ci: minimal testing worklow

Add scripts to setup and run the tests on CI.

===

Note on bpftrace

Using bpftrace -c doesn't work for these tests, when there are
tracepoints refering to dynamic libraries. This is because the .so is
not loaded yet when bpftrace attempts to attach.

In run_test.sh bpftrace terminates at the end of target test
program. After that test output is compared.

.github/scripts/setup.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+set -euo pipefail
+
+BPFTRACE_VERSION=${BPFTRACE_VERSION:-0.22.1}
+
+# Assume sudo in this script
+
+# Install dependencies
+apt update && apt install -y make file gawk libfuse2t64
+
+# Download bpftrace release
+BIN_DIR=/usr/local/bin
+mkdir -p $BIN_DIR
+curl -L -o bpftrace https://github.com/bpftrace/bpftrace/releases/download/v${BPFTRACE_VERSION}/bpftrace
+chmod +x bpftrace
+mv bpftrace $BIN_DIR
+bpftrace --version
+
+# mount tracefs to avoid warnings from bpftrace
+grep -q tracefs /proc/mounts || mount -t tracefs tracefs /sys/kernel/tracing

.github/workflows/test.yml

@@ -0,0 +1,31 @@
+name: USDT CI
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Install prerequisites
+      run: sudo .github/scripts/setup.sh
+
+    - name: Build (static)
+      run: make SHARED=0 -C tests -j$(nproc) build
+
+    - name: Build (shared)
+      run: make SHARED=1 -C tests -j$(nproc) build
+
+    - name: Test (static)
+      run: make SHARED=0 -C tests test
+
+    - name: Test (shared)
+      run: make SHARED=1 -C tests test
+

tests/Makefile

@@ -38,13 +38,13 @@ endif
 NONTESTS = tester common
 
 TESTS := $(filter-out $(NONTESTS), 								\
-		$(shell ls *.{c,cpp} 2>/dev/null | grep -v '^lib' | 				\
-			${AWK} '{split($$0, p, /[^A-Za-z_]+/); print p[1]}' | 			\
+		$(shell ls *.c *.cpp 2>/dev/null | grep -v '^lib' | 				\
+			${AWK} '{split($$0, p, /[^A-Za-z_]+/); print p[1]}' |			\
 			sort | uniq 								\
 		)										\
 )
 LIBS := $(filter-out $(NONTESTS), 								\
-		$(shell ls lib*.{c,cpp} 2>/dev/null | 						\
+		$(shell ls lib*.c lib*.cpp 2>/dev/null | 					\
 			${AWK} '{split($$0, p, /[^A-Za-z_]+/); print substr(p[1], 4)}' |	\
 			sort | uniq 								\
 		)										\
@@ -128,5 +128,4 @@ $(foreach lib, $(LIBS), $(eval $(call BUILD_RULE_LIB,$(lib))))
 $(BUILD_TARGETS): build-%: $(OBJDIR)/%
 
 $(TEST_TARGETS): test-%: build-%
-	$(call msg,TESTING,$(if $(filter 1,$(SHARED)),shared/,static/)$(patsubst test-%,%,$@))
 	$(Q)./run_test.sh $(OBJDIR) $(patsubst test-%,%,$@)

tests/prepare-bt-script.awk

@@ -39,13 +39,15 @@
 
 	# Emit corresponding bpftrace probe spec:
 	# U:./test:group:name { printf("%s: some %s fmt %d spec %d\n", probe, str(arg0), (int)arg1, arg2 - 10); }
-	printf("U:%s:%s:%s { printf(\"%s%s:%s: %s\\n\"%s); }\n",
+	printf("usdt:%s:%s:%s { printf(\"%s%s:%s: %s\\n\"%s); }\n",
 	       path, group, name,
 	       probe[1] == "lib" ? "lib:" : "", group, name,
 	       fmt, args == "" ? "" : ", " args);
 }
 
 END {
-	if (has_contents)
+	if (has_contents) {
+		printf("uretprobe:%s:main { exit(); }\n", OUTPUT "/" TEST);
 		printf("END { printf(\"DONE!\\n\"); }\n");
+	}
 }

tests/run_test.sh

@@ -18,6 +18,15 @@ TEST=$2
 TEST_BIN="$1/$2"
 TEST_LIB="$1/lib$2.so"
 
+TEST_ID=$(realpath --relative-to="$OUTPUT/.." "$TEST_BIN")
+
+if grep -q "$TEST_ID" DENYLIST; then
+	echo "run_test.sh: SKIPPING $TEST_ID"
+	exit 0
+else
+	echo "run_test.sh: TESTING $TEST_ID"
+fi
+
 TEST_USDTS_SPEC=$TEST_BIN.exp_usdts.txt
 TEST_USDTS_OUT=$TEST_BIN.act_usdts.txt
 TEST_PRE_SPEC=$TEST_BIN.exp_pre_out.txt
@@ -69,36 +78,44 @@ if [ -s "$TEST_BTSCRIPT" ]; then
 	bt_pid=$!
 	bt_pgid="$(ps -opgid= "$bt_pid" | tr -d ' ')"
 
+	dump_bt_output() {
+		echo "BPFTRACE SCRIPT:"
+		cat "$TEST_BTSCRIPT"
+		echo "BPFTRACE OUTPUT:"
+		cat "$TEST_BTOUT_RAW"
+	}
+
+	wait_for_bpftrace() {
+		local bt_start=$(date +%s)
+		local stop_word="$1"
+		local msg="$2"
+		while true; do
+			local bt_elapsed=$(( $(date +%s) - bt_start ))
+			if grep -q "$stop_word" "$TEST_BTOUT_RAW"; then
+				break
+			elif [ "$bt_elapsed" -ge "$TIMEOUT" ]; then
+				sudo kill -KILL -$bt_pgid 2>/dev/null
+				echo "BPFTRACE ${msg} TIMEOUT!"
+				dump_bt_output
+				exit 1
+			elif ! kill -s 0 "$bt_pid"; then
+				echo "BPFTRACE ${msg} FAILURE!"
+				dump_bt_output
+				exit 1
+			else
+				sleep 0.2
+			fi
+		done
+	}
+
 	# wait for bpftrace to finish attachment
-	bt_start=$(date +%s)
-	while true; do
-		bt_elapsed=$(( $(date +%s) - bt_start ))
-		if grep -q "STARTED!" "$TEST_BTOUT_RAW"; then
-			break
-		elif [ "$bt_elapsed" -ge "$TIMEOUT" ]; then
-			sudo kill -KILL -$bt_pgid 2>/dev/null
-			echo "BPFTRACE STARTUP TIMEOUT!"
-			echo "BPFTRACE SCRIPT:"
-			cat "$TEST_BTSCRIPT"
-			echo "BPFTRACE OUTPUT:"
-			cat "$TEST_BTOUT_RAW"
-			exit 1
-		elif ! kill -s 0 "$bt_pid"; then
-			echo "BPFTRACE STARTUP FAILURE!"
-			echo "BPFTRACE SCRIPT:"
-			cat "$TEST_BTSCRIPT"
-			echo "BPFTRACE OUTPUT:"
-			cat "$TEST_BTOUT_RAW"
-			exit 1
-		else
-			sleep 0.2
-		fi
-	done
+	wait_for_bpftrace "STARTED!" "STARTUP"
 
 	# get test output while bpftrace is attached
 	$TEST_BIN &>"$TEST_OUT"
 
-	sudo kill -INT -$bt_pgid 2>/dev/null
+	# wait for bpftrace to terminate
+	wait_for_bpftrace "DONE!" "RUNNING"
 
 	$awk '/STARTED!/ {flag=1; next} /DONE!/ {flag=0} flag' $TEST_BTOUT_RAW > $TEST_BTOUT
 	if ! $awk -f check-match.awk $TEST_BTOUT_SPEC $TEST_BTOUT; then