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library: ensure thread group leader retrieval accuracy

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With that recent addition of the autogroup provisions,
it became apparent that '/proc/<pid>/task' information
is sometimes incomplete. In fact, there's no autogroup
file at all in any '/proc/<pid>/task/<pid>' directory!

As a result, when the top -H mode was invoked, all the
processes showed a -1 for AGID, even the group leader.

So, this commit will ensure that for every TGID leader
its basic '/proc/<pid>' directory will always be used.
The 'task' subdirectory is now only used for siblings.

[ and it's time that readeither prologue was updated ]

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner 2021-08-07 00:00:00 -05:00 committed by Craig Small
parent 949382afe5
commit a375262609
1 changed files with 9 additions and 6 deletions
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15
proc/readproc.c
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@ -1452,12 +1452,11 @@ out:
//////////////////////////////////////////////////////////////////////////////////
// readeither: return a pointer to a proc_t filled with requested info about
// the next unique process or task available. If no more are available,
// return a null pointer (boolean false). Use the passed buffer instead
// of allocating space if it is non-NULL.
// return a null pointer (boolean false).
proc_t *readeither (PROCTAB *restrict const PT, proc_t *restrict x) {
static proc_t skel_p; // skeleton proc_t, only uses tid + tgid
static proc_t *new_p; // for process/task transitions
static int canary;
static int canary, leader;
char path[PROCPATHLEN];
proc_t *ret;
@ -1474,16 +1473,20 @@ next_proc:
if (errno == ENOMEM) goto end_procs;
// fills in the PT->path, plus skel_p.tid and skel_p.tgid
if (!PT->finder(PT,&skel_p)) goto end_procs; // simple_nextpid
leader = skel_p.tid;
if (!task_dir_missing) break;
if ((ret = PT->reader(PT,x))) return ret; // simple_readproc
}
next_task:
// fills in our path, plus x->tid and x->tgid
if ((!(PT->taskfinder(PT,&skel_p,x,path))) // simple_nexttid
|| (!(ret = PT->taskreader(PT,x,path)))) { // simple_readtask
if (!(PT->taskfinder(PT,&skel_p,x,path))) // simple_nexttid
goto next_proc;
}
/* to avoid loss of some thread group leader data,
we must check its base dir, not its 'task' dir! */
if (x->tid == leader) ret = PT->reader(PT,x); // simple_readproc
else ret = PT->taskreader(PT,x,path); // simple_readtask
if (!ret) goto next_proc;
if (!new_p) {
new_p = ret;
canary = new_p->tid;