From 09fbd70de33c451dde84254718ded2ccac48aed4 Mon Sep 17 00:00:00 2001
From: Jim Warner <james.warner@comcast.net>
Date: Wed, 20 Sep 2023 00:00:00 -0500
Subject: [PATCH] ps: don't lose tasks when --sort used with forest mode

In an issue cited below the loss of tasks was revealed
whenever the --sort option is used in combination with
forest mode. One could argue against such combinations
and print an error. But we'll take an easier approach.

This patch restores the prior version 3.3.17 behavior.

Reference(s):
https://gitlab.com/procps-ng/procps/-/issues/304

Signed-off-by: Jim Warner <james.warner@comcast.net>
---
 src/ps/display.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/ps/display.c b/src/ps/display.c
index e1a3b0da..325edf38 100644
--- a/src/ps/display.c
+++ b/src/ps/display.c
@@ -357,12 +357,12 @@ next_proc:
 
 /***** forest output requires sorting by ppid; add start_time by default */
 static void prep_forest_sort(void){
-  sort_node *tmp_list = sort_list;
+  sort_node *endp, *tmp_list = sort_list;
   const format_struct *incoming;
 
   if(!sort_list) {     /* assume start time order */
-    incoming = search_format_array("ppid");
-    if(!incoming) { fprintf(stderr, _("could not find ppid\n")); exit(1); }
+    incoming = search_format_array("start_time");
+    if(!incoming) { fprintf(stderr, _("could not find start_time\n")); exit(1); }
     tmp_list = xmalloc(sizeof(sort_node));
     tmp_list->reverse = PIDS_SORT_ASCEND;
     tmp_list->typecode = '?'; /* what was this for? */
@@ -371,14 +371,15 @@ static void prep_forest_sort(void){
     sort_list = tmp_list;
   }
   /* this is required for the forest option */
-  incoming = search_format_array("start_time");
-  if(!incoming) { fprintf(stderr, _("could not find start_time\n")); exit(1); }
+  incoming = search_format_array("ppid");
+  if(!incoming) { fprintf(stderr, _("could not find ppid\n")); exit(1); }
   tmp_list = xmalloc(sizeof(sort_node));
   tmp_list->reverse = PIDS_SORT_ASCEND;
   tmp_list->typecode = '?'; /* what was this for? */
   tmp_list->sr = incoming->sr;
-  tmp_list->next = sort_list;
-  sort_list = tmp_list;
+  tmp_list->next = NULL;
+  endp = sort_list; while(endp->next) endp = endp->next;
+  endp->next = tmp_list;
 }
 
 /* we rely on the POSIX requirement for zeroed memory */
-- 
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