160 lines
4.2 KiB
C++
160 lines
4.2 KiB
C++
/* This is part of libio/iostream, providing -*- C++ -*- input/output.
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Copyright (C) 1993 Free Software Foundation
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This file is part of the GNU IO Library. This library is free
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software; you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option)
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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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this library; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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As a special exception, if you link this library with files
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compiled with a GNU compiler to produce an executable, this does not cause
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the resulting executable to be covered by the GNU General Public License.
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This exception does not however invalidate any other reasons why
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the executable file might be covered by the GNU General Public License. */
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/* Written by Per Bothner (bothner@cygnus.com). */
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#ifdef __GNUG__
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#pragma implementation
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#endif
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#include "libioP.h"
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#include <stdiostream.h>
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// A stdiobuf is "tied" to a FILE object (as used by the stdio package).
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// Thus a stdiobuf is always synchronized with the corresponding FILE,
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// though at the cost of some overhead. (If you use the implementation
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// of stdio supplied with this library, you don't need stdiobufs.)
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// This implementation inherits from filebuf, but implement the virtual
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// functions sys_read/..., using the stdio functions fread/... instead
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// of the low-level read/... system calls. This has the advantage that
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// we get all of the nice filebuf semantics automatically, though
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// with some overhead.
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#ifndef SEEK_SET
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#define SEEK_SET 0
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#endif
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#ifndef SEEK_CUR
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#define SEEK_CUR 1
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#endif
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#ifndef SEEK_END
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#define SEEK_END 2
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#endif
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stdiobuf::stdiobuf(FILE *f) : filebuf(fileno(f))
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{
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_file = f;
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// Turn off buffer in stdiobuf. Instead, rely on buffering in (FILE).
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// Thus the stdiobuf will be synchronized with the FILE.
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setbuf(NULL, 0);
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}
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stdiobuf::~stdiobuf()
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{
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/* Only needed if we're buffered. Not buffered is the default. */
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_IO_do_flush((_IO_FILE*)this);
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}
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streamsize stdiobuf::sys_read(char* buf, streamsize size)
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{
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// A minor optimization, but it makes a noticable difference.
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// A bigger optimization would be to write stdiobuf::underflow,
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// but that has some modularity disadvantages. Re-evaluate that
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// after we have gotten rid of the double indirection. FIXME
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if (size == 1)
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{
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register int ch = getc(_file);
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if (ch == EOF)
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return 0;
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*buf = (char)ch;
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return 1;
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}
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else
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return fread(buf, 1, size, _file);
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}
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streamsize stdiobuf::sys_write(const char *buf, streamsize n)
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{
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_IO_ssize_t count = fwrite(buf, 1, n, _file);
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if (_offset >= 0)
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_offset += n;
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return count;
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}
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streampos stdiobuf::sys_seek(streamoff offset, _seek_dir dir)
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{
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// Normally, equivalent to: fdir=dir
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int fdir =
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(dir == ios::beg) ? SEEK_SET :
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(dir == ios::cur) ? SEEK_CUR :
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(dir == ios::end) ? SEEK_END :
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dir;
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return fseek(_file, offset, fdir);
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}
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int stdiobuf::sys_close()
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{
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int status = fclose(_file);
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_file = NULL;
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return status;
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}
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int stdiobuf::sync()
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{
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if (_IO_do_flush((_IO_FILE*)this))
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return EOF;
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if (!(xflags() & _IO_NO_WRITES))
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if (fflush(_file))
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return EOF;
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return 0;
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}
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int stdiobuf::overflow(int c /* = EOF*/)
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{
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if (filebuf::overflow(c) == EOF)
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return EOF;
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if (c != EOF)
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return c;
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return fflush(_file);
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}
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streamsize stdiobuf::xsputn(const char* s, streamsize n)
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{
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if (buffered ())
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{
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// The filebuf implementation of sputn loses.
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return streambuf::xsputn(s, n);
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}
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else
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return fwrite (s, 1, n, _file);
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}
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void stdiobuf::buffered (int b)
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{
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if (b)
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{
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if (_flags & _IO_UNBUFFERED)
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{ /* Was unbuffered, make it buffered. */
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_flags &= ~_IO_UNBUFFERED;
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}
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}
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else
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{
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if (!(_flags & _IO_UNBUFFERED))
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{ /* Was buffered, make it unbuffered. */
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setbuf(NULL, 0);
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}
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}
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}
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