1 // Copyright 2009 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package os 6 7 import ( 8 "errors" 9 "internal/poll" 10 ) 11 12 // Portable analogs of some common system call errors. 13 var ( 14 ErrInvalid = errors.New("invalid argument") // methods on File will return this error when the receiver is nil 15 ErrPermission = errors.New("permission denied") 16 ErrExist = errors.New("file already exists") 17 ErrNotExist = errors.New("file does not exist") 18 ErrClosed = errors.New("file already closed") 19 ErrNoDeadline = poll.ErrNoDeadline 20 ) 21 22 type timeout interface { 23 Timeout() bool 24 } 25 26 // PathError records an error and the operation and file path that caused it. 27 type PathError struct { 28 Op string 29 Path string 30 Err error 31 } 32 33 func (e *PathError) Error() string { return e.Op + " " + e.Path + ": " + e.Err.Error() } 34 35 // Timeout reports whether this error represents a timeout. 36 func (e *PathError) Timeout() bool { 37 t, ok := e.Err.(timeout) 38 return ok && t.Timeout() 39 } 40 41 // SyscallError records an error from a specific system call. 42 type SyscallError struct { 43 Syscall string 44 Err error 45 } 46 47 func (e *SyscallError) Error() string { return e.Syscall + ": " + e.Err.Error() } 48 49 // Timeout reports whether this error represents a timeout. 50 func (e *SyscallError) Timeout() bool { 51 t, ok := e.Err.(timeout) 52 return ok && t.Timeout() 53 } 54 55 // NewSyscallError returns, as an error, a new SyscallError 56 // with the given system call name and error details. 57 // As a convenience, if err is nil, NewSyscallError returns nil. 58 func NewSyscallError(syscall string, err error) error { 59 if err == nil { 60 return nil 61 } 62 return &SyscallError{syscall, err} 63 } 64 65 // IsExist returns a boolean indicating whether the error is known to report 66 // that a file or directory already exists. It is satisfied by ErrExist as 67 // well as some syscall errors. 68 func IsExist(err error) bool { 69 return isExist(err) 70 } 71 72 // IsNotExist returns a boolean indicating whether the error is known to 73 // report that a file or directory does not exist. It is satisfied by 74 // ErrNotExist as well as some syscall errors. 75 func IsNotExist(err error) bool { 76 return isNotExist(err) 77 } 78 79 // IsPermission returns a boolean indicating whether the error is known to 80 // report that permission is denied. It is satisfied by ErrPermission as well 81 // as some syscall errors. 82 func IsPermission(err error) bool { 83 return isPermission(err) 84 } 85 86 // IsTimeout returns a boolean indicating whether the error is known 87 // to report that a timeout occurred. 88 func IsTimeout(err error) bool { 89 terr, ok := underlyingError(err).(timeout) 90 return ok && terr.Timeout() 91 } 92 93 // underlyingError returns the underlying error for known os error types. 94 func underlyingError(err error) error { 95 switch err := err.(type) { 96 case *PathError: 97 return err.Err 98 case *LinkError: 99 return err.Err 100 case *SyscallError: 101 return err.Err 102 } 103 return err 104 } 105
