encoding/base64: add unpadded encodings, and test all encodings.

Some applications use unpadded base64 format, omitting the trailing
'=' padding characters from the standard base64 format, either to
minimize size or (more justifiably) to avoid use of the '=' character.
Unpadded flavors are standard and documented in section 3.2 of RFC 4648.

To support these unpadded flavors, this change adds two predefined
encoding variables, RawStdEncoding and RawURLEncoding, for unpadded
encodings using the standard and URL character set, respectively.
The change also adds a function WithPadding() to customize the padding
character or disable padding in a custom Encoding.

Finally, I noticed that the existing base64 test-suite was only
exercising the StdEncoding, and not referencing URLEncoding at all.
This change adds test-suite functionality to exercise all four encodings
(the two existing ones and the two new unpadded flavors),
although it still doesn't run *every* test on all four encodings.

Naming: I used the "Raw" prefix because it's more concise than "Unpadded"
and seemed just as expressive, but I have no strong preferences here.
Another short alternative prefix would be "Min" ("minimal" encoding).

Change-Id: Ic0423e02589b39a6b2bb7d0763bd073fd244f469
Reviewed-on: https://go-review.googlesource.com/1511
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
doc: note encoding/base64 unpadded encodings in go1.5.txt

Change-Id: I04d2e83f86f021464190f0b0fe0e450cb4662ad9
Reviewed-on: https://go-review.googlesource.com/1971
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
doc: fix comment type typo

Fixes #9418

Change-Id: I044fa1d26d972f012f00388a84c4d0f143cf4f63
Reviewed-on: https://go-review.googlesource.com/1970
Reviewed-by: Robert Griesemer <gri@golang.org>
liblink: remove class from %#D formatter on 6l

This was a copy-paste error from 9l.  Besides incorrectly referring to
cnames9, 6l doesn't even use a->class, so simply remove this.

Fixes #9320

Change-Id: I0e3440c9dae1c3408eb795b3645f9f1dd8f50aed
Reviewed-on: https://go-review.googlesource.com/1516
Reviewed-by: Russ Cox <rsc@golang.org>
syscall: fs_nacl: Unlock() should be deferred.

Change-Id: Iea08b8f4e74a8cd4b4d317273046457c8db956a1
Reviewed-on: https://go-review.googlesource.com/1640
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
cmd/api: fix race in run.go with multiple builders on a machine

Fixes #9407

Change-Id: I765e8009c7ee22473ac8c2d81c7f6c8ec9866c51
Reviewed-on: https://go-review.googlesource.com/1980
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
cmd/ld: clean up nested if when loading bind local syms

Change-Id: I15269722ca3d2654a9dd7a3f8a89ad375dc9bee0
Reviewed-on: https://go-review.googlesource.com/1759
Reviewed-by: Russ Cox <rsc@golang.org>
encoding/binary: check for unsigned integers in intDataSize.

intDataSize ignores unsigned integers, forcing reads/writes to miss the fast path.

Fixes #8956

Change-Id: Ie79b565b037db3c469aa1dc6d0a8a5a9252d5f0a
Reviewed-on: https://go-review.googlesource.com/1777
Reviewed-by: Russ Cox <rsc@golang.org>
sort: reduce leaf calls in Stable

Move the symMerge recursion stopping condition
from the beginning of symMerge to the callers.

This halves the number of calls to symMerge
while running 'go test sort'.

benchmark                   old ns/op      new ns/op      delta
BenchmarkStable1e6          8358117060     7954143849     -4.83%
BenchmarkStable1e4          40116117       38583285       -3.82%
BenchmarkStableInt1K        119150         115182         -3.33%
BenchmarkStableInt64K       9799845        9515475        -2.90%
BenchmarkStableString1K     388901         393516         +1.19%
BenchmarkStable1e2          124917         123618         -1.04%

Change-Id: I7ba2ca277f213b076fe6830e1139edb47ac53800
Reviewed-on: https://go-review.googlesource.com/1820
Reviewed-by: Robert Griesemer <gri@golang.org>
syscall: check recorded version of ppid instead of 1

Handles the case where the parent is pid 1 (common in docker
containers).

Attempted and failed to write a test for this.

Fixes #9263.

Change-Id: I5c6036446c99e66259a4fab1660b6a594f875020
Reviewed-on: https://go-review.googlesource.com/1372
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
go/build: fix field mismatch in unkeyed struct literal

Fixes #9409

Change-Id: I2404cd8bf3ebb07f4b6a2b3e1d58ab69b9f1e8d8
Reviewed-on: https://go-review.googlesource.com/2040
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
go/build: fix test on Windows

Change-Id: Icba46194bcbfd86b512eef2599242c715ad4e7d3
Reviewed-on: https://go-review.googlesource.com/2041
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
cmd/gc: update hashmap code location in comments

Change-Id: I3b81f2e9eb29ee6349d758b68fe7951b34f15a81
Reviewed-on: https://go-review.googlesource.com/1974
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
runtime: hashmap: move overflow pointer to end of bucket

Pointers to zero-sized values may end up pointing to the next
object in memory, and possibly off the end of a span.  This
can cause memory leaks and/or confuse the garbage collector.

By putting the overflow pointer at the end of the bucket, we
make sure that pointers to any zero-sized keys or values don't
accidentally point to the next object in memory.

fixes #9384

Change-Id: I5d434df176984cb0210b4d0195dd106d6eb28f73
Reviewed-on: https://go-review.googlesource.com/1869
Reviewed-by: Russ Cox <rsc@golang.org>
runtime: a better fallback hash

For arm and powerpc, as well as x86 without aes instructions.
Contains a mixture of ideas from cityhash and xxhash.

Compared to our old fallback on ARM, it's ~no slower on
small objects and up to ~50% faster on large objects.  More
importantly, it is a much better hash function and thus has
less chance of bad behavior.

Fixes #8737

benchmark                         old ns/op     new ns/op     delta
BenchmarkHash5                    173           181           +4.62%
BenchmarkHash16                   252           212           -15.87%
BenchmarkHash64                   575           419           -27.13%
BenchmarkHash1024                 7173          3995          -44.31%
BenchmarkHash65536                516940        313173        -39.42%
BenchmarkHashStringSpeed          300           279           -7.00%
BenchmarkHashBytesSpeed           478           424           -11.30%
BenchmarkHashInt32Speed           217           207           -4.61%
BenchmarkHashInt64Speed           262           231           -11.83%
BenchmarkHashStringArraySpeed     609           631           +3.61%

Change-Id: I0a9335028f32b10ad484966e3019987973afd3eb
Reviewed-on: https://go-review.googlesource.com/1360
Reviewed-by: Russ Cox <rsc@golang.org>
syscall: update go.sys doc reference to golang.org/x/sys

Change-Id: Ie5a36dbcd809fc165f4198d47641d5a95878460c
Reviewed-on: https://go-review.googlesource.com/2000
Reviewed-by: Russ Cox <rsc@golang.org>
test: migrate remaining tests to run.go

* bug248, bug345, bug369, and bug429 were ported from bash commands to run scripts. bug369 remains disabled.
* bug395 is a test for issue 1909, which is still open. It is marked as skip now and will be usable with compile with run.go when issue 1909 is fixed.

Fixes #4139

Updates #1909

Change-Id: Ibb5fbfb5cf72ddc285829245318eeacd3fb5a636
Reviewed-on: https://go-review.googlesource.com/1774
Reviewed-by: Russ Cox <rsc@golang.org>
liblink: code for debugging bad returns

Disabled by default, but invaluable when you need it.

Change-Id: If4a75d11d14f70b6840d339aaec4b940dc406493
Reviewed-on: https://go-review.googlesource.com/2012
Reviewed-by: Russ Cox <rsc@golang.org>
cmd/ld: add a text generation pass

This will be used by ppc64 to add call stubs to the .text section.
ARM needs a similar pass to generate veneers for arm->thumb
transitions.

Change-Id: Iaee74036e60643a56fab15b564718f359c5910eb
Reviewed-on: https://go-review.googlesource.com/2004
Reviewed-by: Russ Cox <rsc@golang.org>
cmd/5l,6l,8l: remove bogus dynsym section indexes

Previously, this code generated bogus section indexes for dynamic
symbols.  It turns out this didn't matter, since we only emit these
when generating an executable and in an executable it only matters
whether a symbol is defined or undefined, but it leads to perplexing
code full of mysterious constants.

Unfortunately, this happens too early to put in real section indexes,
so just use section index 1 to distinguish the symbol from an
undefined symbol.

Change-Id: I0e514604bf31f21683598ebd3e020b66acf767ef
Reviewed-on: https://go-review.googlesource.com/1720
Reviewed-by: Russ Cox <rsc@golang.org>