1 /****************************************************************************

     2 ** 

     3 **

     4 ** Implementation of QBuffer class

     5 **

     6 ** Created : 930812

     7 **

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     9 **

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    14 ** LICENSE.QPL included in the packaging of this file.

    15 **

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    17 ** GNU General Public License version 2 as published by the Free Software

    18 ** Foundation and appearing in the file LICENSE.GPL included in the

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    26 ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

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    31 ** See http://www.trolltech.com/gpl/ for GPL licensing information.

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    36 **********************************************************************/

    37 

    38 #include "qbuffer.h"

    39 #include <stdlib.h>

    40 

    41 // REVISED: paul

    42 /*!

    43   \class QBuffer qbuffer.h

    44   \brief The QBuffer class is an I/O device that operates on a QByteArray

    45 

    46   \ingroup io

    47 

    48   QBuffer allows reading and writing a memory buffer. It is normally

    49   used together with a QTextStream or a QDataStream.  QBuffer has an

    50   associated QByteArray which holds the buffer data. The size() of the

    51   buffer is automatically adjusted as data is written.

    52 

    53   The constructor \c QBuffer(QByteArray) creates a QBuffer with an

    54   existing byte array.  The byte array can also be set with setBuffer().

    55   Writing to the QBuffer will modify the original byte array, since

    56   QByteArray is \link shclass.html explicitly shared.\endlink

    57 

    58   Use open() to open the buffer before use, and to set the mode

    59   (read-only,write-only, etc.).  close() closes the buffer. The buffer

    60   must be closed before reopening or calling setBuffer().

    61 

    62   The common way to use QBuffer is through \l QDataStream or \l QTextStream

    63   which have constructors that take a QBuffer parameter. For

    64   convenience, there are also QDataStream and QTextStream constructors

    65   that take a QByteArray parameter.  These constructors create and open

    66   an internal QBuffer.

    67 

    68   Note that QTextStream can also operate on a QString (a Unicode

    69   string); a QBuffer cannot.

    70 

    71   You can also use QBuffer directly through the standard QIODevice

    72   functions readBlock(), writeBlock() readLine(), at(), getch(), putch() and

    73   ungetch().

    74 

    75   \sa QFile, QDataStream, QTextStream, QByteArray, \link shclass.html Shared Classes\endlink

    76 */

    77 

    78 

    79 /*!

    80   Constructs an empty buffer.

    81 */

    82 

    83 QBuffer::QBuffer()

    84 {

    85     setFlags( IO_Direct );

    86     a_inc = 16;					// initial increment

    87     a_len = 0;

    88     ioIndex = 0;

    89 }

    90 

    91 

    92 /*!

    93   Constructs a buffer that operates on \a buf.

    94   If you open the buffer in write mode (\c IO_WriteOnly or

    95   \c IO_ReadWrite) and write something into the buffer, \a buf

    96   will be modified.

    97 

    98 

    99   Example:

   100   \code

   101     QCString str = "abc";

   102     QBuffer b( str );

   103     b.open( IO_WriteOnly );

   104     b.at( 3 );					// position at \0

   105     b.writeBlock( "def", 4 );			// write including \0

   106     b.close();

   107       // Now, str == "abcdef"

   108   \endcode

   109 

   110 

   111   \sa setBuffer()

   112 */

   113 

   114 QBuffer::QBuffer( QByteArray buf ) : a(buf)

   115 {

   116     setFlags( IO_Direct );

   117     a_len = a.size();

   118     a_inc = (a_len > 512) ? 512 : a_len;	// initial increment

   119     if ( a_inc < 16 )

   120 	a_inc = 16;

   121     ioIndex = 0;

   122 }

   123 

   124 /*!

   125   Destructs the buffer.

   126 */

   127 

   128 QBuffer::~QBuffer()

   129 {

   130 }

   131 

   132 

   133 /*!

   134   Replaces the buffer's contents with \a buf.

   135 

   136   This may not be done when isOpen() is TRUE.

   137 

   138   Note that if you open the buffer in write mode (\c IO_WriteOnly or

   139   IO_ReadWrite) and write something into the buffer, \a buf is also

   140   modified because QByteArray is an explicitly shared class.

   141 

   142   \sa buffer(), open(), close()

   143 */

   144 

   145 bool QBuffer::setBuffer( QByteArray buf )

   146 {

   147     if ( isOpen() ) {

   148 #if defined(CHECK_STATE)

   149 	qWarning( "QBuffer::setBuffer: Buffer is open");

   150 #endif

   151 	return FALSE;

   152     }

   153     a = buf;

   154     a_len = a.size();

   155     a_inc = (a_len > 512) ? 512 : a_len;	// initial increment

   156     if ( a_inc < 16 )

   157 	a_inc = 16;

   158     ioIndex = 0;

   159     return TRUE;

   160 }

   161 

   162 /*!

   163   \fn QByteArray QBuffer::buffer() const

   164 

   165   Returns this buffer's byte array.

   166 

   167   \sa setBuffer()

   168 */

   169 

   170 /*!

   171   \reimp

   172   Opens the buffer in the mode \a m.  Returns TRUE if successful,

   173   otherwise FALSE. The buffer must be opened before use.

   174 

   175   The mode parameter \a m must be a combination of the following flags.

   176   <ul>

   177   <li>\c IO_ReadOnly opens a buffer in read-only mode.

   178   <li>\c IO_WriteOnly opens a buffer in write-only mode.

   179   <li>\c IO_ReadWrite opens a buffer in read/write mode.

   180   <li>\c IO_Append sets the buffer index to the end of the buffer.

   181   <li>\c IO_Truncate truncates the buffer.

   182   </ul>

   183 

   184   \sa close(), isOpen()

   185 */

   186 

   187 bool QBuffer::open( int m  )

   188 {

   189     if ( isOpen() ) {				// buffer already open

   190 #if defined(CHECK_STATE)

   191 	qWarning( "QBuffer::open: Buffer already open" );

   192 #endif

   193 	return FALSE;

   194     }

   195     setMode( m );

   196     if ( m & IO_Truncate ) {			// truncate buffer

   197 	a.resize( 0 );

   198 	a_len = 0;

   199     }

   200     if ( m & IO_Append ) {			// append to end of buffer

   201 	ioIndex = a.size();

   202     } else {

   203 	ioIndex = 0;

   204     }

   205     a_inc = 16;

   206     setState( IO_Open );

   207     setStatus( 0 );

   208     return TRUE;

   209 }

   210 

   211 /*!

   212   \reimp

   213   Closes an open buffer.

   214   \sa open()

   215 */

   216 

   217 void QBuffer::close()

   218 {

   219     if ( isOpen() ) {

   220 	setFlags( IO_Direct );

   221 	ioIndex = 0;

   222 	a_inc = 16;

   223     }

   224 }

   225 

   226 /*!

   227   \reimp

   228   The flush function does nothing for a QBuffer.

   229 */

   230 

   231 void QBuffer::flush()

   232 {

   233     return;

   234 }

   235 

   236 

   237 /*!

   238   \fn int QBuffer::at() const

   239   \reimp

   240 */

   241 

   242 /*!

   243   \fn uint QBuffer::size() const

   244   \reimp

   245 */

   246 

   247 /*!

   248   \reimp

   249 */

   250 

   251 bool QBuffer::at( int pos )

   252 {

   253 #if defined(CHECK_STATE)

   254     if ( !isOpen() ) {

   255 	qWarning( "QBuffer::at: Buffer is not open" );

   256 	return FALSE;

   257     }

   258 #endif

   259     if ( (uint)pos > a_len ) {

   260 #if defined(CHECK_RANGE)

   261 	qWarning( "QBuffer::at: Index %d out of range", pos );

   262 #endif

   263 	return FALSE;

   264     }

   265     ioIndex = pos;

   266     return TRUE;

   267 }

   268 

   269 

   270 /*!

   271   \reimp

   272 */

   273 

   274 int QBuffer::readBlock( char *p, uint len )

   275 {

   276 #if defined(CHECK_STATE)

   277     CHECK_PTR( p );

   278     if ( !isOpen() ) {				// buffer not open

   279 	qWarning( "QBuffer::readBlock: Buffer not open" );

   280 	return -1;

   281     }

   282     if ( !isReadable() ) {			// reading not permitted

   283 	qWarning( "QBuffer::readBlock: Read operation not permitted" );

   284 	return -1;

   285     }

   286 #endif

   287     if ( (uint)ioIndex + len > a.size() ) {	// overflow

   288 	if ( (uint)ioIndex >= a.size() ) {

   289 	    setStatus( IO_ReadError );

   290 	    return -1;

   291 	} else {

   292 	    len = a.size() - (uint)ioIndex;

   293 	}

   294     }

   295     memcpy( p, a.data()+ioIndex, len );

   296     ioIndex += len;

   297     return len;

   298 }

   299 

   300 /*!

   301   \reimp

   302 

   303   Writes \a len bytes from \a p into the buffer at the current index,

   304   overwriting any characters there and extending the buffer if necessary.

   305   Returns the number of bytes actually written.

   306 

   307   Returns -1 if a serious error occurred.

   308 

   309   \sa readBlock()

   310 */

   311 

   312 int QBuffer::writeBlock( const char *p, uint len )

   313 {

   314 #if defined(CHECK_NULL)

   315     if ( p == 0 && len != 0 )

   316 	qWarning( "QBuffer::writeBlock: Null pointer error" );

   317 #endif

   318 #if defined(CHECK_STATE)

   319     if ( !isOpen() ) {				// buffer not open

   320 	qWarning( "QBuffer::writeBlock: Buffer not open" );

   321 	return -1;

   322     }

   323     if ( !isWritable() ) {			// writing not permitted

   324 	qWarning( "QBuffer::writeBlock: Write operation not permitted" );

   325 	return -1;

   326     }

   327 #endif

   328     if ( (uint)ioIndex + len >= a_len ) {		// overflow

   329 	uint new_len = a_len + a_inc*(((uint)ioIndex+len-a_len)/a_inc+1);

   330 	if ( !a.resize( new_len ) ) {		// could not resize

   331 #if defined(CHECK_NULL)

   332 	    qWarning( "QBuffer::writeBlock: Memory allocation error" );

   333 #endif

   334 	    setStatus( IO_ResourceError );

   335 	    return -1;

   336 	}

   337 	a_inc *= 2;				// double increment

   338 	a_len = new_len;

   339 	a.shd->len = (uint)ioIndex + len;

   340     }

   341     memcpy( a.data()+ioIndex, p, len );

   342     ioIndex += len;

   343     if ( a.shd->len < (uint)ioIndex )

   344 	a.shd->len = (uint)ioIndex;		// fake (not alloc'd) length

   345     return len;

   346 }

   347 

   348 

   349 /*!

   350   \reimp

   351 */

   352 

   353 int QBuffer::readLine( char *p, uint maxlen )

   354 {

   355 #if defined(CHECK_STATE)

   356     CHECK_PTR( p );

   357     if ( !isOpen() ) {				// buffer not open

   358 	qWarning( "QBuffer::readLine: Buffer not open" );

   359 	return -1;

   360     }

   361     if ( !isReadable() ) {			// reading not permitted

   362 	qWarning( "QBuffer::readLine: Read operation not permitted" );

   363 	return -1;

   364     }

   365 #endif

   366     if ( maxlen == 0 )

   367 	return 0;

   368     uint start = (uint)ioIndex;

   369     char *d = a.data() + ioIndex;

   370     maxlen--;					// make room for 0-terminator

   371     if ( a.size() - (uint)ioIndex < maxlen )

   372 	maxlen = a.size() - (uint)ioIndex;

   373     while ( maxlen-- ) {

   374 	if ( (*p++ = *d++) == '\n' )

   375 	    break;

   376     }

   377     *p = '\0';

   378     ioIndex = d - a.data();

   379     return (uint)ioIndex - start;

   380 }

   381 

   382 

   383 /*!

   384   \reimp

   385 */

   386 

   387 int QBuffer::getch()

   388 {

   389 #if defined(CHECK_STATE)

   390     if ( !isOpen() ) {				// buffer not open

   391 	qWarning( "QBuffer::getch: Buffer not open" );

   392 	return -1;

   393     }

   394     if ( !isReadable() ) {			// reading not permitted

   395 	qWarning( "QBuffer::getch: Read operation not permitted" );

   396 	return -1;

   397     }

   398 #endif

   399     if ( (uint)ioIndex+1 > a.size() ) {		// overflow

   400 	setStatus( IO_ReadError );

   401 	return -1;

   402     }

   403     return uchar(*(a.data()+ioIndex++));

   404 }

   405 

   406 /*!

   407   \reimp

   408   Writes the character \a ch into the buffer, overwriting

   409   the character at the current index, extending the buffer

   410   if necessary.

   411 

   412   Returns \a ch, or -1 if some error occurred.

   413 

   414   \sa getch(), ungetch()

   415 */

   416 

   417 int QBuffer::putch( int ch )

   418 {

   419 #if defined(CHECK_STATE)

   420     if ( !isOpen() ) {				// buffer not open

   421 	qWarning( "QBuffer::putch: Buffer not open" );

   422 	return -1;

   423     }

   424     if ( !isWritable() ) {			// writing not permitted

   425 	qWarning( "QBuffer::putch: Write operation not permitted" );

   426 	return -1;

   427     }

   428 #endif

   429     if ( (uint)ioIndex + 1 >= a_len ) {		// overflow

   430 	char buf[1];

   431 	buf[0] = (char)ch;

   432 	if ( writeBlock(buf,1) != 1 )

   433 	    return -1;				// write error

   434     } else {

   435 	*(a.data() + ioIndex++) = (char)ch;

   436 	if ( a.shd->len < (uint)ioIndex )

   437 	    a.shd->len = (uint)ioIndex;

   438     }

   439     return ch;

   440 }

   441 

   442 /*!

   443   \reimp

   444 */

   445 

   446 int QBuffer::ungetch( int ch )

   447 {

   448 #if defined(CHECK_STATE)

   449     if ( !isOpen() ) {				// buffer not open

   450 	qWarning( "QBuffer::ungetch: Buffer not open" );

   451 	return -1;

   452     }

   453     if ( !isReadable() ) {			// reading not permitted

   454 	qWarning( "QBuffer::ungetch: Read operation not permitted" );

   455 	return -1;

   456     }

   457 #endif

   458     if ( ch != -1 ) {

   459 	if ( ioIndex )

   460 	    ioIndex--;

   461 	else

   462 	    ch = -1;

   463     }

   464     return ch;

   465 }