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Annotation of GNUtools/libg++/libio/stdiostream.cc, revision 1.1.1.1

1.1       root        1: /* This is part of libio/iostream, providing -*- C++ -*- input/output.
                      2: Copyright (C) 1993 Free Software Foundation
                      3: 
                      4: This file is part of the GNU IO Library.  This library is free
                      5: software; you can redistribute it and/or modify it under the
                      6: terms of the GNU General Public License as published by the
                      7: Free Software Foundation; either version 2, or (at your option)
                      8: any later version.
                      9: 
                     10: This library is distributed in the hope that it will be useful,
                     11: but WITHOUT ANY WARRANTY; without even the implied warranty of
                     12: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     13: GNU General Public License for more details.
                     14: 
                     15: You should have received a copy of the GNU General Public License
                     16: along with GNU CC; see the file COPYING.  If not, write to
                     17: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
                     18: 
                     19: As a special exception, if you link this library with files
                     20: compiled with a GNU compiler to produce an executable, this does not cause
                     21: the resulting executable to be covered by the GNU General Public License.
                     22: This exception does not however invalidate any other reasons why
                     23: the executable file might be covered by the GNU General Public License. */
                     24: 
                     25: /* Written by Per Bothner ([email protected]). */
                     26: 
                     27: #ifdef __GNUG__
                     28: #pragma implementation
                     29: #endif
                     30: 
                     31: #include <stdiostream.h>
                     32: 
                     33: // A stdiobuf is "tied" to a FILE object (as used by the stdio package).
                     34: // Thus a stdiobuf is always synchronized with the corresponding FILE,
                     35: // though at the cost of some overhead.  (If you use the implementation
                     36: // of stdio supplied with this library, you don't need stdiobufs.)
                     37: // This implementation inherits from filebuf, but implement the virtual
                     38: // functions sys_read/..., using the stdio functions fread/... instead
                     39: // of the low-level read/... system calls.  This has the advantage that
                     40: // we get all of the nice filebuf semantics automatically, though
                     41: // with some overhead.
                     42: 
                     43: 
                     44: #ifndef SEEK_SET
                     45: #define SEEK_SET 0
                     46: #endif
                     47: #ifndef SEEK_CUR
                     48: #define SEEK_CUR 1
                     49: #endif
                     50: #ifndef SEEK_END
                     51: #define SEEK_END 2
                     52: #endif
                     53: 
                     54: stdiobuf::stdiobuf(FILE *f) : filebuf(fileno(f))
                     55: {
                     56:     _file = f;
                     57:     // Turn off buffer in stdiobuf.  Instead, rely on buffering in (FILE).
                     58:     // Thus the stdiobuf will be synchronized with the FILE.
                     59:     setbuf(NULL, 0);
                     60: }
                     61: 
                     62: _IO_ssize_t stdiobuf::sys_read(char* buf, _IO_size_t size)
                     63: {
                     64:     return fread(buf, 1, size, _file);
                     65: }
                     66: 
                     67: _IO_ssize_t stdiobuf::sys_write(const void *buf, _IO_size_t n)
                     68: {
                     69:     _IO_ssize_t count = fwrite(buf, 1, n, _file);
                     70:     if (_offset >= 0)
                     71:        _offset += n;
                     72:     return count;
                     73: }
                     74: 
                     75: _IO_pos_t stdiobuf::sys_seek(_IO_pos_t offset, _seek_dir dir)
                     76: {
                     77:     // Normally, equivalent to: fdir=dir
                     78:     int fdir =
                     79:        (dir == ios::beg) ? SEEK_SET :
                     80:         (dir == ios::cur) ? SEEK_CUR :
                     81:         (dir == ios::end) ? SEEK_END :
                     82:         dir;
                     83:     return fseek(_file, offset, fdir);
                     84: }
                     85: 
                     86: int stdiobuf::sys_close()
                     87: {
                     88:     int status = fclose(_file);
                     89:     _file = NULL;
                     90:     return status;
                     91: }
                     92: 
                     93: int stdiobuf::sync()
                     94: {
                     95:     if (filebuf::sync() == EOF)
                     96:        return EOF;
                     97:     if (!(xflags() & _IO_NO_WRITES))
                     98:        if (fflush(_file))
                     99:            return EOF;
                    100: #if 0
                    101:        // This loses when writing to a pipe.
                    102:     if (fseek(_file, 0, SEEK_CUR) == EOF)
                    103:        return EOF;
                    104: #endif
                    105:     return 0;
                    106: }
                    107: 
                    108: int stdiobuf::overflow(int c /* = EOF*/)
                    109: {
                    110:     if (filebuf::overflow(c) == EOF)
                    111:        return EOF;
                    112:     if (c != EOF)
                    113:        return c;
                    114:     return fflush(_file);
                    115: }
                    116: 
                    117: int stdiobuf::xsputn(const char* s, int n)
                    118: {
                    119:     // The filebuf implementation of sputn loses.
                    120:     return streambuf::xsputn(s, n);
                    121: }

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