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px4-firmware/nuttx/libc/stdio/lib_fopen.c

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/****************************************************************************
* lib/stdio/lib_fopen.c
*
* Copyright (C) 2007-2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include "lib_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
enum open_mode_e
{
MODE_NONE = 0, /* No access mode determined */
MODE_R, /* "r" or "rb" open for reading */
MODE_W, /* "w" or "wb" open for writing, truncating or creating file */
MODE_A, /* "a" or "ab" open for writing, appending to file */
MODE_RPLUS, /* "r+", "rb+", or "r+b" open for update (reading and writing) */
MODE_WPLUS, /* "w+", "wb+", or "w+b" open for update, truncating or creating file */
MODE_APLUS /* "a+", "ab+", or "a+b" open for update, appending to file */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: lib_mode2oflags
****************************************************************************/
static int lib_mode2oflags(FAR const char *mode)
{
enum open_mode_e state;
int oflags;
/* Verify that a mode string was provided. No error is */
if (!mode)
{
goto errout;
}
/* Parse the mode string to determine the corresponding open flags */
state = MODE_NONE;
oflags = 0;
for (; *mode; mode++)
{
switch (*mode)
{
/* Open for read access ("r", "r[+]", "r[b]", "r[b+]", or "r[+b]") */
case 'r' :
if (state == MODE_NONE)
{
/* Open for read access */
oflags = O_RDOK;
state = MODE_R;
}
else
{
goto errout;
}
break;
/* Open for write access ("w", "w[+]", "w[b]", "w[b+]", or "w[+b]") */
case 'w' :
if (state == MODE_NONE)
{
/* Open for write access, truncating any existing file */
oflags = O_WROK|O_CREAT|O_TRUNC;
state = MODE_W;
}
else
{
goto errout;
}
break;
/* Open for write/append access ("a", "a[+]", "a[b]", "a[b+]", or "a[+b]") */
case 'a' :
if (state == MODE_NONE)
{
/* Write to the end of the file */
oflags = O_WROK|O_CREAT|O_APPEND;
state = MODE_A;
}
else
{
goto errout;
}
break;
/* Open for update access ("[r]+", "[rb]+]", "[r]+[b]", "[w]+",
* "[wb]+]", "[w]+[b]", "[a]+", "[ab]+]", "[a]+[b]")
*/
case '+' :
switch (state)
{
case MODE_R:
{
/* Retain any binary mode selection */
oflags &= O_BINARY;
/* Open for read/write access */
oflags |= O_RDWR;
state = MODE_RPLUS;
}
break;
case MODE_W:
{
/* Retain any binary mode selection */
oflags &= O_BINARY;
/* Open for write read/access, truncating any existing file */
oflags |= O_RDWR|O_CREAT|O_TRUNC;
state = MODE_WPLUS;
}
break;
case MODE_A:
{
/* Retain any binary mode selection */
oflags &= O_BINARY;
/* Read from the beginning of the file; write to the end */
oflags |= O_RDWR|O_CREAT|O_APPEND;
state = MODE_APLUS;
}
break;
default:
goto errout;
break;
}
break;
/* Open for binary access ("[r]b", "[r]b[+]", "[r+]b", "[w]b",
* "[w]b[+]", "[w+]b", "[a]b", "[a]b[+]", "[a+]b")
*/
case 'b' :
if (state != MODE_NONE)
{
/* The file is opened in binary mode */
oflags |= O_BINARY;
}
else
{
goto errout;
}
break;
/* Unrecognized or unsupported mode */
default:
goto errout;
break;
}
}
return oflags;
/* Both fopen and fdopen should fail with errno == EINVAL if the mode
* string is invalid.
*/
errout:
set_errno(EINVAL);
return ERROR;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: fdopen
****************************************************************************/
FAR FILE *fdopen(int fd, FAR const char *mode)
{
FAR FILE *ret = NULL;
int oflags;
/* Map the open mode string to open flags */
oflags = lib_mode2oflags(mode);
if (oflags >= 0)
{
ret = fs_fdopen(fd, oflags, NULL);
}
return ret;
}
/****************************************************************************
* Name: fopen
****************************************************************************/
FAR FILE *fopen(FAR const char *path, FAR const char *mode)
{
FAR FILE *ret = NULL;
int oflags;
int fd;
/* Map the open mode string to open flags */
oflags = lib_mode2oflags(mode);
if (oflags < 0)
{
return NULL;
}
/* Open the file */
fd = open(path, oflags, 0666);
/* If the open was successful, then fdopen() the fil using the file
* desciptor returned by open. If open failed, then just return the
* NULL stream -- open() has already set the errno.
*/
if (fd >= 0)
{
ret = fs_fdopen(fd, oflags, NULL);
if (!ret)
{
/* Don't forget to close the file descriptor if any other
* failures are reported by fdopen().
*/
(void)close(fd);
}
}
return ret;
}
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