This is wimlib version 1.7.1-BETA (June 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.
+Format (WIM files). wimlib and its command-line frontend 'wimlib-imagex'
+provide a free and cross-platform alternative to Microsoft's WIMGAPI, ImageX,
+and DISM.
INSTALLATION
-To install wimlib and wimlib-imagex on Windows you simply need to download and
-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 Windows, simply download and extract the
+ZIP file containing the latest binaries from the SourceForge page
+(http://sourceforge.net/projects/wimlib/). You probably have already done this!
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
wimlib includes its own compression codecs and does not use the compression API
available on some versions of Windows.
-I have gradually been improving the compression codecs in wimlib, and in some
-cases they now outperform and outcompress the equivalent Microsoft
+I have gradually been improving the compression codecs in wimlib. For XPRESS
+and LZX, they now usually outperform and outcompress the equivalent Microsoft
implementations. Although results will vary depending on the data being
compressed, in the table below I present the results for a common use case:
compressing an x86 Windows PE image. Each row displays the compression type,
implementation in WIMGAPI is included.
=============================================================================
- | Compression type || wimlib (v1.7.0) | WIMGAPI (Windows 8.1) |
+ | Compression || wimlib (v1.7.1) | WIMGAPI (Windows 8.1) |
=============================================================================
- | None [1] || 361,182,560 in 7.6s | 361,183,674 in 11.9s |
- | XPRESS [2] || 138,992,007 in 11.5s | 140,416,657 in 13.9s |
- | LZX (quick) [3] || 131,428,113 in 15.2s | N/A |
- | LZX (normal) [4] || 126,807,853 in 58.9s | 127,259,566 in 55.2s |
- | LZX (slow) [5] || 126,085,971 in 125s | N/A |
- | LZMS (non-solid) [6] || 122,082,982 in 59.8s | N/A |
- | LZMS (solid) [7] || 92,171,126 in 260s | 88,742,356 in 556s |
+ | None [1] || 361,182,560 in 3.7s | 361,183,674 in 4.4s |
+ | XPRESS [2] || 138,349,798 in 5.8s | 140,416,657 in 6.8s |
+ | XPRESS (slow) [3] || 135,234,072 in 19.5s | N/A |
+ | LZX (quick) [4] || 131,816,279 in 6.7s | N/A |
+ | LZX (normal) [5] || 126,808,347 in 28.3s | 127,259,566 in 31.4s |
+ | LZX (slow) [6] || 126,199,523 in 61.4s | N/A |
+ | LZMS (non-solid) [7] || 122,083,126 in 30.4s | N/A |
+ | LZMS (solid) [8] || 93,752,206 in 84.3s | 88,742,238 in 156.1s |
+ | "WIMBoot" [9] || 167,039,787 in 7.6s | 169,051,718 in 14.9s |
+ | "WIMBoot" (slow) [10] || 165,141,503 in 15.8s | N/A |
=============================================================================
Notes:
- [1] '--compress=none' for wimlib-imagex;
- '/compress:none' for DISM.
+ [1] '--compress=none' for wimlib-imagex; '/compress:none' for DISM.
- [2] '--compress=fast' or '--compress=XPRESS' for wimlib-imagex;
- '/compress:fast' for DISM.
- Compression chunk size is 32768 bytes, the default for XPRESS.
+ [2] '--compress=XPRESS' for wimlib-imagex; '/compress:fast' for DISM.
+ Compression chunk size defaults to 32768 bytes in both cases.
- [3] No compression option specified to wimlib-imagex;
- no known equivalent for DISM.
- Compression chunk size is 32768 bytes, the default for LZX.
+ [3] '--compress=XPRESS:80' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
- [4] '--compress=maximum' or '--compress=LZX' for wimlib-imagex;
+ [4] '--compress=LZX:20' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [5] '--compress=LZX' or '--compress=LZX:50' or no option for wimlib-imagex;
'/compress:maximum' for DISM.
- Compression chunk size is 32768 bytes, the default for LZX.
+ Compression chunk size defaults to 32768 bytes in both cases.
+
+ [6] '--compress=LZX:100' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [7] '--compress=LZMS' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 131072 bytes.
+
+ [8] '--solid' for wimlib-imagex. Should be '/compress:recovery' for DISM,
+ but only works for /Export-Image, not /Capture-Image. Compression chunk
+ size in solid blocks defaults to 33554432 for wimlib, 67108864 for DISM.
+
+ [9] '--wimboot' for wimlib-imagex; '/wimboot' for DISM.
+ This is really XPRESS compression with 4096 byte chunks, so the same as
+ '--compress=XPRESS --chunk-size=4096'.
- [5] '--compress=maximum --compress-slow' for wimlib-imagex;
- no known equivalent for DISM.
- Compression chunk size is 32768 bytes, the default for LZX.
+ [10] '--wimboot --compress=XPRESS:80' for wimlib-imagex;
+ no known equivalent for DISM.
+ Same format as [9], but trying harder to get a good compression ratio.
- [6] '--compress=recovery' or '--compress=LZMS' for wimlib-imagex;
- no known equivalent for DISM.
- Compression chunk size is 131072 bytes, the default for LZMS.
+Note: wimlib-imagex's --compress option also accepts the "fast", "maximum", and
+"recovery" aliases for XPRESS, LZX, and LZMS, respectively.
- [7] '--compress=recovery --solid' or '--compress=LZMS --solid' for
- wimlib-imagex. Should be '/compress:recovery' for DISM, but it doesn't
- work; I called WIMGAPI directly instead.
- Compression chunk size in solid blocks is 67108864 bytes in both cases.
+Testing environment:
-I did the timings on Windows 8.1 running in a virtual machine so that
-side-by-side comparisons with the Microsoft implementation would be possible.
-However, do note that wimlib may have even better performance on other operating
-systems such as Linux. I used the 64-bit builds of both programs.
+ - 64 bit binaries
+ - Windows 8.1 virtual machine running on Linux with VT-x
+ - 2 CPUs and 2 GiB memory given to virtual machine
+ - SSD-backed virtual disk
+ - All tests done with page cache warmed
The compression ratio provided by wimlib is also competitive with commonly used
archive formats. Below are file sizes that result when the Canterbury corpus is
PORTABILITY
-wimlib has primarily been tested on Linux and Windows (primarily Windows 7, but
-also Windows XP and Windows 8).
+wimlib works on both UNIX-like systems (Linux, Mac OS X, FreeBSD, etc.) and
+Windows (XP and later).
-wimlib may work on FreeBSD and Mac OS X. However, this is not well tested. If
-you do not have libntfs-3g 2011-4-12 or later available, you must configure
-wimlib with --without-ntfs-3g. On FreeBSD, before mounting a WIM you need to
-load the POSIX message queue module (run `kldload mqueuefs').
+On UNIX-like systems other than Linux, you must compile --without-fuse.
+In addition, --without-ntfs-3g and --without-libcrypto are needed if the
+corresponding libraries are not available on your system.
-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.
+wimlib works on x86 and x86_64, but it should work on any other GCC-supported
+32-bit or 64-bit architecture.
REFERENCES
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.
+overview of the format and is not a formal specification. It also does not
+cover later extensions of the format, such as solid blocks.
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.
+- Microsoft has official documentation for LZX, but in two different documents,
+ neither of which is completely applicable to its use in the WIM format, and
+ the first of which contains multiple 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 algorithms used by wimlib's compression and decompression codecs are
+inspired by a variety of sources, including open source projects and computer
+science papers.
+
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.
-The LZX decompressor (lzx-decompress.c) was originally based on code from the
-cabextract project (http://www.cabextract.org.uk). The LZX compressor
-(lzx-compress.c) was originally based on code written by Matthew Russotto
-(www.russotto.net/chm/). However I have since rewritten and made many
-improvements to both the decompressor and compressor.
-
-lz_hash.c contains LZ77 match-finding code that uses hash chains. It is based
-on code from zlib but I have since rewritten it.
-
-lz_bt.c contains LZ77 match-finding code that uses binary trees. It is based on
-code from liblzma but I have since rewritten it.
-
A limited number of other free programs can handle some parts of the WIM
file format:
other archive formats). However, wimlib is designed specifically to handle
WIM files and provides features previously only available in Microsoft's
implementation, such as the ability to mount WIMs read-write as well as
- read-only, the ability to create compressed WIMs, and the correct handling
- of security descriptors and hard links.
+ read-only, the ability to create compressed WIMs, the correct handling of
+ security descriptors and hard links, support for LZMS compression, and
+ support for solid archives.
* ImagePyX (https://github.com/maxpat78/ImagePyX) is a Python program that
provides similar capabilities to wimlib-imagex. One thing to note, though,
is that it does not support compression and decompression by itself, but
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
-WIMs that appear to be compatible with Microsoft's software.
git://wimlib.net / wimlib / blobdiff