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Factor resources, fix time

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Now there is a generic resource that can generate and parse
application/json as well as text/plain. It can be re-used, only the
from_string and to_string routines have to be written and the resource
properly set up. A new resource format is specified, see
GENERIC_RESOURCE in, e.g., examples/osd/pwm-example. This is now used in
all my examples, namely pwm-example, arduino-sketch, wallclock-time.

There was an off by one error for the month in time formatting (in
gmtime and localtime). And the leap-year computation was broken. Both
fixed now, so we get a correct date. For localtime we are still 2 hours
off because daylight saving isn't implemented yet.

Also renamed gmtime to utc.
This commit is contained in:
Ralf Schlatterbeck 2014-06-27 22:25:51 +02:00
parent 4f20df042f
commit d5284eebe1
12 changed files with 488 additions and 612 deletions
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apps/json-resource/generic_resource.h Normal file
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/*
* Copyright (c) 2014, Ralf Schlatterbeck Open Source Consulting
* 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. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
*/
/**
* \defgroup Generic CoAP Resource Handler
*
* This factors the boilerplate code necessary for defining a resource
* together with the necessary handler. Currently this supports
* text/plain and application/json and outputs the resource with its
* name in json format. This may change in the future as more CoRE
* standards (e.g. see RFC 6690) get defined.
*
* @{
*/
/**
* \file
* Generic CoAP Resource Handler
* \author
* Ralf Schlatterbeck <rsc@runtux.com>
*/
#define STR__(s) #s
#define STR_(s) STR__(s)
/*
* A macro that extends the resource definition and also sets up the
* necessary handler function that calls format/parse routines that
* convert from/to string (fs and ts). The ts function needs to return
* the length written, similar to sprintf.
* The content type definitions ct="0 5" are text/plain and
* application/json, respectively, see rfc7252 Table 9 p. 91.
* Yes, this *is* a hack. But I hate boilerplate code.
*/
#define GENERIC_RESOURCE(name, methods, path, title, unit, fs, ts) \
void name##_handler \
( void *request \
, void *response \
, uint8_t *buffer \
, uint16_t ps \
, int32_t *offset \
) \
{ \
generic_handler \
(request, response, buffer, ps, offset, STR_(name), fs, ts); \
} \
\
RESOURCE ( name, methods, path \
, "title=\"" STR_(title) "\"" \
";rt=UCUM:\"" STR_(unit) "\"" \
";ct=\"0 5\"" \
)
/**
* \brief Parse a resource in json format
* \param bytes: Input string received via coap
* \param len: Length of input string
* \param name: Name to search in json input
* \param buf: Output buffer
* \param buflen: Output buffer length
* \return 0 for success, -1 for error
*
* If compiled with DEBUG also prints the error encountered
*/
extern int8_t json_parse_variable
(const uint8_t *bytes, size_t len, char *name, char *buf, size_t buflen);
/**
* \brief Generic coap resource handler
* \param name: The name of the variable in json
* \param from_str: Application method to parse value from string
* and act on it, may be NULL in which case the resource only
* supports GET not PUT
* \param to_str: Application method to format value for output;
* the function may chose to format differently for coap or text
* The other parameters are the same as a normal resource handler
* This helps avoid boilerplate code for request handlers
*
* The callback functions get the name of the parameter as a first
* argument, this allows to re-use the same function for different
* parameters. The from_str in addition gets the string to parse.
* For the to_str function the is_json flag allows to generate a
* different string depending on the content-type. In addition it gets a
* buffer and the size of the buffer. It needs to return the number of
* bytes output, similar to sprintf.
*/
extern void generic_handler
( void *request
, void *response
, uint8_t *buffer
, uint16_t preferred_size
, int32_t *offset
, char *name
, void (*from_str)(const char *name, const char *s)
, size_t (*to_str)(const char *name, uint8_t is_json, char *buf, size_t bsize)
);
/*
* VI settings, see coding style
* ex:ts=8:et:sw=2
*/
/** @} */