Awesome
coreJSON Library
API Documentation Pages for current and previous releases of this library can be found here
This repository contains the coreJSON library, a parser that strictly enforces the ECMA-404 JSON standard and is suitable for low memory footprint embedded devices. The coreJSON library is distributed under the MIT Open Source License.
This library has gone through code quality checks including verification that no function has a GNU Complexity score over 8, and checks against deviations from mandatory rules in the MISRA coding standard. Deviations from the MISRA C:2012 guidelines are documented under MISRA Deviations. This library has also undergone both static code analysis from Coverity static analysis, and validation of memory safety through the CBMC automated reasoning tool.
See memory requirements for this library here.
coreJSON v3.3.0 source code is part of the FreeRTOS 202406.00 LTS release.
Reference example
#include <stdio.h>
#include "core_json.h"
int main()
{
// Variables used in this example.
JSONStatus_t result;
char buffer[] = "{\"foo\":\"abc\",\"bar\":{\"foo\":\"xyz\"}}";
size_t bufferLength = sizeof( buffer ) - 1;
char queryKey[] = "bar.foo";
size_t queryKeyLength = sizeof( queryKey ) - 1;
char * value;
size_t valueLength;
// Calling JSON_Validate() is not necessary if the document is guaranteed to be valid.
result = JSON_Validate( buffer, bufferLength );
if( result == JSONSuccess )
{
result = JSON_Search( buffer, bufferLength, queryKey, queryKeyLength,
&value, &valueLength );
}
if( result == JSONSuccess )
{
// The pointer "value" will point to a location in the "buffer".
char save = value[ valueLength ];
// After saving the character, set it to a null byte for printing.
value[ valueLength ] = '\0';
// "Found: bar.foo -> xyz" will be printed.
printf( "Found: %s -> %s\n", queryKey, value );
// Restore the original character.
value[ valueLength ] = save;
}
return 0;
}
A search may descend through nested objects when the queryKey
contains
matching key strings joined by a separator, .
. In the example above, bar
has
the value {"foo":"xyz"}
. Therefore, a search for query key bar.foo
would
output xyz
.
Building coreJSON
A compiler that supports C90 or later such as gcc is required to build the library.
Additionally, the library uses 2 header files introduced in ISO C99, stdbool.h
and stdint.h
. For compilers that do not provide this header file, the
source/include directory contains
stdbool.readme and
stdint.readme, which can be renamed to
stdbool.h
and stdint.h
respectively.
For instance, if the example above is copied to a file named example.c
, gcc
can be used like so:
gcc -I source/include example.c source/core_json.c -o example
./example
gcc can also produce an output file to be linked:
gcc -I source/include -c source/core_json.c
Documentation
Existing documentation
For pre-generated documentation, please see the documentation linked in the locations below:
Location |
---|
AWS IoT Device SDK for Embedded C |
GitHub.io |
Note that the latest included version of the coreJSON library may differ across repositories.
Generating documentation
The Doxygen references were created using Doxygen version 1.9.6. To generate the Doxygen pages, please run the following command from the root of this repository:
doxygen docs/doxygen/config.doxyfile
Building unit tests
Checkout Unity Submodule
By default, the submodules in this repository are configured with update=none
in .gitmodules, to avoid increasing clone time and disk space
usage of other repositories (like
amazon-freertos that submodules this
repository).
To build unit tests, the submodule dependency of Unity is required. Use the following command to clone the submodule:
git submodule update --checkout --init --recursive test/unit-test/Unity
Platform Prerequisites
- For running unit tests
- C90 compiler like gcc
- CMake 3.13.0 or later
- Ruby 2.0.0 or later is additionally required for the Unity test framework (that we use).
- For running the coverage target, gcov is additionally required.
Steps to build Unit Tests
-
Go to the root directory of this repository. (Make sure that the Unity submodule is cloned as described above.)
-
Create build directory:
mkdir build && cd build
-
Run cmake while inside build directory:
cmake -S ../test
-
Run this command to build the library and unit tests:
make all
-
The generated test executables will be present in
build/bin/tests
folder. -
Run
ctest
to execute all tests and view the test run summary.
CBMC
To learn more about CBMC and proofs specifically, review the training material here.
The test/cbmc/proofs
directory contains CBMC proofs.
In order to run these proofs you will need to install CBMC and other tools by following the instructions here.
Contributing
See CONTRIBUTING.md for information on contributing.