Add GitHub CI and fix test runner bugs

.github/workflows/ci.yml

@@ -0,0 +1,66 @@
+name: ci
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-23.10
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Java 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'adopt'
+
+      - name: mvn package
+        run: mvn package -DskipTests
+
+      - name: upload bcc/target/bcc.jar
+        uses: actions/upload-artifact@v4
+        with:
+          name: bcc.jar
+          path: bcc/target/bcc.jar
+
+  vm-test:
+    name: Run tests on pre-built kernel
+    runs-on: ubuntu-23.10
+    needs: build
+    timeout-minutes: 10
+    strategy:
+      matrix:
+        version: ["6.6"]
+    env:
+      HBT_KERNEL_VERSION: "${{ matrix.version }}"
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Java
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'adopt'
+
+      - run: sudo pip3 install https://github.com/amluto/virtme/archive/beb85146cd91de37ae455eccb6ab67c393e6e290.zip
+      - run: sudo apt-get update && sudo apt-get install -y --no-install-recommends qemu-system-x86 bpfcc-tools libbpfcc libbpfcc-dev linux-headers-$(uname -r) linux-cloud-tools-generic llvm clang
+
+      - name: Test
+        run: |
+          mvn test -Djvm=testutil/bin/java
+
+      - name: Publish Test Report
+        uses: mikepenz/action-junit-report@v4
+        if: always()
+        with:
+          check_name: 'Test Report (Kernel ${{ matrix.KERNEL_VERSION }})'
+          report_paths: '**/build/test-results/test/TEST-*.xml'

README.md

@@ -1,6 +1,8 @@
 Hello eBPF
 ==========
 
+[![ci](https://github.com/parttimenerd/hello-ebpf/actions/workflows/ci.yml/badge.svg)](https://github.com/parttimenerd/hello-ebpf/actions/workflows/ci.yml)
+
 There are [user land libraries](https://ebpf.io/what-is-ebpf/#development-toolchains) for [eBPF](https://ebpf.io) that allow you to
 write eBPF applications in C++, Rust, Go, Python and even
 Lua. But there are none for Java, which is a pity.

bcc/pom.xml

@@ -120,7 +120,7 @@
         <dependency>
             <groupId>me.bechberger</groupId>
             <artifactId>rawbcc</artifactId>
-            <version>0.1.1</version>
+            <version>0.1.2</version>
         </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>

bcc/src/main/java/me/bechberger/ebpf/bcc/BPF.java

@@ -4,7 +4,9 @@
 import me.bechberger.ebpf.bcc.raw.Lib;
 import org.jetbrains.annotations.Nullable;
 
+import java.io.BufferedReader;
 import java.io.IOException;
+import java.io.InputStreamReader;
 import java.lang.foreign.Arena;
 import java.lang.foreign.FunctionDescriptor;
 import java.lang.foreign.MemorySegment;
@@ -25,6 +27,11 @@
 public class BPF implements AutoCloseable {
 
     static {
+        if (!LibraryLoader.isInstalled()) {
+            throw new RuntimeException("BCC library is not installed");
+        } else {
+            System.err.println("BCC library is installed");
+        }
         LibraryLoader.load();
     }
 
@@ -142,10 +149,13 @@ private BPF(String text, String fileName, @Nullable Path hdrFile, boolean allowR
                                                           cflags_array, len(cflags_array),
                                                           allow_rlimit, device)
          */
-        var maybeModule = bpf_module_create_c_from_string(arena, textNative, debug, MemorySegment.NULL, 0, allowRLimit ? 1 : 0, MemorySegment.NULL);
+        var maybeModule = bpf_module_create_c_from_string(arena, textNative, -1, MemorySegment.NULL, 0, allowRLimit ? 1 : 0, MemorySegment.NULL);
         if (maybeModule.err() != 0 && maybeModule.err() != 2) {
            throw new BPFCallException(STR."Failed to compile BPF module: \{PanamaUtil.errnoString(maybeModule.err())}");
         }
+        if (maybeModule.err() != 0) {
+            System.err.println(STR."Warning BPF constructor: \{fileName} \{maybeModule.err()} \{PanamaUtil.errnoString(maybeModule.err())}");
+        }
         module = maybeModule.result();
 
         if (module == null) throw new RuntimeException(STR."Failed to compile BPF module \{fileName}");

bcc/src/test/java/me/bechberger/ebpf/bcc/structs/HelloBufferTest.java

@@ -63,7 +63,7 @@ int hello(void *ctx) {
                                 
                     return 0;
                 }
-                """).build()) {
+                """).withDebug(-1).build()) {
             var syscall = b.get_syscall_fnname("execve");
             b.attach_kprobe(syscall, "hello");
 

rawbcc/CHANGELOG

@@ -1,5 +1,13 @@
 # Changelog
 
+## 0.1.2
+
+### Fixed
+- Fix loading libraries if the library ends with a version number, like `libbcc.so.0`
+
+### Changed
+- Delegate loading of libraries to `System.load` if possible
+
 ## 0.1.1
 
 ### Fixed

rawbcc/README.md

@@ -12,7 +12,7 @@ These bindings are regurlarly updated and published on Maven Central:
 <dependency>
     <groupId>me.bechberger</groupId>
     <artifactId>rawbcc</artifactId>
-    <version>0.1.1</version>
+    <version>0.1.2</version>
 </dependency>
 ```
 

rawbcc/pom.xml

@@ -8,7 +8,7 @@
     <groupId>me.bechberger</groupId>
     <name>Raw bindings for libbcc</name>
 
-    <version>0.1.1</version>
+    <version>0.1.2</version>
     <url>https://github.com/parttimenerd/hello-ebpf</url>
     <licenses>
         <license>

rawbcc/src/main/java/me/bechberger/ebpf/bcc/raw/LibraryLoader.java

@@ -5,32 +5,36 @@
 import java.io.IOException;
 import java.nio.file.*;
 import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Arrays;
 import java.util.Optional;
+import java.util.stream.Stream;
 
 /**
  * Loads the BCC library
  */
 public class LibraryLoader {
 
+
+    private static Optional<Path> findLibInFolder(Path folder, int depth) {
+        try (var stream = Files.walk(folder, depth, FileVisitOption.FOLLOW_LINKS)) {
+            return stream.filter(p -> p.getFileName().toString().startsWith("libbcc.so")).findFirst();
+        } catch (IOException e) {
+            return Optional.empty();
+        }
+    }
     private static Optional<Path> findBCCLibrary() {
         var javaLibraryPath = System.getProperty("java.library.path");
         if (javaLibraryPath == null) {
             return Optional.empty();
         }
 
-        var paths = javaLibraryPath.split(":");
-        for (var path : paths) {
-            var libPath = Path.of(path + "/libbcc.so");
-            if (libPath.toFile().exists()) {
-                return Optional.of(libPath);
-            }
-        }
-
-        try (var stream = Files.walk(Path.of("/lib"), 2, FileVisitOption.FOLLOW_LINKS)) {
-            return stream.filter(p -> p.endsWith("libbcc.so")).findFirst();
-        } catch (IOException e) {
-            return Optional.empty();
-        }
+        return Arrays.stream(javaLibraryPath.split(":"))
+                .map(f -> findLibInFolder(Path.of(f), 1))
+                .filter(Optional::isPresent).map(Optional::get).findFirst()
+                .or(() -> Stream.of("/lib", "/usr/lib", "/lib64", "/usr/lib64")
+                        .map(Path::of)
+                        .map(p -> findLibInFolder(p, 2))
+                        .filter(Optional::isPresent).map(Optional::get).findFirst());
     }
 
     /**
@@ -44,13 +48,21 @@ public static boolean isInstalled() {
      * Loads the BCC library and {@code System.exit(1)} if it is not available
      */
     public static void load() {
-        var lib = findBCCLibrary();
-        if (lib.isPresent()) {
-            System.load(lib.get().toString());
-            return;
+        try {
+            System.loadLibrary("bcc");
+        } catch (UnsatisfiedLinkError e) {
+            var lib = findBCCLibrary();
+            if (lib.isPresent()) {
+                System.load(lib.get().toString());
+                return;
+            }
+            System.err.println("Failed to load libbcc.so, pass the location of the lib folder " +
+                    "via -Djava.library.path after you installed it");
+            System.exit(1);
         }
-        System.err.println("Failed to load libbcc.so, pass the location of the lib folder " +
-                "via -Djava.library.path after you installed it");
-        System.exit(1);
+    }
+
+    public static void main(String[] args) {
+        System.out.println(isInstalled());
     }
 }

testutil/bin/java

@@ -6,7 +6,7 @@
 #
 # Configuration per environment variables:
 #  - `HBT_JAVA_BINARY` - the java binary to use (default: `java`)
-#  - `HBT_KERNEL_VERSION` - the kernel version to use (default: `6.7`)
+#  - `HBT_KERNEL_VERSION` - the kernel version to use (default: `6.6`)
 #                           see https://ghcr.io/cilium/ci-kernels for available versions
 #
 # Has to reside in bin/java so it can be passed to the `-Djvm` maven option.
@@ -20,8 +20,7 @@ set -e
 HBT_JAVA_BINARY=${HBT_JAVA_BINARY:-java}
 
 # The kernel version to use
-HBT_KERNEL_VERSION=${HBT_KERNEL_VERSION:-6.7}
+HBT_KERNEL_VERSION=${HBT_KERNEL_VERSION:-6.6}
 
 testutil_dir=$(dirname "$0")/..
-$testutil_dir/run-in-container.sh $HBT_KERNEL_VERSION $HBT_JAVA_BINARY $@
-exit 0
+$testutil_dir/run-in-container.sh $HBT_KERNEL_VERSION $HBT_JAVA_BINARY $@

testutil/find_and_get_kernel.py

@@ -135,8 +135,6 @@ def copy_headers_into_dest(arch: str, version: str, dest_root: Path):
     argparse.add_argument("version", help="Kernel version")
     argparse.add_argument("destination", help="Destination folder")
     args = argparse.parse_args()
-    print(
-        f"Downloading headers for {args.version} (arch {get_arch()}) into {args.destination}")
     copy_headers_into_dest(get_arch(),
                            args.version,
                            Path(args.destination))

testutil/run-in-container.sh

@@ -72,6 +72,12 @@ fi
 # get exact kernel version which is "$input/lib/modules/<version>/updates"
 kernel_version=$(basename "$(find "${input}/lib/modules" -maxdepth 1 -type d)")
 
+# /lib is a symlink which causes problems
+mkdir "$input"/lib2
+cp -r "$input"/lib/modules "$input"/lib2
+rm -r "$input"/lib
+mv $input/lib2 $input/lib
+
 "$script_folder"/find_and_get_kernel.py "${kernel_version}" "$input"
 
 mkdir -p "$input"/root

testutil/setup-and-run.sh

@@ -13,4 +13,8 @@ if [[ -d "/run/input/lib/modules" ]]; then
   find /run/input/lib/modules -type f -name bpf_testmod.ko -exec insmod {} \;
 fi
 
+# used for debugging to check if bcc works at all
+#script_dir="$(dirname "$(realpath "$0")")"
+#timeout 5 python3 $script_dir/../pysamples/bcc/hello_world.py
+
 $* && touch /run/output/status