INTRODUCTION
-This is wimlib version 1.6.0 (January 2014). wimlib is a C library for
+This is wimlib version 1.7.1-BETA (June 2014). 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 Windows, simply download and extract the
+ZIP file containing the latest binaries from the SourceForge page
+(http://sourceforge.net/projects/wimlib/). You probably have already done this!
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
A WIM file may be either stand-alone or split into multiple parts. Split WIMs
are read-only and cannot be modified.
+Since version 1.6.0, wimlib also supports ESD (.esd) files, except when
+encrypted. These are still WIM files but they use a newer version of the file
+format.
+
IMAGEX IMPLEMENTATION
wimlib itself is a C library, and it provides a documented public API (See:
COMPRESSION RATIO
-wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM
-archives. The following tables compare the compression ratio and performance
-for creating a compressed x86_64 Windows PE image with XPRESS and LZX. 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 but still compatible (i.e. not changing the
-compression chunk size) LZX 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.
+wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM files.
+wimlib includes its own compression codecs and does not use the compression API
+available on some versions of Windows.
+
+I have gradually been improving the compression codecs in wimlib. For XPRESS
+and LZX, they now usually outperform and outcompress the equivalent Microsoft
+implementations. Although results will vary depending on the data being
+compressed, in the table below I present the results for a common use case:
+compressing an x86 Windows PE image. Each row displays the compression type,
+the size of the resulting WIM file in bytes, and how many seconds it took to
+create the file. When applicable, the results with the equivalent Microsoft
+implementation in WIMGAPI is included.
+
+ =============================================================================
+ | Compression || wimlib (v1.7.1) | WIMGAPI (Windows 8.1) |
+ =============================================================================
+ | None [1] || 361,182,560 in 3.7s | 361,183,674 in 4.4s |
+ | XPRESS [2] || 138,349,798 in 5.8s | 140,416,657 in 6.8s |
+ | XPRESS (slow) [3] || 135,234,072 in 19.5s | N/A |
+ | LZX (quick) [4] || 131,816,279 in 6.7s | N/A |
+ | LZX (normal) [5] || 126,808,347 in 28.3s | 127,259,566 in 31.4s |
+ | LZX (slow) [6] || 126,199,523 in 61.4s | N/A |
+ | LZMS (non-solid) [7] || 122,083,126 in 30.4s | N/A |
+ | LZMS (solid) [8] || 93,752,206 in 84.3s | 88,742,238 in 156.1s |
+ | "WIMBoot" [9] || 167,039,787 in 7.6s | 169,051,718 in 14.9s |
+ | "WIMBoot" (slow) [10] || 165,141,503 in 15.8s | 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 blocks defaults to 33554432 for wimlib, 67108864 for DISM.
+
+ [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
+ - 2 CPUs and 2 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 (v1.7.0), WIMGAPI (Windows 8), and some other
+formats/programs:
+
+ =================================================
+ | Format | Size (bytes) |
+ =================================================
+ | tar | 2,826,240 |
+ | WIM (WIMGAPI, None) | 2,814,278 |
+ | WIM (wimlib, None) | 2,813,856 |
+ | WIM (WIMGAPI, XPRESS) | 825,410 |
+ | WIM (wimlib, XPRESS) | 792,024 |
+ | 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) | 722,196 |
+ | WIM (WIMGAPI, LZX) | 651,766 |
+ | WIM (wimlib, LZX normal) | 649,204 |
+ | WIM (wimlib, LZX slow) | 639,618 |
+ | WIM (wimlib, LZMS non-solid) | 592,136 |
+ | tar.bz2 (bzip, default) | 565,008 |
+ | tar.bz2 (bzip, -9) | 565,008 |
+ | WIM (wimlib, LZMS solid) | 525,270 |
+ | WIM (wimlib, LZMS solid, slow) | 521,700 |
+ | WIM (WIMGAPI, LZMS solid) | 521,232 |
+ | 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
+Windows installation media (Vista, Windows 7, or Windows 8) 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.
from libcrypto (part of OpenSSL). The default is to use libcrypto if it
is found on the system.
---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.
-
--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
PORTABILITY
-wimlib has primarily been tested on Linux and Windows (primarily Windows 7, but
-also Windows XP and Windows 8).
+wimlib works on both UNIX-like systems (Linux, Mac OS X, FreeBSD, etc.) and
+Windows (XP and later).
-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').
+On UNIX-like systems other than Linux, you must compile --without-fuse.
+In addition, --without-ntfs-3g and --without-libcrypto are needed if the
+corresponding libraries are not available on your system.
-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.
+wimlib works on x86 and x86_64, but it should work on any other GCC-supported
+32-bit or 64-bit architecture.
REFERENCES
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.
+overview of the format and is not a formal specification. It also does not
+cover later extensions of the format, such as solid blocks.
With regards to the supported compression formats:
- Microsoft has official documentation for XPRESS that is of reasonable quality.
-- Microsoft has official documentation for LZX but it contains errors.
+- 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 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.
-The LZX decompressor (lzx-decompress.c) was originally based on code from the
-cabextract project (http://www.cabextract.org.uk) but has been rewritten.
-
-The LZX compressor (lzx-compress.c) was originally based on code written by
-Matthew Russotto (www.russotto.net/chm/) but has been rewritten. It now uses
-suffix array construction code from divsufsort
-(https://code.google.com/p/libdivsufsort/) and algorithms from 7-Zip as well as
-several published papers.
-
-lz_hash.c contains a hash-table-based LZ77 matchfinder that is based on code
-from zlib but has been rewritten. This code is applicable to XPRESS, LZX, and
-LZMS, all of which are partly based on LZ77 compression.
-
A limited number of other free programs can handle some parts of the WIM
file format:
other archive formats). However, wimlib is designed specifically to handle
WIM files and provides features previously only available in Microsoft's
implementation, 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.
+ 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.
-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!
-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/).
+ LICENSE AND DISCLAIMER
- LICENSE
-
-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. 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.
git://wimlib.net / wimlib / blobdiff