fuzz: add configure flag --enable-fuzzing

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Message-id: 20200220041118.23264-19-alxndr@bu.edu
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

configure

@@ -505,6 +505,7 @@ debug_mutex="no"
 libpmem=""
 default_devices="yes"
 plugins="no"
+fuzzing="no"
 
 supported_cpu="no"
 supported_os="no"
@@ -635,6 +636,15 @@ int main(void) { return 0; }
 EOF
 }
 
+write_c_fuzzer_skeleton() {
+    cat > $TMPC <<EOF
+#include <stdint.h>
+#include <sys/types.h>
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) { return 0; }
+EOF
+}
+
 if check_define __linux__ ; then
   targetos="Linux"
 elif check_define _WIN32 ; then
@@ -1558,6 +1568,10 @@ for opt do
   ;;
   --disable-containers) use_containers="no"
   ;;
+  --enable-fuzzing) fuzzing=yes
+  ;;
+  --disable-fuzzing) fuzzing=no
+  ;;
   *)
       echo "ERROR: unknown option $opt"
       echo "Try '$0 --help' for more information"
@@ -6072,6 +6086,15 @@ EOF
   fi
 fi
 
+##########################################
+# checks for fuzzer
+if test "$fuzzing" = "yes" ; then
+  write_c_fuzzer_skeleton
+  if compile_prog "$CPU_CFLAGS -Werror -fsanitize=address,fuzzer" ""; then
+      have_fuzzer=yes
+  fi
+fi
+
 ##########################################
 # check for libpmem
 
@@ -6666,6 +6689,7 @@ echo "libpmem support   $libpmem"
 echo "libudev           $libudev"
 echo "default devices   $default_devices"
 echo "plugin support    $plugins"
+echo "fuzzing support   $fuzzing"
 
 if test "$supported_cpu" = "no"; then
     echo
@@ -7504,6 +7528,16 @@ fi
 if test "$sheepdog" = "yes" ; then
   echo "CONFIG_SHEEPDOG=y" >> $config_host_mak
 fi
+if test "$fuzzing" = "yes" ; then
+  if test "$have_fuzzer" = "yes"; then
+    FUZZ_LDFLAGS=" -fsanitize=address,fuzzer"
+    FUZZ_CFLAGS=" -fsanitize=address,fuzzer"
+    CFLAGS=" -fsanitize=address,fuzzer-no-link"
+  else
+    error_exit "Your compiler doesn't support -fsanitize=address,fuzzer"
+    exit 1
+  fi
+fi
 
 if test "$plugins" = "yes" ; then
     echo "CONFIG_PLUGIN=y" >> $config_host_mak
@@ -7605,6 +7639,11 @@ if test "$libudev" != "no"; then
     echo "CONFIG_LIBUDEV=y" >> $config_host_mak
     echo "LIBUDEV_LIBS=$libudev_libs" >> $config_host_mak
 fi
+if test "$fuzzing" != "no"; then
+    echo "CONFIG_FUZZ=y" >> $config_host_mak
+    echo "FUZZ_CFLAGS=$FUZZ_CFLAGS" >> $config_host_mak
+    echo "FUZZ_LDFLAGS=$FUZZ_LDFLAGS" >> $config_host_mak
+fi
 
 if test "$edk2_blobs" = "yes" ; then
   echo "DECOMPRESS_EDK2_BLOBS=y" >> $config_host_mak