Source code of Windows XP (NT5)
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/***
*fdopen.c - open a file descriptor as stream
*
* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _fdopen() - opens a file descriptor as a stream, thus allowing
* buffering, etc.
*
*Revision History:
* 09-02-83 RN initial version
* 03-02-87 JCR added support for 'b' and 't' embedded in mode strings
* 09-28-87 JCR Corrected _iob2 indexing (now uses _iob_index() macro).
* 11-03-87 JCR Multi-thread support
* 12-11-87 JCR Added "_LOAD_DS" to declaration
* 05-31-88 PHG Merged DLL and normal versions
* 06-06-88 JCR Optimized _iob2 references
* 11-20-89 GJF Fixed copyright, indents. Added const to type of mode.
* 02-15-90 GJF _iob[], _iob2[] merge.
* 03-16-90 GJF Replaced _LOAD_DS with _CALLTYPE1, added #include
* <cruntime.h> and removed #include <register.h>.
* 07-23-90 SBM Replaced <assertm.h> by <assert.h>
* 08-24-90 SBM Added support for 'c' and 'n' flags
* 10-02-90 GJF New-style function declarator.
* 01-21-91 GJF ANSI naming.
* 02-14-92 GJF Replaced _nfile with _nhandle for Win32.
* 05-01-92 DJM Replaced _nfile with OPEN_MAX for POSIX.
* 08-03-92 GJF Function name must be "fdopen" for POSIX.
* 04-06-93 SKS Replace _CRTAPI* with __cdecl
* 12-07-93 CFW Wide char enable.
* 04-05-94 GJF #ifdef-ed out _cflush reference for msvcrt*.dll, it
* is unnecessary.
* 09-06-94 CFW Replace MTHREAD with _MT.
* 01-04-95 GJF _WIN32_ -> _WIN32.
* 02-06-94 CFW assert -> _ASSERTE.
* 02-17-95 GJF Merged in Mac version.
* 03-07-95 GJF _[un]lock_str macros now take FILE * arg.
* 10-20-95 GJF Added checks to passed supplied handle is open (for
* Win32 and Mac builds) (Olympus0 10153).
* 09-26-97 BWT Fix POSIX
* 02-26-98 GJF Exception-safe locking.
* 05-17-99 PML Remove all Macintosh support.
* 10-06-99 PML Set errno EMFILE when out of streams.
*
*******************************************************************************/
#include <cruntime.h>
#include <msdos.h>
#include <stdio.h>
#include <file2.h>
#include <dbgint.h>
#include <internal.h>
#include <mtdll.h>
#ifdef _POSIX_
#include <limits.h>
#endif
#include <tchar.h>
#include <errno.h>
/***
*FILE *_fdopen(filedes, mode) - open a file descriptor as a stream
*
*Purpose:
* associates a stream with a file handle, thus allowing buffering, etc.
* The mode must be specified and must be compatible with the mode
* the file was opened with in the low level open.
*
*Entry:
* int filedes - handle referring to open file
* _TSCHAR *mode - file mode to use ("r", "w", "a", etc.)
*
*Exit:
* returns stream pointer and sets FILE struct fields if successful
* returns NULL if fails
*
*Exceptions:
*
*******************************************************************************/
FILE * __cdecl _tfdopen (
int filedes,
REG2 const _TSCHAR *mode
)
{
REG1 FILE *stream;
int whileflag, tbflag, cnflag;
_ASSERTE(mode != NULL);
#if !defined(_POSIX_)
_ASSERTE((unsigned)filedes < (unsigned)_nhandle);
_ASSERTE(_osfile(filedes) & FOPEN);
if ( ((unsigned)filedes >= (unsigned)_nhandle) ||
!(_osfile(filedes) & FOPEN) )
return(NULL);
#else
_ASSERTE((unsigned)filedes < OPEN_MAX);
if ((unsigned)filedes >= OPEN_MAX)
return(NULL);
#endif /* !_POSIX_ */
/* Find a free stream; stream is returned 'locked'. */
if ((stream = _getstream()) == NULL) {
errno = EMFILE;
return(NULL);
}
#ifdef _MT
__try {
#endif
/* First character must be 'r', 'w', or 'a'. */
switch (*mode) {
case _T('r'):
stream->_flag = _IOREAD;
break;
case _T('w'):
case _T('a'):
stream->_flag = _IOWRT;
break;
default:
stream = NULL; /* error */
goto done;
break;
}
/* There can be up to three more optional characters:
(1) A single '+' character,
(2) One of 'b' and 't' and
(3) One of 'c' and 'n'.
Note that currently, the 't' and 'b' flags are syntax checked
but ignored. 'c' and 'n', however, are correctly supported.
*/
whileflag=1;
tbflag=cnflag=0;
stream->_flag |= _commode;
while(*++mode && whileflag)
switch(*mode) {
case _T('+'):
if (stream->_flag & _IORW)
whileflag=0;
else {
stream->_flag |= _IORW;
stream->_flag &= ~(_IOREAD | _IOWRT);
}
break;
case _T('b'):
case _T('t'):
if (tbflag)
whileflag=0;
else
tbflag=1;
break;
case _T('c'):
if (cnflag)
whileflag = 0;
else {
cnflag = 1;
stream->_flag |= _IOCOMMIT;
}
break;
case _T('n'):
if (cnflag)
whileflag = 0;
else {
cnflag = 1;
stream->_flag &= ~_IOCOMMIT;
}
break;
default:
whileflag=0;
break;
}
#ifndef CRTDLL
_cflush++; /* force library pre-termination procedure */
#endif /* CRTDLL */
stream->_file = filedes;
/* Common return */
done:
#ifdef _MT
; }
__finally {
_unlock_str(stream);
}
#endif
return(stream);
}