X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng%2Flttng.c;h=36d4c913df48ab681cbfac27e428c3f7888d339c;hp=7058dd529d1ecd73e3a191f84e08b0883b54628e;hb=af87c45a6179026e263c3a9eb251ccf8ec9537e7;hpb=8db8d1dc9f11aa7995b2f77bb938f2585005413c

diff --git a/src/bin/lttng/lttng.c b/src/bin/lttng/lttng.c
index 7058dd529..36d4c913d 100644
--- a/src/bin/lttng/lttng.c
+++ b/src/bin/lttng/lttng.c
@@ -40,6 +40,7 @@ int opt_verbose;
 static int opt_no_sessiond;
 static char *opt_sessiond_path;
 static pid_t sessiond_pid;
+static volatile int recv_child_signal;
 
 enum {
 	OPT_SESSION_PATH,
@@ -81,23 +82,23 @@ static struct cmd_struct commands[] =  {
 static void usage(FILE *ofp)
 {
 	fprintf(ofp, "LTTng Trace Control " VERSION"\n\n");
-	fprintf(ofp, "usage: lttng [options] <command>\n");
+	fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND>\n");
 	fprintf(ofp, "\n");
 	fprintf(ofp, "Options:\n");
 	fprintf(ofp, "  -h, --help             Show this help\n");
-	fprintf(ofp, "  -g, --group NAME       Unix tracing group name. (default: tracing)\n");
-	fprintf(ofp, "  -v, --verbose          Verbose mode\n");
+	fprintf(ofp, "      --list-options     Simple listing of lttng options\n");
+	fprintf(ofp, "      --list-commands    Simple listing of lttng commands\n");
+	fprintf(ofp, "  -v, --verbose          Increase verbosity\n");
 	fprintf(ofp, "  -q, --quiet            Quiet mode\n");
+	fprintf(ofp, "  -g, --group NAME       Unix tracing group name. (default: tracing)\n");
 	fprintf(ofp, "  -n, --no-sessiond      Don't spawn a session daemon\n");
 	fprintf(ofp, "      --sessiond-path    Session daemon full path\n");
-	fprintf(ofp, "      --list-options     Simple listing of lttng options\n");
-	fprintf(ofp, "      --list-commands    Simple listing of lttng commands\n");
 	fprintf(ofp, "\n");
 	fprintf(ofp, "Commands:\n");
-	fprintf(ofp, "    add-context     Add context to event or/and channel\n");
+	fprintf(ofp, "    add-context     Add context to event and/or channel\n");
 	fprintf(ofp, "    calibrate       Quantify LTTng overhead\n");
 	fprintf(ofp, "    create          Create tracing session\n");
-	fprintf(ofp, "    destroy         Teardown tracing session\n");
+	fprintf(ofp, "    destroy         Tear down tracing session\n");
 	fprintf(ofp, "    enable-channel  Enable tracing channel\n");
 	fprintf(ofp, "    enable-event    Enable tracing event\n");
 	fprintf(ofp, "    disable-channel Disable tracing channel\n");
@@ -181,12 +182,14 @@ static void sighandler(int sig)
 		case SIGCHLD:
 			DBG("SIGCHLD caugth");
 			waitpid(sessiond_pid, &status, 0);
+			recv_child_signal = 1;
 			/* Indicate that the session daemon died */
 			sessiond_pid = 0;
 			ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 			break;
 		case SIGUSR1:
 			/* Notify is done */
+			recv_child_signal = 1;
 			DBG("SIGUSR1 caugth");
 			break;
 		default:
@@ -263,9 +266,6 @@ static int handle_command(int argc, char **argv)
 			case CMD_ERROR:
 				ERR("Command error");
 				break;
-			case CMD_NOT_IMPLEMENTED:
-				ERR("Options not implemented");
-				break;
 			case CMD_UNDEFINED:
 				ERR("Undefined command");
 				break;
@@ -297,6 +297,7 @@ static int spawn_sessiond(char *pathname)
 	pid_t pid;
 
 	MSG("Spawning a session daemon");
+	recv_child_signal = 0;
 	pid = fork();
 	if (pid == 0) {
 		/*
@@ -310,12 +311,25 @@ static int spawn_sessiond(char *pathname)
 		} else {
 			perror("execlp");
 		}
-		kill(getppid(), SIGTERM);	/* unpause parent */
+		kill(getppid(), SIGTERM);	/* wake parent */
 		exit(EXIT_FAILURE);
 	} else if (pid > 0) {
 		sessiond_pid = pid;
-		/* Wait for lttng-sessiond to start */
-		pause();
+		/*
+		 * Wait for lttng-sessiond to start. We need to use a flag to check if
+		 * the signal has been sent to us, because the child can be scheduled
+		 * before the parent, and thus send the signal before this check. In
+		 * the signal handler, we set the recv_child_signal flag, so anytime we
+		 * check it after the fork is fine. Note that sleep() is interrupted
+		 * before the 1 second delay as soon as the signal is received, so it
+		 * will not cause visible delay for the user.
+		 */
+		while (!recv_child_signal) {
+			sleep(1);
+		}
+		/*
+		 * The signal handler will nullify sessiond_pid on SIGCHLD
+		 */
 		if (!sessiond_pid) {
 			exit(EXIT_FAILURE);
 		}
@@ -354,7 +368,7 @@ static int check_sessiond(void)
 			pathname = opt_sessiond_path;
 		} else {
 			/* Try LTTNG_SESSIOND_PATH env variable */
-			pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
+			pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 		}
 
 		/* Let's rock and roll */
@@ -380,15 +394,19 @@ end:
 }
 
 /*
- * Check for the "help" option in the argv. If found, return 1 else return 0.
+ * Check args for specific options that *must* not trigger a session daemon
+ * execution.
+ *
+ * Return 1 if match else 0.
  */
-static int check_help_command(int argc, char **argv)
+static int check_args_no_sessiond(int argc, char **argv)
 {
 	int i;
 
 	for (i = 0; i < argc; i++) {
-		if ((strncmp(argv[i], "-h", 2) == 0) ||
-				strncmp(argv[i], "--h", 3) == 0) {
+		if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
+				strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
+				strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0) {
 			return 1;
 		}
 	}
@@ -451,7 +469,7 @@ static int parse_args(int argc, char **argv)
 	}
 
 	/* Spawn session daemon if needed */
-	if (opt_no_sessiond == 0 && check_help_command(argc, argv) == 0 &&
+	if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 			(check_sessiond() < 0)) {
 		goto error;
 	}
@@ -493,8 +511,9 @@ int main(int argc, char *argv[])
 	progname = argv[0] ? argv[0] : "lttng";
 
 	/* For Mathieu Desnoyers aka Dr Tracing */
-	if (strncmp(progname, "drtrace", 7) == 0) {
-		MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
+	if (strncmp(progname, "drtrace", 7) == 0 ||
+			strncmp("compudj", getenv("USER"), 7) == 0) {
+		MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 	}
 
 	ret = set_signal_handler();