libcrypto
- Build in functions for SHA1 rather than using external SHA1 functions
- from libcrypto (part of OpenSSL). The default is to use libcrypto if it
- is found on the system.
+ Build in functions for SHA-1 rather than using external SHA-1 functions
+ from libcrypto (usually provided by OpenSSL).
---enable-xattr, --disable-xattr
- Enable or disable support for the extended-attributes interface to NTFS
- alternate data streams in mounted WIMs. To support these, wimlib
- requires that the setxattr() function and the attr/xattr.h header are
- available. The default is to autodetect whether support is possible.
+ The default is to use libcrypto if it is found on your system.
---disable-multithreaded-compression
- By default, data will be compressed using multiple threads when writing
- a WIM, unless only 1 processor is detected. Specify this option to
- disable support for this.
+ PORTABILITY
---enable-ssse3-sha1
- Use a very fast assembly language implementation of SHA1 from Intel.
- Only use this if the build target supports the SSSE3 instructions.
+wimlib works on both UNIX-like systems (Linux, Mac OS X, FreeBSD, etc.) and
+Windows (XP and later).
---disable-error-messages
- Save some space by removing all error messages from the library.
+As much code as possible is shared among all supported platforms, but there
+necessarily are some differences in what features are supported on each platform
+and how they are implemented. Most notable is that file tree scanning and
+extraction are implemented separately for Windows, UNIX, and UNIX (NTFS-3g
+mode), to ensure a fast and feature-rich implementation of each platform/mode.
---disable-assertions
- Remove assertions included by default.
+wimlib is mainly used on x86 and x86_64 CPUs, but it should also work on a
+number of other GCC-supported 32-bit or 64-bit architectures. It has been
+tested on the ARM architecture.
- PORTABILITY
+Currently, gcc and clang are the only supported compilers. A few nonstandard
+extensions are used in the code.
-wimlib has primarily been tested on Linux and Windows (primarily Windows 7, but
-also Windows XP and Windows 8).
+ REFERENCES
-wimlib may work on FreeBSD and Mac OS X. However, this is not well tested. If
-you do not have libntfs-3g 2011-4-12 or later available, you must configure
-wimlib with --without-ntfs-3g. On FreeBSD, before mounting a WIM you need to
-load the POSIX message queue module (run `kldload mqueuefs').
+The WIM file format is partially specified in a document that can be found in
+the Microsoft Download Center. However, this document really only provides an
+overview of the format and is not a formal specification. It also does not
+cover later extensions of the format, such as solid resources.
-The code has primarily been tested on x86 and x86_64 CPUs, but it's written to
-be portable to other architectures and I've also tested it on ARM. However,
-although the code is written to correctly deal with endianness, it has not yet
-actually been tested on a big-endian architecture.
+With regards to the supported compression formats:
- REFERENCES
+- Microsoft has official documentation for XPRESS that is of reasonable quality.
+- Microsoft has official documentation for LZX, but in two different documents,
+ neither of which is completely applicable to its use in the WIM format, and
+ the first of which contains multiple errors.
+- There does not seem to be any official documentation for LZMS, so my comments
+ and code in src/lzms_decompress.c may in fact be the best documentation
+ available for this particular compression format.
-The WIM file format is specified in a document that can be found in the
-Microsoft Download Center. There is a similar document that specifies the LZX
-compression format, and a document that specifies the XPRESS compression format.
-However, many parts of these formats are poorly documented, and some parts have
-no documentation whatsoever. Some particularly poorly documented parts of the
-formats have had comments added in various places in the library code. Please
-see the code and/or ask me if you have any questions about the WIM file format
-as it exists in reality and not as it exists in Microsoft's poorly written
-documentation.
+The algorithms used by wimlib's compression and decompression codecs are
+inspired by a variety of sources, including open source projects and computer
+science papers.
The code in ntfs-3g_apply.c and ntfs-3g_capture.c uses the NTFS-3g library,
which is a library for reading and writing to NTFS filesystems (the filesystem
used by recent versions of Windows). See
http://www.tuxera.com/community/ntfs-3g-download/ for more information.
-lzx-decompress.c, the code to decompress WIM file resources that are compressed
-using LZX compression, was originally based on code from the cabextract project
-(http://www.cabextract.org.uk) but has been rewritten.
-
-lzx-compress.c, the code to compress WIM file resources using LZX compression,
-was originally based on code written by Matthew Russotto (www.russotto.net/chm/)
-but has been rewritten.
-
-lz77.c, the code to find LZ77 matches (used for both XPRESS and LZX
-compression), is based on code from zlib but has been rewritten.
-
A limited number of other free programs can handle some parts of the WIM
file format:
* 7-zip is able to extract and create WIMs (as well as files in many
other archive formats). However, wimlib is designed specifically to handle
WIM files and provides features previously only available in Microsoft's
- imagex.exe, such as the ability to mount WIMs read-write as well as
- read-only, the ability to create LZX or XPRESS compressed WIMs, and the
- correct handling of security descriptors and hard links.
+ implementation, such as the ability to mount WIMs read-write as well as
+ read-only, the ability to create compressed WIMs, the correct handling of
+ security descriptors and hard links, support for LZMS compression, and
+ support for solid archives.
* ImagePyX (https://github.com/maxpat78/ImagePyX) is a Python program that
- provides similar capabilities to wimlib-imagex. One thing to note, though,
- is that it does not support compression and decompression by itself, but
- instead relies on external native code, such as the codecs from wimlib.
+ provides some capabilities of wimlib-imagex, with the help of external
+ compression codecs.
-A very early version of wimlib is being used to deploy Windows 7 from the
-Ultimate Deployment Appliance. For more information see
-http://www.ultimatedeployment.org/.
+If you are looking for an archive format that provides features similar to WIM
+but was designed primarily for UNIX, you may want to consider SquashFS
+(http://squashfs.sourceforge.net/). However, you may find that wimlib works
+surprisingly well on UNIX. It will store hard links and symbolic links, and it
+has optional support for storing UNIX owners, groups, modes, and special files
+such as device nodes and FIFOs. Actually, I use it to back up my own files on
+Linux!
-You can see the documentation about Microsoft's version of ImageX at
-http://technet.microsoft.com/en-us/library/cc749447(v=ws.10).aspx, so you can
-see how it compares to wimlib-imagex.
+ HISTORY
-If you are looking for a UNIX archive format that provides features similar to
-WIM, I recommend you take a look at SquashFS (http://squashfs.sourceforge.net/).
+wimlib was originally a project started by Carl Thijssen for use on Linux in the
+Ultimate Deployment Appliance (http://www.ultimatedeployment.org/). Since then
+the code has been entirely rewritten and improved (main author: Eric Biggers).
+Windows support has been available since version 1.3.0 (March 2013). A list of
+version-to-version changes can be found in the NEWS file.
- LICENSE
+ LICENSE AND DISCLAIMER
-As of version 1.0.0, wimlib and all programs and scripts distributed with it are
-released under the GNU GPL version 3.0 or later.
+See COPYING for information about the license.
wimlib is independently developed and does not contain any code, data, or files
copyrighted by Microsoft. It is not known to be affected by any patents.
implementation with built-in code and there will be no difference in
functionality.
- DISCLAIMER
-
-wimlib comes with no warranty whatsoever. Use Microsoft's `imagex.exe' if you
-want to make sure your WIM files are made "correctly" (but beware: Microsoft's
-version contains some bugs).
-
-Please submit a bug report (to ebiggers3@gmail.com) if you find a bug in wimlib
-and/or wimlib-imagex.
-
-Be aware that some parts of the WIM file format are poorly documented or even
-completely undocumented, so I've just had to do the best I can to read and write
-WIMs that appear to be compatible with Microsoft's software.
+wimlib comes with no warranty whatsoever. Please submit a bug report (to
+ebiggers3@gmail.com) if you find a bug in wimlib and/or wimlib-imagex.
git://wimlib.net / wimlib / blobdiff