test: Build fuzz targets into seperate executables

.travis.yml

@@ -97,7 +97,7 @@ jobs:
         PACKAGES="python3-zmq qtbase5-dev qttools5-dev-tools protobuf-compiler libdbus-1-dev libharfbuzz-dev libprotobuf-dev"
         DEP_OPTS="NO_QT=1 NO_UPNP=1 DEBUG=1 ALLOW_HOST_PACKAGES=1"
         GOAL="install"
-        BITCOIN_CONFIG="--enable-zmq --with-gui=qt5 --enable-glibc-back-compat --enable-reduce-exports --enable-debug CXXFLAGS=\"-g0 -O2\""
+        BITCOIN_CONFIG="--enable-zmq --with-gui=qt5 --enable-fuzz --enable-glibc-back-compat --enable-reduce-exports --enable-debug CXXFLAGS=\"-g0 -O2\""
 
     - stage: test
       name: 'x86_64 Linux  [GOAL: install]  [xenial]  [no depends, only system libs, sanitizers: thread (TSan), no wallet]'

configure.ac

@@ -102,7 +102,6 @@ AM_CONDITIONAL([HAVE_DOXYGEN], [test -n "$DOXYGEN"])
 
 AC_ARG_VAR(PYTHONPATH, Augments the default search path for python module files)
 
-# Enable wallet
 AC_ARG_ENABLE([wallet],
   [AS_HELP_STRING([--disable-wallet],
   [disable wallet (enabled by default)])],
@@ -147,6 +146,11 @@ AC_ARG_ENABLE([extended-functional-tests],
     [use_extended_functional_tests=$enableval],
     [use_extended_functional_tests=no])
 
+AC_ARG_ENABLE([fuzz],
+    AS_HELP_STRING([--enable-fuzz],[enable building of fuzz targets (default no)]),
+    [enable_fuzz=$enableval],
+    [enable_fuzz=no])
+
 AC_ARG_WITH([qrencode],
   [AS_HELP_STRING([--with-qrencode],
   [enable QR code support (default is yes if qt is enabled and libqrencode is found)])],
@@ -1394,6 +1398,7 @@ AM_CONDITIONAL([BUILD_DARWIN], [test x$BUILD_OS = xdarwin])
 AM_CONDITIONAL([TARGET_WINDOWS], [test x$TARGET_OS = xwindows])
 AM_CONDITIONAL([ENABLE_WALLET],[test x$enable_wallet = xyes])
 AM_CONDITIONAL([ENABLE_TESTS],[test x$BUILD_TEST = xyes])
+AM_CONDITIONAL([ENABLE_FUZZ],[test x$enable_fuzz = xyes])
 AM_CONDITIONAL([ENABLE_QT],[test x$bitcoin_enable_qt = xyes])
 AM_CONDITIONAL([ENABLE_QT_TESTS],[test x$BUILD_TEST_QT = xyes])
 AM_CONDITIONAL([ENABLE_BIP70],[test x$enable_bip70 = xyes])
@@ -1536,6 +1541,9 @@ if test x$bitcoin_enable_qt != xno; then
 fi
 echo "  with zmq      = $use_zmq"
 echo "  with test     = $use_tests"
+if test x$use_tests != xno; then
+    echo "    with fuzz   = $enable_fuzz"
+fi
 echo "  with bench    = $use_bench"
 echo "  with upnp     = $use_upnp"
 echo "  use asm       = $use_asm"

doc/fuzzing.md

@@ -1,9 +1,9 @@
 Fuzz-testing Bitcoin Core
 ==========================
 
-A special test harness `test_bitcoin_fuzzy` is provided to provide an easy
-entry point for fuzzers and the like. In this document we'll describe how to
-use it with AFL and libFuzzer.
+A special test harness in `src/test/fuzz/` is provided for each fuzz target to
+provide an easy entry point for fuzzers and the like. In this document we'll
+describe how to use it with AFL and libFuzzer.
 
 ## AFL
 
@@ -23,10 +23,10 @@ export AFLPATH=$PWD
 To build Bitcoin Core using AFL instrumentation (this assumes that the
 `AFLPATH` was set as above):
 ```
-./configure --disable-ccache --disable-shared --enable-tests CC=${AFLPATH}/afl-gcc CXX=${AFLPATH}/afl-g++
+./configure --disable-ccache --disable-shared --enable-tests --enable-fuzz CC=${AFLPATH}/afl-gcc CXX=${AFLPATH}/afl-g++
 export AFL_HARDEN=1
 cd src/
-make test/test_bitcoin_fuzzy
+make
 ```
 We disable ccache because we don't want to pollute the ccache with instrumented
 objects, and similarly don't want to use non-instrumented cached objects linked
@@ -35,7 +35,7 @@ in.
 The fuzzing can be sped up significantly (~200x) by using `afl-clang-fast` and
 `afl-clang-fast++` in place of `afl-gcc` and `afl-g++` when compiling. When
 compiling using `afl-clang-fast`/`afl-clang-fast++` the resulting
-`test_bitcoin_fuzzy` binary will be instrumented in such a way that the AFL
+binary will be instrumented in such a way that the AFL
 features "persistent mode" and "deferred forkserver" can be used. See
 https://github.com/mcarpenter/afl/tree/master/llvm_mode for details.
 
@@ -63,7 +63,7 @@ Extract these (or other starting inputs) into the `inputs` directory before star
 
 To start the actual fuzzing use:
 ```
-$AFLPATH/afl-fuzz -i ${AFLIN} -o ${AFLOUT} -m52 -- test/test_bitcoin_fuzzy
+$AFLPATH/afl-fuzz -i ${AFLIN} -o ${AFLOUT} -m52 -- test/fuzz/fuzz_target_foo
 ```
 
 You may have to change a few kernel parameters to test optimally - `afl-fuzz`
@@ -77,7 +77,7 @@ found in the `compiler-rt` runtime libraries package).
 To build the `test/test_bitcoin_fuzzy` executable run
 
 ```
-./configure --disable-ccache --with-sanitizers=fuzzer,address CC=clang CXX=clang++
+./configure --disable-ccache --enable-fuzz --with-sanitizers=fuzzer,address CC=clang CXX=clang++
 make
 ```