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internal/poll: remove detection of buggy splice on old Linux versions
The splice syscall is buggy prior to Linux 2.6.29. CL 113999 added a workaround to detect buggy versions and disable use of splice for these. As of Go 1.18 the minumum Linux version is 2.6.32. Thus, a non-buggy implementation of the splice syscall can be assumed. For #45964 Fixes #54505 Change-Id: Ied3a3334da7a3f7fa1280b7c5b1dfb9030219336 Reviewed-on: https://go-review.googlesource.com/c/go/+/422979 Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com> Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
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@ -5,10 +5,8 @@
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package poll
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import (
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"internal/syscall/unix"
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"runtime"
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"sync"
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"sync/atomic"
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"syscall"
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"unsafe"
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)
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@ -207,40 +205,13 @@ func putPipe(p *splicePipe) {
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splicePipePool.Put(p)
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}
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var disableSplice unsafe.Pointer
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// newPipe sets up a pipe for a splice operation.
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func newPipe() (sp *splicePipe) {
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p := (*bool)(atomic.LoadPointer(&disableSplice))
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if p != nil && *p {
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return nil
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}
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func newPipe() *splicePipe {
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var fds [2]int
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// pipe2 was added in 2.6.27 and our minimum requirement is 2.6.23, so it
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// might not be implemented. Falling back to pipe is possible, but prior to
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// 2.6.29 splice returns -EAGAIN instead of 0 when the connection is
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// closed.
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const flags = syscall.O_CLOEXEC | syscall.O_NONBLOCK
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if err := syscall.Pipe2(fds[:], flags); err != nil {
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if err := syscall.Pipe2(fds[:], syscall.O_CLOEXEC|syscall.O_NONBLOCK); err != nil {
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return nil
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}
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sp = &splicePipe{splicePipeFields: splicePipeFields{rfd: fds[0], wfd: fds[1]}}
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if p == nil {
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p = new(bool)
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defer atomic.StorePointer(&disableSplice, unsafe.Pointer(p))
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// F_GETPIPE_SZ was added in 2.6.35, which does not have the -EAGAIN bug.
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if _, _, errno := syscall.Syscall(unix.FcntlSyscall, uintptr(fds[0]), syscall.F_GETPIPE_SZ, 0); errno != 0 {
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*p = true
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destroyPipe(sp)
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return nil
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}
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}
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return
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return &splicePipe{splicePipeFields: splicePipeFields{rfd: fds[0], wfd: fds[1]}}
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}
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// destroyPipe destroys a pipe.
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