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#include "zipios++/zipios-config.h"
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#include "zipios++/meta-iostreams.h"
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#include "zipios++/fcollexceptions.h"
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#include "zipios++/inflateinputstreambuf.h"
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#include "outputstringstream.h"
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InflateInputStreambuf::InflateInputStreambuf( streambuf *inbuf, int s_pos, bool del_inbuf )
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: FilterInputStreambuf( inbuf, del_inbuf ),
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_zs_initialized ( false ),
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_invec ( _invecsize ),
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_outvec ( _outvecsize )
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// NOTICE: It is important that this constructor and the methods it
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// calls doesn't do anything with the input streambuf _inbuf, other
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// than repositioning it to the specified position. The reason is
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// that this class can be subclassed, and the subclass should get a
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// chance to read from the buffer first)
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// We're not checking the return value of reset() and throwing
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// an exception in case of an error, because we cannot catch the exception
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// in the constructors of subclasses with all compilers.
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InflateInputStreambuf::~InflateInputStreambuf() {
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// Dealloc z_stream stuff
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int err = inflateEnd( &_zs ) ;
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cerr << "~inflatebuf: inflateEnd failed" ;
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cerr << ": " << zError( err ) ;
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int InflateInputStreambuf::underflow() {
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// If not underflow don't fill buffer
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if ( gptr() < egptr() )
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return static_cast< unsigned char >( *gptr() ) ;
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// Prepare _outvec and get array pointers
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_zs.avail_out = _outvecsize ;
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_zs.next_out = reinterpret_cast< unsigned char * >( &( _outvec[ 0 ] ) ) ;
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// Inflate until _outvec is full
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// eof (or I/O prob) on _inbuf will break out of loop too.
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while ( _zs.avail_out > 0 && err == Z_OK ) {
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if ( _zs.avail_in == 0 ) { // fill _invec
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int bc = _inbuf->sgetn( &(_invec[ 0 ] ) ,
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// FIXME: handle i/o problems.
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_zs.next_in = reinterpret_cast< unsigned char * >( &( _invec[0] ) ) ;
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// If we could not read any new data (bc == 0) and inflate isn't
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// done it will return Z_BUF_ERROR and thus breaks out of the
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// loop. This means we don't have to respond to the situation
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// where we can't read more bytes here.
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err = inflate( &_zs, Z_NO_FLUSH ) ;
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// Normally the number of inflated bytes will be the
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// full length of the output buffer, but if we can't read
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// more input from the _inbuf streambuf, we end up with
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int inflated_bytes = _outvecsize - _zs.avail_out ;
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setg( &( _outvec[ 0 ] ),
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&( _outvec[ 0 ] ) + inflated_bytes ) ;
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// FIXME: look at the error returned from inflate here, if there is
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// some way to report it to the InflateInputStreambuf user.
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// Until I find out I'll just print a warning to stdout.
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if( err != Z_OK && err != Z_STREAM_END ) {
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#if defined (HAVE_STD_IOSTREAM) && defined (USE_STD_IOSTREAM)
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// Throw an exception to make istream set badbit
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OutputStringStream msgs ;
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msgs << "InflateInputStreambuf: inflate failed" ;
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msgs << ": " << zError( err ) ;
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throw IOException( msgs.str() ) ;
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// If HAVE_STD_IOSTREAM not defined we just return eof
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// if no output is produced, and that happens anyway
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if (inflated_bytes > 0 )
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return static_cast< unsigned char >( *gptr() ) ;
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return EOF ; // traits_type::eof() ;
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// This method is called in the constructor, so it must not
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// read anything from the input streambuf _inbuf (see notice in constructor)
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bool InflateInputStreambuf::reset( int stream_position ) {
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if ( stream_position >= 0 ) { // reposition _inbuf
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_inbuf->pubseekpos( stream_position ) ;
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// _zs.next_in and avail_in must be set according to
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// zlib.h (inline doc).
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_zs.next_in = reinterpret_cast< unsigned char * >( &( _invec[0] ) ) ;
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if( _zs_initialized ) { // just reset it
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err = inflateReset( &_zs ) ;
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err = inflateInit2( &_zs, -MAX_WBITS ) ;
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/* windowBits is passed < 0 to tell that there is no zlib header.
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Note that in this case inflate *requires* an extra "dummy" byte
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after the compressed stream in order to complete decompression
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and return Z_STREAM_END. We always have an extra "dummy" byte,
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because there is always some trailing data after the compressed
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data (either the next entry or the central directory. */
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_zs_initialized = true ;
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// The important thing here, is that
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// - the pointers are not NULL (which would mean unbuffered)
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// - and that gptr() is not less than egptr() (so we trigger underflow
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// the first time data is read).
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setg( &( _outvec[ 0 ] ),
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&( _outvec[ 0 ] ) + _outvecsize,
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&( _outvec[ 0 ] ) + _outvecsize ) ;
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Implementation of InflateInputStreambuf.
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Zipios++ - a small C++ library that provides easy access to .zip files.
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Copyright (C) 2000 Thomas S�ndergaard
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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lib-src/zipios++/src/inflateinputstreambuf.cpp
