/***
*_open.c - open a stream, with string mode
*
* Copyright (c) 1985-1993, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _openfile() - opens a stream, with string arguments for mode
*
*Revision History:
* 09-02-83 RN initial version
* 03-02-87 JCR made _openfile recognize "wb+" as equal to "w+b", etc.
* got rid of intermediate _openfile flags (internal) and
* now go straight from mode string to open system call
* and system->_flags.
* 09-28-87 JCR Corrected _iob2 indexing (now uses _iob_index() macro).
* 02-21-88 SKS Removed #ifdef IBMC20
* 06-06-88 JCR Optimized _iob2 references
* 06-10-88 JCR Use near pointer to reference _iob[] entries
* 08-19-88 GJF Initial adaption for the 386.
* 11-14-88 GJF Added shflag (file sharing flag) parameter, also some
* cleanup (now specific to the 386).
* 08-17-89 GJF Clean up, now specific to OS/2 2.0 (i.e., 386 flat
* model). Also fixed copyright and indents.
* 02-15-90 GJF _iob[], _iob2[] merge. Also, fixed copyright.
* 03-16-90 GJF Made calling type _CALLTYPE1, added #include
* <cruntime.h> and removed #include <register.h>.
* 03-27-90 GJF Added const qualifier to types of filename and mode.
* Added #include <io.h>.
* 07-11-90 SBM Added support for 'c' and 'n' flags
* 07-23-90 SBM Replaced <assertm.h> by <assert.h>
* 10-03-90 GJF New-style function declarator.
* 01-18-91 GJF ANSI naming.
* 03-11-92 GJF Replaced __tmpnum field with _tmpfname field for
* Win32.
* 03-25-92 DJM POSIX support.
* 08-26-92 GJF Fixed POSIX support.
* 05-24-93 PML Added support for 'D', 'R', 'S' and 'T' flags
*
*******************************************************************************/
#include <cruntime.h>
#include <stdio.h>
#include <fcntl.h>
#include <file2.h>
#include <io.h>
#include <assert.h>
#include <internal.h>
#define CMASK 0644 /* rw-r--r-- */
#define P_CMASK 0666 /* different for Posix */
/***
*FILE *_openfile(filename, mode, shflag, stream) - open a file with string
* mode and file sharing flag.
*
*Purpose:
* parse the string, looking for exactly one of {rwa}, at most one '+',
* at most one of {tb}, at most one of {cn}, at most one of {SR}, at most
* one 'T', and at most one 'D'. pass the result on as an int containing
* flags of what was found. open a file with proper mode if permissions
* allow. buffer not allocated until first i/o call is issued. intended
* for use inside library only
*
*Entry:
* char *filename - file to open
* char *mode - mode to use (see above)
* int shflag - file sharing flag
* FILE *stream - stream to use for file
*
*Exit:
* set stream's fields, and causes system file management by system calls
* returns stream or NULL if fails
*
*Exceptions:
*
*******************************************************************************/
FILE * _CRTAPI1 _openfile (
const char *filename,
REG3 const char *mode,
#ifndef _POSIX_
int shflag,
#endif
FILE *str
)
{
REG2 int modeflag;
#ifdef _POSIX_
int streamflag = 0;
#else
int streamflag = _commode;
int commodeset = 0;
int scanset = 0;
#endif
int whileflag;
int filedes;
REG1 FILE *stream;
assert(filename != NULL);
assert(mode != NULL);
assert(str != NULL);
/* Parse the user's specification string as set flags in
(1) modeflag - system call flags word
(2) streamflag - stream handle flags word. */
/* First mode character must be 'r', 'w', or 'a'. */
switch (*mode) {
case 'r':
#ifdef _POSIX_
modeflag = O_RDONLY;
#else
modeflag = _O_RDONLY;
#endif
streamflag |= _IOREAD;
break;
case 'w':
#ifdef _POSIX_
modeflag = O_WRONLY | O_CREAT | O_TRUNC;
#else
modeflag = _O_WRONLY | _O_CREAT | _O_TRUNC;
#endif
streamflag |= _IOWRT;
break;
case 'a':
#ifdef _POSIX_
modeflag = O_WRONLY | O_CREAT | O_APPEND;
streamflag |= _IOWRT | _IOAPPEND;
#else
modeflag = _O_WRONLY | _O_CREAT | _O_APPEND;
streamflag |= _IOWRT;
#endif
break;
default:
return(NULL);
break;
}
/* There can be up to three more optional mode characters:
(1) A single '+' character,
(2) One of 't' and 'b' and
(3) One of 'c' and 'n'.
*/
whileflag=1;
while(*++mode && whileflag)
switch(*mode) {
case '+':
#ifdef _POSIX_
if (modeflag & O_RDWR)
whileflag=0;
else {
modeflag |= O_RDWR;
modeflag &= ~(O_RDONLY | O_WRONLY);
#else
if (modeflag & _O_RDWR)
whileflag=0;
else {
modeflag |= _O_RDWR;
modeflag &= ~(_O_RDONLY | _O_WRONLY);
#endif
streamflag |= _IORW;
streamflag &= ~(_IOREAD | _IOWRT);
}
break;
case 'b':
#ifndef _POSIX_
if (modeflag & (_O_TEXT | _O_BINARY))
whileflag=0;
else
modeflag |= _O_BINARY;
#endif
break;
#ifndef _POSIX_
case 't':
if (modeflag & (_O_TEXT | _O_BINARY))
whileflag=0;
else
modeflag |= _O_TEXT;
break;
case 'c':
if (commodeset)
whileflag=0;
else {
commodeset = 1;
streamflag |= _IOCOMMIT;
}
break;
case 'n':
if (commodeset)
whileflag=0;
else {
commodeset = 1;
streamflag &= ~_IOCOMMIT;
}
break;
case 'S':
if (scanset)
whileflag=0;
else {
scanset = 1;
modeflag |= _O_SEQUENTIAL;
}
break;
case 'R':
if (scanset)
whileflag=0;
else {
scanset = 1;
modeflag |= _O_RANDOM;
}
break;
case 'T':
if (modeflag & _O_SHORT_LIVED)
whileflag=0;
else
modeflag |= _O_SHORT_LIVED;
break;
case 'D':
if (modeflag & _O_TEMPORARY)
whileflag=0;
else
modeflag |= _O_TEMPORARY;
break;
#endif
default:
whileflag=0;
break;
}
/* Try to open the file. Note that if neither 't' nor 'b' is
specified, _sopen will use the default. */
#ifdef _POSIX_
if ((filedes = open(filename, modeflag, P_CMASK)) < 0)
#else
if ((filedes = _sopen(filename, modeflag, shflag, CMASK)) < 0)
#endif
return(NULL);
/* Set up the stream data base. */
_cflush++; /* force library pre-termination procedure */
/* Init pointers */
stream = str;
stream->_flag = streamflag;
#ifdef _CRUISER_
stream->_cnt = stream->__tmpnum = 0;
stream->_base = stream->_ptr = NULL;
#else /* ndef _CRUISER_ */
stream->_cnt = 0;
stream->_tmpfname = stream->_base = stream->_ptr = NULL;
#endif /* _CRUISER_ */
stream->_file = filedes;
return(stream);
}
