1// Copyright 2017 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 poll supports non-blocking I/O on file descriptors with polling. 6// This supports I/O operations that block only a goroutine, not a thread. 7// This is used by the net and os packages. 8// It uses a poller built into the runtime, with support from the 9// runtime scheduler. 10package poll 11 12import ( 13 "errors" 14) 15 16// errNetClosing is the type of the variable ErrNetClosing. 17// This is used to implement the net.Error interface. 18type errNetClosing struct{} 19 20// Error returns the error message for ErrNetClosing. 21// Keep this string consistent because of issue #4373: 22// since historically programs have not been able to detect 23// this error, they look for the string. 24func (e errNetClosing) Error() string { return "use of closed network connection" } 25 26func (e errNetClosing) Timeout() bool { return false } 27func (e errNetClosing) Temporary() bool { return false } 28 29// ErrNetClosing is returned when a network descriptor is used after 30// it has been closed. 31var ErrNetClosing = errNetClosing{} 32 33// ErrFileClosing is returned when a file descriptor is used after it 34// has been closed. 35var ErrFileClosing = errors.New("use of closed file") 36 37// ErrNoDeadline is returned when a request is made to set a deadline 38// on a file type that does not use the poller. 39var ErrNoDeadline = errors.New("file type does not support deadline") 40 41// Return the appropriate closing error based on isFile. 42func errClosing(isFile bool) error { 43 if isFile { 44 return ErrFileClosing 45 } 46 return ErrNetClosing 47} 48 49// ErrDeadlineExceeded is returned for an expired deadline. 50// This is exported by the os package as os.ErrDeadlineExceeded. 51var ErrDeadlineExceeded error = &DeadlineExceededError{} 52 53// DeadlineExceededError is returned for an expired deadline. 54type DeadlineExceededError struct{} 55 56// Implement the net.Error interface. 57// The string is "i/o timeout" because that is what was returned 58// by earlier Go versions. Changing it may break programs that 59// match on error strings. 60func (e *DeadlineExceededError) Error() string { return "i/o timeout" } 61func (e *DeadlineExceededError) Timeout() bool { return true } 62func (e *DeadlineExceededError) Temporary() bool { return true } 63 64// ErrNotPollable is returned when the file or socket is not suitable 65// for event notification. 66var ErrNotPollable = errors.New("not pollable") 67 68// consume removes data from a slice of byte slices, for writev. 69func consume(v *[][]byte, n int64) { 70 for len(*v) > 0 { 71 ln0 := int64(len((*v)[0])) 72 if ln0 > n { 73 (*v)[0] = (*v)[0][n:] 74 return 75 } 76 n -= ln0 77 (*v)[0] = nil 78 *v = (*v)[1:] 79 } 80} 81 82// TestHookDidWritev is a hook for testing writev. 83var TestHookDidWritev = func(wrote int) {} 84 85// String is an internal string definition for methods/functions 86// that is not intended for use outside the standard libraries. 87// 88// Other packages in std that import internal/poll and have some 89// exported APIs (now we've got some in net.rawConn) which are only used 90// internally and are not intended to be used outside the standard libraries, 91// Therefore, we make those APIs use internal types like poll.FD or poll.String 92// in their function signatures to disable the usability of these APIs from 93// external codebase. 94type String string 95