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unix: merge Linux readv/writev implementation with Darwin/OpenBSD

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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>
This commit is contained in:
Ian Lance Taylor
2026-05-18 07:51:52 -07:00
committed by Gopher Robot
parent e4444cbaaa
commit 99666ae32e
4 changed files with 32 additions and 106 deletions
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unix/syscall_linux.go
+12 -94
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@@ -2150,33 +2150,10 @@ func Signalfd(fd int, sigmask *Sigset_t, flags int) (newfd int, err error) {
//sys exitThread(code int) (err error) = SYS_EXIT
//sys readv(fd int, iovs []Iovec) (n int, err error) = SYS_READV
//sys writev(fd int, iovs []Iovec) (n int, err error) = SYS_WRITEV
//sys preadv(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PREADV
//sys pwritev(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PWRITEV
//sys preadv2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PREADV2
//sys pwritev2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PWRITEV2
// minIovec is the size of the small initial allocation used by
// Readv, Writev, etc.
//
// This small allocation gets stack allocated, which lets the
// common use case of len(iovs) <= minIovs avoid more expensive
// heap allocations.
const minIovec = 8
// appendBytes converts bs to Iovecs and appends them to vecs.
func appendBytes(vecs []Iovec, bs [][]byte) []Iovec {
for _, b := range bs {
var v Iovec
v.SetLen(len(b))
if len(b) > 0 {
v.Base = &b[0]
} else {
v.Base = (*byte)(unsafe.Pointer(&_zero))
}
vecs = append(vecs, v)
}
return vecs
}
//sys preadvSyscall(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PREADV
//sys pwritevSyscall(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PWRITEV
//sys preadv2Syscall(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PREADV2
//sys pwritev2Syscall(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PWRITEV2
// offs2lohi splits offs into its low and high order bits.
func offs2lohi(offs int64) (lo, hi uintptr) {
@@ -2184,69 +2161,23 @@ func offs2lohi(offs int64) (lo, hi uintptr) {
return uintptr(offs), uintptr(uint64(offs) >> (longBits - 1) >> 1) // two shifts to avoid false positive in vet
}
func Readv(fd int, iovs [][]byte) (n int, err error) {
iovecs := make([]Iovec, 0, minIovec)
iovecs = appendBytes(iovecs, iovs)
n, err = readv(fd, iovecs)
readvRacedetect(iovecs, n, err)
return n, err
}
func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
iovecs := make([]Iovec, 0, minIovec)
iovecs = appendBytes(iovecs, iovs)
func preadv(fd int, iovecs []Iovec, offset int64) (n int, err error) {
lo, hi := offs2lohi(offset)
n, err = preadv(fd, iovecs, lo, hi)
readvRacedetect(iovecs, n, err)
return n, err
return preadvSyscall(fd, iovecs, lo, hi)
}
func Preadv2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
iovecs := make([]Iovec, 0, minIovec)
iovecs = appendBytes(iovecs, iovs)
lo, hi := offs2lohi(offset)
n, err = preadv2(fd, iovecs, lo, hi, flags)
readvRacedetect(iovecs, n, err)
n, err = preadv2Syscall(fd, iovecs, lo, hi, flags)
readvRaceDetect(iovecs, n, err)
return n, err
}
func readvRacedetect(iovecs []Iovec, n int, err error) {
if !raceenabled {
return
}
for i := 0; n > 0 && i < len(iovecs); i++ {
m := min(int(iovecs[i].Len), n)
n -= m
if m > 0 {
raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
}
}
if err == nil {
raceAcquire(unsafe.Pointer(&ioSync))
}
}
func Writev(fd int, iovs [][]byte) (n int, err error) {
iovecs := make([]Iovec, 0, minIovec)
iovecs = appendBytes(iovecs, iovs)
if raceenabled {
raceReleaseMerge(unsafe.Pointer(&ioSync))
}
n, err = writev(fd, iovecs)
writevRacedetect(iovecs, n)
return n, err
}
func Pwritev(fd int, iovs [][]byte, offset int64) (n int, err error) {
iovecs := make([]Iovec, 0, minIovec)
iovecs = appendBytes(iovecs, iovs)
if raceenabled {
raceReleaseMerge(unsafe.Pointer(&ioSync))
}
func pwritev(fd int, iovecs []Iovec, offset int64) (n int, err error) {
lo, hi := offs2lohi(offset)
n, err = pwritev(fd, iovecs, lo, hi)
writevRacedetect(iovecs, n)
return n, err
return pwritevSyscall(fd, iovecs, lo, hi)
}
func Pwritev2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
@@ -2256,24 +2187,11 @@ func Pwritev2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error)
raceReleaseMerge(unsafe.Pointer(&ioSync))
}
lo, hi := offs2lohi(offset)
n, err = pwritev2(fd, iovecs, lo, hi, flags)
writevRacedetect(iovecs, n)
n, err = pwritev2Syscall(fd, iovecs, lo, hi, flags)
writevRaceDetect(iovecs, n)
return n, err
}
func writevRacedetect(iovecs []Iovec, n int) {
if !raceenabled {
return
}
for i := 0; n > 0 && i < len(iovecs); i++ {
m := min(int(iovecs[i].Len), n)
n -= m
if m > 0 {
raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
}
}
}
// mmap varies by architecture; see syscall_linux_*.go.
//sys munmap(addr uintptr, length uintptr) (err error)
//sys mremap(oldaddr uintptr, oldlength uintptr, newlength uintptr, flags int, newaddr uintptr) (xaddr uintptr, err error)