Crate ab_contract_file 

Utilities for working with contract files.

File layout

Internally, a contract file contains the following sections in specified order:

• a header: ContractFileHeader, which allows interpreting the rest of file contents
• metadata about callable methods: ContractFileMethodMetadata for each method, which allows calling methods later
• read-only data section: contains contract metadata among other things, allowing to decode names and ABI of the methods mentioned above, and the number of methods in this metadata must match the number of methods in the header
• code section: contains only valid/supported RISC-V instructions

This file is created from an ELF source file and can be converted back to it, though only the details stored in the contract file are preserved. Note that due to the intentional lack of the .bss section equivalent and many other features, only simple RISC-V ELF shared library files can be converted into the contract file. Supporting more complex capabilities would be much more complex and error-prone.

ELF file is expected to have at most a single export for host calls, whose address is stored in the header and jumps to that address are intercepted by the runtime.

The format is designed to be very compact, easy to understand and use, and be such that it can be trivially loaded into a normal RISC-V process for debugging purposes using traditional tools like gdb.

ab-contracts-tooling crate exists that can build and convert contracts to this format and back both programmatically and using CLI interface.

Modules

instruction

Structs

ContractFile

A container for a parsed contract file

ContractFileHeader

Header of the contract file

ContractFileMethod

ContractFileMethodMetadata

Metadata about each method of the contract that can be called from the outside

Enums

ContractFileParseError

Error for ContractFile::parse()

Constants

CONTRACT_FILE_MAGIC

Magic bytes at the beginning of the file