By simply rearranging the logic, we avoid the overhead of a superfluous
call to getsockopt. For, if p is already non empty, there's no point
in having to check if we need to attach dummy payload. This has
performance benefits when using send/recvmsg for high speed
communications.

Change-Id: If47ab5322464aad8e6d2603a369e95327223211f
Reviewed-on: https://go-review.googlesource.com/108337Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Change-Id: I0cd02100844d7565f6fc18278ff52a8cceaacec5
Reviewed-on: https://go-review.googlesource.com/107938Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This structure is used with setsockopt in BGP speaker implementations.

For more information, please see:
https://criticalindirection.com/2015/05/12/tcp_md5sig/.

Fixes golang/go#24830

Change-Id: Ic2137e843ad502dbe9a4227362b63164789c5877
Reviewed-on: https://go-review.googlesource.com/106656Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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As spotted by Brad Fitzpatrick, CL 106838 unexported the value field of
Fsid and Sigset_t, but these types would be useless without any exported
fields. Re-export them via an exception in mkpost.go

Change-Id: I30d3c3b81c8c1b6377f8aa55cad816e3486a4395
Reviewed-on: https://go-review.googlesource.com/107415
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Change-Id: I9f0ca3c2c1cd79f0c996ebbc7f79a42f740e0d2c
GitHub-Last-Rev: ebd0046a4fefcd70d4b21f043a350c6f4df21cfd
GitHub-Pull-Request: golang/sys#10
Reviewed-on: https://go-review.googlesource.com/107302Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This adds a wrapper around perf_event_open, exported constants and
two structs:
 - perf_event_attr, used to configure the syscall
 - perf_event_mmap_page to coordinate the kernel's mmap ring buffer

Change-Id: Ife7ded8344de9e3eb74441bd51ab9a04c81b4965
Reviewed-on: https://go-review.googlesource.com/105756Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
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On linux/s390x these fields are already hidden. Don't export them on any
other platform either.

Preparatory CL for https://golang.org/cl/106656

Change-Id: I421a0ba41ff46081e2576be212e246a4dd982a67
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Change-Id: I3ecf7802c152b82c0d40f8b1bebcb25feda7fb13
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Also avoid installing recommended packages if possible to silightly
reduce the Docker image size.

Change-Id: I7a3ea33f6501cf063b1aa0324b5928f96241d048
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Fixes golang/go#24649
Fixes golang/go#24677

Change-Id: I3faa74ab68e093a097c3f2a8ec7c054431bdfb3f
Reviewed-on: https://go-review.googlesource.com/104736Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Move the common Getsockopt* implementations to syscall_unix.go instead
of duplicating them in syscall_bsd.go and syscall_linux.go. This also
makes all of them available on Solaris and adds GetsockoptByte on Linux.

Change-Id: Ibf49b27be46be579e63e3b3e2ebc1504e5228d5f
Reviewed-on: https://go-review.googlesource.com/104695
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In a Linux user namespace that doesn't have UID 0 mapped, WriteMsgUnix
will return an EINVAL as the uid-valid-in-uns check comes first in the kernel.

Even if in a user and PID namespace, using the wrong PID in Ucred will
always give EPERM.

Change-Id: Ia7452bbf2911c3b9a2aa5d7df1572e8b0790ff38
GitHub-Last-Rev: 341d3f0cba0511411caffd2ac5a6c8dfb7a022ef
GitHub-Pull-Request: golang/sys#7
Reviewed-on: https://go-review.googlesource.com/103857
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Fixes golang/go#8760

Change-Id: Iacb5802ce6256fc5fb61b558f2d0bc0dcf593c96
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Same was done in CL 7940 for the syscall package.

Fixes golang/go#10838

Change-Id: I98efa99f57f21bdcdbfb117af66f673e37767fec
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Fixes golang/go#24515

Change-Id: Icac78e8f2937668c2ce2fd6a695ce44bb702b8f1
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Change-Id: I8d91f4f959b03f71a8f2effdf7f1c6d1308f2217
Reviewed-on: https://go-review.googlesource.com/102135
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Re-run ./mkall.sh to avoid exporting Pad_cgo* fields on Darwin.

Updates golang/go#18632

Change-Id: Id9d264293d0b1f1c5581aff289c6e826d63e71ef
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Change-Id: I3b32b6343e9bc0bb6a205ada9941b4bb9ef91a23
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Change-Id: I7b32bbbfc73e8e05898bd640e9e92a183c72b92b
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On Illumos, TestFchmodat fails with:

--- FAIL: TestFchmodat (0.00s)
        syscall_unix_test.go:502: Fchmodat: unexpected error: operation not supported on transport endpoint

Like Linux, Illumos doesn't support flags != 0 in Fchmodat, see
https://illumos.org/man/2/chmod

Adjust TestFchmodat accordingly to handle EOPNOTSUPP on Illumos.

Change-Id: Icd4564497a41c4aa962cd76604b5ca2c7575d96c
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Now that Fchmodat is available on all Unices, move TestFchmodat to
syscall_unix_test.go and adjust it such that Fchmodat with
AT_SYMLINK_NOFOLLOW in flags is tested where supported.

Change-Id: I41ef5b874e36d84ed4866706dbba075c39aa00d4
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Change-Id: I63889a9e4eb2c9d8846fa6e47f8c74f54ff7ede8
Reviewed-on: https://go-review.googlesource.com/101575
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Change-Id: I3fd96550d588373d75e14bd554d46e2590c266fb
Reviewed-on: https://go-review.googlesource.com/101596
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Change-Id: If7868a3d43eed266496db8a0e2af908de77362eb
Reviewed-on: https://go-review.googlesource.com/101576
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This should call unix.Exec, not syscall.Exec. Thanks Tobias Klauser
for the spot.

Change-Id: Iddae390891a66652b071e05c1a5a25bbfdb19e52
Reviewed-on: https://go-review.googlesource.com/101435
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Currently the doc string forms one run-on sentence when viewed in
a browser. Add an additional newline so the text is presented in
a browser the same way it is in the source code.

Change-Id: If93e45c5aec9edd195c6bf36cb757c5146368507
Reviewed-on: https://go-review.googlesource.com/101284Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The syscall execve has no wrapper in this library, which it seems like
it should - Ian seemed to concur in CL 72550.

Add a docstring and an example, because I always get confused about
how to invoke the syscall.

Change-Id: I6100bbbf4ace9e3e341bf186a04cc03301da9aea
Reviewed-on: https://go-review.googlesource.com/101282Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Change-Id: I98ca1595895213bbc1f2d6bd984e48f84b23ccbc
Reviewed-on: https://go-review.googlesource.com/100995Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
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Change-Id: I3a367e9346b1469d7e577524d3306b3d21f8fc43
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Also enable TestFstatat for all Unices now that they all implement
Fstatat.

Change-Id: I9722437042d5fc0df4a27d3a6a2be3d124c60057
Reviewed-on: https://go-review.googlesource.com/100617
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Updates golang/go#24185

Change-Id: Ia2de9218885e0cfeaec79ed7417475230b063df0
Reviewed-on: https://go-review.googlesource.com/100692Reviewed-by: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Id2ae518a5f6abfdae56398a3ef7f205267057257
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Change-Id: Ibf23c327f1420a55a9de7073e9a4f444fb8f3c1f
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Re-run ./mkall.sh to avoid exporting Pad_cgo* fields on dragonfly/amd64.
This also adds some additional RLIMIT_* constants.

Updates golang/go#18632

Change-Id: I7969d8ab12c07befd7b1ff0d1dbc67f6622c39b1
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Change-Id: Ie4a172a36a274334a49766cc272e74bcc34ebd86
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Re-run ./mkall.sh to avoid exporting Pad_cgo* fields on solaris/amd64.
Akin to CL 89495.

Updates golang/go#18632

Change-Id: Ib80bf6376d0b7c0a5efd0f5d4a0f27e8e37d8abe
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Updates golang/go#24381

Change-Id: I9bd15bb7961f02af12a45b12ac62e07d059c744e
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The basic Getrlimit functionality is already tested in TestRlimit. Use
the Linux-specific test to check whether setting RLIMIT_AS has the
desired effect regarding mmap, as specified in
http://man7.org/linux/man-pages/man2/getrlimit.2.html

Change-Id: I3e2c5769d9144cb4059735709a89a12f42568465
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Fixes golang/go#23361

Change-Id: Ia4fb99b1ac2b109048a1b81f9b1534685f6e31a8
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Change-Id: Iae896dc32e775cb469fc3d0d367fd7c7825161ec
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