Gobra is a prototype verifier for Go programs, based on the Viper verification infrastructure.

We call annotated Go programs Gobra programs and use the file extension .gobra for them. A tutorial can be found in docs/tutorial.md. More examples can be found in src/test/resources.

Compile and Run Gobra

Preliminaries

• Java 64-Bit (tested with version 11 and 15)
• SBT (tested with version 1.4.4)
• Git

Installation

1. Create a folder for your Gobra development. We will refer to this folder as gobraHome.
2. Clone Gobra and Viper dependencies
   • Change directory to gobraHome
   • silver
   • silicon
   • carbon
   • Gobra
3. Add symbolic links
   • To create a symbolic link from A to B, you have to run
     • mklink /D A B (Windows (as admin)) resp.
     • ln -s B A (Linux & macOS) (use forward instead of backward slashes in the following)
   • Change directory to gobraHome/silicon and create the symbolic links:
     • silver -> ..\silver
   • Change directory to gobraHome/carbon and create the symbolic links:
     • silver -> ..\silver
   • Change to gobraHome/gobra-one and create the links:
     • silver -> ..\silver
     • silicon -> ..\silicon
     • carbon -> ..\carbon
4. Install Z3 and Boogie. Steps (iii) and (iv) are specific to Boogie and only necessary when using Carbon as verification backend. Gobra uses the Silicon verification backend by default.
   1. Get a Z3 executable. A precompiled executable can be downloaded here. We tested version 4.8.7 64-Bit.
   2. Set the environment variable Z3_EXE to the path of your Z3 executable.
   3. Get a Boogie executable. Instructions for compilation are given here. Mono is required on Linux and macOS to run Boogie. Alternatively, extract a compiled version from the Viper release tools (Windows, Linux, macOS).
   4. Set the environment variable BOOGIE_EXE to the path of your Boogie executable.

Compilation

1. Change directory to gobraHome/gobra-one
2. Start an sbt shell by running sbt
3. Compile gobra-one by running compile in the sbt shell
   • Important: Do not compile silver, silicon, or carbon separately. If you have compiled them separately, then delete all target folders in these projects.
4. Check your installation by executing all tests (test in the sbt shell)
5. A file can be verified with run -i path/to/file in the sbt shell
   • e.g. run -i src/test/resources/regressions/examples/swap.gobra
6. All command line arguments can be shown by running run --help in the sbt shell

Assembly

1. In an sbt shell, run assembly. The fat jar is then located in the target/scala folder.
2. To verify a file, run java -jar -Xss128m gobra.jar -i path/to/file

Licensing

Most Gobra sources are licensed under the Mozilla Public License Version 2.0. The LICENSE lists the exceptions to this rule. Note that source files (whenever possible) should list their license in a short header. Continuous integration checks these file headers. The same checks can be performed locally by running npx github:viperproject/check-license-header#v1 check --config .github/license-check/config.json --strict in this repository's root directory.

Get in touch

Do you still have questions? Open an issue or contact us on Zulip.