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nuttx/libs/libc/stdio/lib_fopen.c
Michal Lenc 0a107ca6d9 libc: add support for custom streams with fopencookie() 
This commit adds support for custom stream via fopencookie function.
The function allows the programmer the create his own custom stream
for IO operations and hook his custom functions to it.

This is a non POSIX interface defined in Standard C library and implemented
according to it. The only difference is in usage of off_t instead of
off64_t. Programmer can use 64 bits offset if CONFIG_FS_LARGEFILE is
enabled. In that case off_t is defined as int64_t (int32_t otherwise).

Field fs_fd is removed from file_struct and fs_cookie is used instead
as a shared variable for file descriptor or user defined cookie.

The interface will be useful for future fmemopen implementation.

Signed-off-by: Michal Lenc <michallenc@seznam.cz>
2023-10-18 21:13:01 +08:00

418 lines
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/****************************************************************************
* libs/libc/stdio/lib_fopen.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#ifdef CONFIG_FDSAN
# include <android/fdsan.h>
#endif
#include "libc.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Open mode flags */
#define MODE_R (1 << 0) /* Bit 0: "r{b|x|+}" open for reading */
#define MODE_W (1 << 1) /* Bit 1: "w{b|x|+}" open for writing, truncating,
* or creating file */
#define MODE_A (1 << 2) /* Bit 2: "a{b|x|+}" open for writing, appending
* the to file */
#define MODE_NONE 0 /* No access mode determined */
#define MODE_MASK (MODE_R | MODE_W | MODE_A)
#define FLAG_KEEP (O_TEXT | O_CLOEXEC | O_EXCL)
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: fdopen
****************************************************************************/
FAR FILE *fdopen(int fd, FAR const char *mode)
{
FAR struct streamlist *list = lib_get_streams();
FAR FILE *filep = NULL;
int oflags;
int ret;
/* Map the open mode string to open flags */
oflags = lib_mode2oflags(mode);
if (oflags < 0)
{
return NULL;
}
/* Allocate FILE structure */
if (fd >= 3)
{
filep = lib_zalloc(sizeof(FILE));
if (filep == NULL)
{
ret = -ENOMEM;
goto errout;
}
/* Add FILE structure to the stream list */
ret = nxmutex_lock(&list->sl_lock);
if (ret < 0)
{
lib_free(filep);
goto errout;
}
if (list->sl_tail)
{
list->sl_tail->fs_next = filep;
list->sl_tail = filep;
}
else
{
list->sl_head = filep;
list->sl_tail = filep;
}
nxmutex_unlock(&list->sl_lock);
/* Initialize the mutex the manages access to the buffer */
nxrmutex_init(&filep->fs_lock);
}
else
{
filep = &list->sl_std[fd];
}
#if !defined(CONFIG_STDIO_DISABLE_BUFFERING) && CONFIG_STDIO_BUFFER_SIZE > 0
/* Set up pointers */
filep->fs_bufstart = filep->fs_buffer;
filep->fs_bufend = filep->fs_bufstart + CONFIG_STDIO_BUFFER_SIZE;
filep->fs_bufpos = filep->fs_bufstart;
filep->fs_bufread = filep->fs_bufstart;
filep->fs_flags = __FS_FLAG_UBF; /* Fake setvbuf and fclose */
# ifdef CONFIG_STDIO_LINEBUFFER
/* Setup buffer flags */
filep->fs_flags |= __FS_FLAG_LBF; /* Line buffering */
# endif /* CONFIG_STDIO_LINEBUFFER */
#endif /* !CONFIG_STDIO_DISABLE_BUFFERING && CONFIG_STDIO_BUFFER_SIZE > 0 */
/* Save the file description and open flags. Setting the
* file descriptor locks this stream.
*/
filep->fs_cookie = (FAR void *)(intptr_t)fd;
filep->fs_oflags = oflags;
#ifdef CONFIG_FDSAN
android_fdsan_exchange_owner_tag(fd, 0,
android_fdsan_create_owner_tag(ANDROID_FDSAN_OWNER_TYPE_FILE,
(uintptr_t)filep));
#endif
/* Assign custom callbacks to NULL. */
filep->fs_iofunc.read = NULL;
filep->fs_iofunc.write = NULL;
filep->fs_iofunc.seek = NULL;
filep->fs_iofunc.close = NULL;
return filep;
errout:
set_errno(-ret);
return NULL;
}
/****************************************************************************
* Name: fopen
****************************************************************************/
FAR FILE *fopen(FAR const char *path, FAR const char *mode)
{
FAR FILE *filep = 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 call fdopen() using the file
* descriptor returned by open. If open failed, then just return the
* NULL stream -- open() has already set the errno.
*/
if (fd >= 0)
{
filep = fdopen(fd, mode);
if (filep == NULL)
{
/* Don't forget to close the file descriptor if any other
* failures are reported by fdopen().
*/
close(fd);
}
}
return filep;
}
/****************************************************************************
* Name: lib_mode2oflags
****************************************************************************/
int lib_mode2oflags(FAR const char *mode)
{
unsigned int state;
int oflags;
/* Verify that a mode string was provided. */
DEBUGASSERT(mode);
/* 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{m|b|x|+}") */
case 'r' :
if (state == MODE_NONE)
{
/* Open for read access */
oflags = O_RDOK | O_TEXT;
state = MODE_R;
}
else
{
goto errout;
}
break;
/* Open for write access ("w{b|x|+}") */
case 'w' :
if (state == MODE_NONE)
{
/* Open for write access, truncating any existing file */
oflags = O_WROK | O_CREAT | O_TRUNC | O_TEXT;
state = MODE_W;
}
else
{
goto errout;
}
break;
/* Open for write/append access ("a{b|x|+}") */
case 'a' :
if (state == MODE_NONE)
{
/* Write to the end of the file */
oflags = O_WROK | O_CREAT | O_APPEND | O_TEXT;
state = MODE_A;
}
else
{
goto errout;
}
break;
/* Open for update access ("{r|w|a|b|x}+") */
case '+' :
switch (state & MODE_MASK)
{
case MODE_R:
{
/* Retain any binary and exclusive mode selections */
oflags &= FLAG_KEEP;
/* Open for read/write access */
oflags |= O_RDWR;
}
break;
case MODE_W:
{
/* Retain any binary and exclusive mode selections */
oflags &= FLAG_KEEP;
/* Open for write read/access, truncating any existing
* file.
*/
oflags |= O_RDWR | O_CREAT | O_TRUNC;
}
break;
case MODE_A:
{
/* Retain any binary and exclusive mode selections */
oflags &= FLAG_KEEP;
/* Read from the beginning of the file; write to the
* end,
*/
oflags |= O_RDWR | O_CREAT | O_APPEND;
}
break;
default:
goto errout;
break;
}
break;
/* Attempt to access the file using mmap. */
case 'm' :
if (state != MODE_R)
{
goto errout;
}
break;
/* Open for binary access ("{r|w|a|x|+}b") */
case 'b' :
if ((state & MODE_MASK) != MODE_NONE)
{
/* The file is opened in binary mode */
oflags &= ~O_TEXT;
}
else
{
goto errout;
}
break;
/* Open for close on execute */
case 'e' :
if ((state & MODE_MASK) != MODE_NONE)
{
/* The file will be closed on execute */
oflags |= O_CLOEXEC;
}
else
{
goto errout;
}
break;
/* Open for exclusive access ("{r|w|a|b|+}x") */
case 'x' :
if ((state & MODE_MASK) != MODE_NONE)
{
/* The file is opened in exclusive mode */
oflags |= O_EXCL;
}
else
{
goto errout;
}
break;
/* Open for text (translated) access ("{r|w|a|x|+}t") */
case 't' :
if ((state & MODE_MASK) != MODE_NONE)
{
/* The file is opened in text mode */
oflags |= O_TEXT;
}
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;
}
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