3 This is wimlib version 1.6.1 (January 2014). wimlib is a C library for
4 creating, modifying, extracting, and mounting files in the Windows Imaging
5 Format (WIM files). These files are normally created using the ImageX
6 (imagex.exe) or Dism (Dism.exe) utilities on Windows, but wimlib is distributed
7 with a free implementation of ImageX called "wimlib-imagex" for both UNIX-like
12 To install wimlib and wimlib-imagex on Windows you simply need to download and
13 extract the ZIP file containing the latest binaries from the SourceForge page
14 (http://sourceforge.net/projects/wimlib/), which you may have already done.
16 To install wimlib and wimlib-imagex on UNIX-like systems (with Linux being the
17 primary supported and tested platform), you must compile the source code, which
18 is also available at http://sourceforge.net/projects/wimlib/. Alternatively,
19 check if a package has been prepared for your Linux distribution. Example files
20 for Debian and RPM packaging are in the debian/ and rpm/ directories.
24 A Windows Imaging (WIM) file is an archive designed primarily for archiving
25 Windows filesystems. However, it can be used on other platforms as well, with
26 some limitations. Like some other archive formats such as ZIP, files in WIM
27 archives may be compressed. WIM files support multiple compression formats,
28 including LZX, XPRESS, and LZMS. All these formats are supported by wimlib.
30 A WIM file consists of one or more "images". Each image is an independent
31 top-level directory structure and is logically separate from all other images in
32 the WIM. Each image has a name as well as a 1-based index in the WIM file. To
33 save space, WIM archives automatically combine all duplicate files across all
36 A WIM file may be either stand-alone or split into multiple parts. Split WIMs
37 are read-only and cannot be modified.
41 wimlib itself is a C library, and it provides a documented public API (See:
42 http://wimlib.sourceforge.net) for other programs to use. However, it is also
43 distributed with a command-line program called "wimlib-imagex" that uses this
44 library to implement an imaging tool similar to Microsoft's ImageX.
45 wimlib-imagex supports almost all the capabilities of Microsoft's ImageX as well
46 as additional capabilities. wimlib-imagex works on both UNIX-like systems and
47 Windows, although some features differ between the platforms.
49 Run `wimlib-imagex' with no arguments to see an overview of the available
50 commands and their syntax. For additional documentation:
52 * If you have installed wimlib-imagex on a UNIX-like system, you will find
53 further documentation in the man pages; run `man wimlib-imagex' to get
56 * If you have downloaded the Windows binary distribution, you will find the
57 documentation for wimlib-imagex in PDF format in the "doc" directory,
58 ready for viewing with any PDF viewer. Please note that although the PDF
59 files are converted from UNIX-style "man pages", they do document
60 Windows-specific behavior when appropriate.
64 wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM
65 archives. wimlib includes its own compression codecs and does not use the
66 compression API available on some versions of Windows. The below table provides
67 the results (file size, in bytes, and time to create, in seconds) of capturing a
68 WIM containing a x86 Windows PE image, using various compression types and
69 options. When applicable, the results with the equivalent Microsoft
70 implementation in WIMGAPI, which is the library used by ImageX and Dism, are
73 ===========================================================================
74 | Compression type || wimlib (v1.6.1) | WIMGAPI (Windows 8) |
75 ===========================================================================
76 | None [1] || 531,979,435 in 18s | 531,980,333 in 24s |
77 | XPRESS [2] || 207,369,912 in 22s | 209,886,010 in 39s |
78 | LZX (quick) [3] || 194,876,901 in 29s | N/A |
79 | LZX (normal) [4] || 187,962,713 in 158s | 188,163,523 in 125s |
80 | LZX (slow) [5] || 186,913,423 in 358s | N/A |
81 | LZMS (non-solid) [6] || 176,880,594 in 182s | N/A |
82 | LZMS (solid) [7] || 136,507,304 in 494s | 126,735,608 in 623s |
83 ===========================================================================
86 [1] '--compress=none' for wimlib-imagex;
87 '/compress none' or no option for ImageX.
89 [2] '--compress=fast' or '--compress=XPRESS' for wimlib-imagex;
90 '/compress fast' or no option for ImageX.
91 Compression chunk size is 32768 (the default for XPRESS).
93 [3] No compression option specified to wimlib-imagex; no known equivalent for
94 WIMGAPI (ImageX uses XPRESS compression if no option specified).
95 Compression chunk size is 32768 (the default for LZX).
97 [4] '--compress=maximum' or '--compress=LZX' for wimlib-imagex;
98 '/compress maximum' for ImageX.
99 Compression chunk size is 32768 (the default for LZX).
101 [5] '--compress=maximum --compress-slow' for wimlib-imagex;
102 no known equivalent for WIMGAPI.
103 Compression chunk size is 32768 (the default for LZX).
105 [6] '--compress=recovery' or '--compress=LZMS' for wimlib-imagex;
106 no known way to create the equivalent with WIMGAPI.
107 Compression chunk size is 131072 (the default for LZMS). Note: this
108 compression type is not generally recommended due to its limited
109 compatibility with the MS implementations.
111 [7] '--compress=recovery --solid' or '--compress=LZMS --solid' for
112 wimlib-imagex; WIMCreateFile with WIM_COMPRESSION_LZMS and flag
113 0x20000000 for WIMGAPI. Compression chunk size in packed resources is
114 33554432 for wimlib, 67108864 for WIMGAPI. Note: this compression type
115 is not generally recommended due to its limited compatibility with the MS
116 implementations. Also, due to the large chunk size, wimlib uses about
117 500MB of memory per thread when compressing in this format.
119 The above timings were done on Windows 8 (x86) so that side-by-side comparisons
120 with the Microsoft implementation would be possible; however, wimlib may have
121 even better performance on other operating systems such as Linux. The system
122 had 2 CPUs and 2 GiB of memory available. All times were done with the page
123 cache warmed, so the times primarily measure the performance of the compression
124 algorithms and not the time to read data from disk, which presumably is similar
125 in each implementation.
127 Below are results for compressing the Canterbury corpus using wimlib (v1.6.1),
128 WIMGAPI (Windows 8), and some other formats/programs, including the archive size
129 only. Note that the Canterbury corpus includes no duplicate files or hard
130 links, which WIM handles better than most other formats by storing only distinct
133 =================================================
134 | Format | Size (bytes) |
135 =================================================
137 | WIM (WIMGAPI, None) | 2,814,278 |
138 | WIM (wimlib, None) | 2,813,856 |
139 | WIM (WIMGAPI, XPRESS) | 825,410 |
140 | WIM (wimlib, XPRESS) | 792,024 |
141 | tar.gz (gzip, default) | 738,796 |
142 | ZIP (Info-ZIP, default) | 735,334 |
143 | tar.gz (gzip, -9) | 733,971 |
144 | ZIP (Info-ZIP, -9) | 732,297 |
145 | WIM (wimlib, LZX quick) | 722,196 |
146 | WIM (WIMGAPI, LZX) | 651,766 |
147 | WIM (wimlib, LZX normal) | 639,464 |
148 | WIM (wimlib, LZX slow) | 633,144 |
149 | WIM (wimlib, LZMS non-solid) | 590,252 |
150 | tar.bz2 (bzip, default) | 565,008 |
151 | tar.bz2 (bzip, -9) | 565,008 |
152 | WIM (wimlib, LZMS solid) | 534,218 |
153 | WIM (wimlib, LZMS solid, slow) | 529,904 |
154 | WIM (WIMGAPI, LZMS solid) | 521,232 |
155 | tar.xz (xz, default) | 486,916 |
156 | tar.xz (xz, -9) | 486,904 |
157 | 7z (7-zip, default) | 484,700 |
158 | 7z (7-zip, -9) | 483,239 |
159 =================================================
163 WIM images may contain data, such as alternate data streams and
164 compression/encryption flags, that are best represented on the NTFS filesystem
165 used on Windows. Also, WIM images may contain security descriptors which are
166 specific to Windows and cannot be represented on other operating systems.
167 wimlib handles this NTFS-specific or Windows-specific data in a
168 platform-dependent way:
170 * In the Windows version of wimlib and wimlib-imagex, NTFS-specific and
171 Windows-specific data are supported natively.
173 * In the UNIX version of wimlib and wimlib-imagex, NTFS-specific and
174 Windows-specific data are ordinarily ignored; however, there is also special
175 support for capturing and extracting images directly to/from unmounted NTFS
176 volumes. This was made possible with the help of libntfs-3g from the
179 For both platforms the code for NTFS capture and extraction is complete enough
180 that it is possible to apply an image from the "install.wim" contained in recent
181 Windows installation media (Vista, Windows 7, or Windows 8) directly to a NTFS
182 filesystem, and then boot Windows from it after preparing the Boot Configuration
183 Data. In addition, a Windows installation can be captured (or backed up) into a
184 WIM file, and then re-applied later.
188 A major use for wimlib and wimlib-imagex is to create customized images of
189 Windows PE, the Windows Preinstallation Environment, on either UNIX-like systems
190 or Windows without having to rely on Microsoft's software and its restrictions
193 Windows PE is a lightweight version of Windows that can run entirely from memory
194 and can be used to install Windows from local media or a network drive or
195 perform maintenance. It is the operating system that runs when you boot from
196 the Windows installation media.
198 You can find Windows PE on the installation DVD for Windows Vista, Windows 7, or
199 Windows 8, in the file `sources/boot.wim'. Windows PE can also be found in the
200 Windows Automated Installation Kit (WAIK), which is free to download from
201 Microsoft, inside the `WinPE.cab' file, which you can extract natively on
202 Windows, or on UNIX-like systems if you install either the `cabextract' or
205 In addition, Windows installations and recovery partitions frequently contain a
206 WIM containing an image of the Windows Recovery Environment, which is similar to
209 A shell script `mkwinpeimg' is distributed with wimlib on UNIX-like systems to
210 ease the process of creating and customizing a bootable Windows PE image.
214 This section documents the dependencies of wimlib and the programs distributed
215 with it, when building for a UNIX-like system from source. If you have
216 downloaded the Windows binary distribution of wimlib and wimlib-imagex then all
217 dependencies were already included and this section is irrelevant.
220 This is a commonly used free library to read and write XML files. You
221 likely already have it installed as a dependency for some other program.
222 For more information see http://xmlsoft.org/.
224 * libfuse (optional but highly recommended)
225 Unless configured with --without-fuse, wimlib requires a non-ancient
226 version of libfuse to be installed. Most Linux distributions already
227 include this, but make sure you have the libfuse package installed, and
228 also libfuse-dev if your distribution distributes header files
229 separately. FUSE also requires a kernel module. If the kernel module
230 is available it will automatically be loaded if you try to mount a WIM
231 file. For more information see http://fuse.sourceforge.net/. FUSE is
232 also available for FreeBSD.
234 * libntfs-3g (optional but highly recommended)
235 Unless configured with --without-ntfs-3g, wimlib requires the library
236 and headers for libntfs-3g version 2011-4-12 or later to be installed.
237 Versions dated 2010-3-6 and earlier do not work because they are missing
238 the header xattrs.h (and the file xattrs.c, which contains functions we
239 need). libntfs-3g version 2013-1-13 is compatible only with wimlib
242 * OpenSSL / libcrypto (optional)
243 wimlib can use the SHA1 message digest code from OpenSSL instead of
244 compiling in yet another SHA1 implementation. (See LICENSE section.)
248 * syslinux (optional)
249 * cabextract (optional)
250 The `mkwinpeimg' shell script will look for several other programs
251 depending on what options are given to it. Depending on your Linux
252 distribution, you may already have these programs installed, or they may
253 be in the software repository. Making an ISO filesystem requires
254 `mkisofs' from `cdrkit' (http://www.cdrkit.org). Making a disk image
255 requires `mtools' (http://www.gnu.org/software/mtools) and `syslinux'
256 (http://www.syslinux.org). Retrieving files from the Windows Automated
257 Installation Kit requires `cabextract' (http://www.cabextract.org.uk).
261 This section documents the most important options that may be passed to the
262 "configure" script when building from source:
265 If libntfs-3g is not available or is not version 2011-4-12 or later,
266 wimlib can be built without it, in which case it will not be possible to
267 apply or capture images directly to/from NTFS volumes.
270 If libfuse or the FUSE kernel module is not available, wimlib can be
271 compiled with --without-fuse. This will remove the ability to mount and
275 Build in functions for SHA1 rather than using external SHA1 functions
276 from libcrypto (part of OpenSSL). The default is to use libcrypto if it
277 is found on the system.
279 --enable-xattr, --disable-xattr
280 Enable or disable support for the extended-attributes interface to NTFS
281 alternate data streams in mounted WIMs. To support these, wimlib
282 requires that the setxattr() function and the attr/xattr.h header are
283 available. The default is to autodetect whether support is possible.
285 --disable-multithreaded-compression
286 By default, data will be compressed using multiple threads when writing
287 a WIM, unless only 1 processor is detected. Specify this option to
288 disable support for this.
291 Use a very fast assembly language implementation of SHA1 from Intel.
292 Only use this if the build target supports the SSSE3 instructions.
294 --disable-error-messages
295 Save some space by removing all error messages from the library.
298 Remove assertions included by default.
302 wimlib has primarily been tested on Linux and Windows (primarily Windows 7, but
303 also Windows XP and Windows 8).
305 wimlib may work on FreeBSD and Mac OS X. However, this is not well tested. If
306 you do not have libntfs-3g 2011-4-12 or later available, you must configure
307 wimlib with --without-ntfs-3g. On FreeBSD, before mounting a WIM you need to
308 load the POSIX message queue module (run `kldload mqueuefs').
310 The code has primarily been tested on x86 and x86_64 CPUs, but it's written to
311 be portable to other architectures and I've also tested it on ARM. However,
312 although the code is written to correctly deal with endianness, it has not yet
313 actually been tested on a big-endian architecture.
317 The WIM file format is partially specified in a document that can be found in
318 the Microsoft Download Center. However, this document really only provides an
319 overview of the format and is not a formal specification.
321 With regards to the supported compression formats:
323 - Microsoft has official documentation for XPRESS that is of reasonable quality.
324 - Microsoft has official documentation for LZX but it contains errors.
325 - There does not seem to be any official documentation for LZMS, so my comments
326 and code in src/lzms-decompress.c may in fact be the best documentation
327 available for this particular compression format.
329 The code in ntfs-3g_apply.c and ntfs-3g_capture.c uses the NTFS-3g library,
330 which is a library for reading and writing to NTFS filesystems (the filesystem
331 used by recent versions of Windows). See
332 http://www.tuxera.com/community/ntfs-3g-download/ for more information.
334 The LZX decompressor (lzx-decompress.c) was originally based on code from the
335 cabextract project (http://www.cabextract.org.uk) but has been rewritten.
337 The LZX compressor (lzx-compress.c) was originally based on code written by
338 Matthew Russotto (www.russotto.net/chm/) but has been rewritten. It now uses
339 suffix array construction code from divsufsort
340 (https://code.google.com/p/libdivsufsort/) and algorithms from 7-Zip as well as
341 several published papers.
343 lz_hash.c contains a hash-table-based LZ77 matchfinder that is based on code
344 from zlib but has been rewritten. This code is applicable to XPRESS, LZX, and
345 LZMS, all of which are partly based on LZ77 compression.
347 A limited number of other free programs can handle some parts of the WIM
350 * 7-zip is able to extract and create WIMs (as well as files in many
351 other archive formats). However, wimlib is designed specifically to handle
352 WIM files and provides features previously only available in Microsoft's
353 implementation, such as the ability to mount WIMs read-write as well as
354 read-only, the ability to create LZX or XPRESS compressed WIMs, and the
355 correct handling of security descriptors and hard links.
356 * ImagePyX (https://github.com/maxpat78/ImagePyX) is a Python program that
357 provides similar capabilities to wimlib-imagex. One thing to note, though,
358 is that it does not support compression and decompression by itself, but
359 instead relies on external native code, such as the codecs from wimlib.
361 A very early version of wimlib is being used to deploy Windows 7 from the
362 Ultimate Deployment Appliance. For more information see
363 http://www.ultimatedeployment.org/.
365 If you are looking for a UNIX archive format that provides features similar to
366 WIM, I recommend you take a look at SquashFS (http://squashfs.sourceforge.net/).
370 As of version 1.0.0, wimlib and all programs and scripts distributed with it are
371 released under the GNU GPL version 3.0 or later.
373 wimlib is independently developed and does not contain any code, data, or files
374 copyrighted by Microsoft. It is not known to be affected by any patents.
376 On UNIX-like systems, if you do not want wimlib to be dynamically linked with
377 libcrypto (OpenSSL), configure with --without-libcrypto. This replaces the SHA1
378 implementation with built-in code and there will be no difference in
383 wimlib comes with no warranty whatsoever. Please submit a bug report (to
384 ebiggers3@gmail.com) if you find a bug in wimlib and/or wimlib-imagex.
386 Be aware that some parts of the WIM file format are poorly documented or even
387 completely undocumented, so I've just had to do the best I can to read and write
388 WIMs that appear to be compatible with Microsoft's software.
git://wimlib.net / wimlib / blob