qemu/scripts/oss-fuzz/build.sh
Alexander Bulekov a942f64cc4 scripts/oss-fuzz: use hardlinks instead of copying
Prior to this, fuzzers in the output oss-fuzz directory were exactly
the same executable, with a different name to do argv[0]-based
fuzz-target selection. This is a waste of space, especially since these
binaries can weigh many MB.

Instead of copying, use hard links, to cut down on wasted space. We need
to place the primary copy of the executable into DEST_DIR, since this is
a separate file-system on oss-fuzz. We should not place it directly into
$DEST_DIR, since oss-fuzz will treat it as an independent fuzzer and try
to run it for fuzzing. Instead, we create a DEST_DIR/bin directory to
store the primary copy.

Suggested-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20201023150746.107063-17-alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2020-10-26 09:53:54 +01:00

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#!/bin/sh -e
#
# OSS-Fuzz build script. See:
# https://google.github.io/oss-fuzz/getting-started/new-project-guide/#buildsh
#
# The file is consumed by:
# https://github.com/google/oss-fuzz/blob/master/projects/qemu/Dockerfiles
#
# This code is licensed under the GPL version 2 or later. See
# the COPYING file in the top-level directory.
#
# build project
# e.g.
# ./autogen.sh
# ./configure
# make -j$(nproc) all
# build fuzzers
# e.g.
# $CXX $CXXFLAGS -std=c++11 -Iinclude \
# /path/to/name_of_fuzzer.cc -o $OUT/name_of_fuzzer \
# -fsanitize=fuzzer /path/to/library.a
fatal () {
echo "Error : ${*}, exiting."
exit 1
}
OSS_FUZZ_BUILD_DIR="./build-oss-fuzz/"
# There seems to be a bug in clang-11 (used for builds on oss-fuzz) :
# accel/tcg/cputlb.o: In function `load_memop':
# accel/tcg/cputlb.c:1505: undefined reference to `qemu_build_not_reached'
#
# When building with optimization, the compiler is expected to prove that the
# statement cannot be reached, and remove it. For some reason clang-11 doesn't
# remove it, resulting in an unresolved reference to qemu_build_not_reached
# Undefine the __OPTIMIZE__ macro which compiler.h relies on to choose whether
# to " #define qemu_build_not_reached() g_assert_not_reached() "
EXTRA_CFLAGS="$CFLAGS -U __OPTIMIZE__"
if ! { [ -e "./COPYING" ] &&
[ -e "./MAINTAINERS" ] &&
[ -e "./Makefile" ] &&
[ -e "./docs" ] &&
[ -e "./VERSION" ] &&
[ -e "./linux-user" ] &&
[ -e "./softmmu" ];} ; then
fatal "Please run the script from the top of the QEMU tree"
fi
mkdir -p $OSS_FUZZ_BUILD_DIR || fatal "mkdir $OSS_FUZZ_BUILD_DIR failed"
cd $OSS_FUZZ_BUILD_DIR || fatal "cd $OSS_FUZZ_BUILD_DIR failed"
if [ -z ${OUT+x} ]; then
DEST_DIR=$(realpath "./DEST_DIR")
else
DEST_DIR=$OUT
fi
mkdir -p "$DEST_DIR/lib/" # Copy the shared libraries here
mkdir -p "$DEST_DIR/bin/" # Copy executables that shouldn't
# be treated as fuzzers by oss-fuzz here
# Build once to get the list of dynamic lib paths, and copy them over
../configure --disable-werror --cc="$CC" --cxx="$CXX" --enable-fuzzing \
--prefix="$DEST_DIR" --bindir="$DEST_DIR" --datadir="$DEST_DIR/data/" \
--extra-cflags="$EXTRA_CFLAGS" --target-list="i386-softmmu"
if ! make "-j$(nproc)" qemu-fuzz-i386; then
fatal "Build failed. Please specify a compiler with fuzzing support"\
"using the \$CC and \$CXX environment variables"\
"\nFor example: CC=clang CXX=clang++ $0"
fi
for i in $(ldd ./qemu-fuzz-i386 | cut -f3 -d' '); do
cp "$i" "$DEST_DIR/lib/"
done
rm qemu-fuzz-i386
# Build a second time to build the final binary with correct rpath
../configure --disable-werror --cc="$CC" --cxx="$CXX" --enable-fuzzing \
--prefix="$DEST_DIR" --bindir="$DEST_DIR" --datadir="$DEST_DIR/data/" \
--extra-cflags="$EXTRA_CFLAGS" --extra-ldflags="-Wl,-rpath,\$ORIGIN/lib" \
--target-list="i386-softmmu"
make "-j$(nproc)" qemu-fuzz-i386 V=1
# Copy over the datadir
cp -r ../pc-bios/ "$DEST_DIR/pc-bios"
cp "./qemu-fuzz-i386" "$DEST_DIR/bin/"
# Run the fuzzer with no arguments, to print the help-string and get the list
# of available fuzz-targets. Copy over the qemu-fuzz-i386, naming it according
# to each available fuzz target (See 05509c8e6d fuzz: select fuzz target using
# executable name)
for target in $(./qemu-fuzz-i386 | awk '$1 ~ /\*/ {print $2}');
do
ln "$DEST_DIR/bin/qemu-fuzz-i386" \
"$DEST_DIR/qemu-fuzz-i386-target-$target"
done
echo "Done. The fuzzers are located in $DEST_DIR"
exit 0