A sigprof during stack barrier insertion or removal can crash if it
detects an inconsistency between the stkbar array and the stack
itself. Currently we protect against this when scanning another G's
stack using stackLock, but we don't protect against it when unwinding
stack barriers for a recover or a memmove to the stack.

This commit cleans up and improves the stack locking code. It
abstracts out the lock and unlock operations. It uses the lock
consistently everywhere we perform stack operations, and pushes the
lock/unlock down closer to where the stack barrier operations happen
to make it more obvious what it's protecting. Finally, it modifies
sigprof so that instead of spinning until it acquires the lock, it
simply doesn't perform a traceback if it can't acquire it. This is
necessary to prevent self-deadlock.

Updates #11863, which introduced stackLock to fix some of these
issues, but didn't go far enough.

Updates #12528.

Change-Id: I9d1fa88ae3744d31ba91500c96c6988ce1a3a349
Reviewed-on: https://go-review.googlesource.com/17036Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Currently, if a profiling signal happens in the middle of
stackBarrier, gentraceback may see inconsistencies between stkbar and
the barriers on the stack and it will certainly get the wrong return
PC for stackBarrier. In most cases, the return PC won't be a PC at all
and this will immediately abort the traceback (which is considered
okay for a sigprof), but if it happens to be a valid PC this may sent
gentraceback down a rabbit hole.

Fix this by detecting when the gentraceback starts in stackBarrier and
simulating the completion of the barrier to get the correct initial
frame.

Change-Id: Ib11f705ac9194925f63fe5dfbfc84013a38333e6
Reviewed-on: https://go-review.googlesource.com/17035Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This CL adds skipped failing tests, showing differences between HTTP/1
and HTTP/2 behavior. They'll be fixed in later commits.

Only a tiny fraction of the net/http tests have been split into their
"_h1" and "_h2" variants. That will also continue. (help welcome)

Updates #6891
Updates #13315
Updates #13316
Updates #13317

Change-Id: I16c3c381dbe267a3098fb266ab0d804c36473a64
Reviewed-on: https://go-review.googlesource.com/17046
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fix regression from https://golang.org/cl/16829 ("require valid methods
in NewRequest and Transport.RoundTrip").

An empty string is a valid method (it means "GET", per the docs).

Fixes #13311

Change-Id: I26b71dc4ccc146498b5d7e38fbe31ed11dd5a6cf
Reviewed-on: https://go-review.googlesource.com/16952
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

Change-Id: I22d40248e83fcad5ab73c0d402183d06e91064c7
Reviewed-on: https://go-review.googlesource.com/16388Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

Change-Id: If1faa2bba28a4e9a8061693173797c4114a7d699
Reviewed-on: https://go-review.googlesource.com/16387Reviewed-by: Ian Lance Taylor <iant@golang.org>

For #13243.

Change-Id: I802cef3dad5d1236e70d0cd52047008a6a7a311a
Reviewed-on: https://go-review.googlesource.com/17045Reviewed-by: Chris Manghane <cmang@golang.org>

For #13243.

Change-Id: I544a8c44971fad126103157575e983ab528309bf
Reviewed-on: https://go-review.googlesource.com/17044Reviewed-by: Chris Manghane <cmang@golang.org>

Change-Id: Ie24d56422ae2196198a6c306716fa867c1442d6e
Reviewed-on: https://go-review.googlesource.com/17043Reviewed-by: Chris Manghane <cmang@golang.org>

Handling of &(T{}) assumed that the parser would not introduce ()'s.

Also: Better comments around handling of OPAREN syntax tree optimization.

Fixes #13261.

Change-Id: Ifc5047a0448f5e7d74cd42f6608b87dcc9c2f2fb
Reviewed-on: https://go-review.googlesource.com/17040Reviewed-by: Chris Manghane <cmang@golang.org>

Also:
- better error messages in some cases
- factored out function to produce syntax error at given line number

Fixes #13273.

Change-Id: I0192a94731cc23444680a26bd0656ef663e6da0b
Reviewed-on: https://go-review.googlesource.com/16992Reviewed-by: Chris Manghane <cmang@golang.org>

Found by cmd/vet.

Change-Id: Id570ecd76c3f1efd9696680ccd9799610217f8f7
Reviewed-on: https://go-review.googlesource.com/17042
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I97504a11291ee60e656efb7704e37387e864d74f
Reviewed-on: https://go-review.googlesource.com/16385Reviewed-by: Ian Lance Taylor <iant@golang.org>

This works by adding a call to __x86.get_pc_thunk.cx immediately before any
instruction that accesses global data and then assembling the instruction to
use the appropriate offset from CX instead of the absolute address. Some forms
cannot be assembled that way and are rewritten to load the address into CX
first.

-buildmode=pie works now, but is not yet tested.

Fixes #13201 (I think)

Change-Id: I32a8561e7fc9dd4ca6ae3b0e57ad78a6c50bf1f5
Reviewed-on: https://go-review.googlesource.com/17014Reviewed-by: Ian Lance Taylor <iant@golang.org>

I was prodded into doing this in review comments for the ARM version, and it's
going to make shared libs for 386 easier.

Change-Id: Id12de801b1425b8c6b5736fe91b418fc123a4e40
Reviewed-on: https://go-review.googlesource.com/17012Reviewed-by: David Crawshaw <crawshaw@golang.org>

Does not fix #12327 but nicer anyway.

Change-Id: I4ad730a4ca833d76957b7571895b3a08a6a530d4
Reviewed-on: https://go-review.googlesource.com/16964Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #12686.

Change-Id: I7a9f49dbd1f60b1d0240de57787753b425f9548c
Reviewed-on: https://go-review.googlesource.com/17031Reviewed-by: Ian Lance Taylor <iant@golang.org>

Cgo-created threads transition between having associated Go g's and m's and not.
A signal arriving during the transition could think it was safe and appropriate to
run Go signal handlers when it was in fact not.
Avoid the race by masking all signals during the transition.

Fixes #12277.

Change-Id: Ie9711bc1d098391d58362492197a7e0f5b497d14
Reviewed-on: https://go-review.googlesource.com/16915Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I373a64fc30dee804d99e106d4627b780e1846917
Reviewed-on: https://go-review.googlesource.com/16999Reviewed-by: David Crawshaw <crawshaw@golang.org>

This reverts commit 7db77271.

Change-Id: I6d8855eb05ca331025dc49a5533c6da4d1fa4e84
Reviewed-on: https://go-review.googlesource.com/17030Reviewed-by: Russ Cox <rsc@golang.org>

Change-Id: Ieba62c0cb668daeb343f72fdd568e46b0b21b7d6
Reviewed-on: https://go-review.googlesource.com/16998Reviewed-by: Andrew Gerrand <adg@golang.org>

An internal link may need the C compiler support library, libgcc.a.  Add
a -libgcc option to set the name of the compiler support library.  If
-libgcc is not used, run the compiler to find it.  Permit -libgcc=none
to skip using libgcc at all and hope for the best.

Change cmd/dist to not copy libgcc into the distribution.  Add tests to
ensure that all the standard packages that use cgo can be linked in
internal mode without using libgcc.  This ensures that somebody with a
Go installation without a C compiler can build programs.

Change-Id: I8ba35fb87ab0dd20e5cc0166b5f4145b04ce52a4
Reviewed-on: https://go-review.googlesource.com/16993Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

This includes the first parts of the general approach to PIC: load PC into CX
whenever it is needed. This is going to lead to large binaries and poor
performance but it's a start and easy to get right.

Change-Id: Ic8bf1d0a74284cca0d94a68cf75024e8ab063b4e
Reviewed-on: https://go-review.googlesource.com/16383Reviewed-by: Ian Lance Taylor <iant@golang.org>

We might be able to do better than this, but it's a start.

Change-Id: I80ebce9094e084a4746039106ccf1ad9c4b8bb7c
Reviewed-on: https://go-review.googlesource.com/16384Reviewed-by: Ian Lance Taylor <iant@golang.org>

Mostly by avoiding CX entirely, sometimes by reloading it.

I also vetted the assembly in other packages, it's all fine.

Change-Id: I50059669aaaa04efa303cf22ac228f9d14d83db0
Reviewed-on: https://go-review.googlesource.com/16386Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Ie4cdf50fdaf7b368a189a84f4e2aea4cedd5ca7d
Reviewed-on: https://go-review.googlesource.com/17013Reviewed-by: Ian Lance Taylor <iant@golang.org>

BER allows the sender to choose either short form or long form where
both are legal, but DER requires the minimal one be used. Enforce this
and add a test. Fix one test which was not minimally-encoded and another
which would not distinguish rejecting the input because the long form
length wasn't minimally-encoded from rejecting it because long form was
chosen when short form was allowed.

Change-Id: I1b56fcca594dcdeddea9378b4fab427cbe7cd26d
Reviewed-on: https://go-review.googlesource.com/16517Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>

Otherwise _2006 is treated as _2 and then an error.

Fixes #11334

Change-Id: I40a385b45e279e9f4538bf419baab72781cdb215
Reviewed-on: https://go-review.googlesource.com/16311Reviewed-by: Rob Pike <r@golang.org>

Compare basepath and targetpath using strings.EqualFold.  The absence
of this on Windows causes an unterminating condition in `for` statement
later in the function.

Fixes #13258

Change-Id: Ib5a0caba864ee425dc75ece47b9cf6fb626f47f1
Reviewed-on: https://go-review.googlesource.com/16857
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

Only apply RFC 6724's CommonPrefixLen rule for IPv4 source/destination
pairs that are members of the same IPv4 special purpose block.

Fixes #13283.

Change-Id: I2f7c26b408dd4675dfc5c1959e22d05b43bb8241
Reviewed-on: https://go-review.googlesource.com/16995Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

On Windows, Rel emits error messages of the form `Rel: can't make
\windows relative to \windows`. Rather than emitting paths after
stripping volume names, emit the original paths so as to make those of
the form `Rel: can't make d:\windows relative to c:\windows`.  Fixed a
test that expected the error message to emit clean path instead of the
original.

Fixes #13259

Change-Id: I3a9bd5b137205f22794ec8046b4e917ee48cf750
Reviewed-on: https://go-review.googlesource.com/16858
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

no buildmode=c-shared yet.

Update golang/go#9327.

Change-Id: I9989d954d574807bac105da401c3463607fe8a99
Reviewed-on: https://go-review.googlesource.com/16700Reviewed-by: David Crawshaw <crawshaw@golang.org>

Replace the cross platform but unsafe [4]uintptr type with a OS
specific type, sigset. Most OSes already define sigset, and this
change defines a suitable sigset for the OSes that don't (darwin,
openbsd). The OSes that don't use m.sigmask (windows, plan9, nacl)
now defines sigset as the empty type, struct{}.

The gain is strongly typed access to m.sigmask, saving a dynamic
size sanity check and unsafe.Pointer casting. Also, some storage is
saved for each M, since [4]uinptr was conservative for most OSes.

The cost is that OSes that don't need m.sigmask has to define sigset.

completes ./all.bash with GOOS linux, on amd64
completes ./make.bash with GOOSes openbsd, android, plan9, windows,
darwin, solaris, netbsd, freebsd, dragonfly, all amd64.

With GOOS=nacl ./make.bash failed with a seemingly unrelated error.

R=go1.7

Change-Id: Ib460379f063eb83d393e1c5efe7333a643c1595e
Reviewed-on: https://go-review.googlesource.com/16942Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The NamePos value was not being set, and would default to a value
of zero. This would cause the printing logic to get confused as
to where exactly to place the "Has unexported fields" string.

A trivial package changes from

<
type A struct {
	A int // A
	B int
			// B
	// Has unexported fields.
}
>

to

<
type A struct {
	A int // A
	B int // B
	// Has unexported fields.
}
>

Fixes #12971

Change-Id: I53b7799a1f1c0ad7dcaddff83d9aaeb1d6b7823e
Reviewed-on: https://go-review.googlesource.com/16286
Run-TryBot: Joe Tsai <joetsai@digital-static.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

golang.org/cl/16796 broke android/386 by assuming behaviour specific to glibc's
dynamic linker. Copy bionic by using int $0x80 to invoke syscalls on
android/386 as the old alternative (CALL *runtime_vdso(SB)) cannot be compiled
without text relocations, which we want to get rid of on android.

Also remove "CALL *runtime_vdso(SB)" variant from the syscall package.

Change-Id: I6c01849f8dcbd073d000ddc8f13948a836b8b261
Reviewed-on: https://go-review.googlesource.com/16996
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

Fixes #12778

Change-Id: I2ca53180d46180b951749abe453fd560d0f1d9d6
Reviewed-on: https://go-review.googlesource.com/16950Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Id164a099e0ac8bd231ee7ed8d7b7a34c91f5f68f
Reviewed-on: https://go-review.googlesource.com/16991
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

Completes sniffing for mp4 signature according
to the spec at:
  https://mimesniff.spec.whatwg.org/#signature-for-mp4
Clause 6.2.1

Fixes #8773

Change-Id: Icfc4a23324ae249db52c94a21c0e8509e1833e19
Reviewed-on: https://go-review.googlesource.com/16951Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Not all tests passing yet, but a good chunk are.

Change-Id: I5daebaeabf3aecb380674ece8830a86751a8d139
Reviewed-on: https://go-review.googlesource.com/16458Reviewed-by: Rahul Chaudhry <rahulchaudhry@google.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

Inspect the crypto/tls error to recognize this case and give a more
helpful error.

Fixes #11111.

Change-Id: I63f6af8c375aa892326ccccbd29655d54d68df0b
Reviewed-on: https://go-review.googlesource.com/16079
Run-TryBot: Caleb Spare <cespare@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>