[PATCH] gitlab-ci.yml: Add oss-fuzz build tests

[Alexander Bulekov <alxndr@bu.edu>]

This tries to build and run the fuzzers with the same build-script used
by oss-fuzz. This doesn't guarantee that the builds on oss-fuzz will
also succeed, since oss-fuzz provides its own compiler and fuzzer vars,
but it can catch changes that are not compatible with the the
./scripts/oss-fuzz/build.sh script.
The strange way of finding fuzzer binaries stems from the method used by
oss-fuzz:
https://github.com/google/oss-fuzz/blob/master/infra/base-images/base-runner/targets_list

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---

Similar to Thomas' patch:

> Note: This patch needs two other patches merged first to work correctly:

> - 'fuzz: Expect the cmdline in a freeable GString' from Alexander

> - 'qom: Plug memory leak in "info qom-tree"' from Markus

Otherwise the test will fail due to detected memory leaks.

Fair warning: I haven't been able to trigger this new job yet. I tried
to run the pipeline with these changes on my forked repo on gitlab, but
did not reach the build-oss-fuzz. I think this is due to some failures
in the Containers-layer-2 stage:

...
Error response from daemon: manifest for
registry.gitlab.com/a1xndr/qemu/qemu/debian-all-test-cross:latest not
found: manifest unknown: manifest unknown
#2 [internal] load .dockerignore
#2 transferring context:
#2 transferring context: 2B 0.1s done
#2 DONE 0.1s
#1 [internal] load build definition from tmpg8j4xoop.docker
#1 transferring dockerfile: 2.21kB 0.1s done
#1 DONE 0.2s
#3 [internal] load metadata for docker.io/qemu/debian10:latest
#3 ERROR: pull access denied, repository does not exist or may require
authorization: server message: insufficient_scope: authorization failed
#4 [1/3] FROM docker.io/qemu/debian10:latest
#4 resolve docker.io/qemu/debian10:latest 0.1s done
#4 ERROR: pull access denied, repository does not exist or may require
authorization: server message: insufficient_scope: authorization failed
------
 > [internal] load metadata for docker.io/qemu/debian10:latest:
------
------
 > [1/3] FROM docker.io/qemu/debian10:latest:
------
failed to solve with frontend dockerfile.v0: failed to build LLB: failed
to load cache key: pull access denied, repository does not exist or may
require authorization: server message: insufficient_scope: authorization
failed
...

 .gitlab-ci.yml | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e96f8794b9..a50df420c9 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -182,6 +182,20 @@ build-fuzzer:
             || exit 1 ;
       done
 
+build-oss-fuzz:
+  <<: *native_build_job_definition
+  variables:
+    IMAGE: fedora
+  script:
+    - OUT_DIR="./build" CC=clang-9 CXX=clang++-9 CFLAGS="-fsanitize=address"
+      LIB_FUZZING_ENGINE="-fsanitize=fuzzer" CFL
+      ./scripts/oss-fuzz/build.sh
+    - for fuzzer in $(find ./build-oss-fuzz/DEST_DIR/ -executable -type f); do
+        grep "LLVMFuzzerTestOneInput" ${fuzzer} > /dev/null 2>&1 || continue ;
+        echo Testing ${fuzzer} ... ;
+        "${fuzzer}" -runs=1000 || exit 1 ;
+      done
+
 build-tci:
   <<: *native_build_job_definition
   variables:
-- 
2.26.2