[ios-fuzzing] Use bundled version of libclang_rt.asan_osx_dynamic.dylib

The WebKit build directory contains a copy of
libclang_rt.asan_osx_dynamic.dylib inside
WebKitTestRunnerApp.app. This file is also needed at the top
level when fuzzing, since trying to dynamically load a
version of this library from other locations leads to crashes.

This CL makes copy_webkit_for_clusterfuzz.py copy this
library to the top level, and makes run-clusterfuzz.sh set
DYLD_LIBRARY_PATH to this top level directory.

Bug: 1064181
Change-Id: I7de42891c39c12ae422beb6e8031745ff36640b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2202682Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Ali Juma <ajuma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#768984}

ios/third_party/webkit/BUILD.gn

@@ -158,6 +158,8 @@ if (_build_custom_webkit) {
     ]
     outputs = [ "$root_out_dir/WebKitMacOS" ]
 
+    _clang_asan_lib = rebase_path(sources[0], root_build_dir) + "/WebKitTestRunnerApp.app/Contents/Frameworks/libclang_rt.asan_osx_dynamic.dylib"
+
     args = [
       "--output",
       rebase_path(outputs[0], root_build_dir),
@@ -165,6 +167,8 @@ if (_build_custom_webkit) {
       rebase_path(sources[0], root_build_dir),
       "--clusterfuzz_script",
       rebase_path(sources[1], root_build_dir),
+      "--clang_asan_library",
+      "$_clang_asan_lib",
     ]
 
     public_deps = [ ":compile_webkit_mac_minibrowser" ]

ios/third_party/webkit/copy_webkit_for_clusterfuzz.py

@@ -13,11 +13,13 @@ def main():
   description = 'Packages WebKit build for Clusterfuzz.'
   parser = argparse.ArgumentParser(description=description)
   parser.add_argument('--output',
-                    help='Name of the outout file.')
+                    help='Name of the output file.')
   parser.add_argument('--webkit_build',
                       help='WebKit build directory to copy.')
   parser.add_argument('--clusterfuzz_script',
                       help='Clusterfuzz script to copy.')
+  parser.add_argument('--clang_asan_library',
+                      help='Clang ASan library to copy.')
 
   opts = parser.parse_args()
 
@@ -29,6 +31,10 @@ def main():
         opts.clusterfuzz_script,
         os.path.join(opts.output,
                      os.path.basename(opts.clusterfuzz_script)))
+  shutil.copyfile(
+        opts.clang_asan_library,
+        os.path.join(opts.output,
+                     os.path.basename(opts.clang_asan_library)))
 
   zip_command = ['zip', '--symlinks', '-r', os.extsep.join([opts.output, 'zip']), opts.output]
   proc = subprocess.Popen(zip_command)

ios/third_party/webkit/run-clusterfuzz.sh

@@ -6,5 +6,4 @@
 # This script is used to launch WebKitTestRunner on ClusterFuzz bots.
 
 BASEDIR=$(dirname "$0")
-LIBDIR=$(xcode-select --print-path)/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/10.0.1/lib/darwin
-DYLD_FRAMEWORK_PATH=$BASEDIR DYLD_LIBRARY_PATH=$LIBDIR ./WebKitTestRunner $@
+DYLD_FRAMEWORK_PATH=$BASEDIR DYLD_LIBRARY_PATH=$BASEDIR ./WebKitTestRunner $@