preparing for the syscall package freeze.
the change for issue 8218 is only applied to go.sys/unix.

««« original CL description
syscall: implement setresuid(2) and setresgid(2) on OpenBSD/FreeBSD/DragonflyBSD

Fixes #8218.

LGTM=iant
R=golang-codereviews, iant, minux
CC=golang-codereviews
https://golang.org/cl/107150043

»»»

LGTM=r
R=r, iant, golang-codereviews
CC=golang-codereviews
https://golang.org/cl/138840044

Prevents non-rooted queries with > ndots dots from being tried twice on error.
Fixes #8616.

Benchmark results on linux/amd64
benchmark                        old ns/op    new ns/op    delta
BenchmarkGoLookupIPNoSuchHost      8212394      4413293  -46.26%

benchmark                       old allocs   new allocs    delta
BenchmarkGoLookupIPNoSuchHost          216          108  -50.00%

benchmark                        old bytes    new bytes    delta
BenchmarkGoLookupIPNoSuchHost        17460         8726  -50.02%

LGTM=iant, mikioh.mikioh
R=golang-codereviews, iant, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/137870043

It is anyway, just an allocated one.
Giving it a sized type makes Go access nicer.

LGTM=iant
R=dvyukov, iant
CC=golang-codereviews
https://golang.org/cl/139960043

LGTM=r, iant
R=golang-codereviews, r, iant
CC=dvyukov, golang-codereviews, khr
https://golang.org/cl/139930043

I had to rename Kevent and Sigaction to avoid the functions of the
same (lowercase) name.

LGTM=iant, r
R=golang-codereviews, r, iant, aram.h
CC=dvyukov, golang-codereviews, khr
https://golang.org/cl/140740043

Signer is an interface to support opaque private keys.
These keys typically result from being kept in special hardware
(i.e. a TPM) although sometimes operating systems provide a
similar interface using process isolation for security rather
than hardware boundaries.

This changes provides interfaces for representing them and
alters crypto/tls so that client certificates can use
opaque keys.

LGTM=bradfitz
R=bradfitz
CC=golang-codereviews, jdeprez
https://golang.org/cl/114680043

Needless except that the api tool complains. We could fix that issue instead.

TBR=bradfitz
R=golang-codereviews
CC=golang-codereviews
https://golang.org/cl/133290043

Run it right before main.init.
There is still some runtime initialization that
happens before runtime.init, and some of that
may call into Go code (for example to acquire locks)
so this timing is not perfect, but I believe it is the
best we can do.

This came up because global variables intialized
to func values are done in the generated init code,
not in the linker.

LGTM=dvyukov
R=dvyukov
CC=golang-codereviews, iant, khr, r
https://golang.org/cl/135210043

As part of the translation of the runtime, we need to rewrite
C printf calls to Go print calls. Consider this C printf:

        runtime·printf("[signal %x code=%p addr=%p pc=%p]\n",
                g->sig, g->sigcode0, g->sigcode1, g->sigpc);

Today the only way to write that in Go is:

        print("[signal ")
        printhex(uint64(g->sig))
        print(" code=")
        printhex(uint64(g->sigcode0))
        print(" addr=")
        printhex(uint64(g->sigcode1))
        print(" pc=")
        printhex(uint64(g->sigpc))
        print("]\n")

(That's nearly exactly what runtime code looked like in C before
I added runtime·printf.)

This CL recognizes the unexported type runtime.hex as an integer
that should be printed in hexadecimal instead of decimal.
It's a little kludgy, but it's restricted to package runtime.
Other packages can define type hex with no effect at all.

Now we can translate that original printf as the more compact:

        print("[signal ", hex(g->sig), " code=", hex(g->sigcode0),
                " addr=", hex(g->sigcode1), " pc=", hex(g->sigpc), "]\n")

LGTM=r, iant
R=r, iant
CC=golang-codereviews
https://golang.org/cl/133220043

LGTM=rsc, dave
R=minux, rsc, remyoudompheng, dave
CC=golang-codereviews
https://golang.org/cl/133790043

ErrorContext now has all the information it needs from the Node,
rather than depending on the template that contains it. This makes
it easier for html/template to generate correct locations in its
error messages.

Updated html/template to use this ability where it is easy, which is
not everywhere, but more work can probably push it through.

Fixes #8577.

LGTM=adg
R=golang-codereviews, adg
CC=golang-codereviews
https://golang.org/cl/130620043

Remove C version of GC.
Convert freeOSMemory to Go.
Restore g0 check in GC.
Remove unknownGCPercent check in GC,
it's initialized explicitly now.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews, khr
https://golang.org/cl/139910043

Breaks on Plan 9, apparently.
The other systems must not run sprintf during all.bash.
I'd write a test but it's all going away.

TBR=r
CC=0intro, golang-codereviews
https://golang.org/cl/133260044

Convert them to Go in the process.

LGTM=dvyukov, dave
R=khr, dvyukov, rsc, dave
CC=golang-codereviews
https://golang.org/cl/131600043

I've started with just one function with 8 arguments,
but stdcall is called from nosplit functions
and 8 args overflow nosplit area.

LGTM=aram, alex.brainman
R=golang-codereviews, aram, alex.brainman, dave
CC=golang-codereviews, iant, khr, rsc
https://golang.org/cl/135090043

PNG filters are applied to get better compression ratio.
It does not make sense to apply them if we are not going
to compress.

LGTM=nigeltao
R=nigeltao
CC=golang-codereviews
https://golang.org/cl/137830043

Also fix a bunch of bugs:
1. Accesses to last_gc must be atomic (it's int64).
2. last_gc still can be 0 during first checks in sysmon, check for 0.
3. forcegc.g can be unitialized when sysmon accesses it:
        forcegc.g is initialized by main goroutine (forcegc.g = newproc1(...)),
        and main goroutine is unsynchronized with both sysmon and forcegc goroutine.
        Initialize forcegc.g in the forcegc goroutine itself instead.

LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews, rsc
https://golang.org/cl/136770043

LGTM=dave
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/139890043

LGTM=bradfitz, rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://golang.org/cl/135150043

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/126450043

LGTM=iant
R=golang-codereviews, iant
CC=dvyukov, golang-codereviews, khr, r
https://golang.org/cl/135930043

Update #8612

LGTM=minux
R=golang-codereviews, minux
CC=golang-codereviews
https://golang.org/cl/135170043

Clang 3.2 and older (as shipped with OS X Mountain Lion and older)
outputs ambiguous DWARF debug info that makes it impossible for us to
reconstruct accurate type information as required for this test.

Fixes #8611.

LGTM=rsc
R=r, rsc, minux
CC=golang-codereviews
https://golang.org/cl/135990043

Shrinks the text segment size by about 1.5% for the "go", "gofmt",
and "camlistored" commands on linux/amd64.

Before:
$ size go gofmt camlistored
   text	   data	    bss	    dec	    hex	filename
6506842	 136996	 105784	6749622	 66fdb6	go
2376046	  85232	  90984	2552262	 26f1c6	gofmt
17051050	 190256	 130320	17371626	10911ea	camlistored

After:
$ size go gofmt camlistored
   text	   data	    bss	    dec	    hex	filename
6403034	 136996	 105784	6645814	 656836	go
2331118	  85232	  90984	2507334	 264246	gofmt
16842586	 190256	 130320	17163162	105e39a	camlistored

Fixes #8604.

LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://golang.org/cl/137790043

LGTM=0intro, rsc
R=rsc, 0intro
CC=golang-codereviews
https://golang.org/cl/132320043

This is a reapplication of CL 93520045 (changeset 5012df7fac58)
since that was lost during the move to an internal package.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/134020043

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/129650043

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/137750043

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/132230043

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/134940043

In revision 05c3fee13eb3, openbsd/386's tfork implementation was
accidentally changed in one instruction from using the "params"
parameter to using the "psize" parameter.

While here, OpenBSD's __tfork system call returns a pid_t which is an
int32 on all OpenBSD architectures, so change runtime.tfork's return
type from int64 to int32 and update the assembly implementations
accordingly.

LGTM=iant
R=rsc, iant
CC=golang-codereviews, jsing
https://golang.org/cl/133190043

LGTM=dvyukov
R=golang-codereviews, dvyukov, khr
CC=golang-codereviews
https://golang.org/cl/124630043

Package addition.

PositionFor permits access to both, positions
adjusted by //line comments (like the Position
accessors), and unadjusted "raw" positions
unaffected by //line comments.

Raw positions are required for correct formatting
of source code via go/printer which until now had
to manually fix adjusted positions.

Fixes #7702.

LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://golang.org/cl/135110044

Only grab the lock once, don't allocate, add more tests.

LGTM=ruiu
R=ruiu, josharian
CC=golang-codereviews
https://golang.org/cl/139780043

Follow-up to https://golang.org/cl/107020044/
Also add a little comment.

LGTM=ruiu, josharian
R=josharian, ruiu
CC=golang-codereviews
https://golang.org/cl/139760043

LGTM=bradfitz
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/139770043

Preparation for fixing issue 5769 (method selectors
do not auto-dereference): The actual fix may require
some cleanups in all these sections, and syntactically,
method expressions and method values are selector
expressions. Moving them next to each other so that
it's easy to see the actual changes (next CL).

No content changes besides the section moves.

LGTM=iant, rsc
R=r, rsc, iant, ken
CC=golang-codereviews
https://golang.org/cl/132300043

This is getting a little annoying, but once the runtime structs are
being defined in Go, these will go away. So it's only a temporary cost.

TBR=bradfitz
CC=golang-codereviews
https://golang.org/cl/135940043

Significantly reduces the number of allocations, while also
simplifying the code and increasing performance by a 1-2%.

benchmark                          old ns/op     new ns/op     delta
BenchmarkConcurrentDBExec          13290567      13026236      -1.99%
BenchmarkConcurrentStmtQuery       13249399      13008879      -1.82%
BenchmarkConcurrentStmtExec        8806237       8680182       -1.43%
BenchmarkConcurrentTxQuery         13628379      12756293      -6.40%
BenchmarkConcurrentTxExec          4794800       4722440       -1.51%
BenchmarkConcurrentTxStmtQuery     5040804       5200721       +3.17%
BenchmarkConcurrentTxStmtExec      1366574       1336626       -2.19%
BenchmarkConcurrentRandom          11119120      10926113      -1.74%

benchmark                          old allocs     new allocs     delta
BenchmarkConcurrentDBExec          14191          13684          -3.57%
BenchmarkConcurrentStmtQuery       16020          15514          -3.16%
BenchmarkConcurrentStmtExec        4179           3672           -12.13%
BenchmarkConcurrentTxQuery         16025          15518          -3.16%
BenchmarkConcurrentTxExec          12717          12709          -0.06%
BenchmarkConcurrentTxStmtQuery     15532          15525          -0.05%
BenchmarkConcurrentTxStmtExec      2175           2168           -0.32%
BenchmarkConcurrentRandom          12320          11997          -2.62%

benchmark                          old bytes     new bytes     delta
BenchmarkConcurrentDBExec          2164827       2139760       -1.16%
BenchmarkConcurrentStmtQuery       2418070       2394030       -0.99%
BenchmarkConcurrentStmtExec        1728782       1704371       -1.41%
BenchmarkConcurrentTxQuery         2477144       2452620       -0.99%
BenchmarkConcurrentTxExec          588920        588343        -0.10%
BenchmarkConcurrentTxStmtQuery     790866        796578        +0.72%
BenchmarkConcurrentTxStmtExec      98502         98143         -0.36%
BenchmarkConcurrentRandom          1725906       1710220       -0.91%

LGTM=ruiu, dave, bradfitz
R=golang-codereviews, ruiu, gobot, bradfitz, dave, minux
CC=bradfitz, golang-codereviews
https://golang.org/cl/107020044

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/134030043