From 288d759b8bdf22f194bdda88dbee0192bbc75bb0 Mon Sep 17 00:00:00 2001
From: Jim Warner <james.warner@comcast.net>
Date: Thu, 10 Jan 2019 00:00:00 -0600
Subject: [PATCH] library: adapt readproc for the latest lxc conventions

The merge request shown below prompted (thankfully) an
examination of our lxc containers logic in readproc.c.

As it turns out, the lxc folks changed that eyecatcher
used to identify containers within a task cgroup file.

So this patch, with little extra cost, will enable the
libprocps lxc_containers() guy to handle both strings.

[ additionally, I was shocked to find lxc allows the ]
[ eyecatcher to be changed at ./configure time. such ]
[ a provision has always existed. unfortunately, the ]
[ changed value was only available to root, assuming ]
[ one wished to tackle that undocumented liblxc api. ]

Reference(s):
. what prompted lxc support reevaluation
https://gitlab.com/procps-ng/procps/merge_requests/82
. original lxc support introduced
commit 0557504f9cb84987f9d9038755404be017bdb7d1

Signed-off-by: Jim Warner <james.warner@comcast.net>
---
 proc/readproc.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/proc/readproc.c b/proc/readproc.c
index af02446d..b522d1f6 100644
--- a/proc/readproc.c
+++ b/proc/readproc.c
@@ -926,22 +926,28 @@ static char *lxc_containers (const char *path) {
            1:cpuset,cpu,cpuacct,devices,freezer,net_cls,blkio,perf_event,net_prio:/lxc/lxc-P
     */
     if (file2str(path, "cgroup", &ub) > 0) {
-        static const char lxc_delm[] = "/lxc/";
+        /* ouch, next two defaults could be changed at lxc ./configure time
+           ( and a changed 'lxc.cgroup.pattern' is only available to root ) */
+        static const char lxc_delm1[] = "/lxc/";          // thru lxc-3.0.3
+        static const char lxc_delm2[] = "/lxc.payload/";  // with lxc-3.1.0
+        const char *delim;
         char *p1;
 
-        if ((p1 = strstr(ub.buf, lxc_delm))) {
+        if ((p1 = strstr(ub.buf, (delim = lxc_delm1)))
+        || ((p1 = strstr(ub.buf, (delim = lxc_delm2))))) {
             static struct lxc_ele {
                 struct lxc_ele *next;
                 char *name;
             } *anchor = NULL;
             struct lxc_ele *ele = anchor;
+            int delim_len = strlen(delim);
             char *p2;
 
             if ((p2 = strchr(p1, '\n')))       // isolate a controller's line
                 *p2 = '\0';
             do {                               // deal with nested containers
-                p2 = p1 + (sizeof(lxc_delm)-1);
-                p1 = strstr(p2, lxc_delm);
+                p2 = p1 + (delim_len);
+                p1 = strstr(p2, delim);
             } while (p1);
             if ((p1 = strchr(p2, '/')))        // isolate name only substring
                 *p1 = '\0';