[fork-tester.c] Get PPID from env MANAGERPID when systemd run with --…

…user

Fix [#3148](#3148)
On certain distributions, `systemd` run with the flag `--user`. This
means that the manager PID is not 1 but one of it's child process.
To fix this, we call the environment variable `MANAGERPID` set by systemd
that expose this PID.
As `make test` uses sudo rights, you need to pass your local `MANAGERPID`
env var to sudo. If the variable is not set, the flag is ignored

Signed-off-by: Tristan d'Audibert <[email protected]>

Makefile

@@ -258,7 +258,7 @@ copy-golangci-lint:
 
 .PHONY: test
 test: tester-progs tetragon-bpf ## Run Go tests.
-	$(GO) test -exec "$(SUDO)" -p 1 -parallel 1 $(GOFLAGS) -gcflags=$(GO_BUILD_GCFLAGS) -timeout $(GO_TEST_TIMEOUT) -failfast -cover ./pkg/... ./cmd/... ./operator/... ${EXTRA_TESTFLAGS}
+	$(GO) test -exec "$(SUDO) --preserve-env=MANAGERPID" -p 1 -parallel 1 $(GOFLAGS) -gcflags=$(GO_BUILD_GCFLAGS) -timeout $(GO_TEST_TIMEOUT) -failfast -cover ./pkg/... ./cmd/... ./operator/... ${EXTRA_TESTFLAGS}
 
 .PHONY: tester-progs
 tester-progs: ## Compile helper programs for unit testing.

contrib/tester-progs/fork-tester.c

@@ -29,11 +29,18 @@ void child1()
 		perror("fork");
 		exit(1);
 	} else if (pid == 0) {
+		int systemd_manager_pid = 1;
+		const char *manager_pid_str = getenv("MANAGERPID");
+		if (manager_pid_str) {
+			int user_manager_pid = atoi(manager_pid_str);
+			if (user_manager_pid) {
+				systemd_manager_pid = user_manager_pid;
+			}
+		}
 		for (int i = 0;; i++) {
 			int ppid = getppid();
-			if (ppid == 1) {
+			if (ppid == systemd_manager_pid)
 				break;
-			}
 			if (i == 30) {
 				fprintf(stderr, "giving up on waiting our parent to die\n");
 				exit(1);