cached build: Re-build for every sanitizer.

infra/build/functions/build_lib.py

@@ -442,7 +442,8 @@ def get_project_image_steps(  # pylint: disable=too-many-arguments
     config,
     architectures=None,
     experiment=False,
-    cache_image=None):
+    cache_image=None,
+    srcmap=True):
   """Returns GCB steps to build OSS-Fuzz project image."""
   if architectures is None:
     architectures = []
@@ -459,29 +460,25 @@ def get_project_image_steps(  # pylint: disable=too-many-arguments
     steps.extend(get_pull_test_images_steps(config.test_image_suffix))
   src_root = 'oss-fuzz' if not experiment else '.'
 
-  steps.append({
-      'name': 'ubuntu',
-      'args': ['bash', '-c', f'cat {src_root}/projects/{name}/Dockerfile'],
-  })
-
   docker_build_step = get_docker_build_step([image],
                                             os.path.join('projects', name),
                                             src_root=src_root,
                                             cache_image=cache_image)
   steps.append(docker_build_step)
-  srcmap_step_id = get_srcmap_step_id()
-  steps.extend([{
-      'name': image,
-      'args': [
-          'bash', '-c',
-          'srcmap > /workspace/srcmap.json && cat /workspace/srcmap.json'
-      ],
-      'env': [
-          'OSSFUZZ_REVISION=$REVISION_ID',
-          'FUZZING_LANGUAGE=%s' % language,
-      ],
-      'id': srcmap_step_id
-  }])
+  if srcmap:
+    srcmap_step_id = get_srcmap_step_id()
+    steps.extend([{
+        'name': image,
+        'args': [
+            'bash', '-c',
+            'srcmap > /workspace/srcmap.json && cat /workspace/srcmap.json'
+        ],
+        'env': [
+            'OSSFUZZ_REVISION=$REVISION_ID',
+            'FUZZING_LANGUAGE=%s' % language,
+        ],
+        'id': srcmap_step_id
+    }])
 
   if has_arm_build(architectures):
     builder_name = 'buildxbuilder'

infra/build/functions/build_project.py

@@ -354,22 +354,19 @@ def get_build_steps_for_project(project,
 
   timestamp = get_datetime_now().strftime('%Y%m%d%H%M')
 
-  # If we use caching, then we need to use the right name. We assume that
-  # there is only a single sanitizer.
   if use_caching:
-    project.cached_sanitizer = project.sanitizers[0]
-    cache_image = project.cached_image
+    # For cached builds: the cache images are sanitizer-specific, so we need to
+    # do a rebuild prior to each compile.
+    build_steps = []
   else:
-    cache_image = None
-
-  build_steps = build_lib.get_project_image_steps(
-      project.name,
-      project.image,
-      project.fuzzing_language,
-      config=config,
-      architectures=project.architectures,
-      experiment=config.experiment,
-      cache_image=cache_image)
+    # Non-cached builds just use a single builder image to build all sanitizers.
+    build_steps = build_lib.get_project_image_steps(
+        project.name,
+        project.image,
+        project.fuzzing_language,
+        config=config,
+        architectures=project.architectures,
+        experiment=config.experiment)
 
   # Sort engines to make AFL first to test if libFuzzer has an advantage in
   # finding bugs first since it is generally built first.
@@ -379,6 +376,15 @@ def get_build_steps_for_project(project,
     for sanitizer in sorted(project.sanitizers):
       if use_caching and sanitizer in _CACHED_SANITIZERS:
         project.cached_sanitizer = sanitizer
+        build_steps.extend(
+            build_lib.get_project_image_steps(
+                project.name,
+                project.image,
+                project.fuzzing_language,
+                config=config,
+                architectures=project.architectures,
+                experiment=config.experiment,
+                cache_image=project.cached_image))
 
       # Build x86_64 before i386.
       for architecture in reversed(sorted(project.architectures)):

infra/build/functions/target_experiment.py

@@ -220,6 +220,15 @@ def run_experiment(project_name,
 
   if use_cached_image:
     project.cached_sanitizer = 'coverage'
+    steps.extend(
+        build_lib.get_project_image_steps(project.name,
+                                          project.image,
+                                          project.fuzzing_language,
+                                          config=config,
+                                          architectures=project.architectures,
+                                          experiment=config.experiment,
+                                          cache_image=project.cached_image,
+                                          srcmap=False))
 
   steps.append(
       build_project.get_compile_step(project, build, env, config.parallel))