3 This is wimlib version 1.2.3 (January 2013). 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.
43 There is an additional program, `wimapply', that is not installed by default.
44 It can be used to build a small executable with the ability to apply a WIM image
45 from a standalone WIM, without having to build the whole shared library. This
46 could be useful on Linux boot clients that only need to be able to apply a WIM,
47 not capture/split/join/append/export/mount a WIM. See `programs/wimapply.c'.
51 wimlib can create XPRESS or LZX compressed WIM archives. Currently, the XPRESS
52 compression ratio is slightly better than that provided by Microsoft's software,
53 while the LZX compression ratio is approaching that of Microsoft's software but
54 is not quite there yet. Running time is as good as or better than Microsoft's
55 software, especially with multithreaded compression, available in wimlib v1.1.0
58 The following tables compare the compression ratio and performance for creating
59 a compressed Windows PE image (disk usage of about 524 MB, uncompressed WIM size
64 XPRESS Compression LZX Compression
65 wimlib imagex (v1.2.1): 138,971,353 bytes 131,379,943 bytes
66 Microsoft imagex.exe: 140,406,981 bytes 127,249,176 bytes
68 Table 2. Time to create WIM
70 XPRESS Compression LZX Compression
71 wimlib imagex (v1.2.1, 2 threads): 11 sec 17 sec
72 Microsoft imagex.exe: 25 sec 89 sec
76 As of version 1.0.0, wimlib supports capturing and applying images directly to
77 NTFS volumes. This was made possible with the help of libntfs-3g from the
78 NTFS-3g project. This feature supports capturing and restoring NTFS-specific
79 data such as security descriptors, alternate data streams, and reparse point
82 The code for NTFS image capture and image application is complete enough that it
83 is possible to apply an image from the "install.wim" contained in recent Windows
84 installation media (Vista, Windows 7, or Windows 8) directly to a NTFS volume,
85 and then boot Windows from it after preparing the Boot Configuration Data. In
86 addition, a Windows installation can be captured (or backed up) into a WIM file,
87 and then re-applied later.
91 A major use for this library is to create customized images of Windows PE, the
92 Windows Preinstallation Environment, without having to rely on Windows. Windows
93 PE is a lightweight version of Windows that can run entirely from memory and can
94 be used to install Windows from local media or a network drive or perform
95 maintenance. Windows PE is the operating system that runs when you boot from
96 the Windows installation media.
98 You can find Windows PE on the installation DVD for Windows Vista, Windows 7, or
99 Windows 8, in the file `sources/boot.wim'. Windows PE can also be found in the
100 Windows Automated Installation Kit (WAIK), which is free to download from
101 Microsoft, inside the `WinPE.cab' file, which you can extract if you install
102 either the `cabextract' or `p7zip' programs.
104 In addition, Windows installations and recovery partitions frequently contain a
105 WIM containing an image of the Windows Recovery Environment, which is similar to
111 This is a commonly used free library to read and write XML files. You
112 likely already have it installed as a dependency for some other program.
113 For more information see http://xmlsoft.org/.
115 * libfuse (optional but highly recommended)
116 Unless configured with --without-fuse, wimlib requires a non-ancient
117 version of libfuse to be installed. Most GNU/Linux distributions
118 already include this, but make sure you have the libfuse package
119 installed, and also libfuse-dev if your distribution distributes header
120 files separately. FUSE also requires a kernel module. If the kernel
121 module is available it will automatically be loaded if you try to mount
122 a WIM file. For more information see http://fuse.sourceforge.net/.
123 FUSE is also available for FreeBSD.
125 * libntfs-3g (optional but highly recommended)
126 Unless configured with --without-ntfs-3g, wimlib requires the library
127 and headers for libntfs-3g version 2011-4-12 or later to be installed.
128 Versions dated 2010-3-6 and earlier do not work because they are missing
129 the header xattrs.h (and the file xattrs.c, which contains functions we
132 * OpenSSL / libcrypto (optional)
133 wimlib can use the SHA1 message digest code from OpenSSL instead of
134 compiling in yet another SHA1 implementation. (See LICENSE section.)
138 * syslinux (optional)
139 * cabextract (optional)
140 The `mkwinpeimg' shell script will look for several other programs
141 depending on what options are given to it. Depending on your GNU/Linux
142 distribution, you may already have these programs installed, or they may
143 be in the software repository. Making an ISO filesystem requires
144 `mkisofs' from `cdrkit' (http://www.cdrkit.org). Making a disk image
145 requires `mtools' (http://www.gnu.org/software/mtools) and `syslinux'
146 (http://www.syslinux.org). Retrieving files from the Windows Automated
147 Installation Kit requires `cabextract' (http://www.cabextract.org.uk).
151 Besides the various well-known options, the following options can be passed to
152 wimlib's `configure' script:
155 If libntfs-3g is not available or is not version 2011-4-12 or later,
156 wimlib can be built without it, in which case it will not be possible to
157 apply or capture images directly to/from NTFS volumes.
160 If libfuse or the FUSE kernel module is not available, wimlib can be
161 compiled with --without-fuse. This will remove the ability to mount and
165 Build in functions for SHA1 rather than using external SHA1 functions
166 from libcrypto (part of OpenSSL). The default is to use libcrypto if it
167 is found on the system.
169 --enable-xattr, --disable-xattr
170 Enable or disable support for the extended-attributes interface to NTFS
171 alternate data streams in mounted WIMs. To support these, wimlib
172 requires that the setxattr() function and the attr/xattr.h header are
173 available. The default is to autodetect whether support is possible.
175 --disable-multithreaded-compression
176 By default, data will be compressed using multiple threads when writing
177 a WIM, unless only 1 processor is detected. Specify this option to
178 disable support for this.
181 Use a very fast assembly language implementation of SHA1 from Intel.
182 Only use this if the build target supports the SSSE3 instructions.
184 --disable-custom-memory-allocator
185 If this option is given, a very small amount of space will be saved by
186 removing support for the wimlib_set_memory_allocator() function. imagex
189 --disable-verify-compression
190 Unless this option is given, every time wimlib compresses a data block,
191 it will decompress it into a temporary buffer and abort the program with
192 an error message if the decompressed data does not exactly match the
193 original data. This only makes compression about 10% slower. However,
194 this checking can probably be safely disabled because there are no known
195 bugs in the compression code, and the SHA1 message digest of every
196 extracted file is checked anyway.
198 --disable-error-messages
199 Save some space by removing all error messages from the library.
202 Remove all assertions, even the ones that are included by default.
204 --enable-more-assertions
205 Enable assertions that are not included by default.
208 Include debugging messages. Only use this option if you have found a
212 Include more debugging messages. Only use this option if you have found
213 a bug in the library.
217 wimlib has mostly been developed and tested on x86_64 (64-bit) GNU/Linux.
219 It has been tested on x86 (32-bit) GNU/Linux occasionally.
221 wimlib may work on FreeBSD and Mac OS X. However, this is not well tested. If
222 you do not have libntfs-3g 2011-4-12 or later available, you must configure
223 wimlib with --without-ntfs-3g. On FreeBSD, before mounting a WIM you need to
224 load the POSIX message queue module (run `kldload mqueuefs').
226 The code pays attention to endianness, so it should work on big-endian
227 architectures, but I've never tested this so do not expect it to work.
229 There are no plans to port wimlib to Windows since the programming interface on
230 Windows is very different and Microsoft's imagex.exe is already available.
234 The WIM file format is specified in a document that can be found in the
235 Microsoft Download Center. There is a similar document that specifies the LZX
236 compression format, and a document that specifies the XPRESS compression format.
237 However, many parts of these formats are poorly documented, and some parts have
238 no documentation whatsoever. Some particularly poorly documented parts of the
239 formats have had comments added in various places in the library. Please see
240 the code and/or ask me if you have any questions about the WIM file format as it
241 exists in reality and not as it exists in Microsoft's poorly written
244 The code in ntfs-apply.c and ntfs-capture.c uses the NTFS-3g library, which is a
245 library for reading and writing to NTFS filesystems (the filesystem used by
246 recent versions of Windows). See
247 http://www.tuxera.com/community/ntfs-3g-download/ for more information.
249 lzx-decompress.c, the code to decompress WIM file resources that are compressed
250 using LZX compression, is originally based on code from the cabextract project
251 (http://www.cabextract.org.uk).
253 lzx-compress.c, the code to compress WIM file resources using LZX compression,
254 is originally based on code written by Matthew Russotto (www.russotto.net/chm/).
256 lz77.c, the code to find LZ77 matches (used for both XPRESS and LZX compression),
257 is based on code from zlib.
259 A very limited number of other free programs can handle some parts of the WIM
260 file format. 7-zip is able to extract and create WIMs (as well as files in many
261 other archive formats). However, wimlib is designed specifically to handle WIM
262 files and provides features previously only available in Microsoft's imagex.exe,
263 such as the ability to mount WIMs read-write as well as read-only, and the
264 ability to create LZX or XPRESS compressed WIMs.
266 An earlier version of wimlib is being used to deploy Windows 7 from the Ultimate
267 Deployment Appliance. For more information see
268 http://www.ultimatedeployment.org/.
270 You can see the documentation about Microsoft's version of the imagex program at
271 http://technet.microsoft.com/en-us/library/cc749447(v=ws.10).aspx, so you can
272 see how it compares to the version provided by this library.
274 GNU/Linux equivalents of WIM format
276 What's the equivalent way to capture the filesystem of a GNU/Linux operating
277 system into an archive file? You have a few options:
280 SquashFS (http://squashfs.sourceforge.net/) provides a compressed,
281 read-only filesystem for Linux, and it's probably the closest equivalent
282 of the WIM format and better designed. Although you can't mount
283 SquashFS read-write, when wimlib does this for WIM files it's really an
284 illusion since the WIM isn't actually modified until the image is
285 unmounted. Multiple top-level images in SquashFS files are not
286 supported, although nothing stops you from just putting each image in a
290 FSArchiver (http://www.fsarchiver.org/Main_Page) is not widely used, but
291 it appears to have some features quite similar to the WIM format.
294 The well-known tar format can usually capture a UNIX filesystem just
295 fine, and compressing the tar file produces a good compression ratio
296 (better than WIM, especially if using XZ compression), but there is no
297 support for random access, file deduplication, multiple images per
298 archive, or extended attributes.
301 Zip shares some features with WIM but is not designed to store entire
305 The 7z format has some nice features but is unfortunately not designed
310 See the manual pages for `imagex', the manual pages for the subcommands of
311 `imagex', and the manual page for `mkwinpeimg'.
313 As of version 0.5.0, wimlib's public API is documented. Doxygen is required to
314 build the documentation. To build the documentation, run `configure', then
315 enter the directory `doc' and run `doxygen'. The HTML documentation will be
316 created in a directory named `html'.
320 As of version 1.0.0, wimlib is released under the GNU GPL version 3.0 or later.
321 This includes the files in the `programs' directory as well as the files in the
324 wimlib is independently developed and does not contain any code, data, or files
325 copyrighted by Microsoft. It is not known to be affected by any patents.
327 By default, wimlib will be linked to the system library "libcrypto", which
328 probably will be OpenSSL. Some people believe that GPL code cannot be linked to
329 OpenSSL without a linking exception. As far as I know, I cannot officially
330 include a linking exception with the license of this library because several
331 files could be considered derived works of code copyrighted by others. If you
332 believe this to be a problem, configure with --without-libcrypto to avoid
333 linking with OpenSSL. There is no difference in functionality--- there will
334 just be stand-alone SHA1 message digest code built into the library.
338 wimlib is experimental. Use Microsoft's `imagex.exe' if you want to make sure
339 your WIM files are made correctly (but beware: Microsoft's version contains some
342 Please submit a bug report (to ebiggers3@gmail.com) if you find a bug in wimlib.
344 Some parts of the WIM file format are poorly documented or even completely
345 undocumented, so I've just had to do the best I can to read and write WIMs that
346 appear to be compatible with Microsoft's software.
git://wimlib.net / wimlib / blob