Fix: Remove dependency on glibc 2.12 caused by pthread_setname_np

[lttng-tools.git] / src / common / runas.c

diff --git a/src/common/runas.c b/src/common/runas.c
index 08979fb79c15bee3bfd9f60bd3d084a141e79d08..bc7356b6a6641b9d28a83d1171081a1d0b2ab7d9 100644 (file)
--- a/src/common/runas.c
+++ b/src/common/runas.c
@@ -31,6 +31,7 @@
 #include <sched.h>
 #include <sys/signal.h>
 #include <assert.h>
+#include <sys/prctl.h>
 
 #include <common/common.h>
 #include <common/utils.h>
@@ -322,12 +323,11 @@ int run_as_worker(struct run_as_worker *worker)
        memset(worker->procname, 0, proc_orig_len);
        strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len);
 
-       ret = pthread_setname_np(pthread_self(), DEFAULT_RUN_AS_WORKER_NAME);
+       ret = prctl(PR_SET_NAME, DEFAULT_RUN_AS_WORKER_NAME, 0, 0, 0);
        if (ret) {
-               errno = ret;
-               ret = -1;
-               PERROR("pthread_setname_np");
-               return EXIT_FAILURE;
+               /* Don't fail as this is not essential. */
+               PERROR("prctl PR_SET_NAME");
+               ret = 0;
        }
 
        sendret.ret = 0;
@@ -528,10 +528,11 @@ int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid)
 }
 
 static
-void reset_sighandler(void)
+int reset_sighandler(void)
 {
-       int sig;
+       int sig, ret = 0;
 
+       DBG("Resetting run_as worker signal handlers to default");
        for (sig = SIGHUP; sig <= SIGUNUSED; sig++) {
                /* Skip unblockable signals. */
                if (sig == SIGKILL || sig == SIGSTOP) {
@@ -539,8 +540,67 @@ void reset_sighandler(void)
                }
                if (signal(sig, SIG_DFL) == SIG_ERR) {
                        PERROR("reset signal %d", sig);
+                       ret = -1;
+                       goto end;
                }
        }
+end:
+       return ret;
+}
+
+static
+void worker_sighandler(int sig)
+{
+       const char *signame;
+
+       /*
+        * The worker will its parent's signals since they are part of the same
+        * process group. However, in the case of SIGINT and SIGTERM, we want
+        * to give the worker a chance to teardown gracefully when its parent
+        * closes the command socket.
+        */
+       switch (sig) {
+       case SIGINT:
+               signame = "SIGINT";
+               break;
+       case SIGTERM:
+               signame = "SIGTERM";
+               break;
+       default:
+               signame = "Unknown";
+       }
+
+       DBG("run_as worker received signal %s", signame);
+}
+
+static
+int set_worker_sighandlers(void)
+{
+       int ret = 0;
+       sigset_t sigset;
+       struct sigaction sa;
+
+       if ((ret = sigemptyset(&sigset)) < 0) {
+               PERROR("sigemptyset");
+               goto end;
+       }
+
+       sa.sa_handler = worker_sighandler;
+       sa.sa_mask = sigset;
+       sa.sa_flags = 0;
+       if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
+               PERROR("sigaction SIGINT");
+               goto end;
+       }
+
+       if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
+               PERROR("sigaction SIGTERM");
+               goto end;
+       }
+
+       DBG("run_as signal handler set for SIGTERM and SIGINT");
+end:
+       return ret;
 }
 
 LTTNG_HIDDEN
@@ -584,6 +644,8 @@ int run_as_create_worker(char *procname)
 
                reset_sighandler();
 
+               set_worker_sighandlers();
+
                /* The child has no use for this lock. */
                pthread_mutex_unlock(&worker_lock);
                /* Just close, no shutdown. */
@@ -598,6 +660,7 @@ int run_as_create_worker(char *procname)
                        ret = -1;
                }
                worker->sockpair[1] = -1;
+               LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret);
                exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
        } else {
                /* Parent */
@@ -647,11 +710,13 @@ void run_as_destroy_worker(void)
 {
        struct run_as_worker *worker = global_worker;
 
+       DBG("Destroying run_as worker");
        pthread_mutex_lock(&worker_lock);
        if (!worker) {
                goto end;
        }
        /* Close unix socket */
+       DBG("Closing run_as worker socket");
        if (lttcomm_close_unix_sock(worker->sockpair[0])) {
                PERROR("close");
        }