Add bin and edit workflow

bin/gems/ffi-1.17.4-x86_64-linux-gnu/samples/pty.rb

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+require 'ffi'
+
+module PTY
+  private
+  module LibC
+    extend FFI::Library
+    ffi_lib FFI::Library::LIBC
+    attach_function :forkpty, [ :buffer_out, :buffer_out, :buffer_in, :buffer_in ], :int
+    attach_function :openpty, [ :buffer_out, :buffer_out, :buffer_out, :buffer_in, :buffer_in ], :int
+    attach_function :login_tty, [ :int ], :int
+    attach_function :close, [ :int ], :int
+    attach_function :strerror, [ :int ], :string
+    attach_function :fork, [], :int
+    attach_function :execv, [ :string, :buffer_in ], :int
+    attach_function :execvp, [ :string, :buffer_in ], :int
+    attach_function :dup2, [ :int, :int ], :int
+    attach_function :dup, [ :int ], :int
+  end
+  Buffer = FFI::Buffer
+  def self.build_args(args)
+    cmd = args.shift
+    cmd_args = args.map do |arg|
+      MemoryPointer.from_string(arg)
+    end
+    exec_args = MemoryPointer.new(:pointer, 1 + cmd_args.length + 1)
+    exec_cmd = MemoryPointer.from_string(cmd)
+    exec_args[0].put_pointer(0, exec_cmd)
+    cmd_args.each_with_index do |arg, i|
+      exec_args[i + 1].put_pointer(0, arg)
+    end
+    [ cmd, exec_args ]
+  end
+  public
+  def self.getpty(*args)
+    mfdp = Buffer.new :int
+    name = Buffer.new 1024
+    #
+    # All the execv setup is done in the parent, since doing anything other than
+    # execv in the child after fork is really flakey
+    #
+    exec_cmd, exec_args = build_args(args)
+    pid = LibC.forkpty(mfdp, name, nil, nil)
+    raise "forkpty failed: #{LibC.strerror(FFI.errno)}" if pid < 0
+    if pid == 0
+      LibC.execvp(exec_cmd, exec_args)
+      exit 1
+    end
+    masterfd = mfdp.get_int(0)
+    rfp = FFI::IO.for_fd(masterfd, "r")
+    wfp = FFI::IO.for_fd(LibC.dup(masterfd), "w")
+    if block_given?
+      yield rfp, wfp, pid
+      rfp.close unless rfp.closed?
+      wfp.close unless wfp.closed?
+    else
+      [ rfp, wfp, pid ]
+    end
+  end
+  def self.spawn(*args, &block)
+    self.getpty("/bin/sh", "-c", args[0], &block)
+  end
+end
+module LibC
+  extend FFI::Library
+  attach_function :close, [ :int ], :int
+  attach_function :write, [ :int, :buffer_in, :ulong ], :long
+  attach_function :read, [ :int, :buffer_out, :ulong ], :long
+end
+PTY.getpty("/bin/ls", "-alR", "/") { |rfd, wfd, pid|
+#PTY.spawn("ls -laR /") { |rfd, wfd, pid|
+  puts "child pid=#{pid}"
+  while !rfd.eof? && (buf = rfd.gets)
+    puts "child: '#{buf.strip}'"
+  end
+}