file.h

mgcp协议源代码。支持多种编码：g711

/*
 * file.h
 *
 * Operating System file I/O channel class.
 *
 * Portable Windows Library
 *
 * Copyright (c) 1993-1998 Equivalence Pty. Ltd.
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Portable Windows Library.
 *
 * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
 *
 * Portions are Copyright (C) 1993 Free Software Foundation, Inc.
 * All Rights Reserved.
 *
 * Contributor(s): ______________________________________.
 *
 * $Log: file.h,v $
 * Revision 1.33  2000/07/09 14:05:46  robertj
 * Added file share options.
 *
 * Revision 1.32  1999/06/13 13:54:07  robertj
 * Added PConsoleChannel class for access to stdin/stdout/stderr.
 *
 * Revision 1.31  1999/06/09 02:05:20  robertj
 * Added ability to open file as standard input, output and error streams.
 *
 * Revision 1.30  1999/03/09 02:59:49  robertj
 * Changed comments to doc++ compatible documentation.
 *
 * Revision 1.29  1999/02/16 08:07:11  robertj
 * MSVC 6.0 compatibility changes.
 *
 * Revision 1.28  1998/09/23 06:20:35  robertj
 * Added open source copyright license.
 *
 * Revision 1.27  1995/07/31 12:15:43  robertj
 * Removed PContainer from PChannel ancestor.
 *
 * Revision 1.26  1995/06/17 11:12:33  robertj
 * Documentation update.
 *
 * Revision 1.25  1995/04/22 00:43:57  robertj
 * Added Move() function and changed semantics of Rename().
 * Changed all file name strings to PFilePath objects.
 *
 * Revision 1.24  1995/03/14 12:41:23  robertj
 * Updated documentation to use HTML codes.
 *
 * Revision 1.23  1995/03/12  04:37:13  robertj
 * Moved GetHandle() function from PFile to PChannel.
 *
 * Revision 1.22  1995/01/14  06:22:11  robertj
 * Documentation
 *
 * Revision 1.21  1994/12/21  11:52:54  robertj
 * Documentation and variable normalisation.
 *
 * Revision 1.20  1994/08/23  11:32:52  robertj
 * Oops
 *
 * Revision 1.19  1994/08/22  00:46:48  robertj
 * Added pragma fro GNU C++ compiler.
 *
 * Revision 1.18  1994/08/21  23:43:02  robertj
 * Added "remove on close" feature for temporary files.
 * Added "force" option to Remove/Rename etc to override write protection.
 * Added function to set file permissions.
 *
 * Revision 1.17  1994/07/17  10:46:06  robertj
 * Moved data to platform dependent files.
 *
 * Revision 1.16  1994/06/25  11:55:15  robertj
 * Unix version synchronisation.
 *
 * Revision 1.15  1994/04/20  12:17:44  robertj
 * Split name into PFilePath
 *
 * Revision 1.14  1994/04/01  14:11:03  robertj
 * Added const to functions.
 * Added SetName function.
 *
 * Revision 1.13  1994/03/07  07:38:19  robertj
 * Major enhancementsacross the board.
 *
 * Revision 1.12  1994/01/13  03:40:22  robertj
 * Added hidden flag to file info.
 *
 * Revision 1.12  1994/01/13  03:36:48  robertj
 * Created intermediate class PInteractorLayout for dialog-ish windows.
 *
 * Revision 1.11  1994/01/03  04:42:23  robertj
 * Mass changes to common container classes and interactors etc etc etc.
 *
 * Revision 1.10  1993/12/31  06:45:38  robertj
 * Made inlines optional for debugging purposes.
 *
 * Revision 1.9  1993/09/27  16:35:25  robertj
 * Changed GetName() to GetTitle(), better naming convention.
 * Moved internal functions to private section.
 *
 * Revision 1.8  1993/08/31  03:38:02  robertj
 * Changed PFile::Status to PFile::Info due to X-Windows compatibility.
 *
 * Revision 1.7  1993/08/27  18:17:47  robertj
 * Moved code from MS-DOS platform to common files.
 *
 * Revision 1.6  1993/08/21  04:40:19  robertj
 * Added Copy() function.
 *
 * Revision 1.5  1993/08/21  01:50:33  robertj
 * Made Clone() function optional, default will assert if called.
 *
 * Revision 1.4  1993/08/01  14:05:27  robertj
 * Added GetFileName() function required for proper portability.
 * Improved some comments.
 *
 * Revision 1.3  1993/07/14  12:49:16  robertj
 * Fixed RCS keywords.
 *
 */


#define _PFILE

#ifdef __GNUC__
#pragma interface
#endif


///////////////////////////////////////////////////////////////////////////////
// Binary Files

/**This class represents a disk file. This is a particular type of I/O channel
   that has certain attributes. All platforms have a disk file, though exact
   details of naming convertions etc may be different.

   The basic model for files is that they are a named sequence of bytes that
   persists within a directory structure. The transfer of data to and from
   the file is made at a current position in the file. This may be set to
   random locations within the file.
 */
class PFile : public PChannel
{
  PCLASSINFO(PFile, PChannel);

  public:
  /**@name Construction */
  //@{
    /**Create a file object but do not open it. It does not initially have a
       valid file name. However, an attempt to open the file using the
       #Open()# function will generate a unique temporary file.
     */
    PFile();

    /**When a file is opened, it may restrict the access available to
       operations on the object instance. A value from this enum is passed to
       the #Open()# function to set the mode.
     */
    enum OpenMode {
      /// File can be read but not written.
      ReadOnly,
      /// File can be written but not read.
      WriteOnly,
      /// File can be both read and written.
      ReadWrite
    };

    /**When a file is opened, a number of options may be associated with the
       open file. These describe what action to take on opening the file and
       what to do on closure. A value from this enum is passed to the
       #Open()# function to set the options.

       The #ModeDefault# option will use the following values:
\begin{tabular}{rr}
          Mode  & Options   \\
\hline
          #ReadOnly#  &    #MustExist# \\
          #WriteOnly# &    #Create | Truncate# \\
          #ReadWrite# &    #Create# \\
\hline
\end{tabular}
     */
    enum OpenOptions {
      /// File options depend on the OpenMode parameter.
      ModeDefault = -1, 
      /// File open fails if file does not exist.
      MustExist = 0,    
      /// File is created if it does not exist.
      Create = 1,       
      /// File is set to zero length if it already exists.
      Truncate = 2,     
      /// File open fails if file already exists.
      Exclusive = 4,    
      /// File is temporary and is to be deleted when closed.
      Temporary = 8,
      /// File may not be read by another process.
      DenySharedRead = 16,
      /// File may not be written by another process.
      DenySharedWrite = 32
    };

    /**Create a unique temporary file name, and open the file in the specified
       mode and using the specified options. Note that opening a new, unique,
       temporary file name in ReadOnly mode will always fail. This would only
       be usefull in a mode and options that will create the file.

       The #PChannel::IsOpen()# function may be used after object
       construction to determine if the file was successfully opened.
     */
    PFile(
      OpenMode mode,          /// Mode in which to open the file.
      int opts = ModeDefault  /// #OpenOptions enum# for open operation.
    );

    /**Create a file object with the specified name and open it in the
       specified mode and with the specified options.

       The #PChannel::IsOpen()# function may be used after object
       construction to determine if the file was successfully opened.
     */
    PFile(
      const PFilePath & name,    /// Name of file to open.
      OpenMode mode = ReadWrite, /// Mode in which to open the file.
      int opts = ModeDefault     /// #OpenOptions enum# for open operation.
    );

    /// Close the file on destruction.
    ~PFile();
  //@}


  /**@name Overrides from class PObject */
  //@{
    /**Determine the relative rank of the two objects. This is essentially the
       string comparison of the #PFilePath# names of the files.

       @return
       relative rank of the file paths.
     */
    Comparison Compare(
      const PObject & obj   /// Other file to compare against.
    ) const;
  //@}


  /**@name Overrides from class PChannel */
  //@{
    /**Get the platform and I/O channel type name of the channel. For example,
       it would return the filename in #PFile# type channels.

       @return
       the name of the channel.
     */
    virtual PString GetName() const;

    /**Low level read from the file channel. The read timeout is ignored for
       file I/O. The GetLastReadCount() function returns the actual number
       of bytes read.

       The GetErrorCode() function should be consulted after Read() returns
       FALSE to determine what caused the failure.

       @return
       TRUE indicates that at least one character was read from the channel.
       FALSE means no bytes were read due to timeout or some other I/O error.
     */
    virtual BOOL Read(
      void * buf,   /// Pointer to a block of memory to receive the read bytes.
      PINDEX len    /// Maximum number of bytes to read into the buffer.
    );

    /**Low level write to the file channel. The write timeout is ignored for
       file I/O. The GetLastWriteCount() function returns the actual number
       of bytes written.

       The GetErrorCode() function should be consulted after Write() returns
       FALSE to determine what caused the failure.

       @return TRUE if at least len bytes were written to the channel.
     */
    virtual BOOL Write(
      const void * buf, /// Pointer to a block of memory to write.
      PINDEX len        /// Number of bytes to write.
    );

    /** Close the file channel.
        @return TRUE if close was OK.
      */
    virtual BOOL Close();
  //@}


  /**@name File manipulation functions */
  //@{
    /**Check for file existance. 
       Determine if the file specified actually exists within the platforms
       file system.

       @return
       TRUE if the file exists.
     */
    static BOOL Exists(
      const PFilePath & name  /// Name of file to see if exists.
    );

    /**Check for file existance.
       Determine if the file path specification associated with the instance
       of the object actually exists within the platforms file system.

       @return
       TRUE if the file exists.
     */