[libfuzzer] supporting libfuzzer on mac with asan

Experimental support for fuzzing on mac.

BUG=597066
Committed: https://crrev.com/e9aba58f6cbfee6fec2af0ec4832a3c23ec66b9f
Cr-Commit-Position: refs/heads/master@{#383389}

[aizatsky, 2016-03-22 22:07:02]

Description was changed from

==========
[libfuzzer] hacking libfuzzer in chrome on mac

BUG=
==========

to

==========
Experimental support for fuzzing on mac.


BUG=597066
==========

[aizatsky, 2016-03-22 22:07:03]

aizatsky@chromium.org changed reviewers:
+ dpranke@chromium.org, glider@chromium.org, kcc@chromium.org

[Robert Sesek, 2016-03-22 22:12:58]

rsesek@chromium.org changed reviewers:
+ rsesek@chromium.org

[Dirk Pranke, 2016-03-23 19:08:30]

lgtm

[Alexander Potapenko, 2016-03-24 21:58:43]

LGTM + a couple of questions.

https://codereview.chromium.org/1818273002/diff/80001/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/1818273002/diff/80001/BUILD.gn#newcode1
BUILD.gn:1: # Copyright (c) 2013 The Chromium Authors. All rights reserved.
You don't need GYP configs for this, right?

https://codereview.chromium.org/1818273002/diff/80001/BUILD.gn#newcode716
BUILD.gn:716: if ((is_linux && !is_chromeos && !is_chromecast) || is_mac) {
Can you please add a comment about why CrOS and Chromecast aren't supported?

https://codereview.chromium.org/1818273002/diff/80001/build/config/sanitizers...
File build/config/sanitizers/BUILD.gn (right):

https://codereview.chromium.org/1818273002/diff/80001/build/config/sanitizers...
build/config/sanitizers/BUILD.gn:293: if (is_mac && is_asan) {
Does is_mac mean only OSX, or both OSX and iOS/iossim?
Not sure you want to support the latter now though.

https://codereview.chromium.org/1818273002/diff/80001/build/config/sanitizers...
build/config/sanitizers/BUILD.gn:312:
"//third_party/llvm-build/Release+Asserts/compiler-rt/lib/darwin/libclang_rt.tsan_osx_dynamic.dylib",
You don't seem to need TSan/UBSan runtimes for ASan?

[aizatsky, 2016-03-24 22:31:34]

https://codereview.chromium.org/1818273002/diff/80001/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/1818273002/diff/80001/BUILD.gn#newcode1
BUILD.gn:1: # Copyright (c) 2013 The Chromium Authors. All rights reserved.
On 2016/03/24 21:58:43, Alexander Potapenko wrote:
> You don't need GYP configs for this, right?

No. We support libfuzzer only with GN.

https://codereview.chromium.org/1818273002/diff/80001/BUILD.gn#newcode716
BUILD.gn:716: if ((is_linux && !is_chromeos && !is_chromecast) || is_mac) {
On 2016/03/24 21:58:43, Alexander Potapenko wrote:
> Can you please add a comment about why CrOS and Chromecast aren't supported?

There's no particular reason. They are just not supported and they are disabled
because we don't want to spend time dealing with compilation problems/build
bots.

https://codereview.chromium.org/1818273002/diff/80001/build/config/sanitizers...
File build/config/sanitizers/BUILD.gn (right):

https://codereview.chromium.org/1818273002/diff/80001/build/config/sanitizers...
build/config/sanitizers/BUILD.gn:293: if (is_mac && is_asan) {
On 2016/03/24 21:58:43, Alexander Potapenko wrote:
> Does is_mac mean only OSX, or both OSX and iOS/iossim?
> Not sure you want to support the latter now though.

Ios is is_ios. No I don't want to support any of those now.

https://codereview.chromium.org/1818273002/diff/80001/build/config/sanitizers...
build/config/sanitizers/BUILD.gn:312:
"//third_party/llvm-build/Release+Asserts/compiler-rt/lib/darwin/libclang_rt.tsan_osx_dynamic.dylib",
On 2016/03/24 21:58:43, Alexander Potapenko wrote:
> You don't seem to need TSan/UBSan runtimes for ASan?

I do not at this time. But other sanitizers might. I figured it would be more
generic to copy all of them. BTW we do want to support libfuzzer + ubsan
eventually.

[aizatsky, 2016-03-25 21:13:35]

The CQ bit was checked by aizatsky@chromium.org

[commit-bot: I haz the power, 2016-03-25 21:13:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1818273002/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1818273002/80001

[commit-bot: I haz the power, 2016-03-25 21:33:11]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-03-25 21:33:12]

Try jobs failed on following builders:
  linux_chromium_clobber_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[aizatsky, 2016-03-25 21:58:54]

The CQ bit was checked by aizatsky@chromium.org

[aizatsky, 2016-03-25 21:58:55]

The patchset sent to the CQ was uploaded after l-g-t-m from
dpranke@chromium.org, glider@chromium.org
Link to the patchset: https://codereview.chromium.org/1818273002/#ps100001
(title: "wrapping copy in if (is_mac)")

[commit-bot: I haz the power, 2016-03-25 21:59:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1818273002/100001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1818273002/100001

[commit-bot: I haz the power, 2016-03-25 22:37:27]

Description was changed from

==========
Experimental support for fuzzing on mac.


BUG=597066
==========

to

==========
Experimental support for fuzzing on mac.


BUG=597066
==========

[commit-bot: I haz the power, 2016-03-25 22:37:28]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2016-03-25 22:39:26]

Description was changed from

==========
Experimental support for fuzzing on mac.


BUG=597066
==========

to

==========
Experimental support for fuzzing on mac.

BUG=597066

Committed: https://crrev.com/e9aba58f6cbfee6fec2af0ec4832a3c23ec66b9f
Cr-Commit-Position: refs/heads/master@{#383389}
==========

[commit-bot: I haz the power, 2016-03-25 22:39:27]

Patchset 6 (id:??) landed as
https://crrev.com/e9aba58f6cbfee6fec2af0ec4832a3c23ec66b9f
Cr-Commit-Position: refs/heads/master@{#383389}

[Alexander Potapenko, 2016-03-30 11:05:00]

Mike,

Henrik and Peter say trybots can't find asan_osx_dynamic.dylib (see
https://build.chromium.org/p/tryserver.webrtc/builders/mac_gn_rel/builds/8169...)
Looks like the path is wrong, can you please fix it?

https://codereview.chromium.org/1818273002/diff/100001/build/config/sanitizer...
File build/config/sanitizers/BUILD.gn (right):

https://codereview.chromium.org/1818273002/diff/100001/build/config/sanitizer...
build/config/sanitizers/BUILD.gn:31: if (is_mac) {
Why is this flag checked only under use_custom_libcxx?

https://codereview.chromium.org/1818273002/diff/100001/build/config/sanitizer...
build/config/sanitizers/BUILD.gn:311:
"//third_party/llvm-build/Release+Asserts/compiler-rt/lib/darwin/libclang_rt.asan_osx_dynamic.dylib",
This path is incorrect.

[kjellander_chromium, 2016-03-30 14:25:07]

kjellander@chromium.org changed reviewers:
+ kjellander@chromium.org

[kjellander_chromium, 2016-03-30 14:25:08]

https://codereview.chromium.org/1818273002/diff/100001/build/config/sanitizer...
File build/config/sanitizers/BUILD.gn (right):

https://codereview.chromium.org/1818273002/diff/100001/build/config/sanitizer...
build/config/sanitizers/BUILD.gn:311:
"//third_party/llvm-build/Release+Asserts/compiler-rt/lib/darwin/libclang_rt.asan_osx_dynamic.dylib",
On 2016/03/30 11:05:00, Alexander Potapenko wrote:
> This path is incorrect.

Right, on my Mac the path is:
third_party/llvm-build/Release+Asserts/lib/clang/3.9.0/lib/darwin/libclang_rt.asan_osx_dynamic.dylib

[kjellander_chromium, 2016-03-31 15:06:24]

A revert of this CL (patchset #6 id:100001) has been created in
https://codereview.chromium.org/1847803003/ by kjellander@chromium.org.

The reason for reverting is: I've spent a fair amount of time trying to debug
this and come up with a workaround for us. 
Our bot
(https://build.chromium.org/p/tryserver.webrtc/builders/mac_gn_rel/builds/8218/)
doesn't have ASan enabled do I don't even see why we're hit by the error we're
seeing.

I'll revert this for now waiting for the correct fix since there were several
problems with this CL.

FYI: I'm also unable to locate the tsan and ubsan libraries in LLVM: my checkout
only has the asan one:
$ find third_party/llvm-build/Release+Asserts/ -name libclang* 
third_party/llvm-build/Release+Asserts//lib/clang/3.9.0/lib/darwin/libclang_rt.asan_osx_dynamic.dylib
third_party/llvm-build/Release+Asserts//lib/clang/3.9.0/lib/darwin/libclang_rt.profile_osx.a
.