From 9c5c4677fa22c2fc87599c15ca972627ceb17bd7 Mon Sep 17 00:00:00 2001
From: Evgeny Vereshchagin <evvers@ya.ru>
Date: Thu, 9 May 2019 00:03:41 +0200
Subject: [PATCH] fuzzers: use -fsanitizer=fuzzer if clang supports it

Closes https://github.com/systemd/systemd/issues/10645
---
 meson.build       | 19 +++++++++++++++++--
 tools/oss-fuzz.sh |  4 ++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/meson.build b/meson.build
index eaf0eddcb1..9506274239 100644
--- a/meson.build
+++ b/meson.build
@@ -303,7 +303,14 @@ else
 endif
 
 if want_libfuzzer
-        fuzzing_engine = meson.get_compiler('cpp').find_library('Fuzzer')
+        fuzzing_engine = meson.get_compiler('cpp').find_library('Fuzzer', required : false)
+        if fuzzing_engine.found()
+                add_project_arguments('-fsanitize-coverage=trace-pc-guard,trace-cmp', language : 'c')
+        elif cc.has_argument('-fsanitize=fuzzer-no-link')
+                add_project_arguments('-fsanitize=fuzzer-no-link', language : 'c')
+        else
+                error('Looks like neither libFuzzer nor -fsanitize=fuzzer-no-link is supported')
+        endif
 elif want_ossfuzz
         fuzzing_engine = meson.get_compiler('cpp').find_library('FuzzingEngine')
 elif want_fuzzbuzz
@@ -2825,9 +2832,16 @@ foreach tuple : fuzzers
         dependencies = tuple[2]
         defs = tuple.length() >= 4 ? tuple[3] : []
         incs = tuple.length() >= 5 ? tuple[4] : includes
+        link_args = []
 
-        if fuzzer_build
+        if want_ossfuzz or want_fuzzbuzz
                 dependencies += fuzzing_engine
+        elif want_libfuzzer
+                if fuzzing_engine.found()
+                        dependencies += fuzzing_engine
+                else
+                        link_args += ['-fsanitize=fuzzer']
+                endif
         else
                 sources += 'src/fuzz/fuzz-main.c'
         endif
@@ -2845,6 +2859,7 @@ foreach tuple : fuzzers
                 link_with : link_with,
                 dependencies : dependencies,
                 c_args : defs,
+                link_args: link_args,
                 install : false)
 endforeach
 endif
diff --git a/tools/oss-fuzz.sh b/tools/oss-fuzz.sh
index 610bb9c235..6d9010ce16 100755
--- a/tools/oss-fuzz.sh
+++ b/tools/oss-fuzz.sh
@@ -10,7 +10,7 @@ export CXX=${CXX:-clang++}
 clang_version="$($CC --version | sed -nr 's/.*version ([^ ]+?) .*/\1/p' | sed -r 's/-$//')"
 
 SANITIZER=${SANITIZER:-address -fsanitize-address-use-after-scope}
-flags="-O1 -fno-omit-frame-pointer -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=$SANITIZER -fsanitize-coverage=trace-pc-guard,trace-cmp"
+flags="-O1 -fno-omit-frame-pointer -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=$SANITIZER"
 
 clang_lib="/usr/lib64/clang/${clang_version}/lib/linux"
 [ -d "$clang_lib" ] || clang_lib="/usr/lib/clang/${clang_version}/lib/linux"
@@ -33,7 +33,7 @@ if [ -z "$FUZZING_ENGINE" ]; then
 fi
 
 meson $build -D$fuzzflag -Db_lundef=false
-ninja -C $build fuzzers
+ninja -v -C $build fuzzers
 
 # The seed corpus is a separate flat archive for each fuzzer,
 # with a fixed name ${fuzzer}_seed_corpus.zip.