Any idea why this ugly solution works:

t = Tempfile.new('f')
t.write(f.content)
t.fsync
puts `iconv -f #{f.detect_charset} -t utf-8 #{t.path}`

But this clean pure Ruby solution fails:

puts Iconv.new(f.detect_charset, ''utf-8').iconv(f.content)

The latter gives this error:

in `iconv': "\310\355\362\345\360\355\345\362-\350\347\344\340\355\350\345"... (Iconv::IllegalSequence)

I have double checked that the file does not have any illegal sequences, and iconv converts it perfectly from the command line.. just not through Iconv in Ruby.