[cifuzz] Fix corpus usage in coverage reports (#6093)

Fixes #6089

infra/base-images/base-runner/coverage

@@ -61,6 +61,8 @@ objects=""
 # Number of CPUs available, this is needed for running tests in parallel.
 NPROC=$(nproc)
 
+CORPUS_DIR=${CORPUS_DIR:-"/corpus"}
+
 function run_fuzz_target {
   local target=$1
 
@@ -69,7 +71,7 @@ function run_fuzz_target {
   local profraw_file="$DUMPS_DIR/$target.%1m.profraw"
   local profraw_file_mask="$DUMPS_DIR/$target.*.profraw"
   local profdata_file="$DUMPS_DIR/$target.profdata"
-  local corpus_real="/corpus/${target}"
+  local corpus_real="$CORPUS_DIR/${target}"
 
   # -merge=1 requires an output directory, create a new, empty dir for that.
   local corpus_dummy="$OUT/dummy_corpus_dir_for_${target}"
@@ -122,7 +124,7 @@ function run_go_fuzz_target {
   local target=$1
 
   echo "Running go target $target"
-  export FUZZ_CORPUS_DIR="/corpus/${target}/"
+  export FUZZ_CORPUS_DIR="$CORPUS_DIR/${target}/"
   export FUZZ_PROFILE_NAME="$DUMPS_DIR/$target.perf"
   $OUT/$target -test.coverprofile $DUMPS_DIR/$target.profdata &> $LOGS_DIR/$target.log
   # translate from golangish paths to current absolute paths
@@ -138,7 +140,7 @@ function run_java_fuzz_target {
   local exec_file="$DUMPS_DIR/$target.exec"
   local class_dump_dir="$DUMPS_DIR/${target}_classes/"
   mkdir "$class_dump_dir"
-  local corpus_real="/corpus/${target}"
+  local corpus_real="$CORPUS_DIR/${target}"
 
   # -merge=1 requires an output directory, create a new, empty dir for that.
   local corpus_dummy="$OUT/dummy_corpus_dir_for_${target}"

infra/cifuzz/generate_coverage_report.py

@@ -24,6 +24,7 @@ def run_coverage_command(workspace, config):
                                                    config.language)
   docker_args += [
       '-e', 'COVERAGE_EXTRA_ARGS=', '-e', 'HTTP_PORT=', '-e',
+      f'CORPUS_DIR={workspace.corpora}', '-e',
       f'COVERAGE_OUTPUT_DIR={workspace.coverage_report}', '-t',
       docker.BASE_RUNNER_TAG, 'coverage'
   ]
@@ -32,8 +33,7 @@ def run_coverage_command(workspace, config):
 
 def download_corpora(fuzz_target_paths, clusterfuzz_deployment):
   """Downloads corpora for fuzz targets in |fuzz_target_paths| using
-  clusterfuzz_deployment| to download corpora from ClusterFuzz/OSS-Fuzz."""
-  # TODO(metzman): Download to /corpus dir.
+  |clusterfuzz_deployment| to download corpora from ClusterFuzz/OSS-Fuzz."""
   for target_path in fuzz_target_paths:
     target = os.path.basename(target_path)
     clusterfuzz_deployment.download_corpus(target)

infra/cifuzz/generate_coverage_report_test.py

@@ -40,6 +40,7 @@ class TestRunCoverageCommand(unittest.TestCase):
         'OUT=/workspace/build-out', '-v',
         f'{workspace.workspace}:{workspace.workspace}', '-e',
         'COVERAGE_EXTRA_ARGS=', '-e', 'HTTP_PORT=', '-e',
+        f'CORPUS_DIR={workspace.corpora}', '-e',
         f'COVERAGE_OUTPUT_DIR={workspace.coverage_report}', '-t',
         'gcr.io/oss-fuzz-base/base-runner', 'coverage'
     ]