lwip/contrib/examples/httpd/fs_example/fs_example.c

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/**
* @file
* HTTPD custom file system example
*
* This file demonstrates how to add support for an external file system to httpd.
* It provides access to the specified root directory and uses stdio.h file functions
* to read files.
*
* ATTENTION: This implementation is *not* secure: no checks are added to ensure
* files are only read below the specified root directory!
*/
/*
* Copyright (c) 2017 Simon Goldschmidt
* All rights reserved.
*
* 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. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
* This file is part of the lwIP TCP/IP stack.
*
* Author: Simon Goldschmidt <goldsimon@gmx.de>
*
*/
#include "lwip/opt.h"
#include "fs_example.h"
#include "lwip/apps/fs.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include <stdio.h>
#include <string.h>
/** define LWIP_HTTPD_EXAMPLE_CUSTOMFILES to 1 to enable this file system */
#ifndef LWIP_HTTPD_EXAMPLE_CUSTOMFILES
#define LWIP_HTTPD_EXAMPLE_CUSTOMFILES 0
#endif
/** define LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED to 1 to delay open and read
* as if e.g. reading from external SPI flash */
#ifndef LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
#define LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED 1
#endif
/** define LWIP_HTTPD_EXAMPLE_CUSTOMFILES_LIMIT_READ to the number of bytes
* to read to emulate limited transfer buffers and don't read whole files in
* one chunk.
* WARNING: lowering this slows down the connection!
*/
#ifndef LWIP_HTTPD_EXAMPLE_CUSTOMFILES_LIMIT_READ
#define LWIP_HTTPD_EXAMPLE_CUSTOMFILES_LIMIT_READ 0
#endif
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES
#if !LWIP_HTTPD_CUSTOM_FILES
#error This needs LWIP_HTTPD_CUSTOM_FILES
#endif
#if !LWIP_HTTPD_DYNAMIC_HEADERS
#error This needs LWIP_HTTPD_DYNAMIC_HEADERS
#endif
#if !LWIP_HTTPD_DYNAMIC_FILE_READ
#error This wants to demonstrate read-after-open, so LWIP_HTTPD_DYNAMIC_FILE_READ is required!
#endif
#if !LWIP_HTTPD_FS_ASYNC_READ
#error This needs LWIP_HTTPD_FS_ASYNC_READ
#endif
#if !LWIP_HTTPD_FILE_EXTENSION
#error This needs LWIP_HTTPD_FILE_EXTENSION
#endif
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
#include "lwip/tcpip.h"
#endif
struct fs_custom_data {
FILE *f;
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
int delay_read;
fs_wait_cb callback_fn;
void *callback_arg;
#endif
};
const char* fs_ex_root_dir;
void
fs_ex_init(const char *httpd_root_dir)
{
fs_ex_root_dir = strdup(httpd_root_dir);
}
#if LWIP_HTTPD_CUSTOM_FILES
int
fs_open_custom(struct fs_file *file, const char *name)
{
char full_filename[256];
FILE *f;
snprintf(full_filename, 255, "%s%s", fs_ex_root_dir, name);
full_filename[255] = 0;
f = fopen(full_filename, "rb");
if (f != NULL) {
if (!fseek(f, 0, SEEK_END)) {
int len = (int)ftell(f);
if(!fseek(f, 0, SEEK_SET)) {
struct fs_custom_data *data = (struct fs_custom_data *)mem_malloc(sizeof(struct fs_custom_data));
LWIP_ASSERT("out of memory?", data != NULL);
memset(file, 0, sizeof(struct fs_file));
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
file->len = 0; /* read size delayed */
data->delay_read = 3;
LWIP_UNUSED_ARG(len);
#else
file->len = len;
#endif
file->flags = FS_FILE_FLAGS_HEADER_PERSISTENT;
data->f = f;
file->pextension = data;
return 1;
}
}
fclose(f);
}
return 0;
}
void
fs_close_custom(struct fs_file *file)
{
if (file && file->pextension) {
struct fs_custom_data *data = (struct fs_custom_data *)file->pextension;
if (data->f != NULL) {
fclose(data->f);
data->f = NULL;
}
mem_free(data);
}
}
#if LWIP_HTTPD_FS_ASYNC_READ
u8_t
fs_canread_custom(struct fs_file *file)
{
/* This function is only necessary for asynchronous I/O:
If reading would block, return 0 and implement fs_wait_read_custom() to call the
supplied callback if reading works. */
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
struct fs_custom_data *data;
LWIP_ASSERT("file != NULL", file != NULL);
data = (struct fs_custom_data *)file->pextension;
if (data == NULL) {
/* file transfer has been completed already */
LWIP_ASSERT("transfer complete", file->index == file->len);
return 1;
}
LWIP_ASSERT("data != NULL", data != NULL);
/* This just simulates a simple delay. This delay would normally come e.g. from SPI transfer */
if (data->delay_read == 3) {
/* delayed file size mode */
data->delay_read = 1;
LWIP_ASSERT("", file->len == 0);
if (!fseek(data->f, 0, SEEK_END)) {
int len = (int)ftell(data->f);
if(!fseek(data->f, 0, SEEK_SET)) {
file->len = len; /* read size delayed */
data->delay_read = 1;
return 0;
}
}
/* if we come here, something is wrong with the file */
LWIP_ASSERT("file error", 0);
}
if (data->delay_read == 1) {
/* tell read function to delay further */
}
#endif
LWIP_UNUSED_ARG(file);
return 1;
}
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
static void
fs_example_read_cb(void *arg)
{
struct fs_custom_data *data = (struct fs_custom_data *)arg;
fs_wait_cb callback_fn = data->callback_fn;
void *callback_arg = data->callback_arg;
data->callback_fn = NULL;
data->callback_arg = NULL;
LWIP_ASSERT("no callback_fn", callback_fn != NULL);
callback_fn(callback_arg);
}
#endif
u8_t
fs_wait_read_custom(struct fs_file *file, fs_wait_cb callback_fn, void *callback_arg)
{
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
err_t err;
struct fs_custom_data *data = (struct fs_custom_data *)file->pextension;
LWIP_ASSERT("data not set", data != NULL);
data->callback_fn = callback_fn;
data->callback_arg = callback_arg;
err = tcpip_try_callback(fs_example_read_cb, data);
LWIP_ASSERT("out of queue elements?", err == ERR_OK);
LWIP_UNUSED_ARG(err);
#else
LWIP_ASSERT("not implemented in this example configuration", 0);
#endif
LWIP_UNUSED_ARG(file);
LWIP_UNUSED_ARG(callback_fn);
LWIP_UNUSED_ARG(callback_arg);
/* Return
- 0 if ready to read (at least one byte)
- 1 if reading should be delayed (call 'tcpip_callback(callback_fn, callback_arg)' when ready) */
return 1;
}
int
fs_read_async_custom(struct fs_file *file, char *buffer, int count, fs_wait_cb callback_fn, void *callback_arg)
{
struct fs_custom_data *data = (struct fs_custom_data *)file->pextension;
FILE *f;
int len;
int read_count = count;
LWIP_ASSERT("data not set", data != NULL);
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_DELAYED
/* This just simulates a delay. This delay would normally come e.g. from SPI transfer */
LWIP_ASSERT("invalid state", data->delay_read >= 0 && data->delay_read <= 2);
if (data->delay_read == 2) {
/* no delay next time */
data->delay_read = 0;
return FS_READ_DELAYED;
} else if (data->delay_read == 1) {
err_t err;
/* execute requested delay */
data->delay_read = 2;
LWIP_ASSERT("duplicate callback request", data->callback_fn == NULL);
data->callback_fn = callback_fn;
data->callback_arg = callback_arg;
err = tcpip_try_callback(fs_example_read_cb, data);
LWIP_ASSERT("out of queue elements?", err == ERR_OK);
LWIP_UNUSED_ARG(err);
return FS_READ_DELAYED;
}
/* execute this read but delay the next one */
data->delay_read = 1;
#endif
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_LIMIT_READ
read_count = LWIP_MIN(read_count, LWIP_HTTPD_EXAMPLE_CUSTOMFILES_LIMIT_READ);
#endif
f = data->f;
len = (int)fread(buffer, 1, read_count, f);
LWIP_UNUSED_ARG(callback_fn);
LWIP_UNUSED_ARG(callback_arg);
file->index += len;
/* Return
- FS_READ_EOF if all bytes have been read
- FS_READ_DELAYED if reading is delayed (call 'tcpip_callback(callback_fn, callback_arg)' when done) */
if (len == 0) {
/* all bytes read already */
return FS_READ_EOF;
}
return len;
}
#else /* LWIP_HTTPD_FS_ASYNC_READ */
int
fs_read_custom(struct fs_file *file, char *buffer, int count)
{
struct fs_custom_data *data = (struct fs_custom_data *)file->pextension;
FILE *f;
int len;
int read_count = count;
LWIP_ASSERT("data not set", data != NULL);
#if LWIP_HTTPD_EXAMPLE_CUSTOMFILES_LIMIT_READ
read_count = LWIP_MIN(read_count, LWIP_HTTPD_EXAMPLE_CUSTOMFILES_LIMIT_READ);
#endif
f = data->f;
len = (int)fread(buffer, 1, read_count, f);
file->index += len;
/* Return FS_READ_EOF if all bytes have been read */
return len;
}
#endif /* LWIP_HTTPD_FS_ASYNC_READ */
#endif /* LWIP_HTTPD_CUSTOM_FILES */
#endif /* LWIP_HTTPD_EXAMPLE_CUSTOMFILES */