mirror of
https://github.com/rwinkhart/sys.git
synced 2026-08-28 04:46:44 -04:00
Ian Lance Taylor
99666ae32e
This reduces some code duplication. Change-Id: Ib648f90a26960d0bc25d2fe27e9b3fb1419ac02d Reviewed-on: https://go-review.googlesource.com/c/sys/+/777161 Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Cherry Mui <cherryyz@google.com> Auto-Submit: Ian Lance Taylor <iant@golang.org>
104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
// Copyright 2026 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build darwin || linux || openbsd
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package unix
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import "unsafe"
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// minIovec is the size of the small initial allocation used by
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// Readv, Writev, etc.
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//
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// This small allocation gets stack allocated, which lets the
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// common use case of len(iovs) <= minIovec avoid more expensive
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// heap allocations.
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const minIovec = 8
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// appendBytes converts bs to Iovecs and appends them to vecs.
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func appendBytes(vecs []Iovec, bs [][]byte) []Iovec {
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for _, b := range bs {
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var v Iovec
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v.SetLen(len(b))
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if len(b) > 0 {
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v.Base = &b[0]
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} else {
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v.Base = (*byte)(unsafe.Pointer(&_zero))
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}
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vecs = append(vecs, v)
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}
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return vecs
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}
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// writevRaceDetect tells the race detector that the program
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// has read the first n bytes stored in iovecs.
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func writevRaceDetect(iovecs []Iovec, n int) {
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if !raceenabled {
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return
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}
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for i := 0; n > 0 && i < len(iovecs); i++ {
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m := min(int(iovecs[i].Len), n)
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n -= m
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if m > 0 {
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raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
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}
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}
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}
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// readvRaceDetect tells the race detector that the program
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// has written to the first n bytes stored in iovecs.
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func readvRaceDetect(iovecs []Iovec, n int, err error) {
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if !raceenabled {
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return
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}
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for i := 0; n > 0 && i < len(iovecs); i++ {
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m := min(int(iovecs[i].Len), n)
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n -= m
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if m > 0 {
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raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
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}
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}
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if err == nil {
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raceAcquire(unsafe.Pointer(&ioSync))
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}
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}
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func Readv(fd int, iovs [][]byte) (n int, err error) {
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iovecs := make([]Iovec, 0, minIovec)
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iovecs = appendBytes(iovecs, iovs)
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n, err = readv(fd, iovecs)
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readvRaceDetect(iovecs, n, err)
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return n, err
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}
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func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
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iovecs := make([]Iovec, 0, minIovec)
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iovecs = appendBytes(iovecs, iovs)
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n, err = preadv(fd, iovecs, offset)
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readvRaceDetect(iovecs, n, err)
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return n, err
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}
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func Writev(fd int, iovs [][]byte) (n int, err error) {
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iovecs := make([]Iovec, 0, minIovec)
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iovecs = appendBytes(iovecs, iovs)
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if raceenabled {
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raceReleaseMerge(unsafe.Pointer(&ioSync))
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}
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n, err = writev(fd, iovecs)
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writevRaceDetect(iovecs, n)
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return n, err
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}
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func Pwritev(fd int, iovs [][]byte, offset int64) (n int, err error) {
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iovecs := make([]Iovec, 0, minIovec)
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iovecs = appendBytes(iovecs, iovs)
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if raceenabled {
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raceReleaseMerge(unsafe.Pointer(&ioSync))
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}
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n, err = pwritev(fd, iovecs, offset)
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writevRaceDetect(iovecs, n)
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return n, err
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}
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