PR libgcj/14856:

	* Imported zlib 1.2.1; merged local changes.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@88898 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 231 insertions, 16 deletions

diff --git a/zlib/FAQ b/zlib/FAQ
index 47a7d60c6de..7115ec38d60 100644
--- a/zlib/FAQ
+++ b/zlib/FAQ
@@ -1,8 +1,8 @@
 
-		Frequently Asked Questions about zlib
+                Frequently Asked Questions about zlib
 
 
-If your question is not there, please check the zlib home page 
+If your question is not there, please check the zlib home page
 http://www.zlib.org which may have more recent information.
 The lastest zlib FAQ is at http://www.gzip.org/zlib/zlib_faq.html
 
@@ -13,14 +13,15 @@ The lastest zlib FAQ is at http://www.gzip.org/zlib/zlib_faq.html
 
  2. Where can I get a Windows DLL version?
 
-    The zlib sources can be compiled without change to produce a DLL. If you
-    want a precompiled DLL, see http://www.winimage.com/zLibDll/ . Questions
-    about the zlib DLL should be sent to Gilles Vollant (info@winimage.com).
+    The zlib sources can be compiled without change to produce a DLL.
+    See the file win32/DLL_FAQ.txt in the zlib distribution.
+    Pointers to the precompiled DLL are found in the zlib web site at
+    http://www.zlib.org.
 
  3. Where can I get a Visual Basic interface to zlib?
 
     See
-        * http://www.winimage.com/zLibDll/cmp-z-it.zip
+        * http://www.winimage.com/zLibDll/
         * http://www.dogma.net/markn/articles/zlibtool/zlibtool.htm
         * contrib/visual-basic.txt in the zlib distribution
 
@@ -36,6 +37,11 @@ The lastest zlib FAQ is at http://www.gzip.org/zlib/zlib_faq.html
     Before making the call, make sure that avail_in and avail_out are not
     zero. When setting the parameter flush equal to Z_FINISH, also make sure
     that avail_out is big enough to allow processing all pending input.
+    Note that a Z_BUF_ERROR is not fatal--another call to deflate() or
+    inflate() can be made with more input or output space. A Z_BUF_ERROR
+    may in fact be unavoidable depending on how the functions are used, since
+    it is not possible to tell whether or not there is more output pending
+    when strm.avail_out returns with zero.
 
  6. Where's the zlib documentation (man pages, etc.)?
 
@@ -61,14 +67,13 @@ The lastest zlib FAQ is at http://www.gzip.org/zlib/zlib_faq.html
     If "make test" produces something like
 
        example.o(.text+0x154): undefined reference to `gzputc'
-      
+
     check that you don't have old files libz.* in /usr/lib, /usr/local/lib or
     /usr/X11R6/lib. Remove any old versions, then do "make install".
 
 10. I need a Delphi interface to zlib.
 
-    See the directories contrib/delphi and contrib/delphi2 in the zlib
-    distribution.
+    See the contrib/delphi directory in the zlib distribution.
 
 11. Can zlib handle .zip archives?
 
@@ -85,16 +90,226 @@ The lastest zlib FAQ is at http://www.gzip.org/zlib/zlib_faq.html
     ./configure -s
     make
 
-14. Why does "make test" fail on Mac OS X?
+14. How do I install a shared zlib library on Unix?
+
+    make install
 
-    Mac OS X already includes zlib as a shared library, and so -lz links the
-    shared library instead of the one that the "make" compiled. For zlib
-    1.1.3, the two are incompatible due to different compile-time
-    options. Simply change the -lz in the Makefile to libz.a, and it will use
-    the compiled library instead of the shared one and the "make test" will
-    succeed.
+    However, many flavors of Unix come with a shared zlib already installed.
+    Before going to the trouble of compiling a shared version of zlib and
+    trying to install it, you may want to check if it's already there! If you
+    can #include <zlib.h>, it's there. The -lz option will probably link to it.
 
 15. I have a question about OttoPDF
 
     We are not the authors of OttoPDF. The real author is on the OttoPDF web
     site Joel Hainley jhainley@myndkryme.com.
+
+16. Why does gzip give an error on a file I make with compress/deflate?
+
+    The compress and deflate functions produce data in the zlib format, which
+    is different and incompatible with the gzip format. The gz* functions in
+    zlib on the other hand use the gzip format. Both the zlib and gzip
+    formats use the same compressed data format internally, but have different
+    headers and trailers around the compressed data.
+
+17. Ok, so why are there two different formats?
+
+    The gzip format was designed to retain the directory information about
+    a single file, such as the name and last modification date. The zlib
+    format on the other hand was designed for in-memory and communication
+    channel applications, and has a much more compact header and trailer and
+    uses a faster integrity check than gzip.
+
+18. Well that's nice, but how do I make a gzip file in memory?
+
+    You can request that deflate write the gzip format instead of the zlib
+    format using deflateInit2(). You can also request that inflate decode
+    the gzip format using inflateInit2(). Read zlib.h for more details.
+
+    Note that you cannot specify special gzip header contents (e.g. a file
+    name or modification date), nor will inflate tell you what was in the
+    gzip header. If you need to customize the header or see what's in it,
+    you can use the raw deflate and inflate operations and the crc32()
+    function and roll your own gzip encoding and decoding. Read the gzip
+    RFC 1952 for details of the header and trailer format.
+
+19. Is zlib thread-safe?
+
+    Yes. However any library routines that zlib uses and any application-
+    provided memory allocation routines must also be thread-safe. zlib's gz*
+    functions use stdio library routines, and most of zlib's functions use the
+    library memory allocation routines by default. zlib's Init functions allow
+    for the application to provide custom memory allocation routines.
+
+    Of course, you should only operate on any given zlib or gzip stream from a
+    single thread at a time.
+
+20. Can I use zlib in my commercial application?
+
+    Yes. Please read the license in zlib.h.
+
+21. Is zlib under the GNU license?
+
+    No. Please read the license in zlib.h.
+
+22. The license says that altered source versions must be "plainly marked". So
+    what exactly do I need to do to meet that requirement?
+
+    You need to change the ZLIB_VERSION and ZLIB_VERNUM #defines in zlib.h. In
+    particular, the final version number needs to be changed to "f", and an
+    identification string should be appended to ZLIB_VERSION. Version numbers
+    x.x.x.f are reserved for modifications to zlib by others than the zlib
+    maintainers. For example, if the version of the base zlib you are altering
+    is "1.2.3.4", then in zlib.h you should change ZLIB_VERNUM to 0x123f, and
+    ZLIB_VERSION to something like "1.2.3.f-zachary-mods-v3". You can also
+    update the version strings in deflate.c and inftrees.c.
+
+    For altered source distributions, you should also note the origin and
+    nature of the changes in zlib.h, as well as in ChangeLog and README, along
+    with the dates of the alterations. The origin should include at least your
+    name (or your company's name), and an email address to contact for help or
+    issues with the library.
+
+    Note that distributing a compiled zlib library along with zlib.h and
+    zconf.h is also a source distribution, and so you should change
+    ZLIB_VERSION and ZLIB_VERNUM and note the origin and nature of the changes
+    in zlib.h as you would for a full source distribution.
+
+23. Will zlib work on a big-endian or little-endian architecture, and can I
+    exchange compressed data between them?
+
+    Yes and yes.
+
+24. Will zlib work on a 64-bit machine?
+
+    It should. It has been tested on 64-bit machines, and has no dependence
+    on any data types being limited to 32-bits in length. If you have any
+    difficulties, please provide a complete problem report to zlib@gzip.org
+
+25. Will zlib decompress data from the PKWare Data Compression Library?
+
+    No. The PKWare DCL uses a completely different compressed data format
+    than does PKZIP and zlib. However, you can look in zlib's contrib/blast
+    directory for a possible solution to your problem.
+
+26. Can I access data randomly in a compressed stream?
+
+    No, not without some preparation. If when compressing you periodically
+    use Z_FULL_FLUSH, carefully write all the pending data at those points,
+    and keep an index of those locations, then you can start decompression
+    at those points. You have to be careful to not use Z_FULL_FLUSH too
+    often, since it can significantly degrade compression.
+
+27. Does zlib work on MVS, OS/390, CICS, etc.?
+
+    We don't know for sure. We have heard occasional reports of success on
+    these systems. If you do use it on one of these, please provide us with
+    a report, instructions, and patches that we can reference when we get
+    these questions. Thanks.
+
+28. Is there some simpler, easier to read version of inflate I can look at
+    to understand the deflate format?
+
+    First off, you should read RFC 1951. Second, yes. Look in zlib's
+    contrib/puff directory.
+
+29. Does zlib infringe on any patents?
+
+    As far as we know, no. In fact, that was originally the whole point behind
+    zlib. Look here for some more information:
+
+    http://www.gzip.org/#faq11
+
+30. Can zlib work with greater than 4 GB of data?
+
+    Yes. inflate() and deflate() will process any amount of data correctly.
+    Each call of inflate() or deflate() is limited to input and output chunks
+    of the maximum value that can be stored in the compiler's "unsigned int"
+    type, but there is no limit to the number of chunks. Note however that the
+    strm.total_in and strm_total_out counters may be limited to 4 GB. These
+    counters are provided as a convenience and are not used internally by
+    inflate() or deflate(). The application can easily set up its own counters
+    updated after each call of inflate() or deflate() to count beyond 4 GB.
+    compress() and uncompress() may be limited to 4 GB, since they operate in a
+    single call. gzseek() and gztell() may be limited to 4 GB depending on how
+    zlib is compiled. See the zlibCompileFlags() function in zlib.h.
+
+    The word "may" appears several times above since there is a 4 GB limit
+    only if the compiler's "long" type is 32 bits. If the compiler's "long"
+    type is 64 bits, then the limit is 16 exabytes.
+
+31. Does zlib have any security vulnerabilities?
+
+    The only one that we are aware of is potentially in gzprintf(). If zlib
+    is compiled to use sprintf() or vsprintf(), then there is no protection
+    against a buffer overflow of a 4K string space, other than the caller of
+    gzprintf() assuring that the output will not exceed 4K. On the other
+    hand, if zlib is compiled to use snprintf() or vsnprintf(), which should
+    normally be the case, then there is no vulnerability. The ./configure
+    script will display warnings if an insecure variation of sprintf() will
+    be used by gzprintf(). Also the zlibCompileFlags() function will return
+    information on what variant of sprintf() is used by gzprintf().
+
+    If you don't have snprintf() or vsnprintf() and would like one, you can
+    find a portable implementation here:
+
+        http://www.ijs.si/software/snprintf/
+
+    Note that you should be using the most recent version of zlib. Versions
+    1.1.3 and before were subject to a double-free vulnerability.
+
+32. Is there a Java version of zlib?
+
+    Probably what you want is to use zlib in Java. zlib is already included
+    as part of the Java SDK in the java.util.zip package. If you really want
+    a version of zlib written in the Java language, look on the zlib home
+    page for links: http://www.zlib.org/
+
+33. I get this or that compiler or source-code scanner warning when I crank it
+    up to maximally-pendantic. Can't you guys write proper code?
+
+    Many years ago, we gave up attempting to avoid warnings on every compiler
+    in the universe. It just got to be a waste of time, and some compilers
+    were downright silly. So now, we simply make sure that the code always
+    works.
+
+34. Will zlib read the (insert any ancient or arcane format here) compressed
+    data format?
+
+    Probably not. Look in the comp.compression FAQ for pointers to various
+    formats and associated software.
+
+35. How can I encrypt/decrypt zip files with zlib?
+
+    zlib doesn't support encryption. The original PKZIP encryption is very weak
+    and can be broken with freely available programs. To get strong encryption,
+    use gpg ( http://www.gnupg.org/ ) which already includes zlib compression.
+    For PKZIP compatible "encryption", look at http://www.info-zip.org/
+
+36. What's the difference between the "gzip" and "deflate" HTTP 1.1 encodings?
+
+    "gzip" is the gzip format, and "deflate" is the zlib format. They should
+    probably have called the second one "zlib" instead to avoid confusion
+    with the raw deflate compressed data format. While the HTTP 1.1 RFC 2616
+    correctly points to the zlib specification in RFC 1950 for the "deflate"
+    transfer encoding, there have been reports of servers and browsers that
+    incorrectly produce or expect raw deflate data per the deflate
+    specficiation in RFC 1951, most notably Microsoft. So even though the
+    "deflate" transfer encoding using the zlib format would be the more
+    efficient approach (and in fact exactly what the zlib format was designed
+    for), using the "gzip" transfer encoding is probably more reliable due to
+    an unfortunate choice of name on the part of the HTTP 1.1 authors.
+
+    Bottom line: use the gzip format for HTTP 1.1 encoding.
+
+37. Does zlib support the new "Deflate64" format introduced by PKWare?
+
+    No. PKWare has apparently decided to keep that format proprietary, since
+    they have not documented it as they have previous compression formats.
+    In any case, the compression improvements are so modest compared to other
+    more modern approaches, that it's not worth the effort to implement.
+
+38. Can you please sign these lengthy legal documents and fax them back to us
+    so that we can use your software in our product?
+
+    No. Go away. Shoo.