libbpf: don't crash on object files with no symbol tables

.github/actions/debian/action.yml

@@ -0,0 +1,16 @@
+name: 'debian'
+description: 'Build'
+inputs:
+  target:
+    description: 'Run target'
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - run: |
+        source /tmp/ci_setup
+        bash -x $CI_ROOT/managers/debian.sh SETUP
+        bash -x $CI_ROOT/managers/debian.sh ${{ inputs.target }}
+        bash -x $CI_ROOT/managers/debian.sh CLEANUP
+      shell: bash
+

.github/actions/get_scripts/action.yml

@@ -0,0 +1,35 @@
+name: 'get_scripts'
+description: 'Partially checkout CI files onto build dir'
+inputs:
+  branch:
+    description: 'Branch'
+    required: false
+    default: 'master'
+  repo:
+    description: 'Repo'
+    required: false
+    default: 'https://github.com/libbpf/ci'
+  files:
+    description: 'Files to copy separated with space'
+    required: false
+    default: 'custom-workflows travis-ci'
+  destdir:
+    description: 'Destination of checkout'
+    required: false
+    default: './'
+runs:
+  using: "composite"
+  steps:
+    - name: Clone
+      run: |
+         # using nested actions not implemented https://github.com/actions/runner/pull/612
+         # so just plaint git clone
+         git clone -b ${{ inputs.branch }} ${{ inputs.repo }} /tmp/_temp_get_scripts
+      shell: bash
+    - name: Copy files
+      run: |
+        for f in ${{ inputs.files }};
+          do cp -a /tmp/_temp_get_scripts/$f ${{ inputs.destdir }}
+        done
+        rm -rf /tmp/_temp_get_scripts
+      shell: bash

.github/actions/setup/action.yml

@@ -0,0 +1,23 @@
+name: 'setup'
+description: 'setup env, create /tmp/ci_setup'
+runs:
+  using: "composite"
+  steps:
+    - id: variables
+      run: |
+        export REPO_ROOT=$GITHUB_WORKSPACE
+        export CI_ROOT=$REPO_ROOT/travis-ci
+        # this is somewhat ugly, but that is the easiest way to share this code with
+        # arch specific docker
+        echo 'echo ::group::Env setup' > /tmp/ci_setup
+        echo export DEBIAN_FRONTEND=noninteractive >> /tmp/ci_setup
+        echo sudo apt-get update >> /tmp/ci_setup
+        echo sudo apt-get install -y aptitude qemu-kvm zstd binutils-dev elfutils libcap-dev libelf-dev libdw-dev >> /tmp/ci_setup
+        echo export PROJECT_NAME='libbpf' >> /tmp/ci_setup
+        echo export AUTHOR_EMAIL="$(git log -1 --pretty=\"%aE\")" >> /tmp/ci_setup
+        echo export REPO_ROOT=$GITHUB_WORKSPACE >> /tmp/ci_setup
+        echo export CI_ROOT=$REPO_ROOT/travis-ci >> /tmp/ci_setup
+        echo export VMTEST_ROOT=$CI_ROOT/vmtest >> /tmp/ci_setup
+        echo 'echo ::endgroup::' >> /tmp/ci_setup
+      shell: bash
+

.github/actions/vmtest/action.yml

@@ -0,0 +1,36 @@
+name: 'vmtest'
+description: 'Build + run vmtest'
+inputs:
+  kernel:
+    description: 'kernel version or LATEST'
+    required: true
+    default: 'LATEST'
+  kernel-rev:
+    description: 'CHECKPOINT or rev/tag/branch'
+    required: true
+    default: 'CHECKPOINT'
+  kernel-origin:
+    description: 'kernel repo'
+    required: true
+    default: 'https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git'
+  pahole:
+    description: 'pahole rev/tag/branch'
+    required: true
+    default: 'master'
+  pahole-origin:
+    description: 'pahole repo'
+    required: true
+    default: 'https://git.kernel.org/pub/scm/devel/pahole/pahole.git'
+runs:
+  using: "composite"
+  steps:
+    - run: |
+        find ./ | grep travis
+        source /tmp/ci_setup
+        export KERNEL=${{ inputs.kernel }}
+        export KERNEL_BRANCH=${{ inputs.kernel-rev }}
+        export KERNEL_ORIGIN=${{ inputs.kernel-origin }}
+        export PAHOLE_BRANCH=${{ inputs.pahole }}
+        export PAHOLE_ORIGIN=${{ inputs.pahole-origin }}
+        $CI_ROOT/vmtest/run_vmtest.sh
+      shell: bash

.github/workflows/test.yml

@@ -0,0 +1,31 @@
+name: bpf-ci
+
+on:
+  pull_request:
+
+concurrency: 
+  group: ci-test-${{ github.head_ref }}
+  cancel-in-progress: true
+
+jobs:
+  vmtest:
+    runs-on: ubuntu-latest
+    name: Kernel ${{ matrix.kernel }} + selftests
+    env:
+      CHECKOUT_KERNEL: 0
+      SELFTEST_REPO_PATH: "."
+      SOURCE_FULLCOPY: 0
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - kernel: 'LATEST'
+    steps:
+      - uses: actions/checkout@v2
+        name: Checkout
+      - uses: ./.github/actions/setup
+        name: Setup
+      - uses: ./.github/actions/vmtest
+        name: vmtest
+        with:
+          kernel: ${{ matrix.kernel }}

custom-workflows/bpf/test.yml

@@ -0,0 +1,31 @@
+name: bpf-ci
+
+on:
+  pull_request:
+
+concurrency: 
+  group: ci-test-${{ github.head_ref }}
+  cancel-in-progress: true
+
+jobs:
+  vmtest:
+    runs-on: ubuntu-latest
+    name: Kernel ${{ matrix.kernel }} + selftests
+    env:
+      CHECKOUT_KERNEL: 0
+      SELFTEST_REPO_PATH: "."
+      SOURCE_FULLCOPY: 0
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - kernel: 'LATEST'
+    steps:
+      - uses: actions/checkout@v2
+        name: Checkout
+      - uses: ./.github/actions/setup
+        name: Setup
+      - uses: ./.github/actions/vmtest
+        name: vmtest
+        with:
+          kernel: ${{ matrix.kernel }}

tools/lib/bpf/libbpf.c

@@ -2993,6 +2993,12 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 		}
 	}
 
+	if (!obj->efile.symbols) {
+		pr_warn("elf: couldn't find symbol table in %s - stripped object file?\n",
+			obj->path);
+		return -ENOENT;
+	}
+
 	scn = NULL;
 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
 		idx++;

travis-ci/managers/debian.sh

@@ -0,0 +1,89 @@
+#!/bin/bash
+
+PHASES=(${@:-SETUP RUN RUN_ASAN CLEANUP})
+DEBIAN_RELEASE="${DEBIAN_RELEASE:-testing}"
+CONT_NAME="${CONT_NAME:-libbpf-debian-$DEBIAN_RELEASE}"
+ENV_VARS="${ENV_VARS:-}"
+DOCKER_RUN="${DOCKER_RUN:-docker run}"
+REPO_ROOT="${REPO_ROOT:-$PWD}"
+ADDITIONAL_DEPS=(clang pkg-config gcc-10)
+CFLAGS="-g -O2 -Werror -Wall"
+
+function info() {
+    echo -e "\033[33;1m$1\033[0m"
+}
+
+function error() {
+    echo -e "\033[31;1m$1\033[0m"
+}
+
+function docker_exec() {
+    docker exec $ENV_VARS $CONT_NAME "$@"
+}
+
+set -eu
+
+source "$(dirname $0)/travis_wait.bash"
+
+for phase in "${PHASES[@]}"; do
+    case $phase in
+        SETUP)
+            info "Setup phase"
+            info "Using Debian $DEBIAN_RELEASE"
+
+            docker --version
+
+            docker pull debian:$DEBIAN_RELEASE
+            info "Starting container $CONT_NAME"
+            $DOCKER_RUN -v $REPO_ROOT:/build:rw \
+                        -w /build --privileged=true --name $CONT_NAME \
+                        -dit --net=host debian:$DEBIAN_RELEASE /bin/bash
+            echo -e "::group::Build Env Setup"
+            docker_exec bash -c "echo deb-src http://deb.debian.org/debian $DEBIAN_RELEASE main >>/etc/apt/sources.list"
+            docker_exec apt-get -y update
+            docker_exec apt-get -y install aptitude
+            docker_exec aptitude -y build-dep libelf-dev
+            docker_exec aptitude -y install libelf-dev
+            docker_exec aptitude -y install "${ADDITIONAL_DEPS[@]}"
+            echo -e "::endgroup::"
+            ;;
+        RUN|RUN_CLANG|RUN_GCC10|RUN_ASAN|RUN_CLANG_ASAN|RUN_GCC10_ASAN)
+            CC="cc"
+            if [[ "$phase" = *"CLANG"* ]]; then
+                ENV_VARS="-e CC=clang -e CXX=clang++"
+                CC="clang"
+            elif [[ "$phase" = *"GCC10"* ]]; then
+                ENV_VARS="-e CC=gcc-10 -e CXX=g++-10"
+                CC="gcc-10"
+                CFLAGS="${CFLAGS} -Wno-stringop-truncation"
+            else
+                CFLAGS="${CFLAGS} -Wno-stringop-truncation"
+            fi
+            if [[ "$phase" = *"ASAN"* ]]; then
+                CFLAGS="${CFLAGS} -fsanitize=address,undefined"
+            fi
+            docker_exec mkdir build install
+            docker_exec ${CC} --version
+            info "build"
+            docker_exec make -j$((4*$(nproc))) CFLAGS="${CFLAGS}" -C ./src -B OBJDIR=../build
+            info "ldd build/libbpf.so:"
+            docker_exec ldd build/libbpf.so
+            if ! docker_exec ldd build/libbpf.so | grep -q libelf; then
+                error "No reference to libelf.so in libbpf.so!"
+                exit 1
+            fi
+            info "install"
+            docker_exec make -j$((4*$(nproc))) -C src OBJDIR=../build DESTDIR=../install install
+            info "link binary"
+            docker_exec bash -c "CFLAGS=\"${CFLAGS}\" ./travis-ci/managers/test_compile.sh"
+            ;;
+        CLEANUP)
+            info "Cleanup phase"
+            docker stop $CONT_NAME
+            docker rm -f $CONT_NAME
+            ;;
+        *)
+            echo >&2 "Unknown phase '$phase'"
+            exit 1
+    esac
+done

travis-ci/managers/test_compile.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+set -euox pipefail
+
+CFLAGS=${CFLAGS:-}
+
+cat << EOF > main.c
+#include <bpf/libbpf.h>
+int main() {
+  return bpf_object__open(0) < 0;
+}
+EOF
+
+# static linking
+${CC:-cc} ${CFLAGS} -o main -I./install/usr/include main.c ./build/libbpf.a -lelf -lz

travis-ci/managers/travis_wait.bash

@@ -0,0 +1,61 @@
+# This was borrowed from https://github.com/travis-ci/travis-build/tree/master/lib/travis/build/bash
+# to get around https://github.com/travis-ci/travis-ci/issues/9979. It should probably be removed
+# as soon as Travis CI has started to provide an easy way to export the functions to bash scripts.
+
+travis_jigger() {
+  local cmd_pid="${1}"
+  shift
+  local timeout="${1}"
+  shift
+  local count=0
+
+  echo -e "\\n"
+
+  while [[ "${count}" -lt "${timeout}" ]]; do
+    count="$((count + 1))"
+    echo -ne "Still running (${count} of ${timeout}): ${*}\\r"
+    sleep 60
+  done
+
+  echo -e "\\n${ANSI_RED}Timeout (${timeout} minutes) reached. Terminating \"${*}\"${ANSI_RESET}\\n"
+  kill -9 "${cmd_pid}"
+}
+
+travis_wait() {
+  local timeout="${1}"
+
+  if [[ "${timeout}" =~ ^[0-9]+$ ]]; then
+    shift
+  else
+    timeout=20
+  fi
+
+  local cmd=("${@}")
+  local log_file="travis_wait_${$}.log"
+
+  "${cmd[@]}" &>"${log_file}" &
+  local cmd_pid="${!}"
+
+  travis_jigger "${!}" "${timeout}" "${cmd[@]}" &
+  local jigger_pid="${!}"
+  local result
+
+  {
+    set +e
+    wait "${cmd_pid}" 2>/dev/null
+    result="${?}"
+    ps -p"${jigger_pid}" &>/dev/null && kill "${jigger_pid}"
+    set -e
+  }
+
+  if [[ "${result}" -eq 0 ]]; then
+    echo -e "\\n${ANSI_GREEN}The command ${cmd[*]} exited with ${result}.${ANSI_RESET}"
+  else
+    echo -e "\\n${ANSI_RED}The command ${cmd[*]} exited with ${result}.${ANSI_RESET}"
+  fi
+
+  echo -e "\\n${ANSI_GREEN}Log:${ANSI_RESET}\\n"
+  cat "${log_file}"
+
+  return "${result}"
+}

travis-ci/managers/ubuntu.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+set -eux
+
+RELEASE="focal"
+
+apt-get update
+apt-get install -y pkg-config
+
+source "$(dirname $0)/travis_wait.bash"
+
+cd $REPO_ROOT
+
+CFLAGS="-g -O2 -Werror -Wall -fsanitize=address,undefined -Wno-stringop-truncation"
+mkdir build install
+cc --version
+make -j$((4*$(nproc))) CFLAGS="${CFLAGS}" -C ./src -B OBJDIR=../build
+ldd build/libbpf.so
+if ! ldd build/libbpf.so | grep -q libelf; then
+    echo "FAIL: No reference to libelf.so in libbpf.so!"
+    exit 1
+fi
+make -j$((4*$(nproc))) -C src OBJDIR=../build DESTDIR=../install install
+CFLAGS=${CFLAGS} $(dirname $0)/test_compile.sh