ack/plat/msdos/libsys/open.c

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/* $Source$
* $State$
* $Revision$
*/
/*
* Derived from dos-open.c for newlib-ia16 which was written for the
* gcc-ia16 toolchain.
*
* Copyright (c) 2018 Bart Oldeman
* Copyright (c) 2019--2021 TK Chia
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice is included verbatim in any distributions. No written agreement,
* license, or royalty fee is required for any of the authorized uses.
* Modifications to this software may be copyrighted by their authors
* and need not follow the licensing terms described here, provided that
* the new terms are clearly indicated on the first page of each file where
* they apply.
*/
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <unistd.h>
#include "libsys.h"
int open(const char* pathname, int flags, ...)
{
int fd = -1, binmode;
off_t ret;
if ((flags & ~(O_ACCMODE | O_CREAT | O_TRUNC | O_APPEND
| O_TEXT | O_BINARY)))
{
/* bail out if there are unknown flags */
errno = EINVAL;
return -1;
}
binmode = flags & (O_TEXT | O_BINARY);
if (binmode != O_TEXT && binmode != O_BINARY && binmode != 0)
{
/* bail out if both O_TEXT and O_BINARY are specified (!) */
errno = EINVAL;
return -1;
}
if ((flags & O_CREAT))
{
/* special but common case O_WRONLY | O_CREAT | O_TRUNC
* should be handled by only calling _sys_rawcreat */
int fileexists = 0;
if (!(flags & O_TRUNC))
fileexists = _sys_exists(pathname);
if (!fileexists)
{
va_list ap;
mode_t mode;
va_start(ap, flags);
mode = va_arg(ap, mode_t);
va_end(ap);
fd = _sys_rawcreat(pathname, mode & 0200 ? 0 : 1);
if (fd != -1)
{
if ((flags & O_ACCMODE) == O_WRONLY)
return fd;
close(fd);
fd = -1;
}
}
}
/* try to open file with mode */
if (fd == -1)
fd = _sys_rawopen(pathname, flags & O_ACCMODE);
if (fd == -1)
return fd;
ret = 0;
/* handle O_TRUNC and O_APPEND */
if ((flags & O_TRUNC))
ret = _sys_rawwrite(fd, NULL, 0);
else if ((flags & O_APPEND))
ret = _sys_rawlseek(fd, 0L, SEEK_END);
if (ret == -1)
{
close(fd);
return -1;
}
/* handle O_TEXT and O_BINARY, and reset "end of file encountered" */
_sys_setmode(fd, binmode == O_BINARY ? O_BINARY : O_TEXT);
_sys_seteof(fd, 0);
return fd;
}