[libfuzzer] dump_coverage command line flag

Reviewers: kcc, vitalybuka

Differential Revision: https://reviews.llvm.org/D27942

llvm-svn: 290138

llvm/lib/Fuzzer/FuzzerDriver.cpp

@@ -433,6 +433,7 @@ int FuzzerDriver(int *argc, char ***argv, UserCallback Callback) {
   Options.PrintFinalStats = Flags.print_final_stats;
   Options.PrintCorpusStats = Flags.print_corpus_stats;
   Options.PrintCoverage = Flags.print_coverage;
+  Options.DumpCoverage = Flags.dump_coverage;
   if (Flags.exit_on_src_pos)
     Options.ExitOnSrcPos = Flags.exit_on_src_pos;
   if (Flags.exit_on_item)

llvm/lib/Fuzzer/FuzzerFlags.def

@@ -81,6 +81,8 @@ FUZZER_FLAG_INT(print_corpus_stats, 0,
   "If 1, print statistics on corpus elements at exit.")
 FUZZER_FLAG_INT(print_coverage, 0, "If 1, print coverage information at exit."
                                    " Experimental, only with trace-pc-guard")
+FUZZER_FLAG_INT(dump_coverage, 0, "If 1, dump coverage information at exit."
+                                  " Experimental, only with trace-pc-guard")
 FUZZER_FLAG_INT(handle_segv, 1, "If 1, try to intercept SIGSEGV.")
 FUZZER_FLAG_INT(handle_bus, 1, "If 1, try to intercept SIGSEGV.")
 FUZZER_FLAG_INT(handle_abrt, 1, "If 1, try to intercept SIGABRT.")

llvm/lib/Fuzzer/FuzzerLoop.cpp

@@ -375,6 +375,8 @@ void Fuzzer::PrintStats(const char *Where, const char *End, size_t Units) {
 void Fuzzer::PrintFinalStats() {
   if (Options.PrintCoverage)
     TPC.PrintCoverage();
+  if (Options.DumpCoverage)
+    TPC.DumpCoverage();
   if (Options.PrintCorpusStats)
     Corpus.PrintStats();
   if (!Options.PrintFinalStats) return;

llvm/lib/Fuzzer/FuzzerOptions.h

@@ -51,6 +51,7 @@ struct FuzzingOptions {
   bool PrintFinalStats = false;
   bool PrintCorpusStats = false;
   bool PrintCoverage = false;
+  bool DumpCoverage = false;
   bool DetectLeaks = true;
   int  TraceMalloc = 0;
   bool HandleAbrt = false;

llvm/lib/Fuzzer/FuzzerTracePC.cpp

@@ -20,6 +20,7 @@
 #include "FuzzerTracePC.h"
 #include "FuzzerValueBitMap.h"
 #include <map>
+#include <sanitizer/coverage_interface.h>
 #include <set>
 #include <sstream>
 
@@ -188,6 +189,10 @@ void TracePC::PrintCoverage() {
   }
 }
 
+void TracePC::DumpCoverage() {
+  __sanitizer_dump_coverage(PCs, GetNumPCs());
+}
+
 // Value profile.
 // We keep track of various values that affect control flow.
 // These values are inserted into a bit-set-based hash map.

llvm/lib/Fuzzer/FuzzerTracePC.h

@@ -71,6 +71,7 @@ class TracePC {
   void PrintModuleInfo();
 
   void PrintCoverage();
+  void DumpCoverage();
 
   void AddValueForMemcmp(void *caller_pc, const void *s1, const void *s2,
                          size_t n);

llvm/lib/Fuzzer/test/dump_coverage.test

@@ -0,0 +1,16 @@
+RUN: DIR=%t_workdir
+RUN: BUILD_DIR=$(pwd)
+RUN: rm -rf $DIR && mkdir -p $DIR && cd $DIR
+RUN: not $BUILD_DIR/LLVMFuzzer-NullDerefTest -dump_coverage=1 2>&1 | FileCheck %s
+RUN: $BUILD_DIR/LLVMFuzzer-DSOTest -dump_coverage=1 -runs=0 2>&1 | FileCheck %s --check-prefix=DSO
+RUN: not $BUILD_DIR/LLVMFuzzer-NullDerefTest -dump_coverage=0 2>&1 | FileCheck %s --check-prefix=NOCOV
+RUN: rm -rf $DIR
+
+
+CHECK: SanitizerCoverage: ./LLVMFuzzer-NullDerefTest.{{.*}}.sancov {{.*}} PCs written
+
+DSO: SanitizerCoverage: ./LLVMFuzzer-DSOTest.{{.*}}.sancov {{.*}} PCs written
+DSO-DAG: SanitizerCoverage: ./libLLVMFuzzer-DSO1.{{.*}}.sancov {{.*}} PCs written
+DSO-DAG: SanitizerCoverage: ./libLLVMFuzzer-DSO2.{{.*}}.sancov {{.*}} PCs written
+
+NOCOV-NOT: SanitizerCoverage: {{.*}} PCs written