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Diffstat (limited to 'zlib/examples/zlib_how.html')
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1 files changed, 29 insertions, 7 deletions
diff --git a/zlib/examples/zlib_how.html b/zlib/examples/zlib_how.html index 40998dbf0..444ff1c9a 100644 --- a/zlib/examples/zlib_how.html +++ b/zlib/examples/zlib_how.html @@ -4,7 +4,7 @@ <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>zlib Usage Example</title> -<!-- Copyright (c) 2004 Mark Adler. --> +<!-- Copyright (c) 2004, 2005 Mark Adler. --> </head> <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#00A000"> <h2 align="center"> zlib Usage Example </h2> @@ -21,13 +21,16 @@ Without further adieu, here is the program <a href="zpipe.c"><tt>zpipe.c</tt></a <pre><b> /* zpipe.c: example of proper use of zlib's inflate() and deflate() Not copyrighted -- provided to the public domain - Version 1.2 9 November 2004 Mark Adler */ + Version 1.4 11 December 2005 Mark Adler */ /* Version history: 1.0 30 Oct 2004 First version 1.1 8 Nov 2004 Add void casting for unused return values Use switch statement for inflate() return values 1.2 9 Nov 2004 Add assertions to document zlib guarantees + 1.3 6 Apr 2005 Remove incorrect assertion in inf() + 1.4 11 Dec 2005 Add hack to avoid MSDOS end-of-line conversions + Avoid some compiler warnings for input and output buffers */ </b></pre><!-- --> We now include the header files for the required definitions. From @@ -47,6 +50,21 @@ functions <tt>inflateInit()</tt>, <tt>inflate()</tt>, and #include <assert.h> #include "zlib.h" </b></pre><!-- --> +This is an ugly hack required to avoid corruption of the input and output data on +Windows/MS-DOS systems. Without this, those systems would assume that the input and output +files are text, and try to convert the end-of-line characters from one standard to +another. That would corrupt binary data, and in particular would render the compressed data unusable. +This sets the input and output to binary which suppresses the end-of-line conversions. +<tt>SET_BINARY_MODE()</tt> will be used later on <tt>stdin</tt> and <tt>stdout</tt>, at the beginning of <tt>main()</tt>. +<pre><b> +#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__) +# include <fcntl.h> +# include <io.h> +# define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY) +#else +# define SET_BINARY_MODE(file) +#endif +</b></pre><!-- --> <tt>CHUNK</tt> is simply the buffer size for feeding data to and pulling data from the <em>zlib</em> routines. Larger buffer sizes would be more efficient, especially for <tt>inflate()</tt>. If the memory is available, buffers sizes @@ -80,8 +98,8 @@ is used to pass information to and from the <em>zlib</em> routines, and to maint int ret, flush; unsigned have; z_stream strm; - char in[CHUNK]; - char out[CHUNK]; + unsigned char in[CHUNK]; + unsigned char out[CHUNK]; </b></pre><!-- --> The first thing we do is to initialize the <em>zlib</em> state for compression using <tt>deflateInit()</tt>. This must be done before the first use of <tt>deflate()</tt>. @@ -313,8 +331,8 @@ can tell from the <em>zlib</em> stream itself when the stream is complete. int ret; unsigned have; z_stream strm; - char in[CHUNK]; - char out[CHUNK]; + unsigned char in[CHUNK]; + unsigned char out[CHUNK]; </b></pre><!-- --> The initialization of the state is the same, except that there is no compression level, of course, and two more elements of the structure are initialized. <tt>avail_in</tt> @@ -494,6 +512,10 @@ int main(int argc, char **argv) { int ret; + /* avoid end-of-line conversions */ + SET_BINARY_MODE(stdin); + SET_BINARY_MODE(stdout); + /* do compression if no arguments */ if (argc == 1) { ret = def(stdin, stdout, Z_DEFAULT_COMPRESSION); @@ -518,6 +540,6 @@ int main(int argc, char **argv) } </b></pre> <hr> -<i>Copyright (c) 2004 by Mark Adler<br>Last modified 13 November 2004</i> +<i>Copyright (c) 2004, 2005 by Mark Adler<br>Last modified 11 December 2005</i> </body> </html> |