1 files changed, 74 insertions, 0 deletions
diff --git a/scripts/clusterfuzz/extract_wasms.py b/scripts/clusterfuzz/extract_wasms.py
new file mode 100644
index 000000000..bb727810d
--- /dev/null
+++ b/scripts/clusterfuzz/extract_wasms.py
@@ -0,0 +1,74 @@
+#
+# Copyright 2024 WebAssembly Community Group participants
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+'''
+Wasm extractor for testcases generated by the ClusterFuzz run.py script. Usage:
+
+extract_wasms.py INFILE.js OUTFILE
+
+That will find embedded wasm files in INFILE.js, of the form
+
+  var .. = new Uint8Array([..wasm_contents..]);
+
+and extract them into OUTFILE.0.wasm, OUTFILE.1.wasm, etc. It also emits
+OUTFILE.js which will no longer contain the embedded contents, after which the
+script can be run as
+
+  d8 OUTFILE.js -- OUTFILE.0.wasm
+
+That is, the embedded file can now be provided as a filename argument.
+'''
+
+import re
+import sys
+
+file_counter = 0
+
+
+def get_wasm_filename():
+    global file_counter
+    file_counter += 1
+    return f'{out}.{file_counter - 1}.wasm'
+
+
+in_js = sys.argv[1]
+out = sys.argv[2]
+
+with open(in_js) as f:
+    js = f.read()
+
+
+def repl(text):
+    # We found something of the form
+    #
+    #   var binary = new Uint8Array([..binary data as numbers..]);
+    #
+    # Parse out the numbers into a binary wasm file.
+    numbers = text.groups()[0]
+    numbers = numbers.split(',')
+    numbers = [int(n) for n in numbers]
+    with open(get_wasm_filename(), 'wb') as f:
+        f.write(bytes(numbers))
+
+    # Replace it with nothing.
+    return ''
+
+
+# Replace the wasm files and write them out.
+js = re.sub(r'var \w+ = new Uint8Array\(\[([\d,]+)\]\);', repl, js)
+
+# Write out the new JS.
+with open(f'{out}.js', 'w') as f:
+    f.write(js)