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go/src/os/wait_unimp.go

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os: on GNU/Linux use waitid to avoid wait/kill race On systems that support the POSIX.1-2008 waitid function, we can use it to block until a wait will succeed. This avoids a possible race condition: if a program calls p.Kill/p.Signal and p.Wait from two different goroutines, then it is possible for the wait to complete just before the signal is sent. In that case, it is possible that the system will start a new process using the same PID between the wait and the signal, causing the signal to be sent to the wrong process. The Process.isdone field attempts to avoid that race, but there is a small gap of time between when wait returns and isdone is set when the race can occur. This CL avoids that race by using waitid to wait until the process has exited without actually collecting the PID. Then it sets isdone, then waits for any active signals to complete, and only then collects the PID. No test because any plausible test would require starting enough processes to recycle all the process IDs. Update #13987. Update #16028. Change-Id: Id2939431991d3b355dfb22f08793585fc0568ce8 Reviewed-on: https://go-review.googlesource.com/23967 Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-06-09 23:24:40 -06:00
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
all: remove the nacl port (part 1) You were a useful port and you've served your purpose. Thanks for all the play. A subsequent CL will remove amd64p32 (including assembly files and toolchain bits) and remaining bits. The amd64p32 removal will be separated into its own CL in case we want to support the Linux x32 ABI in the future and want our old amd64p32 support as a starting point. Updates #30439 Change-Id: Ia3a0c7d49804adc87bf52a4dea7e3d3007f2b1cd Reviewed-on: https://go-review.googlesource.com/c/go/+/199499 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-10-08 13:19:13 -06:00
// +build aix darwin dragonfly js,wasm netbsd openbsd solaris
os: on GNU/Linux use waitid to avoid wait/kill race On systems that support the POSIX.1-2008 waitid function, we can use it to block until a wait will succeed. This avoids a possible race condition: if a program calls p.Kill/p.Signal and p.Wait from two different goroutines, then it is possible for the wait to complete just before the signal is sent. In that case, it is possible that the system will start a new process using the same PID between the wait and the signal, causing the signal to be sent to the wrong process. The Process.isdone field attempts to avoid that race, but there is a small gap of time between when wait returns and isdone is set when the race can occur. This CL avoids that race by using waitid to wait until the process has exited without actually collecting the PID. Then it sets isdone, then waits for any active signals to complete, and only then collects the PID. No test because any plausible test would require starting enough processes to recycle all the process IDs. Update #13987. Update #16028. Change-Id: Id2939431991d3b355dfb22f08793585fc0568ce8 Reviewed-on: https://go-review.googlesource.com/23967 Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-06-09 23:24:40 -06:00
package os
// blockUntilWaitable attempts to block until a call to p.Wait will
all: use "reports whether" consistently instead of "returns whether" Follow-up for CL 147037 and after Brad noticed the "returns whether" pattern during the review of CL 150621. Go documentation style for boolean funcs is to say: // Foo reports whether ... func Foo() bool (rather than "returns whether") Created with: $ perl -i -npe 's/returns whether/reports whether/' $(git grep -l "returns whether" | grep -v vendor) Change-Id: I15fe9ff99180ad97750cd05a10eceafdb12dc0b4 Reviewed-on: https://go-review.googlesource.com/c/150918 Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2018-11-22 03:46:44 -07:00
// succeed immediately, and reports whether it has done so.
os: on GNU/Linux use waitid to avoid wait/kill race On systems that support the POSIX.1-2008 waitid function, we can use it to block until a wait will succeed. This avoids a possible race condition: if a program calls p.Kill/p.Signal and p.Wait from two different goroutines, then it is possible for the wait to complete just before the signal is sent. In that case, it is possible that the system will start a new process using the same PID between the wait and the signal, causing the signal to be sent to the wrong process. The Process.isdone field attempts to avoid that race, but there is a small gap of time between when wait returns and isdone is set when the race can occur. This CL avoids that race by using waitid to wait until the process has exited without actually collecting the PID. Then it sets isdone, then waits for any active signals to complete, and only then collects the PID. No test because any plausible test would require starting enough processes to recycle all the process IDs. Update #13987. Update #16028. Change-Id: Id2939431991d3b355dfb22f08793585fc0568ce8 Reviewed-on: https://go-review.googlesource.com/23967 Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-06-09 23:24:40 -06:00
// It does not actually call p.Wait.
// This version is used on systems that do not implement waitid,
// or where we have not implemented it yet.
func (p *Process) blockUntilWaitable() (bool, error) {
return false, nil
}
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