A PNG Encoder

This project represent a message encoder for a PNG file. It is implemented in Rust.

Features of the program

• encoding messages;
• decoding messages;
• print the bytes of a PNG file;
• remove a chunk from a PNG file;

How to run the program

Each command can be run separately. I used clap library for parsing the commands and their arguments. For each command is a specific way to run it. In arguments.rs file are located the structures that represent the arguments of the commands.

For encode command:

cargo run encode <file_path> <chunk_type> <message>;

For decode command:

cargo run decode <file_path> <chunk_type>;

For remove command:

cargo run remove <file_path> <chunk_type>;

For print command:

cargo run print <file_path>;

OBSERVATION: The decode and remove commands will action for the first chunk that have the type requested by the commands.

For information about the project:

cargo run -- --help;

Structure of the program

chunk_types.rs - contains the chunk type structure and functions from converts [u8; 4] arrays and str to a chunk_type structure;

chunk.rs - representing the chunks of the PNG file. Each chunk contains a length (4 bytes), a type (4 bytes), data (length size) and a crc (4 bytes). The crc is used for verifying if the chunk is still valid;

png.rs - representing the PNG that contains a STANDARD_HEADER and a vec of chunks;

commands.rs - this file contains the code for the four commands;

arguments.rs - contains the structures that represent the arguments of the commands;

main.rs - this is the file that runs the commands. Contains a match that verifies the type of command.