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require 'ffi'
module PTY
private
module LibUtil
extend FFI::Library
# forkpty(3) is in libutil on linux, libc on MacOS/BSD
if FFI::Platform.linux?
ffi_lib 'libutil'
end
attach_function :forkpty, [ :buffer_out, :buffer_out, :buffer_in, :buffer_in ], :pid_t
end
module LibC
extend FFI::Library
attach_function :close, [ :int ], :int
attach_function :strerror, [ :int ], :string
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
attach_function :_exit, [ :int ], :void
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.alloc_out :int
name = Buffer.alloc_out 1024
exec_cmd, exec_args = build_args(args)
pid = LibUtil.forkpty(mfdp, name, nil, nil)
#
# We want to do as little as possible in the child process, since we're running
# without any GC thread now, so test for the child case first
#
if pid == 0
LibC.execvp(exec_cmd, exec_args)
LibC._exit(1)
end
raise "forkpty failed: #{LibC.strerror(FFI.errno)}" if pid < 0
masterfd = mfdp.get_int(0)
rfp = FFI::IO.for_fd(masterfd, "r")
wfp = FFI::IO.for_fd(LibC.dup(masterfd), "w")
if block_given?
retval = yield rfp, wfp, pid
begin; rfp.close; rescue Exception; end
begin; wfp.close; rescue Exception; end
retval
else
[ rfp, wfp, pid ]
end
end
def self.spawn(*args, &block)
self.getpty("/bin/sh", "-c", args[0], &block)
end
end
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