3 This is wimlib version 1.2.0 (November 2012). wimlib can be used to read,
4 write, and mount files in the Windows Imaging Format (WIM files). These files
5 are normally created by using the `imagex.exe' utility on Windows, but this
6 library provides a free implementation of imagex for UNIX-based systems.
10 A Windows Imaging (WIM) file is an archive. Like some other archive formats
11 such as ZIP, files in WIM archives may be compressed. WIM archives support two
12 Microsoft-specific compression formats: LZX and XPRESS. Both are based on LZ77
13 and Huffman encoding, and both are supported by wimlib.
15 Unlike ZIP files, WIM files can contain multiple independent toplevel directory
16 trees known as images. While each image has its own metadata describing a
17 directory tree and file access modes, files are not duplicated for each image;
18 instead, each file is included only once in the entire WIM. Microsoft did this
19 so that in one WIM file, they could do things like have 5 different versions of
20 Windows that are almost exactly the same.
22 Microsoft provides documentation for the WIM file format, XPRESS compression
23 format, and LZX compression format. The XPRESS documentation is acceptable, but
24 the LZX documentation is not entirely correct, and the WIM documentation itself
27 A WIM file may be either stand-alone or split into multiple parts.
31 wimlib provides a public API for other programs to use, but also comes with two
32 programs: `imagex' and `mkwinpeimg'.
34 `imagex' is intended to be like the imagex.exe program from Windows. `imagex'
35 can be used to create, extract, and mount WIM files. Both read-only and
36 read-write mounts are supported. See the man page `doc/imagex.1' for more
39 `mkwinpeimg' is shell script that makes it easy to create a customized bootable
40 image of Windows PE that can be put on a CD or USB drive, or published on a
41 server for PXE booting. See the main page `doc/mkwinpeimg.1' for more details.
45 wimlib can create XPRESS or LZX compressed WIM archives. As of wimlib v1.0.3,
46 the XPRESS compression ratio is slightly better than that provided by
47 Microsoft's software, while the LZX compression ratio is approaching that of
48 Microsoft's software but is not quite there yet. Running time is as good as or
49 better than Microsoft's software, especially with multithreaded compression,
50 available in v1.1.0 and later.
52 The following tables compare the compression ratio and performance for creating
53 a compressed Windows PE image (disk usage of about 524 MB, uncompressed WIM size
58 XPRESS Compression LZX Compression
59 wimlib imagex (v1.0.2): 145,283,871 bytes 139,288,293 bytes
60 wimlib imagex (v1.0.3): 139,288,293 bytes 131,379,869 bytes
61 Microsoft imagex.exe: 140,406,981 bytes 127,249,176 bytes
63 Table 2. Time to create WIM
65 XPRESS Compression LZX Compression
66 wimlib imagex (v1.0.2): 18 sec 49 sec
67 wimlib imagex (v1.0.3): 19 sec 30 sec
68 wimlib imagex (v1.1.0, 2 threads): 11 sec 17 sec
69 Microsoft imagex.exe: 25 sec 89 sec
73 As of version 1.0.0, wimlib supports capturing and applying images directly to
74 NTFS volumes. This was made possible with the help of libntfs-3g from the
75 NTFS-3g project. This feature supports capturing and restoring NTFS-specific
76 data such as security descriptors, alternate data streams, and reparse point
79 The code for NTFS image capture and image application is complete enough that it
80 is possible to apply an image from the "install.wim" contained in recent Windows
81 installation media (Vista, Windows 7, or Windows 8) directly to a NTFS volume,
82 and then boot Windows from it after preparing the Boot Configuration Data. In
83 addition, a Windows installation can be captured (or backed up) into a WIM file,
84 and then re-applied later.
88 A major use for this library is to create customized images of Windows PE, the
89 Windows Preinstallation Environment, without having to rely on Windows. Windows
90 PE is a lightweight version of Windows that can run entirely from memory and can
91 be used to install Windows from local media or a network drive or perform
92 maintenance. Windows PE is the operating system that runs when you boot from
93 the Windows installation media.
95 You can find Windows PE on the installation DVD for Windows Vista, Windows 7, or
96 Windows 8, in the file `sources/boot.wim'. Windows PE can also be found in the
97 Windows Automated Installation Kit (WAIK), which is free to download from
98 Microsoft, inside the `WinPE.cab' file, which you can extract if you install
99 either the `cabextract' or `p7zip' programs.
101 In addition, Windows installations and recovery partitions frequently contain a
102 WIM containing an image of the Windows Recovery Environment, which is similar to
108 This is a commonly used free library to read and write XML files. You
109 likely already have it installed as a dependency for some other program.
110 For more information see http://xmlsoft.org/.
112 * libfuse (optional but highly recommended)
113 Unless configured with --without-fuse, wimlib requires a non-ancient
114 version of libfuse to be installed. Most GNU/Linux distributions
115 already include this, but make sure you have the libfuse package
116 installed, and also libfuse-dev if your distribution distributes header
117 files separately. FUSE also requires a kernel module. If the kernel
118 module is available it will automatically be loaded if you try to mount
119 a WIM file. For more information see http://fuse.sourceforge.net/.
120 FUSE is also available for FreeBSD.
122 * libntfs-3g (optional but highly recommended)
123 Unless configured with --without-ntfs-3g, wimlib requires the library
124 and headers for libntfs-3g version 2011-4-12 or later to be installed.
125 Versions dated 2010-3-6 and earlier do not work because they are missing
126 the header xattrs.h (and the file xattrs.c, which contains functions we
129 * OpenSSL / libcrypto (optional)
130 wimlib can use the SHA1 message digest code from OpenSSL instead of
131 compiling in yet another SHA1 implementation. (See LICENSE section.)
135 * syslinux (optional)
136 * cabextract (optional)
137 The `mkwinpeimg' shell script will look for several other programs
138 depending on what options are given to it. Depending on your GNU/Linux
139 distribution, you may already have these programs installed, or they may
140 be in the software repository. Making an ISO filesystem requires
141 `mkisofs' from `cdrkit' (http://www.cdrkit.org). Making a disk image
142 requires `mtools' (http://www.gnu.org/software/mtools) and `syslinux'
143 (http://www.syslinux.org). Retrieving files from the Windows Automated
144 Installation Kit requires `cabextract' (http://www.cabextract.org.uk).
148 Besides the various well-known options, the following options can be passed to
149 wimlib's `configure' script:
152 If libntfs-3g is not available or is not version 2011-4-12 or later, we
153 can build without it. wimlib will then not be able to apply or capture
154 images directly to NTFS volumes.
157 If libfuse or the FUSE kernel module is not available, wimlib can be
158 compiled with --without-fuse. This will remove the ability to mount and
159 unmount WIM files. wimlib_mount() and wimlib_unmount() will fail with
160 WIMLIB_ERR_UNSUPPORTED.
163 Build in functions for SHA1 rather than using external SHA1 functions
164 from libcrypto (part of OpenSSL). The default is to use libcrypto if it
165 is found on the system.
167 --enable-xattr, --disable-xattr
168 Enable or disable support for the extended-attributes interface to NTFS
169 alternate data streams in mounted WIMs. To support these, we require
170 the setxattr() function and the attr/xattr.h header be available. The
171 default is to autodetect whether support is possible.
173 --disable-multithreaded-compression
174 By default, data will be compressed using multiple threads when writing
175 a WIM, unless only 1 processor is detected. Specify this option to
176 disable support for this.
179 Use a very fast assembly language implementation of SHA1 from Intel.
180 Only use this if the build target supports the SSSE3 instructions.
182 --disable-custom-memory-allocator
183 If this option is given, MALLOC(), FREE(), CALLOC(), and STRDUP() will
184 directly call the appropriate functions in the C library.
185 wimlib_set_memory_allocator() will fail with WIMLIB_ERR_UNSUPPORTED.
187 --disable-verify-compression
188 Unless this option is given, every time wimlib compresses a data block
189 it will decompress it into a temporary buffer and abort() the program
190 with an error message if the decompressed data does not exactly match
191 the original data. This is to find bugs.
193 --disable-error-messages
194 Removes all error messages from the library. If left in, they still
195 have to explicitly turned on with wimlib_set_print_errors() in order to
196 see them. Also, error codes will still be returned regardless of
197 whether error messages are printed or not.
199 If --disable-error-messages is given, wimlib_set_print_errors() will
200 fail with WIMLIB_ERR_UNSUPPORTED if the action is to turn error messages
204 Remove all assertions. Without this option, wimlib will abort() the
205 program if an assertion fails. An assertion failure should only occur
206 if there is a bug in the library.
209 Include debugging messages. Only use this option if you have found a
213 Include more debugging messages. Only use this option if you have found
214 a bug in the library.
218 wimlib has mostly been developed and tested on x86_64 (64-bit) GNU/Linux.
220 It has been tested on x86 (32-bit) GNU/Linux occasionally.
222 wimlib may work on FreeBSD. However, this is not well tested. If you do not
223 have libntfs-3g 2011-4-12 or later available, you must configure with
224 --without-ntfs-3g. Also, GNU coreutils is needed to run the test suite. Before
225 mounting a WIM you need to load the POSIX message queue module (run `kldload
228 wimlib should work on big endian machines but it has not been tested.
230 There are no plans to port wimlib to Windows since the programming interface on
231 Windows is very different and Microsoft's imagex.exe is already available.
235 The WIM file format is specified in a document that can be found in the
236 Microsoft Download Center. There is a similar document that specifies the LZX
237 compression format, and a document that specifies the XPRESS compression format.
238 However, many parts of these formats are poorly documented, and some parts have
239 no documentation whatsoever. Some particularly poorly documented parts of the
240 formats have had comments added in various places in the library. Please see
241 the code and/or ask me if you have any questions about the WIM file format as it
242 exists in reality and not as it exists in Microsoft's poorly written
245 The code in ntfs-apply.c and ntfs-capture.c uses the NTFS-3g library, which is a
246 library for reading and writing to NTFS filesystems (the filesystem used by
247 recent versions of Windows). See
248 http://www.tuxera.com/community/ntfs-3g-download/ for more information.
250 lzx-decomp.c, the code to decompress WIM file resources that are compressed
251 using LZX compression, is originally based on code from the cabextract project
252 (http://www.cabextract.org.uk).
254 lzx-comp.c, the code to compress WIM file resources using LZX compression, is
255 originally based on code written by Matthew Russotto (www.russotto.net/chm/).
257 lz.c, the code to find LZ77 matches (used for both XPRESS and LZX compression),
258 is based on code from zlib.
260 A very limited number of other free programs can handle some parts of the WIM
261 file format. 7-zip is able to extract and create WIMs (as well as files in many
262 other archive formats). However, wimlib is designed specifically to handle WIM
263 files and provides features previously only available in Microsoft's imagex.exe,
264 such as the ability to mount WIMs read-write as well as read-only, and the
265 ability to create LZX or XPRESS compressed WIMs.
267 An earlier version of wimlib is being used to deploy Windows 7 from the Ultimate
268 Deployment Appliance. For more information see
269 http://www.ultimatedeployment.org/.
271 You can see the documentation about Microsoft's version of the imagex program at
272 http://technet.microsoft.com/en-us/library/cc749447(v=ws.10).aspx, so you can
275 GNU/Linux equivalents of WIM format
277 What's the equivalent way to capture the filesystem of a GNU/Linux operating
278 system into an archive file? You have a few options:
281 SquashFS (http://squashfs.sourceforge.net/) provides a compressed,
282 read-only filesystem for Linux, and it's probably the closest equivalent
283 of the WIM format and better designed. Although you can't mount
284 SquashFS read-write, when wimlib does this for WIM files it's really an
285 illusion since the WIM isn't actually modified until the image is
286 unmounted. Multiple top-level images in SquashFS files are not
287 supported, although nothing stops you from just putting each image in a
291 FSArchiver (http://www.fsarchiver.org/Main_Page) is not widely used, but
292 it appears to have some features quite similar to the WIM format.
295 The well-known tar format can usually capture a UNIX filesystem just
296 fine, and compressing the tar file produces a good compression ratio
297 (better than WIM, especially if using XZ compression), but there is no
298 support for random access, file deduplication, multiple images per
299 archive, or extended attributes.
302 Zip shares some features with WIM but is not designed to store entire
306 The 7z format has some nice features but is unfortunately not designed
311 See the manual pages for `imagex', the manual pages for the subcommands of
312 `imagex', and the manual page for `mkwinpeimg'.
314 As of version 0.5.0, wimlib's public API is documented. Doxygen is required to
315 build the documentation. To build the documentation, run `configure', then
316 enter the directory `doc' and run `doxygen'. The HTML documentation will be
317 created in a directory named `html'.
321 As of version 1.0.0, wimlib is released under the GNU GPL version 3.0 or later.
322 This includes the files in the `programs' directory as well as the files in the
325 wimlib is independently developed and does not contain any code, data, or files
326 copyrighted by Microsoft. It is not known to be affected by any patents.
328 By default, wimlib will be linked to the system library "libcrypto", which
329 probably will be OpenSSL. Some people believe that GPL code cannot be linked to
330 OpenSSL without a linking exception. As far as I know, I cannot officially
331 include a linking exception with the license of this library because several
332 files could be considered derived works of LGPL code copyrighted by others. If
333 you believe this to be a problem, configure with --without-libcrypto to avoid
334 linking with OpenSSL. There is no difference in functionality--- there will
335 just be stand-alone SHA1 message digest code built into the library.
339 wimlib is experimental. Use Microsoft's `imagex.exe' if you want to make sure
340 your WIM files are made correctly (but beware: Microsoft's version contains some
343 Please submit a bug report (to ebiggers3@gmail.com) if you find a bug in wimlib.
345 Some parts of the WIM file format are poorly documented or even completely
346 undocumented, so I've just had to do the best I can to read and write WIMs that
347 appear to be compatible with Microsoft's software.
git://wimlib.net / wimlib / blob