libps (_proc_stat_free): Fix memory leak

The thread_waits field was never freed; this change adds the code to do
so if the corresponding flag is set.

Users are also warned of the consequences, namely, that they should not
free process proc_stats before all their associated thread ones are
gone, since the latter may reference the former's thread_waits field.
However, with the normal interface (ie.  ps_context_free), all
proc_stats are freed at once, so this is not an issue.

* libps/procstat.c (_proc_stat_free): Free ps->thread_waits if
PSTAT_THREAD_WAITS flag is set.
* libps/ps.h (_proc_stat_free): Document that thread proc_stats must be
freed before process proc_stat can be.

2 files changed, 5 insertions, 1 deletions

diff --git a/libps/procstat.c b/libps/procstat.c
index 33a01cc1..0717065c 100644
--- a/libps/procstat.c
+++ b/libps/procstat.c
@@ -1058,6 +1058,8 @@ _proc_stat_free (ps)
   MFREEMEM (PSTAT_ENV, env, ps->env_len, ps->env_vm_alloced, 0, char);
   MFREEMEM (PSTAT_TASK_EVENTS, task_events_info, ps->task_events_info_size,
 	    0, &ps->task_events_info_buf, char);
+  MFREEMEM (PSTAT_THREAD_WAITS, thread_waits, ps->thread_waits_len,
+	    ps->thread_waits_vm_alloced, 0, char);
 
   FREE (ps);
 }
diff --git a/libps/ps.h b/libps/ps.h
index 27f2e787..23e2cc3e 100644
--- a/libps/ps.h
+++ b/libps/ps.h
@@ -454,7 +454,9 @@ error_t _proc_stat_create (pid_t pid, struct ps_context *context,
 
 /* Frees PS and any memory/ports it references.  Users shouldn't use this
    routine; proc_stats are normally freed only when their ps_context goes
-   away.  */
+   away.  Insubordinate users will make sure they free the thread proc_stats
+   before they free the corresponding process proc_stat since the thread_wait
+   fields of the former may reference the latter.  */
 void _proc_stat_free (struct proc_stat *ps);
 
 /* Adds FLAGS to PS's flags, fetching information as necessary to validate