libass: fix build, upgrade Ubuntu, update contacts (#6423)

* libass: update contact list

One contact is retired; another is currently inactive.

* libass: don't build HarfBuzz tests

They won't be used, so this just wastes resources.

* libass: upgrade to Ubuntu 20.04

The build failures on 20.04 were due to explicit listing
of static library dependencies, which have changed on 20.04:
png12 was replaced by png16, fontconfig was missing -luuid,
and png needed -lz to follow it, not precede.

Replace the explicit -l list by $(pkg-config --static --libs).
However, -lm must be filtered out as it causes linker errors:
  > undefined reference to `_dl_x86_cpu_features'

While we are at it, Ubuntu 20.04 comes with new-enough FriBidi,
so we can stop building it.

It also has new-enough HarfBuzz, but it depends on libgraphite2,
which lacks a static library in the system package, and dynamically
linking against a system library does not work in OSS-Fuzz
as the shared object will not exist in the run-time environment.

Reorder the dependencies alphabetically for consistency.

projects/libass/Dockerfile

@@ -14,16 +14,11 @@
 #
 ################################################################################
 
-# Using Ubuntu 16.04 because of breakage on Ubuntu 20.04.
-# See https://github.com/google/oss-fuzz/issues/6291 for more details.
-FROM gcr.io/oss-fuzz-base/base-builder:xenial
-# Delete line above and uncomment line below to upgrade to 20.04.
-# FROM gcr.io/oss-fuzz-base/base-builder
-RUN apt-get update && apt-get install -y make autoconf automake libtool pkg-config libfreetype6-dev libfontconfig1-dev python3-pip && \
+FROM gcr.io/oss-fuzz-base/base-builder
+RUN apt-get update && apt-get install -y make autoconf automake libtool pkg-config libfontconfig1-dev libfreetype-dev libfribidi-dev python3-pip && \
     pip3 install meson==0.53.0 ninja
 
 RUN git clone --depth 1 https://github.com/libass/libass.git
-RUN git clone --depth 1 https://github.com/behdad/fribidi.git
 RUN git clone --depth 1 https://github.com/harfbuzz/harfbuzz.git
 
 COPY build.sh libass_fuzzer.cc *.dict *.options $SRC/

projects/libass/build.sh

@@ -15,10 +15,6 @@
 #
 ################################################################################
 
-cd $SRC/fribidi
-./autogen.sh --disable-docs --enable-static=yes --enable-shared=no --with-pic=yes --prefix=/work/
-make install
-
 cd $SRC/harfbuzz
 
 # setup
@@ -33,6 +29,7 @@ CFLAGS="$CFLAGS -fno-sanitize=vptr" \
 CXXFLAGS="$CXXFLAGS -fno-sanitize=vptr" \
 meson --default-library=static --wrap-mode=nodownload \
       -Dfuzzer_ldflags="$(echo $LIB_FUZZING_ENGINE)" \
+      -Dtests=disabled \
       --prefix=/work/ --libdir=lib $build \
   || (cat build/meson-logs/meson-log.txt && false)
 meson install -C $build
@@ -44,10 +41,11 @@ export PKG_CONFIG_PATH=/work/lib/pkgconfig
 ./configure --disable-asm
 make -j$(nproc)
 
-$CXX $CXXFLAGS -std=c++11 -I$SRC/libass -L/work/lib \
+$CXX $CXXFLAGS -std=c++11 -I$SRC/libass \
     $SRC/libass_fuzzer.cc -o $OUT/libass_fuzzer \
     $LIB_FUZZING_ENGINE libass/.libs/libass.a \
-    -Wl,-Bstatic -lfontconfig  -lfribidi -lfreetype -lharfbuzz -lz -lpng12 \
-    -lexpat -Wl,-Bdynamic
+    -Wl,-Bstatic \
+    $(pkg-config --static --libs fontconfig freetype2 fribidi harfbuzz | sed 's/-lm //g') \
+    -Wl,-Bdynamic
 
 cp $SRC/*.dict $SRC/*.options $OUT/

projects/libass/project.yaml

@@ -1,10 +1,9 @@
 homepage: "https://github.com/libass/libass"
 language: c++
-primary_contact: "greg@kinoho.net"
+primary_contact: "chortos@inbox.lv"
 auto_ccs:
+  - "greg@kinoho.net"
   - "rodger.combs@gmail.com"
-  - "nfxjfg@gmail.com"
-  - "chortos@inbox.lv"
   - "vabnick@gmail.com"
 sanitizers:
   - address