1 /* 2 Copyright 2020 The Kubernetes Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package editor 18 19 import ( 20 "io" 21 "os" 22 23 "github.com/moby/term" 24 "github.com/sirupsen/logrus" 25 ) 26 27 // TTY helps invoke a function and preserve the state of the terminal, even if the process is 28 // terminated during execution. It also provides support for terminal resizing for remote command 29 // execution/attachment. 30 type TTY struct { 31 // In is a reader representing stdin. It is a required field. 32 In io.Reader 33 // Out is a writer representing stdout. It must be set to support terminal resizing. It is an 34 // optional field. 35 Out io.Writer 36 // Raw is true if the terminal should be set raw. 37 Raw bool 38 // TryDev indicates the TTY should try to open /dev/tty if the provided input 39 // is not a file descriptor. 40 TryDev bool 41 } 42 43 // Safe invokes the provided function and will attempt to ensure that when the 44 // function returns (or a termination signal is sent) that the terminal state 45 // is reset to the condition it was in prior to the function being invoked. If 46 // t.Raw is true the terminal will be put into raw mode prior to calling the function. 47 // If the input file descriptor is not a TTY and TryDev is true, the /dev/tty file 48 // will be opened (if available). 49 func (t TTY) Safe(fn func() error) error { 50 inFd, isTerminal := term.GetFdInfo(t.In) 51 52 if !isTerminal && t.TryDev { 53 if f, err := os.Open("/dev/tty"); err == nil { 54 defer f.Close() 55 inFd = f.Fd() 56 isTerminal = term.IsTerminal(inFd) 57 } 58 } 59 if !isTerminal { 60 return fn() 61 } 62 63 var state *term.State 64 var err error 65 if t.Raw { 66 state, err = term.MakeRaw(inFd) 67 } else { 68 state, err = term.SaveState(inFd) 69 } 70 if err != nil { 71 return err 72 } 73 74 defer func() { 75 if err := term.RestoreTerminal(inFd, state); err != nil { 76 logrus.Errorf("Error resetting terminal: %v", err) 77 } 78 }() 79 return fn() 80 } 81