add a session_locking option in tlog-rec-session.conf

defaults to true, preserving previous behaviour, only one tlog
session will be recorded at a time per session ID.

setting to false disables this locking, multiple recordings can
be made simultaneously.

Author: ajf8

lib/tlog/rec.c

@@ -1126,6 +1126,7 @@ tlog_rec(struct tlog_errs **perrs, uid_t euid, gid_t egid,
     clockid_t clock_id;
     unsigned int session_id;
     bool lock_acquired = false;
+    bool session_locking = true;
     struct json_object *obj;
     int64_t num;
     unsigned int latency;
@@ -1144,6 +1145,11 @@ tlog_rec(struct tlog_errs **perrs, uid_t euid, gid_t egid,
         }
     }
 
+    /* Check for the session_locking flag */
+    if (json_object_object_get_ex(conf, "session_locking", &obj)) {
+        session_locking = json_object_get_boolean(obj);
+    }
+
     /* Check for the version flag */
     if (json_object_object_get_ex(conf, "version", &obj)) {
         if (json_object_get_boolean(obj)) {
@@ -1198,7 +1204,7 @@ tlog_rec(struct tlog_errs **perrs, uid_t euid, gid_t egid,
         TLOG_ERRS_RAISECS(grc, "Failed retrieving session ID");
     }
 
-    if (opts & TLOG_REC_OPT_LOCK_SESS) {
+    if (opts & TLOG_REC_OPT_LOCK_SESS && session_locking) {
         /* Attempt to lock the session */
         grc = tlog_session_lock(perrs, session_id, euid, egid, &lock_acquired);
         if (grc != TLOG_RC_OK) {

m4/tlog/rec_session_conf_schema.m4

@@ -30,6 +30,12 @@ M4_PARAM(`', `shell', `file-env',
          `SHELL is the ', `The ',
          `M4_LINES(`path to the shell executable which should be spawned.')')m4_dnl
 m4_dnl
+M4_PARAM(`', `session_locking', `file-env',
+         `M4_TYPE_BOOL(true)', true,
+         `n', `true', `Enable locking by session ID',
+         `If specified, ', `If true ',
+         `M4_LINES(`locking by session ID is enabled.')')m4_dnl
+m4_dnl
 M4_PARAM(`', `login', `name-',
          `M4_TYPE_BOOL()', false,
          `l', `', `Make the shell a login shell',