INTRODUCTION
-This is wimlib version 1.4.1 (May 2013). wimlib is a C library for creating,
-modifying, extracting, and mounting files in the Windows Imaging Format (WIM
-files). These files are normally created by using the `imagex.exe' utility on
-Windows, but wimlib is distributed with a free implementation of ImageX called
-"wimlib-imagex" for both UNIX and Windows.
+This is wimlib version 1.6.1 (January 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.
INSTALLATION
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 UNIX (with Linux being the primary
-supported and tested platform), you must compile it from the source code. At
-some point I might start posting RPMs and Debian packages for convenience.
+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
+is also available at http://sourceforge.net/projects/wimlib/. Alternatively,
+check if a package has been prepared for your Linux distribution. Example files
+for Debian and RPM packaging are in the debian/ and rpm/ directories.
WIM FILES
A Windows Imaging (WIM) file is an archive designed primarily for archiving
Windows filesystems. However, it can be used on other platforms as well, with
some limitations. Like some other archive formats such as ZIP, files in WIM
-archives may be compressed. WIM files support two compression formats: LZX and
-XPRESS. Both are supported by wimlib.
+archives may be compressed. WIM files support multiple compression formats,
+including LZX, XPRESS, and LZMS. All these formats are supported by wimlib.
A WIM file consists of one or more "images". Each image is an independent
top-level directory structure and is logically separate from all other images in
distributed with a command-line program called "wimlib-imagex" that uses this
library to implement an imaging tool similar to Microsoft's ImageX.
wimlib-imagex supports almost all the capabilities of Microsoft's ImageX as well
-as additional capabilities. wimlib-imagex works on both UNIX and Windows,
-although some features differ between the platforms.
+as additional capabilities. wimlib-imagex works on both UNIX-like systems and
+Windows, although some features differ between the platforms.
Run `wimlib-imagex' with no arguments to see an overview of the available
commands and their syntax. For additional documentation:
- * If you have installed wimlib-imagex on UNIX, you will find further
- documentation in the man pages; run `man wimlib-imagex' to get started.
+ * If you have installed wimlib-imagex on a UNIX-like system, you will find
+ further documentation in the man pages; run `man wimlib-imagex' to get
+ started.
* If you have downloaded the Windows binary distribution, you will find the
documentation for wimlib-imagex in PDF format in the "doc" directory,
COMPRESSION RATIO
-wimlib (and wimlib-imagex) can create XPRESS or LZX compressed WIM archives.
-Currently, the XPRESS compression ratio is slightly better than that provided by
-Microsoft's software, while the LZX compression ratio is approaching that of
-Microsoft's software but is not quite there yet. Running time is as good as or
-better than Microsoft's software, especially with multithreaded compression,
-available in wimlib v1.1.0 and later.
-
-The following tables compare the compression ratio and performance for creating
-a compressed x86_64 Windows PE image. Note: these timings were done on Windows
-7 so that the times would be fully comparable; however, wimlib-imagex may have
-even better performance on Linux.
-
- Table 1. WIM size
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.4.0): 165,301,379 bytes 155,254,385 bytes
- Microsoft imagex.exe: 167,212,939 bytes 149,973,212 bytes
-
- Table 2. Time to create WIM
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.4.0, 2 threads): 18 sec 51 sec
- Microsoft imagex.exe: 25 sec 93 sec
+wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM
+archives. wimlib includes its own compression codecs and does not use the
+compression API available on some versions of Windows. The below table provides
+the results (file size, in bytes, and time to create, in seconds) of capturing a
+WIM containing an x86 Windows PE image, using various compression types and
+options. When applicable, the results with the equivalent Microsoft
+implementation in WIMGAPI, which is the library used by ImageX and Dism, are
+included.
+
+ ===========================================================================
+ | Compression type || wimlib (v1.6.1) | WIMGAPI (Windows 8) |
+ ===========================================================================
+ | None [1] || 531,979,435 in 18s | 531,980,333 in 24s |
+ | XPRESS [2] || 207,369,912 in 22s | 209,886,010 in 39s |
+ | LZX (quick) [3] || 194,876,901 in 29s | N/A |
+ | LZX (normal) [4] || 187,962,713 in 158s | 188,163,523 in 125s |
+ | LZX (slow) [5] || 186,913,423 in 358s | N/A |
+ | LZMS (non-solid) [6] || 176,880,594 in 182s | N/A |
+ | LZMS (solid) [7] || 136,507,304 in 494s | 126,735,608 in 623s |
+ ===========================================================================
+
+Notes:
+ [1] '--compress=none' for wimlib-imagex;
+ '/compress none' or no option for ImageX.
+
+ [2] '--compress=fast' or '--compress=XPRESS' for wimlib-imagex;
+ '/compress fast' or no option for ImageX.
+ Compression chunk size is 32768 (the default for XPRESS).
+
+ [3] No compression option specified to wimlib-imagex; no known equivalent for
+ WIMGAPI (ImageX uses XPRESS compression if no option specified).
+ Compression chunk size is 32768 (the default for LZX).
+
+ [4] '--compress=maximum' or '--compress=LZX' for wimlib-imagex;
+ '/compress maximum' for ImageX.
+ Compression chunk size is 32768 (the default for LZX).
+
+ [5] '--compress=maximum --compress-slow' for wimlib-imagex;
+ no known equivalent for WIMGAPI.
+ Compression chunk size is 32768 (the default for LZX).
+
+ [6] '--compress=recovery' or '--compress=LZMS' for wimlib-imagex;
+ no known way to create the equivalent with WIMGAPI.
+ Compression chunk size is 131072 (the default for LZMS). Note: this
+ compression type is not generally recommended due to its limited
+ compatibility with the MS implementations.
+
+ [7] '--compress=recovery --solid' or '--compress=LZMS --solid' for
+ wimlib-imagex; WIMCreateFile with WIM_COMPRESSION_LZMS and flag
+ 0x20000000 for WIMGAPI. Compression chunk size in packed resources is
+ 33554432 for wimlib, 67108864 for WIMGAPI. Note: this compression type
+ is not generally recommended due to its limited compatibility with the MS
+ implementations. Also, due to the large chunk size, wimlib uses about
+ 500MB of memory per thread when compressing in this format.
+
+The above timings were done on Windows 8 (x86) so that side-by-side comparisons
+with the Microsoft implementation would be possible; however, wimlib may have
+even better performance on other operating systems such as Linux. The system
+had 2 CPUs and 2 GiB of memory available. All times were done with the page
+cache warmed, so the times primarily measure the performance of the compression
+algorithms and not the time to read data from disk, which presumably is similar
+in each implementation.
+
+Below are results for compressing the Canterbury corpus using wimlib (v1.6.1),
+WIMGAPI (Windows 8), and some other formats/programs, including the archive size
+only. Note that the Canterbury corpus includes no duplicate files or hard
+links, which WIM handles better than most other formats by storing only distinct
+data streams.
+
+ =================================================
+ | 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) | 639,464 |
+ | WIM (wimlib, LZX slow) | 633,144 |
+ | WIM (wimlib, LZMS non-solid) | 590,252 |
+ | tar.bz2 (bzip, default) | 565,008 |
+ | tar.bz2 (bzip, -9) | 565,008 |
+ | WIM (wimlib, LZMS solid) | 534,218 |
+ | WIM (wimlib, LZMS solid, slow) | 529,904 |
+ | 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 |
+ =================================================
NTFS SUPPORT
WINDOWS PE
A major use for wimlib and wimlib-imagex is to create customized images of
-Windows PE, the Windows Preinstallation Environment, on either UNIX or Windows
-without having to rely on Microsoft's software and its restrictions and
-limitations.
+Windows PE, the Windows Preinstallation Environment, on either UNIX-like systems
+or Windows without having to rely on Microsoft's software and its restrictions
+and limitations.
Windows PE is a lightweight version of Windows that can run entirely from memory
and can be used to install Windows from local media or a network drive or
Windows 8, in the file `sources/boot.wim'. Windows PE can also be found in the
Windows Automated Installation Kit (WAIK), which is free to download from
Microsoft, inside the `WinPE.cab' file, which you can extract natively on
-Windows, or on UNIX if you install either the `cabextract' or `p7zip' programs.
+Windows, or on UNIX-like systems if you install either the `cabextract' or
+`p7zip' programs.
In addition, Windows installations and recovery partitions frequently contain a
WIM containing an image of the Windows Recovery Environment, which is similar to
Windows PE.
-A shell script `mkwinpeimg' is distributed with wimlib on UNIX to ease the
-process of creating and customizing a bootable Windows PE image.
+A shell script `mkwinpeimg' is distributed with wimlib on UNIX-like systems to
+ease the process of creating and customizing a bootable Windows PE image.
DEPENDENCIES
This section documents the dependencies of wimlib and the programs distributed
-with it, when building for UNIX from source. If you have downloaded the Windows
-binary distribution of wimlib and wimlib-imagex then all dependencies were
-already included and this section is irrelevant.
+with it, when building for a UNIX-like system from source. If you have
+downloaded the Windows binary distribution of wimlib and wimlib-imagex then all
+dependencies were already included and this section is irrelevant.
* libxml2 (required)
This is a commonly used free library to read and write XML files. You
CONFIGURATION
This section documents the most important options that may be passed to the
-"configure" script when building the UNIX version from source:
+"configure" script when building from source:
--without-ntfs-3g
If libntfs-3g is not available or is not version 2011-4-12 or later,
wimlib with --without-ntfs-3g. On FreeBSD, before mounting a WIM you need to
load the POSIX message queue module (run `kldload mqueuefs').
-wimlib has not been tested on big-endian CPU architectures.
+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.
REFERENCES
-The WIM file format is specified in a document that can be found in the
-Microsoft Download Center. There is a similar document that specifies the LZX
-compression format, and a document that specifies the XPRESS compression format.
-However, many parts of these formats are poorly documented, and some parts have
-no documentation whatsoever. Some particularly poorly documented parts of the
-formats have had comments added in various places in the library code. Please
-see the code and/or ask me if you have any questions about the WIM file format
-as it exists in reality and not as it exists in Microsoft's poorly written
-documentation.
+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.
+
+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.
+- 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 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.
-lzx-decompress.c, the code to decompress WIM file resources that are compressed
-using LZX compression, was originally based on code from the cabextract project
-(http://www.cabextract.org.uk) but has been rewritten.
+The LZX decompressor (lzx-decompress.c) was originally based on code from the
+cabextract project (http://www.cabextract.org.uk) but has been rewritten.
-lzx-compress.c, the code to compress WIM file resources using LZX compression,
-was originally based on code written by Matthew Russotto (www.russotto.net/chm/)
-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.
-lz77.c, the code to find LZ77 matches (used for both XPRESS and LZX
-compression), is based on code from zlib but has been rewritten.
+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:
* 7-zip is able to extract and create WIMs (as well as files in many
other archive formats). However, wimlib is designed specifically to handle
WIM files and provides features previously only available in Microsoft's
- imagex.exe, such as the ability to mount WIMs read-write as well as
+ 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.
* ImagePyX (https://github.com/maxpat78/ImagePyX) is a Python program that
Ultimate Deployment Appliance. For more information see
http://www.ultimatedeployment.org/.
-You can see the documentation about Microsoft's version of ImageX at
-http://technet.microsoft.com/en-us/library/cc749447(v=ws.10).aspx, so you can
-see how it compares to wimlib-imagex.
-
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/).
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.
-On UNIX, if you do not want wimlib to be dynamically linked with libcrypto
-(OpenSSL), configure with --without-libcrypto. This replaces the SHA1
+On UNIX-like systems, if you do not want wimlib to be dynamically linked with
+libcrypto (OpenSSL), configure with --without-libcrypto. This replaces the SHA1
implementation with built-in code and there will be no difference in
functionality.
DISCLAIMER
-wimlib comes with no warranty whatsoever. Use Microsoft's `imagex.exe' if you
-want to make sure your WIM files are made "correctly" (but beware: Microsoft's
-version contains some bugs).
-
-Please submit a bug report (to ebiggers3@gmail.com) if you find a bug in wimlib
-and/or wimlib-imagex.
+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
git://wimlib.net / wimlib / blobdiff