github.com/timstclair/heapster@v0.20.0-alpha1/Godeps/_workspace/src/k8s.io/kubernetes/pkg/util/exec/exec.go (about) 1 /* 2 Copyright 2014 The Kubernetes Authors All rights reserved. 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 exec 18 19 import ( 20 osexec "os/exec" 21 "syscall" 22 ) 23 24 // ErrExecutableNotFound is returned if the executable is not found. 25 var ErrExecutableNotFound = osexec.ErrNotFound 26 27 // Interface is an interface that presents a subset of the os/exec API. Use this 28 // when you want to inject fakeable/mockable exec behavior. 29 type Interface interface { 30 // Command returns a Cmd instance which can be used to run a single command. 31 // This follows the pattern of package os/exec. 32 Command(cmd string, args ...string) Cmd 33 34 // LookPath wraps os/exec.LookPath 35 LookPath(file string) (string, error) 36 } 37 38 // Cmd is an interface that presents an API that is very similar to Cmd from os/exec. 39 // As more functionality is needed, this can grow. Since Cmd is a struct, we will have 40 // to replace fields with get/set method pairs. 41 type Cmd interface { 42 // CombinedOutput runs the command and returns its combined standard output 43 // and standard error. This follows the pattern of package os/exec. 44 CombinedOutput() ([]byte, error) 45 SetDir(dir string) 46 } 47 48 // ExitError is an interface that presents an API similar to os.ProcessState, which is 49 // what ExitError from os/exec is. This is designed to make testing a bit easier and 50 // probably loses some of the cross-platform properties of the underlying library. 51 type ExitError interface { 52 String() string 53 Error() string 54 Exited() bool 55 ExitStatus() int 56 } 57 58 // Implements Interface in terms of really exec()ing. 59 type executor struct{} 60 61 // New returns a new Interface which will os/exec to run commands. 62 func New() Interface { 63 return &executor{} 64 } 65 66 // Command is part of the Interface interface. 67 func (executor *executor) Command(cmd string, args ...string) Cmd { 68 return (*cmdWrapper)(osexec.Command(cmd, args...)) 69 } 70 71 // LookPath is part of the Interface interface 72 func (executor *executor) LookPath(file string) (string, error) { 73 return osexec.LookPath(file) 74 } 75 76 // Wraps exec.Cmd so we can capture errors. 77 type cmdWrapper osexec.Cmd 78 79 func (cmd *cmdWrapper) SetDir(dir string) { 80 cmd.Dir = dir 81 } 82 83 // CombinedOutput is part of the Cmd interface. 84 func (cmd *cmdWrapper) CombinedOutput() ([]byte, error) { 85 out, err := (*osexec.Cmd)(cmd).CombinedOutput() 86 if err != nil { 87 if ee, ok := err.(*osexec.ExitError); ok { 88 // Force a compile fail if exitErrorWrapper can't convert to ExitError. 89 var x ExitError = &exitErrorWrapper{ee} 90 return out, x 91 } 92 if ee, ok := err.(*osexec.Error); ok { 93 if ee.Err == osexec.ErrNotFound { 94 return out, ErrExecutableNotFound 95 } 96 } 97 return out, err 98 } 99 return out, nil 100 } 101 102 // exitErrorWrapper is an implementation of ExitError in terms of os/exec ExitError. 103 // Note: standard exec.ExitError is type *os.ProcessState, which already implements Exited(). 104 type exitErrorWrapper struct { 105 *osexec.ExitError 106 } 107 108 // ExitStatus is part of the ExitError interface. 109 func (eew exitErrorWrapper) ExitStatus() int { 110 ws, ok := eew.Sys().(syscall.WaitStatus) 111 if !ok { 112 panic("can't call ExitStatus() on a non-WaitStatus exitErrorWrapper") 113 } 114 return ws.ExitStatus() 115 }