git2fossil.rb

#!/usr/bin/env ruby

# Convert Git repository to Fossil
#
# Use this script inside git working copy:
# (make a backup copy before using it!)
#
# $ cd git-repo
# $ ruby ../git2fossil.rb
# 
# fossil repository will be created at ../repo.fossil
# The script doesn't convert tags, branches, or users.
# It works by checking out every change from git and
# committing them to fossil.

require 'time'

log = []
ci = nil

IO.popen("git log master --date=iso8601","r").each do |line| 
  if line =~ /^commit/
    log.push(ci) unless ci.nil?
    ci = {}
    ci['commit'] = line.scan(/commit (.*)/)[0][0]
    ci['date'] = ""
    ci['message'] = ""
  elsif line =~ /^Date:/ 
    date_str = line.scan(/Date:(.*)/)[0][0].strip
    date = Time.parse(date_str)
    ci['date'] = date.xmlschema[0..-7]
  elsif line =~ /[ ]{4}/  # commit message after 4 spaces 
    ci['message'] += line.strip
  end
end 
log.push(ci)

`fossil new ../repo.fossil`
`fossil open ../repo.fossil`

log.reverse_each do |ci|
  if ci['commit'].length > 0
    IO.popen("fossil changes","r").each do |line| 
      if line =~ /^MISSING/
        file = line.scan(/MISSING (.*)/)[0][0].strip
        system("fossil rm \"#{file}\"")
      end
    end

    system("git checkout #{ci['commit']} --force")
    `fossil add .`
    system("fossil commit --nosign -m \"#{ci['message']}\" " +
          "--date-override #{ci['date']}")
  end
end