oss-fuzz: add script for building native only (#2006)

Am often doing this and it makes it easier having a single script.

Signed-off-by: David Korczynski <[email protected]>

oss_fuzz_integration/build_native_post_processing.sh

@@ -0,0 +1,45 @@
+#!/bin/bash -eux
+# Copyright 2025 Fuzz Introspector Authors
+#
+# 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.
+#
+################################################################################
+
+if [ -d "oss-fuzz" ]
+then
+  echo "OSS-Fuzz directory exists. Reusing existing one"
+else
+  echo "Cloning oss-fuzz"
+  git clone https://github.com/google/oss-fuzz
+  echo "Applying diffs"
+  cd oss-fuzz
+  git apply  --ignore-space-change --ignore-whitespace ../oss-fuzz-patches.diff
+  echo "Done"
+  cd ../
+
+  echo "Pulling latest base-clang OSS-Fuzz image."
+  docker pull gcr.io/oss-fuzz-base/base-clang:latest
+fi
+
+echo "Building base-build, base-builder-python and base-runner for fuzz introspector"
+# This script should be run from the fuzz-introspector/oss_fuzz_integration folder
+# Copy over new post-processing
+rm -rf ./oss-fuzz/infra/base-images/base-builder/src
+cp -rf ../src ./oss-fuzz/infra/base-images/base-builder/src
+
+rm -rf ./oss-fuzz/infra/base-images/base-builder/frontends
+cp -rf ../frontends/ ./oss-fuzz/infra/base-images/base-builder/frontends
+
+cd oss-fuzz
+docker build -t gcr.io/oss-fuzz-base/base-builder infra/base-images/base-builder
+docker build -t gcr.io/oss-fuzz-base/base-runner infra/base-images/base-runner