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library: refactor flawed function fatal_proc_unmounted

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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>
This commit is contained in:
Jim Warner 2022-07-28 00:00:00 -05:00 committed by Craig Small
parent 116ce62304
commit 52bd019d8c
1 changed files with 10 additions and 24 deletions
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34
proc/pids.c
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@ -82,8 +82,8 @@ struct pids_info {
int curitems; // includes 'logical_end' delimiter int curitems; // includes 'logical_end' delimiter
enum pids_item *items; // includes 'logical_end' delimiter enum pids_item *items; // includes 'logical_end' delimiter
struct stacks_extent *extents; // anchor for all resettable extents struct stacks_extent *extents; // anchor for all resettable extents
struct stacks_extent *otherexts; // anchor for single stack invariant extents struct stacks_extent *otherexts; // anchor for invariant extents // <=== currently unused
struct fetch_support fetch; // support for procps_pids_reap & select struct fetch_support fetch; // support for procps_pids_reap, select, fatal
int history_yes; // need historical data int history_yes; // need historical data
struct history_info *hist; // pointer to historical support data struct history_info *hist; // pointer to historical support data
proc_t*(*read_something)(PROCTAB*, proc_t*); // readproc/readeither via which 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 } // 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 * This routine exists in case we ever want to offer something like
* 'static' or 'invarient' results stacks. By unsplicing an extent * 'static' or 'invarient' results stacks. By unsplicing an extent
@ -925,6 +926,7 @@ static struct stacks_extent *pids_extent_cut (
} }
return NULL; return NULL;
} // end: pids_extent_cut } // end: pids_extent_cut
#endif // ----------------------------------------------------------------
static inline struct pids_result *pids_itemize_stack ( static inline struct pids_result *pids_itemize_stack (
@ -1377,8 +1379,9 @@ PROCPS_EXPORT struct pids_stack *fatal_proc_unmounted (
struct pids_info *info, struct pids_info *info,
int return_self) int return_self)
{ {
static __thread proc_t self; struct pids_fetch *fetched;
struct stacks_extent *ext; unsigned tid;
proc_t self;
/* this is very likely the *only* newlib function where the /* this is very likely the *only* newlib function where the
context (pids_info) of NULL will ever be permitted */ context (pids_info) of NULL will ever be permitted */
@ -1386,27 +1389,10 @@ PROCPS_EXPORT struct pids_stack *fatal_proc_unmounted (
|| (!return_self)) || (!return_self))
return NULL; return NULL;
errno = EINVAL; tid = getpid();
if (info == NULL) if (!(fetched = procps_pids_select(info, &tid, 1, PIDS_SELECT_PID)))
return NULL; return NULL;
/* with items & numitems technically optional at 'new' time, it's return fetched->stacks[0];
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;
return NULL;
}
ext->next = info->otherexts;
info->otherexts = ext;
if (!pids_assign_results(info, ext->stacks[0], &self))
return NULL;
return ext->stacks[0];
} // end: fatal_proc_unmounted } // end: fatal_proc_unmounted