Add group ID or parent PID to procfs output (if available)

fs/procfs/fs_procfsproc.c

@@ -72,6 +72,18 @@
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
+/* See include/nuttx/sched.h: */
+
+#undef HAVE_GROUPID
+
+#if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS)
+#  define HAVE_GROUPID  1
+#endif
+
+#ifdef CONFIG_DISABLE_PTHREAD
+#  undef HAVE_GROUPID
+#endif
+
 /* Determines the size of an intermediate buffer that must be large enough
  * to handle the longest line generated by this logic.
  */
@@ -362,6 +374,8 @@ static FAR const struct proc_node_s *proc_findnode(FAR const char *relpath)
  *   123456789012345678901234567890
  *   Name:       xxxx...            Task/thread name (See CONFIG_TASK_NAME_SIZE)
  *   Type:       xxxxxxx            {Task, pthread, Kthread, Invalid}
+ *   PPID:       xxxxx              Parent thread ID
+ *   Group:      xxxxx              Group ID
  *   State:      xxxxxxxx,xxxxxxxxx {Invalid, Waiting, Ready, Running, Inactive},
  *                                  {Unlock, Semaphore, Signal, MQ empty, MQ full}
  *   Flags:      xxx                N,P,X
@@ -375,6 +389,9 @@ static ssize_t proc_status(FAR struct proc_file_s *procfile,
                            FAR struct tcb_s *tcb, FAR char *buffer,
                            size_t buflen, off_t offset)
 {
+#ifdef HAVE_GROUPID
+  FAR struct task_group_s *group;
+#endif
   FAR const char *policy;
   FAR const char *name;
   size_t remaining;
@@ -421,6 +438,30 @@ static ssize_t proc_status(FAR struct proc_file_s *procfile,
       return totalsize;
     }
 
+#ifdef CONFIG_SCHED_HAVE_PARENT
+#ifdef HAVE_GROUPID
+  group = tcb->group;
+  DEBUGASSERT(group);
+
+  linesize   = snprintf(procfile->line, STATUS_LINELEN, "%-12s%d\n", "Group:",
+                        group->tg_pgid);
+#else
+  linesize   = snprintf(procfile->line, STATUS_LINELEN, "%-12s%d\n", "PPID:",
+                        tcb->ppid);
+#endif
+
+  copysize   = procfs_memcpy(procfile->line, linesize, buffer, remaining, &offset);
+
+  totalsize += copysize;
+  buffer    += copysize;
+  remaining -= copysize;
+
+  if (totalsize >= buflen)
+    {
+      return totalsize;
+    }
+#endif
+
   /* Show the thread state */
 
   linesize   = snprintf(procfile->line, STATUS_LINELEN, "%-12s%s\n", "State:",