281 lines
9.2 KiB
C
281 lines
9.2 KiB
C
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/***
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*_open.c - open a stream, with string mode
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*
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* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines _openfile() - opens a stream, with string arguments for mode
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*
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*Revision History:
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* 09-02-83 RN initial version
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* 03-02-87 JCR made _openfile recognize "wb+" as equal to "w+b", etc.
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* got rid of intermediate _openfile flags (internal) and
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* now go straight from mode string to open system call
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* and system->_flags.
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* 09-28-87 JCR Corrected _iob2 indexing (now uses _iob_index() macro).
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* 02-21-88 SKS Removed #ifdef IBMC20
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* 06-06-88 JCR Optimized _iob2 references
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* 06-10-88 JCR Use near pointer to reference _iob[] entries
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* 08-19-88 GJF Initial adaption for the 386.
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* 11-14-88 GJF Added shflag (file sharing flag) parameter, also some
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* cleanup (now specific to the 386).
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* 08-17-89 GJF Clean up, now specific to OS/2 2.0 (i.e., 386 flat
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* model). Also fixed copyright and indents.
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* 02-15-90 GJF _iob[], _iob2[] merge. Also, fixed copyright.
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* 03-16-90 GJF Made calling type _CALLTYPE1, added #include
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* <cruntime.h> and removed #include <register.h>.
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* 03-27-90 GJF Added const qualifier to types of filename and mode.
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* Added #include <io.h>.
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* 07-11-90 SBM Added support for 'c' and 'n' flags
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* 07-23-90 SBM Replaced <assertm.h> by <assert.h>
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* 10-03-90 GJF New-style function declarator.
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* 01-18-91 GJF ANSI naming.
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* 03-11-92 GJF Replaced __tmpnum field with _tmpfname field for
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* Win32.
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* 03-25-92 DJM POSIX support.
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* 08-26-92 GJF Fixed POSIX support.
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* 04-06-93 SKS Replace _CRTAPI* with __cdecl
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* 05-24-93 PML Added support for 'D', 'R', 'S' and 'T' flags
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* 11-01-93 CFW Enable Unicode variant, rip out CRUISER.
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* 04-05-94 GJF #ifdef-ed out _cflush reference for msvcrt*.dll, it
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* is unnecessary.
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* 02-06-94 CFW assert -> _ASSERTE.
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* 02-17-95 GJF Appended Mac version of source file (somewhat cleaned
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* up), with appropriate #ifdef-s.
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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 <stdio.h>
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#include <fcntl.h>
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#include <file2.h>
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#include <io.h>
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#include <dbgint.h>
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#include <internal.h>
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#include <tchar.h>
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#define CMASK 0644 /* rw-r--r-- */
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#define P_CMASK 0666 /* different for Posix */
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/***
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*FILE *_openfile(filename, mode, shflag, stream) - open a file with string
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* mode and file sharing flag.
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*
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*Purpose:
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* parse the string, looking for exactly one of {rwa}, at most one '+',
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* at most one of {tb}, at most one of {cn}, at most one of {SR}, at most
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* one 'T', and at most one 'D'. pass the result on as an int containing
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* flags of what was found. open a file with proper mode if permissions
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* allow. buffer not allocated until first i/o call is issued. intended
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* for use inside library only
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*
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*Entry:
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* char *filename - file to open
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* char *mode - mode to use (see above)
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* int shflag - file sharing flag
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* FILE *stream - stream to use for file
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*
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*Exit:
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* set stream's fields, and causes system file management by system calls
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* returns stream or NULL if fails
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*
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*Exceptions:
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*
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*******************************************************************************/
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#ifdef _UNICODE
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FILE * __cdecl _wopenfile (
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#else
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FILE * __cdecl _openfile (
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#endif
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const _TSCHAR *filename,
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REG3 const _TSCHAR *mode,
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#ifndef _POSIX_
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int shflag,
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#endif
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FILE *str
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)
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{
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REG2 int modeflag;
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#ifdef _POSIX_
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int streamflag = 0;
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#else
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int streamflag = _commode;
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int commodeset = 0;
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int scanset = 0;
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#endif
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int whileflag;
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int filedes;
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REG1 FILE *stream;
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_ASSERTE(filename != NULL);
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_ASSERTE(mode != NULL);
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_ASSERTE(str != NULL);
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/* Parse the user's specification string as set flags in
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(1) modeflag - system call flags word
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(2) streamflag - stream handle flags word. */
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/* First mode character must be 'r', 'w', or 'a'. */
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switch (*mode) {
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case _T('r'):
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#ifdef _POSIX_
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modeflag = O_RDONLY;
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#else
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modeflag = _O_RDONLY;
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#endif
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streamflag |= _IOREAD;
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break;
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case _T('w'):
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#ifdef _POSIX_
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modeflag = O_WRONLY | O_CREAT | O_TRUNC;
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#else
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modeflag = _O_WRONLY | _O_CREAT | _O_TRUNC;
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#endif
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streamflag |= _IOWRT;
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break;
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case _T('a'):
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#ifdef _POSIX_
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modeflag = O_WRONLY | O_CREAT | O_APPEND;
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streamflag |= _IOWRT | _IOAPPEND;
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#else
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modeflag = _O_WRONLY | _O_CREAT | _O_APPEND;
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streamflag |= _IOWRT;
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#endif
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break;
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default:
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return(NULL);
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break;
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}
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/* There can be up to three more optional mode characters:
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(1) A single '+' character,
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(2) One of 't' and 'b' and
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(3) One of 'c' and 'n'.
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*/
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whileflag=1;
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while(*++mode && whileflag)
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switch(*mode) {
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case _T('+'):
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#ifdef _POSIX_
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if (modeflag & O_RDWR)
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whileflag=0;
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else {
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modeflag |= O_RDWR;
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modeflag &= ~(O_RDONLY | O_WRONLY);
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#else
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if (modeflag & _O_RDWR)
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whileflag=0;
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else {
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modeflag |= _O_RDWR;
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modeflag &= ~(_O_RDONLY | _O_WRONLY);
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#endif
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streamflag |= _IORW;
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streamflag &= ~(_IOREAD | _IOWRT);
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}
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break;
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case _T('b'):
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#ifndef _POSIX_
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if (modeflag & (_O_TEXT | _O_BINARY))
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whileflag=0;
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else
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modeflag |= _O_BINARY;
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#endif
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break;
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#ifndef _POSIX_
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case _T('t'):
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if (modeflag & (_O_TEXT | _O_BINARY))
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whileflag=0;
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else
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modeflag |= _O_TEXT;
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break;
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case _T('c'):
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if (commodeset)
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whileflag=0;
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else {
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commodeset = 1;
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streamflag |= _IOCOMMIT;
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}
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break;
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case _T('n'):
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if (commodeset)
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whileflag=0;
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else {
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commodeset = 1;
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streamflag &= ~_IOCOMMIT;
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}
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break;
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case _T('S'):
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if (scanset)
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whileflag=0;
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else {
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scanset = 1;
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modeflag |= _O_SEQUENTIAL;
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}
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break;
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case _T('R'):
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if (scanset)
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whileflag=0;
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else {
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scanset = 1;
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modeflag |= _O_RANDOM;
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}
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break;
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case _T('T'):
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if (modeflag & _O_SHORT_LIVED)
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whileflag=0;
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else
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modeflag |= _O_SHORT_LIVED;
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break;
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case _T('D'):
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if (modeflag & _O_TEMPORARY)
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whileflag=0;
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else
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modeflag |= _O_TEMPORARY;
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break;
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#endif
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default:
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whileflag=0;
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break;
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}
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/* Try to open the file. Note that if neither 't' nor 'b' is
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specified, _sopen will use the default. */
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#ifdef _POSIX_
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if ((filedes = _topen(filename, modeflag, P_CMASK)) < 0)
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#else
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if ((filedes = _tsopen(filename, modeflag, shflag, CMASK)) < 0)
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#endif
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return(NULL);
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/* Set up the stream data base. */
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#ifndef CRTDLL
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_cflush++; /* force library pre-termination procedure */
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#endif /* CRTDLL */
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/* Init pointers */
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stream = str;
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stream->_flag = streamflag;
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stream->_cnt = 0;
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stream->_tmpfname = stream->_base = stream->_ptr = NULL;
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stream->_file = filedes;
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return(stream);
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}
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