3 This is wimlib version 1.0.4 (October 2012). wimlib can be used to read,
4 write, and mount files in the Windows Imaging Format (WIM files). These
5 files are normally created by using the `imagex.exe' utility on Windows,
6 but this library provides a free implementation of imagex for UNIX-based
11 A Windows Imaging (WIM) file is an archive. Like some other archive formats
12 such as ZIP, files in WIM archives may be compressed. WIM archives support two
13 Microsoft-specific compression formats: LZX and XPRESS. Both are based on LZ77
14 and Huffman encoding, and both are supported by wimlib.
16 Unlike ZIP files, WIM files can contain multiple independent toplevel directory
17 trees known as images. While each image has its own metadata describing a
18 directory tree and file access modes, files are not duplicated for each image;
19 instead, each file is included only once in the entire WIM. Microsoft did this
20 so that in one WIM file, they could do things like have 5 different versions of
21 Windows that are almost exactly the same.
23 Microsoft provides documentation for the WIM file format, XPRESS compression
24 format, and LZX compression format. The XPRESS documentation is acceptable, but
25 the LZX documentation is not entirely correct, and the WIM documentation itself
26 is very incomplete and is of unacceptable quality.
28 A WIM file may be either stand-alone or split into multiple parts.
32 A major use for this library is to create customized images of Windows PE, the
33 Windows Preinstallation Environment, without having to rely on Windows. Windows
34 PE is a lightweight version of Windows that can run entirely from memory and can
35 be used to install Windows from local media or a network drive or perform
36 maintenance. Windows PE is the operating system that runs when you boot from
37 the Windows installation media.
39 You can find Windows PE on the installation DVD for Windows Vista, Windows 7, or
40 Windows 8, in the file `sources/boot.wim'. Windows PE can also be found in the
41 Windows Automated Installation Kit (WAIK), which is free to download from
42 Microsoft, inside the `WinPE.cab' file, which you can extract if you install
43 either the `cabextract' or `p7zip' programs.
45 In addition, Windows installations and recovery partitions frequently contain a
46 WIM containing an image of the Windows Recovery Environment, which is similar to
51 As of version 1.0.0, wimlib supports capturing and applying images directly to
52 NTFS volumes. This was made possible with the help of libntfs-3g from the
53 NTFS-3g project. This feature supports capturing and restoring NTFS-specific
54 data such as security descriptors, alternate data streams, and reparse point
57 The code for NTFS image capture and image application is complete enough that it
58 is possible to apply an image from the "install.wim" contained in recent Windows
59 installation media (Vista, Windows 7, or Windows 8) directly to a NTFS volume,
60 and then boot Windows from it after preparing the Boot Configuration Data. In
61 addition, a Windows installation can be captured (or backed up) into a WIM file,
62 and then re-applied later.
66 wimlib provides a public API for other programs to use, but also comes with two
67 programs: `imagex' and `mkwinpeimg'.
69 `imagex' is intended to be like the imagex.exe program from Windows. `imagex'
70 can be used to create, extract, and mount WIM files. Both read-only and
71 read-write mounts are supported. See the man page `doc/imagex.1' for more
74 `mkwinpeimg' is shell script that makes it easy to create a customized bootable
75 image of Windows PE that can be put on a CD or USB drive, or published on a
76 server for PXE booting. See the main page `doc/mkwinpeiso.1' for more details.
80 wimlib can create XPRESS or LZX compressed WIM archives. As of wimlib v1.0.3,
81 the XPRESS compression ratio is slightly better than that provided by
82 Microsoft's software, while the LZX compression ratio is approaching that of
83 Microsoft's software but is not quite there yet. Running time is as good as or
84 better than Microsoft's software.
86 The following tables compare the compression ratio and performance for creating
87 a compressed Windows PE image (disk usage of about 524 MB, uncompressed WIM size
92 XPRESS Compression LZX Compression
93 wimlib imagex (v1.0.2): 145,283,871 bytes 139,288,293 bytes
94 wimlib imagex (v1.0.3): 139,288,293 bytes 131,379,869 bytes
95 Microsoft imagex.exe: 140,406,981 bytes 127,249,176 bytes
97 Table 2. Time to create WIM
99 XPRESS Compression LZX Compression
100 wimlib imagex (v1.0.2): 18 sec 49 sec
101 wimlib imagex (v1.0.3): 19 sec 30 sec
102 Microsoft imagex.exe: 25 sec 89 sec
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/.
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.
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
131 * syslinux (optional)
132 * cabextract (optional)
133 The `mkwinpeimg' shell script will look for several other programs
134 depending on what options are given to it. Depending on your GNU/Linux
135 distribution, you may already have these programs installed, or they may
136 be in the software repository. Making an ISO filesystem requires
137 `mkisofs' from `cdrkit' (http://www.cdrkit.org). Making a disk image
138 requires `mtools' (http://www.gnu.org/software/mtools) and `syslinux'
139 (http://www.syslinux.org). Retrieving files from the Windows Automated
140 Installation Kit requires `cabextract' (http://www.cabextract.org.uk).
145 Besides the various well-known options, the following options can be passed to
146 wimlib's `configure' script:
149 If libntfs-3g is not available or is not the correct version, we can
150 build without it. wimlib will then not be able to apply or capture
151 images directly to NTFS volumes.
154 If libfuse or the FUSE kernel module is not available, wimlib can be
155 compiled with --without-fuse. This will remove the ability to mount and
156 unmount WIM files. wimlib_mount() and wimlib_unmount() will fail with
157 WIMLIB_ERR_UNSUPPORTED.
160 Build in functions for SHA1 rather than using external SHA1 functions
161 from libcrypto (part of OpenSSL). The default is to use libcrypto if it
162 is found on the system.
164 --enable-xattr, --disable-xattr
165 Enable or disable support for the extended-attributes interface to NTFS
166 alternate data streams in mounted WIMs. To support these, we require
167 the setxattr() function and the attr/xattr.h header be available. The
168 default is to autodetect whether support is possible.
171 Use a very fast assembly language implementation of SHA1 from Intel.
172 Only use this if the build target supports the SSSE3 instructions.
174 --disable-custom-memory-allocator
175 If this option is given, MALLOC(), FREE(), CALLOC(), and STRDUP() will
176 directly call the appropriate functions in the C library.
177 wimlib_set_memory_allocator() will fail with WIMLIB_ERR_UNSUPPORTED.
179 --disable-verify-compression
180 Unless this option is given, every time wimlib compresses a data block
181 it will decompress it into a temporary buffer and abort() the program
182 with an error message if the decompressed data does not exactly match
183 the original data. This is to find bugs.
185 --disable-error-messages
186 Removes all error messages from the library. If left in, they still
187 have to explicitly turned on with wimlib_set_print_errors() in order to
188 see them. Also, error codes will still be returned regardless of
189 whether error messages are printed or not.
191 If --disable-error-messages is given, wimlib_set_print_errors() will
192 fail with WIMLIB_ERR_UNSUPPORTED if the action is to turn error messages
196 Remove all assertions. Without this option, wimlib will abort() the
197 program if an assertion fails. An assertion failure should only occur
198 if there is a bug in wimlib.
201 Include debugging messages. Only use this option if you have found a
205 Include more debugging messages. Only use this option if you have found
206 a bug in the library.
210 wimlib has mostly been developed and tested on x86_64 (64-bit) GNU/Linux.
212 It has been tested on x86 (32-bit) GNU/Linux occasionally.
214 wimlib may work on FreeBSD. However, this is not well tested. If you do not
215 have libntfs-3g 2011-4-12 or later available, you must configure with
216 --without-ntfs-3g. Also, GNU coreutils is needed to run the test suite. Before
217 mounting a WIM you need to load the POSIX message queue module (run `kldload
220 wimlib should work on big endian machines but it has not been tested.
222 There are no plans to port wimlib to Windows since the programming interface on
223 Windows is very different and Microsoft's imagex.exe is already available.
227 The WIM file format is specified in a document that can be found in the
228 Microsoft Download Center. There is a similar document that specifies the LZX
229 compression format, and a document that specifies the XPRESS compression format.
230 However, many parts of these formats are poorly documented, and some parts have
231 no documentation whatsoever. Some particularly poorly documented parts of the
232 formats have had comments added in various places in the library. Please see
233 the code and/or ask me if you have any questions about the WIM file format as it
234 exists in reality and not as it exists in Microsoft's poorly written
237 The code in ntfs-apply.c and ntfs-capture.c uses the NTFS-3g library, which is a
238 library for reading and writing to NTFS filesystems (the filesystem used by
239 recent versions of Windows). See
240 http://www.tuxera.com/community/ntfs-3g-download/ for more information.
242 lzx-decomp.c, the code to decompress WIM file resources that are compressed
243 using LZX compression, is originally based on code from the cabextract project
244 (http://www.cabextract.org.uk).
246 lzx-comp.c, the code to compress WIM file resources using LZX compression, is
247 originally based on code written by Matthew Russotto (www.russotto.net/chm/).
249 lz.c, the code to find LZ77 matches (used for both XPRESS and LZX compression),
250 is based on code from zlib.
252 A very limited number of other free programs can handle some parts of the WIM
253 file format. 7-zip is able to extract and create WIMs (as well as files in many
254 other archive formats). However, wimlib is designed specifically to handle WIM
255 files and provides features previously only available in Microsoft's imagex.exe,
256 such as the ability to mount WIMs read-write as well as read-only, and the
257 ability to create LZX or XPRESS compressed WIMs.
259 An earlier version of wimlib is being used to deploy Windows 7 from the Ultimate
260 Deployment Appliance. For more information see
261 http://www.ultimatedeployment.org/.
263 You can see the documentation about Microsoft's version of the imagex program at
264 http://technet.microsoft.com/en-us/library/cc749447(v=ws.10).aspx, so you can
267 GNU/Linux equivalents of WIM format
269 What's the equivalent way to capture the filesystem of a GNU/Linux operating
270 system into an archive file? You have a few options:
273 SquashFS (http://squashfs.sourceforge.net/) provides a compressed,
274 read-only filesystem for Linux, and it's probably the closest equivalent
275 of the WIM format and better designed. Although you can't mount
276 SquashFS read-write, when wimlib does this for WIM files it's really an
277 illusion since the WIM isn't actually modified until the image is
278 unmounted. Multiple top-level images in SquashFS files are not
279 supported, although nothing stops you from just putting each image in a
283 FSArchiver (http://www.fsarchiver.org/Main_Page) is not widely used, but
284 it appears to have some features quite similar to the WIM format.
287 The well-known tar format can usually capture a UNIX filesystem just
288 fine, and compressing the tar file produces a good compression ratio
289 (better than WIM, especially if using XZ compression), but there is no
290 support for random access, file deduplication, multiple images per
291 archive, or extended attributes.
294 Zip shares some features with WIM but is not designed to store entire
298 The 7z format has some nice features but is unfortunately not designed
303 See the manual pages for `imagex', the manual pages for the subcommands of
304 `imagex', and the manual page for `mkwinpeimg'.
306 As of version 0.5.0, wimlib's public API is documented. Doxygen is required to
307 build the documentation. To build the documentation, run `configure', then
308 enter the directory `doc' and run `doxygen'. The HTML documentation will be
309 created in a directory named `html'.
313 As of version 1.0.0, wimlib is released under the GNU GPL version 3.0 or later.
314 This includes the files in the `programs' directory as well as the files in the
317 wimlib is independently developed and does not contain any code, data, or files
318 copyrighted by Microsoft. It is not known to be affected by any patents.
322 wimlib is experimental. Use Microsoft's `imagex.exe' if you want to make sure
323 your WIM files are made correctly (but beware: Microsoft's version contains some
326 Please submit a bug report (to ebiggers3@gmail.com) if you find a bug in wimlib.
328 Some parts of the WIM file format are poorly documented or even completely
329 undocumented, so I've just had to do the best I can to read and write WIMs that
330 appear to be compatible with Microsoft's software.