libgo/go/os/error.go

   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 }