sandboxed-api/contrib/jsonnet/README.md

# Jsonnet Sandboxed API

This library was sandboxed as part of Google's summer 2020 internship program
([blog post](https://security.googleblog.com/2020/12/improving-open-source-security-during.html)).

This directory contains a sandbox for the
[Jsonnet](https://github.com/google/jsonnet) library.

## How to use from an existing Project

If your project does not include Sandboxed API as a dependency yet, add the
following lines to the main `CMakeLists.txt`:

```cmake
include(FetchContent)

FetchContent_Declare(sandboxed-api
  GIT_REPOSITORY https://github.com/google/sandboxed-api
  GIT_TAG        main  # Or pin a specific commit/tag
)
FetchContent_MakeAvailable(sandboxed-api)  # CMake 3.14 or higher

add_sapi_subdirectory(contrib/jsonnet)
```

The `add_sapi_subdirectory()` macro sets up the source and binary directories
for the sandboxed jsonnet targets.

Afterwards your project's code can link to `sapi_contrib::jsonnet` and use the
corresponding header `contrib/jsonnet/jsonnet_base_sandbox.h`.

## Examples

The `examples/` directory contains code to produce three command-line tools --
`jsonnet_sandboxed`, `jsonnet_yaml_stream_sandboxed` and
`jsonnet_multiple_files_sandboxed` to evaluate jsonnet code. The first one
enables the user to evaluate jsonnet code held in one file and writing to one
output file. The second evaluates one jsonnet file into one file, which can be
interepreted as YAML stream. The third one is for evaluating one jsonnet file
into multiple output files. All three tools are based on what can be found
[here](https://github.com/google/jsonnet/blob/master/cmd/jsonnet.cpp).

Apart from these, there is also a file producing `jsonnet_formatter_sandboxed`
executable. It is based on a tool found from
[here](https://github.com/google/jsonnet/blob/master/cmd/jsonnetfmt.cpp). It is
a jsonnet code formatter -- it changes poorly written jsonnet files into their
canonical form.

### Build as part of Sandboxed API

To build these examples, after cloning the whole Sandbox API project, run this
in the `contrib/jsonnet` directory:

```
mkdir -p build && cd build
cmake .. -G Ninja -Wno-dev -DSAPI_ENABLE_TESTS=ON
ninja
```

To run `jsonnet_sandboxed` (or `jsonnet_yaml_stream_sandboxed` or
`jsonnet_formatter_sandboxed` in a similar way):

```
cd examples
./jsonnet_sandboxed \
    absolute/path/to/the/input_file.jsonnet \
    absolute/path/to/the/output_file
```

To run `jsonnet_mutiple_files_sandboxed`:

```
cd examples
./jsonnet_mutiple_files_sandboxed \
    absolute/path/to/the/input_file.jsonnet \
    absolute/path/to/the/output_directory
```

All three tools support evaluating one input file (possibly relying on multiple
other files, e.x. by jsonnet `import` command; the files must be held in the
same directory as input file) into one or more output files. Example jsonnet
codes to evaluate in a one-in-one-out manner can be found
[here](https://github.com/google/jsonnet/tree/master/examples). Example code
producing multiple output files or YAML stream files can be found in the
`examples/jsonnet_codes` directory (along with some other examples copied with
minimal changes from the library files), in files called
`multiple_files_example.jsonnet` and `yaml_stream_example.jsonnet`,
respectively. In the `examples/jsonnet_codes_expected_output` directory one can
found outputs the mentioned above files' evaluation should produce.

The formatter reads one input file and produces one output file as a result.
Example code for this tool can also be found in `examples/jsonnet_codes`
directory, in a file called `formatter_example.jsonnet`.

### Running the tests

A few tests prepared with a use of
[Google Test](https://github.com/google/googletest) framework are included. To
run them type:

```
ctest -R JsonnetTest.
```