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  31       </style><link rel="home" href="index.html" title="GnomeVFS - Filesystem Abstraction library"><link rel="up" href="gnome-vfs-file-operations.html" title="File Handling"><link rel="previous" href="gnome-vfs-gnome-vfs-file-basic-ops.html" title="Basic File Operations"><link rel="next" href="gnome-vfs-gnome-vfs-file-info-ops.html" title="Getting and Setting File Information"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><table class="navigation" width="100%" summary="Navigation header" cellpadding="2" cellspacing="2"><tr valign="middle"><td><a accesskey="p" href="gnome-vfs-gnome-vfs-file-basic-ops.html"><img src="left.png" width="24" height="24" border="0" alt="Prev"></a></td><td><a accesskey="u" href="gnome-vfs-file-operations.html"><img src="up.png" width="24" height="24" border="0" alt="Up"></a></td><td><a accesskey="h" href="index.html"><img src="home.png" width="24" height="24" border="0" alt="Home"></a></td><th width="100%" align="center">GnomeVFS - Filesystem Abstraction library</th><td><a accesskey="n" href="gnome-vfs-gnome-vfs-file-info-ops.html"><img src="right.png" width="24" height="24" border="0" alt="Next"></a></td></tr></table><div class="refentry" lang="en"><a name="gnome-vfs-gnome-vfs-file-rw-ops"></a><div class="titlepage"><div></div><div></div></div><div class="refnamediv"><h2><span class="refentrytitle">Reading and Writing</span></h2><p>Reading and Writing &#8212; </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
  32
  33
  34
  35 enum        <a href="gnome-vfs-gnome-vfs-file-rw-ops.html#GnomeVFSSeekPosition">GnomeVFSSeekPosition</a>;
  36 <a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> <a href="gnome-vfs-gnome-vfs-file-rw-ops.html#gnome-vfs-read">gnome_vfs_read</a>               (GnomeVFSHandle *handle,
  37                                              <a
  38 href="../glib/glib-Basic-Types.html#gpointer"
  39 >gpointer</a> buffer,
  40                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> bytes,
  41                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> *bytes_read);
  42 <a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> <a href="gnome-vfs-gnome-vfs-file-rw-ops.html#gnome-vfs-write">gnome_vfs_write</a>              (GnomeVFSHandle *handle,
  43                                              <a
  44 href="../glib/glib-Basic-Types.html#gconstpointer"
  45 >gconstpointer</a> buffer,
  46                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> bytes,
  47                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> *bytes_written);
  48 <a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> <a href="gnome-vfs-gnome-vfs-file-rw-ops.html#gnome-vfs-seek">gnome_vfs_seek</a>               (GnomeVFSHandle *handle,
  49                                              <a href="gnome-vfs-gnome-vfs-file-rw-ops.html#GnomeVFSSeekPosition">GnomeVFSSeekPosition</a> whence,
  50                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileOffset">GnomeVFSFileOffset</a> offset);
  51 <a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> <a href="gnome-vfs-gnome-vfs-file-rw-ops.html#gnome-vfs-tell">gnome_vfs_tell</a>               (GnomeVFSHandle *handle,
  52                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> *offset_return);
  53 </pre></div><div class="refsect1" lang="en"><h2>Description</h2><p>
  54   Reading and writing operations are explained, also <i class="parameter"><tt>gnome_vfs_seek</tt></i>, which
  55   is used to move the file pointer inside the file.
  56 </p></div><div class="refsect1" lang="en"><h2>Details</h2><div class="refsect2" lang="en"><h3><a name="GnomeVFSSeekPosition"></a>enum GnomeVFSSeekPosition</h3><pre class="programlisting">typedef enum {
  57         GNOME_VFS_SEEK_START,
  58         GNOME_VFS_SEEK_CURRENT,
  59         GNOME_VFS_SEEK_END
  60 } GnomeVFSSeekPosition;
  61 </pre><p>
  62 This is used to specify the start position for seek operations.</p><p>
  63
  64 </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><span class="term"><tt class="literal">GNOME_VFS_SEEK_START</tt></span></td><td> Start of the file.
  65 </td></tr><tr><td><span class="term"><tt class="literal">GNOME_VFS_SEEK_CURRENT</tt></span></td><td> Current position.
  66 </td></tr><tr><td><span class="term"><tt class="literal">GNOME_VFS_SEEK_END</tt></span></td><td> End of the file.
  67 </td></tr></tbody></table></div></div><hr><div class="refsect2" lang="en"><h3><a name="gnome-vfs-read"></a>gnome_vfs_read ()</h3><pre class="programlisting"><a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> gnome_vfs_read               (GnomeVFSHandle *handle,
  68                                              <a
  69 href="../glib/glib-Basic-Types.html#gpointer"
  70 >gpointer</a> buffer,
  71                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> bytes,
  72                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> *bytes_read);</pre><p>
  73 Read <i class="parameter"><tt>bytes</tt></i> from <i class="parameter"><tt>handle</tt></i>.  As with Unix system calls, the number of
  74 bytes read can effectively be less than <i class="parameter"><tt>bytes</tt></i> on return and will be
  75 stored in <i class="parameter"><tt>bytes_read</tt></i>.</p><p>
  76
  77 </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><span class="term"><i class="parameter"><tt>handle</tt></i> :</span></td><td> Handle of the file to read data from
  78 </td></tr><tr><td><span class="term"><i class="parameter"><tt>buffer</tt></i> :</span></td><td> Pointer to a buffer that must be at least <i class="parameter"><tt>bytes</tt></i> bytes large
  79 </td></tr><tr><td><span class="term"><i class="parameter"><tt>bytes</tt></i> :</span></td><td> Number of bytes to read
  80 </td></tr><tr><td><span class="term"><i class="parameter"><tt>bytes_read</tt></i> :</span></td><td> Pointer to a variable that will hold the number of bytes
  81 effectively read on return.
  82 </td></tr><tr><td><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></td><td> An integer representing the result of the operation
  83 </td></tr></tbody></table></div></div><hr><div class="refsect2" lang="en"><h3><a name="gnome-vfs-write"></a>gnome_vfs_write ()</h3><pre class="programlisting"><a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> gnome_vfs_write              (GnomeVFSHandle *handle,
  84                                              <a
  85 href="../glib/glib-Basic-Types.html#gconstpointer"
  86 >gconstpointer</a> buffer,
  87                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> bytes,
  88                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> *bytes_written);</pre><p>
  89 Write <i class="parameter"><tt>bytes</tt></i> into the file opened through <i class="parameter"><tt>handle</tt></i>.  As with Unix system
  90 calls, the number of bytes written can effectively be less than <i class="parameter"><tt>bytes</tt></i> on
  91 return and will be stored in <i class="parameter"><tt>bytes_written</tt></i>.</p><p>
  92
  93 </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><span class="term"><i class="parameter"><tt>handle</tt></i> :</span></td><td> Handle of the file to write data to
  94 </td></tr><tr><td><span class="term"><i class="parameter"><tt>buffer</tt></i> :</span></td><td> Pointer to the buffer containing the data to be written
  95 </td></tr><tr><td><span class="term"><i class="parameter"><tt>bytes</tt></i> :</span></td><td> Number of bytes to write
  96 </td></tr><tr><td><span class="term"><i class="parameter"><tt>bytes_written</tt></i> :</span></td><td> Pointer to a variable that will hold the number of bytes
  97 effectively written on return.
  98 </td></tr><tr><td><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></td><td> An integer representing the result of the operation
  99 </td></tr></tbody></table></div></div><hr><div class="refsect2" lang="en"><h3><a name="gnome-vfs-seek"></a>gnome_vfs_seek ()</h3><pre class="programlisting"><a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> gnome_vfs_seek               (GnomeVFSHandle *handle,
 100                                              <a href="gnome-vfs-gnome-vfs-file-rw-ops.html#GnomeVFSSeekPosition">GnomeVFSSeekPosition</a> whence,
 101                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileOffset">GnomeVFSFileOffset</a> offset);</pre><p>
 102 Set the current position for reading/writing through <i class="parameter"><tt>handle</tt></i>.</p><p>
 103
 104 </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><span class="term"><i class="parameter"><tt>handle</tt></i> :</span></td><td> Handle for which the current position must be changed
 105 </td></tr><tr><td><span class="term"><i class="parameter"><tt>whence</tt></i> :</span></td><td> Integer value representing the starting position
 106 </td></tr><tr><td><span class="term"><i class="parameter"><tt>offset</tt></i> :</span></td><td> Number of bytes to skip from the position specified by <i class="parameter"><tt>whence</tt></i>
 107 (a positive value means to move forward; a negative one to move backwards)
 108 </td></tr><tr><td><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></td><td>
 109 </td></tr></tbody></table></div></div><hr><div class="refsect2" lang="en"><h3><a name="gnome-vfs-tell"></a>gnome_vfs_tell ()</h3><pre class="programlisting"><a href="gnome-vfs-gnome-vfs-result.html#GnomeVFSResult">GnomeVFSResult</a> gnome_vfs_tell               (GnomeVFSHandle *handle,
 110                                              <a href="gnome-vfs-gnome-vfs-file-size.html#GnomeVFSFileSize">GnomeVFSFileSize</a> *offset_return);</pre><p>
 111 Return the current position on <i class="parameter"><tt>handle</tt></i>. This is the point in the file
 112 pointed to by handle that reads and writes will occur on.</p><p>
 113
 114 </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><span class="term"><i class="parameter"><tt>handle</tt></i> :</span></td><td> Handle for which the current position must be retrieved
 115 </td></tr><tr><td><span class="term"><i class="parameter"><tt>offset_return</tt></i> :</span></td><td> Pointer to a variable that will contain the current position
 116 on return
 117 </td></tr><tr><td><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></td><td> An integer representing the result of the operation
 118 </td></tr></tbody></table></div></div></div></div><table class="navigation" width="100%" summary="Navigation footer" cellpadding="2" cellspacing="0"><tr valign="middle"><td align="left"><a accesskey="p" href="gnome-vfs-gnome-vfs-file-basic-ops.html"><b>&lt;&lt; Basic File Operations</b></a></td><td align="right"><a accesskey="n" href="gnome-vfs-gnome-vfs-file-info-ops.html"><b>Getting and Setting File Information &gt;&gt;</b></a></td></tr></table></body></html>