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libc's ioctl for Crystal.

• Maps in the libc ioctl function.

• Provides C equivalent macros for defining and working with ioctl numbers:

  C	Crystal
  _IOC	ioctl_ioc(dir,type,nr,size)
  _IO	ioctl_io(type,nr)
  _IOR	ioctl_ior(type,nr,size)
  _IOW	ioctl_iow(type,nr,size)
  _IOWR	ioctl_iowr(type,nr,size)
  _IOR_BAD	ioctl_ior_bad(type,nr,size)
  _IOW_BAD	ioctl_iow_bad(type,nr,size)
  _IOWR_BAD	ioctl_iowr_bad(type,nr,size)
  _IOC_DIR	ioctl_dir(nr)
  _IOC_TYPE	ioctl_type(nr)
  _IOC_NR	ioctl_nr(nr)
  _IOC_SIZE	ioctl_size(nr)

1. Add the dependency to your shard.yml:

   dependencies:
     ioctl:
       github: postmodern/ioctl.cr

2. Run shards install

require "ioctl"

output = MyStruct.new

begin
  IOCTL.ioctl(fd, IOCTL::..., pointerof(output))
rescue error : IOCTL::Error
  # ...
end

Returning -1 instead of raising an exception:

if LibC.ioctl(fd, IOCTL::..., pointerof(output)) == -1
  # ...
end

Get the terminal window size:

winsize = LibC::Winsize.new

begin
  IOCTL.ioctl(STDOUT.fd, IOCTL::TIOCGWINSZ, pointerof(winsize))
rescue error : IOCTL::Error
  STDERR.puts error.message
  exit -1
end

puts "Rows: #{winsize.ws_row}"
puts "Cols: #{winsize.ws_col}"

• macOS / BSD support

1. Fork it (https://github.com/postmodern/ioctl/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

• Postmodern - creator and maintainer