And then revert the bootstrap cmd directories and certain testdata.
And adjust tests as needed.
Not reverting the changes in std that are bootstrapped,
because some of those changes would appear in API docs,
and we want to use any consistently.
Instead, rewrite 'any' to 'interface{}' in cmd/dist for those directories
when preparing the bootstrap copy.
A few files changed as a result of running gofmt -w
not because of interface{} -> any but because they
hadn't been updated for the new //go:build lines.
Fixes#49884.
Change-Id: Ie8045cba995f65bd79c694ec77a1b3d1fe01bb09
Reviewed-on: https://go-review.googlesource.com/c/go/+/368254
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
When these packages are released as part of Go 1.18,
Go 1.16 will no longer be supported, so we can remove
the +build tags in these files.
Ran go fix -fix=buildtag std cmd and then reverted the bootstrapDirs
as defined in src/cmd/dist/buildtool.go, which need to continue
to build with Go 1.4 for now.
Also reverted src/vendor and src/cmd/vendor, which will need
to be updated in their own repos first.
Manual changes in runtime/pprof/mprof_test.go to adjust line numbers.
For #41184.
Change-Id: Ic0f93f7091295b6abc76ed5cd6e6746e1280861e
Reviewed-on: https://go-review.googlesource.com/c/go/+/344955
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Many uses of Index/IndexByte/IndexRune/Split/SplitN
can be written more clearly using the new Cut functions.
Do that. Also rewrite to other functions if that's clearer.
For #46336.
Change-Id: I68d024716ace41a57a8bf74455c62279bde0f448
Reviewed-on: https://go-review.googlesource.com/c/go/+/351711
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Currently, GroupIds (a method that returns supplementary group IDs
for a user) is not implemented when cgo is not available, or osusergo
build tag is set, or the underlying OS lacks getgrouplist(3).
This adds a native Go implementation of GroupIds (which parses
/etc/group) for such cases, together with some tests.
This implementation is used:
- when cgo is not available;
- when osusergo build tag is set;
- on AIX (which lacks getgrouplist(3));
- on Illumos (which only recently added getgrouplist(3)).
This commit moves listgroups_unix.go to cgo_listgroups_unix.go, and adds
listgroups_unix.go which implements the feature.
NOTE the +build equivalent of go:build expression in listgroups_unix.go
is not provided as it is going to be bulky. Go 1.17 already prefers
go:build over +build, and no longer fail if a file contains go:build
without +build, so the absence of +build is not a problem even with Go
1.17, and this code is targeted for Go 1.18.
Updates #14709
Updates #30563
Change-Id: Icc95cda97ee3bcb03ef028b16eab7d3faba9ffab
Reviewed-on: https://go-review.googlesource.com/c/go/+/330753
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
This is not implemented on AIX and Illumos, and we already have a
mechanism to skip the test case -- let's use it.
Change-Id: Idb1cc2d716cf6d0731e93dfc3aa7853b9edec41f
Reviewed-on: https://go-review.googlesource.com/c/go/+/330752
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
CL 37664 implemented this functionality, yet the tests were skipped.
Introduce and use additional variable groupListImplemented to
distinguish between these cases and enable TestLookupGroup for
supported configurations (which looks like all but plan9).
Change-Id: Iabaa7f08b4551dc67e67bdb6e715f15bb20d6218
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/330751
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
There's no need to specifically check for runtime.GOOS as there's
already a generic mechanism for that.
Change-Id: I7125443ead456548bd503c5e71cd56e9eb30b446
Reviewed-on: https://go-review.googlesource.com/c/go/+/330750
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
It seems like getgrouplist is supported since Solaris 11.3 (released in
2016):
https://docs.oracle.com/cd/E86824_01/html/E54766/getgrouplist-3c.html
Use it to implement (*User).GroupIds on solaris, like on other Unix
platforms.
Unfortunately it looks like getgrouplist was added to illumos only
fairly recently, see
f2c438c505
Thus, don't use it on GOOS=illumos for now.
Updates #14709
Change-Id: Ibfcdbfca6b7d1af96630512d08921e5637ca76d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/315278
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The existing implementation of user.LookupGroupId function works
incorrectly with very large (>64K symbols) entries in /etc/group file.
This patch fixes this.
Fixes#43636
Change-Id: I453321f1ab15fd4d0002f97fcec7d0789e1e0da5
Reviewed-on: https://go-review.googlesource.com/c/go/+/283601
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Make all our package sources use Go 1.17 gofmt format
(adding //go:build lines).
Part of //go:build change (#41184).
See https://golang.org/design/draft-gobuild
Change-Id: Ia0534360e4957e58cd9a18429c39d0e32a6addb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/294430
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
As part of #42026, these helpers from io/ioutil were moved to os.
(ioutil.TempFile and TempDir became os.CreateTemp and MkdirTemp.)
Update the Go tree to use the preferred names.
As usual, code compiled with the Go 1.4 bootstrap toolchain
and code vendored from other sources is excluded.
ReadDir changes are in a separate CL, because they are not a
simple search and replace.
For #42026.
Change-Id: If318df0216d57e95ea0c4093b89f65e5b0ababb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/266365
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
CL 208617 introduced syscall.utf16PtrToString and
internal/syscall/windows.UTF16PtrToString functions.
Original version of CL 208617 did not include syscall.utf16PtrToString
and internal/syscall/windows.UTF16PtrToString max parameter. The
parameter was added by Brad at the request of Ian. Ian said:
"In some cases it seems at least possible that the null terminator is
not present. I think it would be safer if we passed a maximum length
here."
The syscall.utf16PtrToString and
internal/syscall/windows.UTF16PtrToString function are designed to work
with only null terminated strings. So max parameter is superfluous.
This change removes max parameter.
Updates #34972
Change-Id: Ifea65dbd86bca8a08353579c6b9636c6f963d165
Reviewed-on: https://go-review.googlesource.com/c/go/+/228858
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
This change replaces
buf := [HUGE_CONST]*T)(unsafe.Pointer(p))[:]
with
buf := [HUGE_CONST]*T)(unsafe.Pointer(p))[:n:n]
Pointer p points to n of T elements. New unsafe pointer conversion
logic verifies that both first and last elements point into the same
Go variable.
This change replaces [:] with [:n:n] to please pointer checker.
According to @mdempsky, compiler specially recognizes when you
combine a pointer conversion with a full slice operation in a single
expression and makes an exception.
After this, only one failure in net remains when running:
go test -a -short -gcflags=all=-d=checkptr std cmd
Updates #34972
Change-Id: I2c8731650c856264bc788e4e07fa0530f7c250fa
Reviewed-on: https://go-review.googlesource.com/c/go/+/208617
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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>
Some were never used, and some haven't been used for years.
One exception is net/http's readerAndCloser, which was only used in a
test. Move it to a test file.
While at it, remove a check in regexp that could never fire; the field
is an uint32, so it can never be negative.
Change-Id: Ia2200f6afa106bae4034045ea8233b452f38747b
Reviewed-on: https://go-review.googlesource.com/c/go/+/192621
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Like GOOS=android which implies the "linux" build tag, GOOS=illumos
implies the "solaris" build tag. This lets the existing ecosystem of
packages still work on illumos, but still permits packages to start
differentiating between solaris and illumos.
Fixes#20603
Change-Id: I8f4eabf1a66060538dca15d7658c1fbc6c826622
Reviewed-on: https://go-review.googlesource.com/c/go/+/174457
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Using os.UserHomeDir for user.HomeDir helps us deduplicate the
logic and keep the behavior consistent.
Also make os.UserHomeDir return "/sdcard" in android.
See: https://go-review.googlesource.com/c/go/+/37960/1/src/os/user/lookup_stubs.go#48Fixes#31070
Change-Id: I521bad050bc5761ecc5c0085501374d2cf8e6897
Reviewed-on: https://go-review.googlesource.com/c/go/+/169540
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
user.Current caches the current user after its first call, so changes to
the uid after the first call will not affect its result. As this might
be unexpected, it should be mentioned in the docs.
Fixes#27659
Change-Id: I8b3323d55441d9a79bc9534c6490884d8561889b
Reviewed-on: https://go-review.googlesource.com/136315
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Per golang/go#27524 there are situations where the username for the
uid does not match the value in the $USER environment variable and it
seems sensible to choose the value in /etc/passwd when they disagree.
This may make the Current() call slightly more expensive, since we
read /etc/passwd with cgo disabled instead of just checking the
environment. However, we cache the result of Current() calls, so we
only invoke this cost once in the lifetime of the process.
Fixes#14626.
Fixes#27524.
Updates #24884.
Change-Id: I0dcd224cf7f61dd5292f3fcc363aa2e9656a2cb1
Reviewed-on: https://go-review.googlesource.com/134218
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit adds the js/wasm architecture to the os package.
Access to the actual file system is supported through Node.js.
Updates #18892
Change-Id: I6fa642fb294ca020b2c545649d4324d981aa0408
Reviewed-on: https://go-review.googlesource.com/109977
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Would've caught two regressions so far, and found two more.
Updates #24841
Updates #24845 (package net remains)
Change-Id: I57ad06eb54e04b8c99b5d2e7f24c77ad865224e8
Reviewed-on: https://go-review.googlesource.com/107300
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This provides a way to enforce pure Go implementation of os/user
lookup functions on UNIX platforms by means of "osusergo" build tag,
in a manner similar to netgo/netcgo tags in the net package.
If "osusergo" build tag is set, Go implementation is selected.
If "osusergo" build tag is NOT set, the old behavior is retained,
that is to use cgo (libc-backed) implementation if both cgo and such
and such implementation are available.
The reason behind this change is to make it possible to build proper
static binaries on Linux. The problem is, glibc implementation of
getpw*, getgrp* and getgrouplist functions relies on presense of
libnss*.so libraries during runtime, making it impossible to build
a self-contained static binary which uses both cgo and os/user.
In such case, linker warnings like this are shown:
> warning: Using 'getgrouplist' in statically linked applications
> requires at runtime the shared libraries from the glibc version
> used for linking
While this can be solved by recompiling glibc with --enable-static-nss
flag or using a different libc implementation (like musl on Alpine Linux),
it is not always practical or even possible.
Fixes#23265
Change-Id: I383a448a2ecf15493ec93dbd5d076b6330cb14cb
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Reviewed-on: https://go-review.googlesource.com/92456
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Add the following helpers in lookup_windows.go:
1) lookupGroupName() is used to obtain the SID of a group based
on name.
2) listGroupsForUsernameAndDomain() uses NetUserGetLocalGroups()
as a WINAPI backend to obtain the list of local groups for this
user.
3) lookupUserPrimaryGroup() is now used to populate the User.Gid
field when looking up a user by name.
Implement listGroups(), lookupGroupId(), lookupGroup() and no longer
return unimplemented errors.
Do not skip Windows User.Gid tests in user_test.go.
Change-Id: I81fd41b406da51f9a4cb24e50d392a333df81141
GitHub-Last-Rev: d1448fd55d
GitHub-Pull-Request: golang/go#24222
Reviewed-on: https://go-review.googlesource.com/98137
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
newUserFromSid() is extended so that the retriaval of the user home
path based on a user SID becomes possible.
(1) The primary method it uses is to lookup the Windows registry for
the following key:
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\[SID]
If the key does not exist the user might not have logged in yet.
If (1) fails it falls back to (2)
(2) The second method the function uses is to look at the default home
path for users (e.g. WINAPI's GetProfilesDirectory()) and append
the username to that. The procedure is in the lines of:
c:\Users + \ + <username>
The function newUser() now requires the following arguments:
uid, gid, dir, username, domain
This is done to avoid multiple calls to usid.String() and
usid.LookupAccount("") in the case of a newUserFromSid()
call stack.
The functions current() and newUserFromSid() both call newUser()
supplying the arguments in question. The helpers
lookupUsernameAndDomain() and findHomeDirInRegistry() are
added.
This commit also updates:
- go/build/deps_test.go, so that the test now includes the
"internal/syscall/windows/registry" import.
- os/user/user_test.go, so that User.HomeDir is tested on Windows.
GitHub-Last-Rev: 25423e2a38
GitHub-Pull-Request: golang/go#23822
Change-Id: I6c3ad1c4ce3e7bc0d1add024951711f615b84ee5
Reviewed-on: https://go-review.googlesource.com/93935
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
If a Mac user has more than 256 groups, getGroupList returns -1 but
does not correctly set n. We need to retry the syscall with an
ever-increasing group size until we get all of the user's groups.
The easiest way to test this change is to set n to a value lower than
the current user's number of groups, test on a Mac and observe
a failure, then apply the patch and test that it passes.
Fixes#21067.
Change-Id: I0f5c4eac1c465226a460bc0803eff791dcfd4200
Reviewed-on: https://go-review.googlesource.com/51892
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
strings.IndexByte was introduced in go1.2 and it can be used
effectively wherever the second argument to strings.Index is
exactly one byte long.
This avoids generating unnecessary string symbols and saves
a few calls to strings.Index.
Change-Id: I1ab5edb7c4ee9058084cfa57cbcc267c2597e793
Reviewed-on: https://go-review.googlesource.com/65930
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
We're making two extra round-trips to C to malloc and free strings
that originate in Go and don't escape. Skip those round-trips by
allocating null-terminated slices in Go memory instead.
Change-Id: I9e4c5ad999a7924ba50b82293c52073ec75518be
Reviewed-on: https://go-review.googlesource.com/56530
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
On Android devices where the stub fallback for Current fails to
extract a User from the environment, return a dummy fallback instead
of failing.
While we're here, use / instead of /home/nacl for the NaCL fallback.
Hopefully fixes the Android builder.
Change-Id: Ia29304fbc224ee5f9c0f4e706d1756f765a7eae5
Reviewed-on: https://go-review.googlesource.com/37960
Run-TryBot: Elias Naur <elias.naur@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Using the stubs, user.Current will no longer fail on Android, fixing
the os/exec.TestCredentialNoSetGroups test.
Change-Id: I8b9842aa6704c0cde383c549a614bab0a0ed7695
Reviewed-on: https://go-review.googlesource.com/37765
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
If you cross compile for a Unix target and call user.Lookup("root")
or user.LookupId("0"), we'll try to read the answer out of
/etc/passwd instead of returning an "unimplemented" error.
The equivalent cgo function calls getpwuid_r in glibc, which
may reach out to the NSS database or allow callers to register
extensions. The pure Go implementation only reads from /etc/passwd.
Change-Id: I56a302d634b15ba5097f9f0d6a758c68e486ba6d
Reviewed-on: https://go-review.googlesource.com/37664
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
If cgo is not available, parse /etc/group in Go to find the name/gid
we need. This does not consult the Network Information System (NIS),
/etc/nsswitch.conf or any other libc extensions to /etc/group.
Fixes#18102.
Change-Id: I6ae4fe0e2c899396c45cdf243d5483113932657c
Reviewed-on: https://go-review.googlesource.com/33713
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In another CL, I'll add a pure Go implementation of lookupGroup and
lookupGroupId in lookup_unix.go, but attempting that in one CL makes
the diff too difficult to read.
Updates #18102.
Change-Id: If8e26cee5efd30385763430f34304c70165aef32
Reviewed-on: https://go-review.googlesource.com/37497
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This has a notable impact on systems with very large passwd files.
Before:
BenchmarkCurrent-12 30000 42546 ns/op
After:
BenchmarkCurrent-12 20000000 77.5 ns/op
Saved in perf dashboard:
https://perf.golang.org/search?q=upload:20170206.1Fixes#11625
Change-Id: Iebc9bf122cc64a4cab24ac06843c7b2bc450ded9
Reviewed-on: https://go-review.googlesource.com/36391
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Instead of exporting the C function mygetgrouplist as a global symbol to
conflict with other symbols of the same name, use trivial Go code and a
static C function.
Change-Id: I98dd667814d0a0ed8f7b1d4cfc6483d5a6965b26
Reviewed-on: https://go-review.googlesource.com/23008
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Even with -D_POSIX_PTHREAD_SEMANTICS, Solaris seems to not define
getgrnam_r in a POSIX compatible way.
Fixes#14967
Change-Id: I78cb7e5b30b2d8b860e336060a0a06f4720c0475
Reviewed-on: https://go-review.googlesource.com/21385
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
On my Mac I am in group 5000 which apparently has no name
(I suspect because it is an LDAP group and I cannot reach the
LDAP server). Do not make the test fail in that case.
Fixes#14806
Change-Id: I56b11a8e86b048abfb00812eaad37802fd2adcc5
Reviewed-on: https://go-review.googlesource.com/20710
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>