gopacker

A UPX-like packer to shrink executables.

Quick Start

go get github.com/nirhaas/gopacker
gopacker <executable_to_pack>

How does it work

Packing

Copy gopacker executable itself to output file.
Compress and stream (append) to output file.
Append compressed size.
Append magic string.

Output file is now a functional executable.

Unpacking

When running the packed executable:

Checks the last few bytes to see if magic string is there.
Reading compressed size.
Reading compressed data.
Uncompressing to memory.
Overriding the packed executable.
syscall exec to run the unpacked executable.

Possible TODO:

Better compression.
Encryption.