396 lines
10 KiB
C++
396 lines
10 KiB
C++
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/***
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*filebuf.cpp - core filebuf member functions
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*
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* Copyright (c) 1991-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* Contains the core member functions for filebuf class.
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*
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*Revision History:
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* 08-08-91 KRS Created.
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* 08-20-91 KRS Added virtual xsgetn()/xsputn() functions.
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* 08-21-91 KRS Fix circular reference between sync() and seekoff().
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* Close file in destructor only if we opened it!
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* 09-06-91 KRS Fix ios::ate case in filebuf::open().
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* 09-09-91 KRS Add support for ios::binary in filebuf::open().
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* 09-10-91 KRS Remove virtual xsputn()/xsgetn().
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* 09-11-91 KRS Fix filebuf::seekoff() for ios::cur and in_avail().
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* 09-12-91 KRS Make sure close() always closes even if sync() fails.
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* Fix seekoff call in filebuf::sync() and pbackfail().
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* 09-16-91 KRS Make virtual filebuf::setbuf() more robust.
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* 09-19-91 KRS Add calls to delbuf(1) in constructors.
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* 09-20-91 KRS C700 #4453: Improve efficiency in overflow().
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* 09-29-91 KRS Granularity split. Move fstream into separate file.
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* 10-24-91 KRS Avoid virtual calls from virtual functions.
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* 11-13-91 KRS Use allocate() properly in overflow() and underflow().
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* Fix constructor.
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* 01-03-92 KRS Remove virtual keyword. Add function headers and PCH.
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* 01-20-92 KRS In text mode, account for CR/LF pairs in sync().
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* 02-03-92 KRS Change for new compiler destructor behavior.
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* 08-19-92 KRS Remove sh_compat for NT.
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* 08-27-92 KRS Fix bug in close() introduced in MTHREAD work.
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* 02-23-95 CFW Fix bug: buffer overwritten when disk full.
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* 06-14-95 CFW Comment cleanup.
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* 06-19-95 GJF Replaced _osfile[] with _osfile() (which references
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* a field in the ioinfo struct).
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* 05-17-99 PML Remove all Macintosh support.
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*
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*******************************************************************************/
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#include <cruntime.h>
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#include <internal.h>
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#include <string.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <crtdbg.h>
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#include <sys\types.h>
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#include <io.h>
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#include <fstream.h>
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#pragma hdrstop
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#include <msdos.h>
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#include <sys\stat.h>
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const int filebuf::openprot = 0644;
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const int filebuf::sh_none = 04000; // deny rw
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const int filebuf::sh_read = 05000; // deny wr
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const int filebuf::sh_write = 06000; // deny rd
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const int filebuf::binary = O_BINARY;
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const int filebuf::text = O_TEXT;
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/***
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*filebuf::filebuf() - filebuf default constructor
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*
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*Purpose:
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* Default constructor.
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*
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*Entry:
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*
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*******************************************************************************/
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filebuf::filebuf()
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: streambuf()
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{
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x_fOpened = 0;
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x_fd = -1;
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}
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/***
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*filebuf::filebuf(filedesc fd) - filebuf constructor
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*
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*Purpose:
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* Constructor. Initialize filebuf and attach to file descriptor.
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*
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*Entry:
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* fd = file descriptor to attach to filebuf
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*
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*******************************************************************************/
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filebuf::filebuf(filedesc fd)
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: streambuf()
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{
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x_fOpened = 0;
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x_fd=fd;
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}
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/***
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*filebuf::filebuf(filedesc fd, char* p, int len) - filebuf constructor
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*
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*Purpose:
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* Constructor. Initialize filebuf and attach to file descriptor.
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*
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*Entry:
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* fd = file descriptor to attach to filebuf
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* p = user-supplied buffer
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* len = length of buffer
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*
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*******************************************************************************/
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filebuf::filebuf(filedesc fd, char* p, int len)
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: streambuf()
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{
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filebuf::setbuf(p,len);
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x_fOpened = 0;
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x_fd=fd;
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}
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/***
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*filebuf::~filebuf() - filebuf destructor
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*
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*Purpose:
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* Destructor. Close attached file only if we opened it.
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*
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*Entry:
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* None.
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*
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*******************************************************************************/
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filebuf::~filebuf()
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{
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lock(); // no need to unlock...
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if (x_fOpened)
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close(); // calls filebuf::sync()
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else
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filebuf::sync();
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}
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/***
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*filebuf* filebuf::close() - close an attached file
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*
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*Purpose:
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* Close attached file.
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*
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*Entry:
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* None.
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*Exit:
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* Returns NULL if error, otherwise returns "this" pointer.
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*
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*******************************************************************************/
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filebuf* filebuf::close()
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{
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int retval;
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if (x_fd==-1)
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return NULL;
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lock();
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retval = sync();
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if ((_close(x_fd)==-1) || (retval==EOF))
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{
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unlock();
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return NULL;
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}
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x_fd = -1;
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unlock();
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return this;
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}
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/***
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*virtual int filebuf::overflow(int c) - overflow virtual function
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*
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*Purpose:
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* flush any characters in the reserve area and handle 'c'.
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*
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*Entry:
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* c = character to output (if not EOF)
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*
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*Exit:
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* Returns EOF if error, otherwise returns something else.
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*
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*Exceptions:
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* Returns EOF if error.
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*
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*******************************************************************************/
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int filebuf::overflow(int c)
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{
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if (allocate()==EOF) // make sure there is a reserve area
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return EOF;
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if (filebuf::sync()==EOF) // sync before new buffer created below
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return EOF;
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if (!unbuffered())
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setp(base(),ebuf());
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if (c!=EOF)
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{
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if ((!unbuffered()) && (pptr() < epptr())) // guard against recursion
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sputc(c);
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else
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{
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if (_write(x_fd,&c,1)!=1)
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return(EOF);
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}
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}
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return(1); // return something other than EOF if successful
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}
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/***
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*virtual int filebuf::underflow() - underflow virtual function
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*
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*Purpose:
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* return next character in get area, or get more characters from source.
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*
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*Entry:
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* None.
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*
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*Exit:
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* Returns current character in file. Does not advance get pointer.
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*
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*Exceptions:
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* Returns EOF if error.
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*
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*******************************************************************************/
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int filebuf::underflow()
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{
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int count;
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unsigned char tbuf;
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if (in_avail())
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return (int)(unsigned char) *gptr();
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if (allocate()==EOF) // make sure there is a reserve area
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return EOF;
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if (filebuf::sync()==EOF)
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return EOF;
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if (unbuffered())
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{
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if (_read(x_fd,(void *)&tbuf,1)<=0)
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return EOF;
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return (int)tbuf;
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}
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if ((count=_read(x_fd,(void *)base(),blen())) <= 0)
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return EOF; // reached EOF
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setg(base(),base(),base()+count);
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return (int)(unsigned char) *gptr();
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}
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/***
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*virtual streampos filebuf::seekoff() - seekoff virtual function
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*
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*Purpose:
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* Seeks to given absolute or relative file offset.
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*
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*Entry:
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* off = offset to seek to relative to beginning, end or current
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* position in the file.
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* dir = one of ios::beg, ios::cur, or ios::end
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*
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*Exit:
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* Returns current file position after seek.
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*
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*Exceptions:
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* Returns EOF if error.
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*
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*******************************************************************************/
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streampos filebuf::seekoff(streamoff off, ios::seek_dir dir, int)
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{
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int fdir;
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long retpos;
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switch (dir) {
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case ios::beg :
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fdir = SEEK_SET;
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break;
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case ios::cur :
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fdir = SEEK_CUR;
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break;
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case ios::end :
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fdir = SEEK_END;
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break;
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default:
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// error
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return(EOF);
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}
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if (filebuf::sync()==EOF)
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return EOF;
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if ((retpos=_lseek(x_fd, off, fdir))==-1L)
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return (EOF);
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return((streampos)retpos);
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}
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/***
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*virtual int filebuf::sync() - synchronize buffers with external file postion.
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*
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*Purpose:
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* Synchronizes buffer with external file, by flushing any output and/or
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* discarding any unread input data. Discards any get or put area(s).
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*
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*Entry:
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* None.
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*
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*Exit:
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* Returns EOF if error, else 0.
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*
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*Exceptions:
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* Returns EOF if error.
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*
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*******************************************************************************/
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int filebuf::sync()
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{
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long count, nout;
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char * p;
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if (x_fd==-1)
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return(EOF);
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if (!unbuffered())
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{
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if ((count=out_waiting())!=0)
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{
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if ((nout =_write(x_fd,(void *) pbase(),(unsigned int)count)) != count)
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{
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if (nout > 0) {
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// should set _pptr -= nout
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pbump(-(int)nout);
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memmove(pbase(), pbase()+nout, (int)(count-nout));
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}
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return(EOF);
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}
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}
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setp(0,0); // empty put area
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if ((count=in_avail()) > 0)
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{
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// can't use seekoff here!!
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if (_osfile(x_fd) & FTEXT)
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{
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// If text mode, need to account for CR/LF etc.
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for (p = gptr(); p < egptr(); p++)
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if (*p == '\n')
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count++;
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// account for EOF if read, not counted by _read
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if ((_osfile(x_fd) & FEOFLAG))
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count++;
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}
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if (_lseek(x_fd, -count, SEEK_CUR)==-1L)
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{
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// unlock();
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return (EOF);
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}
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}
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setg(0,0,0); // empty get area
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}
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// unlock();
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return(0);
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}
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/***
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*virtual streambuf* filebuf::setbuf(char* ptr, int len) - set reserve area.
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*
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*Purpose:
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* Synchronizes buffer with external file, by flushing any output and/or
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* discarding any unread input data. Discards any get or put area(s).
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*
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*Entry:
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* ptr = requested reserve area. If NULL, request is for unbuffered.
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* len = size of reserve area. If <= 0, request is for unbuffered.
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*
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*Exit:
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* Returns this pointer if request is honored, else NULL.
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*
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*Exceptions:
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* Returns NULL if request is not honored.
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*
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*******************************************************************************/
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streambuf * filebuf::setbuf(char * ptr, int len)
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{
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if (is_open() && (ebuf()))
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return NULL;
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if ((!ptr) || (len <= 0))
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unbuffered(1);
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else
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{
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lock();
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setb(ptr, ptr+len, 0);
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unlock();
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}
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return this;
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}
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