library: refactor flawed function fatal_proc_unmounted

This commit addresses a potentially disastrous flaw in
that fatal_proc_unmounted() function wherein requested
item(s) might not have been returned to the caller yet
were specified at the time of a 'new' or 'reset' call.

The root cause, uncovered by Craig, was due to the old
library look_up_our_self() support function which only
would populate a proc_t with limited 'stat' file data.

This routine will now act the same as all other <pids>
functions which return a stack or stacks. Whatever was
specified with a 'new' or 'reset' will be returned, if
the passed 'return_self' parameter is other than zero.

[ as is so often the case, when flawed code is fixed ]
[ former complexity can be reduced as a side benefit ]

Reference(s):
https://www.freelists.org/post/procps/issue-245-plus-one,2

Signed-off-by: Jim Warner <james.warner@comcast.net>

diff --git a/proc/pids.c b/proc/pids.c
index 0d88313953b99c7a4d0a5a4e981ea868c5c3f6ee..ac10df46aed0a9e785a15933e2f84f45263a1aa6 100644 (file)
--- a/proc/pids.c
+++ b/proc/pids.c
@@ -82,8 +82,8 @@ struct pids_info {
     int curitems;                      // includes 'logical_end' delimiter
     enum pids_item *items;             // includes 'logical_end' delimiter
     struct stacks_extent *extents;     // anchor for all resettable extents
-    struct stacks_extent *otherexts;   // anchor for single stack invariant extents
-    struct fetch_support fetch;        // support for procps_pids_reap & select
+    struct stacks_extent *otherexts;   // anchor for invariant extents // <=== currently unused
+    struct fetch_support fetch;        // support for procps_pids_reap, select, fatal
     int history_yes;                   // need historical data
     struct history_info *hist;         // pointer to historical support data
     proc_t*(*read_something)(PROCTAB*, proc_t*); // readproc/readeither via which
@@ -900,6 +900,7 @@ static inline void pids_cleanup_stacks_all (
 } // end: pids_cleanup_stacks_all
 
 
+#if 0   // not currently needed after 'fatal_proc_unmounted' was refactored
         /*
          * This routine exists in case we ever want to offer something like
          * 'static' or 'invarient' results stacks.  By unsplicing an extent
@@ -925,6 +926,7 @@ static struct stacks_extent *pids_extent_cut (
     }
     return NULL;
 } // end: pids_extent_cut
+#endif  // ----------------------------------------------------------------
 
 
 static inline struct pids_result *pids_itemize_stack (
@@ -1377,8 +1379,9 @@ PROCPS_EXPORT struct pids_stack *fatal_proc_unmounted (
         struct pids_info *info,
         int return_self)
 {
-    static __thread proc_t self;
-    struct stacks_extent *ext;
+    struct pids_fetch *fetched;
+    unsigned tid;
+    proc_t self;
 
     /* this is very likely the *only* newlib function where the
        context (pids_info) of NULL will ever be permitted */
@@ -1386,27 +1389,10 @@ PROCPS_EXPORT struct pids_stack *fatal_proc_unmounted (
     || (!return_self))
         return NULL;
 
-    errno = EINVAL;
-    if (info == NULL)
-        return NULL;
-    /* with items & numitems technically optional at 'new' time, it's
-       expected 'reset' will have been called -- but just in case ... */
-    if (!info->curitems)
-        return NULL;
-    errno = 0;
-
-    if (!(ext = pids_stacks_alloc(info, 1)))
-        return NULL;
-    if (!pids_extent_cut(info, ext)) {
-        errno = EADDRNOTAVAIL;
+    tid = getpid();
+    if (!(fetched = procps_pids_select(info, &tid, 1, PIDS_SELECT_PID)))
         return NULL;
-    }
-    ext->next = info->otherexts;
-    info->otherexts = ext;
-    if (!pids_assign_results(info, ext->stacks[0], &self))
-        return NULL;
-
-    return ext->stacks[0];
+    return fetched->stacks[0];
 } // end: fatal_proc_unmounted