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library: introduced 'Item_table' validation provisions

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The recent work on updating the <meminfo> and <vmstat>
modules with some newly added linux fields reminded me
(again) of a need for some mechanism guaranteeing that
a header file agrees with the source file assumptions.

Sadly, in the past, if a table entry was omitted or if
the table and header are ordered differently, then the
library would silently return the wrong results values
or even potentially experience a SIGSEGV abnormal end.

This patch offers a much needed development assist for
ensuring that Item_table entries are synchronized with
header file enumerators in terms of number plus order.

It's intended solely for our use as libprocps evolves.

Now, by activating ITEMTABLE_DEBUG, either directly or
via ./configure CFLAGS='-DITEMTABLE_DEBUG', the number
and order will be verified. It is envisioned that this
feature will be used at least once prior to a release.

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner
2020-08-10 00:00:00 -05:00
committed by Craig Small
parent c865b06c30
commit 92d0297e1e
6 changed files with 199 additions and 23 deletions
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35
proc/pids.c
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@ -52,6 +52,13 @@
#define STACKS_INCR 128 // amount reap stack allocations grow
#define NEWOLD_INCR 128 // amt by which hist allocations grow
/* ------------------------------------------------------------------------- +
this provision can be used to ensure that our Item_table was synchronized |
with those enumerators found in the associated header file. It's intended |
to only be used locally (& temporarily) at some point prior to a release! | */
// #define ITEMTABLE_DEBUG //----------------------------------------------- |
// ------------------------------------------------------------------------- +
struct stacks_extent {
int ext_numstacks;
@ -357,7 +364,11 @@ typedef void (*SET_t)(struct pids_info *, struct pids_result *, proc_t *);
typedef void (*FRE_t)(struct pids_result *);
typedef int (*QSR_t)(const void *, const void *, void *);
#ifdef ITEMTABLE_DEBUG
#define RS(e) (SET_t)setNAME(e), PIDS_ ## e, STRINGIFY(PIDS_ ## e)
#else
#define RS(e) (SET_t)setNAME(e)
#endif
#define FF(t) (FRE_t)freNAME(t)
#define QS(t) (QSR_t)srtNAME(t)
#define TS(t) STRINGIFY(t)
@ -369,6 +380,10 @@ typedef int (*QSR_t)(const void *, const void *, void *);
* those 'enum pids_item' guys ! */
static struct {
SET_t setsfunc; // the actual result setting routine
#ifdef ITEMTABLE_DEBUG
int enumnumb; // enumerator (must match position!)
char *enum2str; // enumerator name as a char* string
#endif
unsigned oldflags; // PROC_FILLxxxx flags for this item
FRE_t freefunc; // free function for strings storage
QSR_t sortfunc; // sort cmp func for a specific type
@ -499,9 +514,6 @@ static struct {
{ RS(VM_USED), f_status, NULL, QS(ul_int), 0, TS(ul_int) },
{ RS(VSIZE_PGS), f_stat, NULL, QS(ul_int), 0, TS(ul_int) },
{ RS(WCHAN_NAME), 0, FF(str), QS(str), 0, TS(str) }, // oldflags: tid already free
// dummy entry corresponding to PIDS_logical_end ...
{ NULL, 0, NULL, NULL, 0, NULL }
};
/* please note,
@ -1116,6 +1128,23 @@ PROCPS_EXPORT int procps_pids_new (
double uptime_secs;
int pgsz;
#ifdef ITEMTABLE_DEBUG
int i, failed = 0;
for (i = 0; i < MAXTABLE(Item_table); i++) {
if (i != Item_table[i].enumnumb) {
fprintf(stderr, "%s: enum/table error: Item_table[%d] was %s, but its value is %d\n"
, __FILE__, i, Item_table[i].enum2str, Item_table[i].enumnumb);
failed = 1;
}
}
if (i != PIDS_logical_end) {
fprintf(stderr, "%s: PIDS_logical_end is %d, expected %d\n"
, __FILE__, PIDS_logical_end, i);
failed = 1;
}
if (failed) _Exit(EXIT_FAILURE);
#endif
if (info == NULL || *info != NULL)
return -EINVAL;
if (!(p = calloc(1, sizeof(struct pids_info))))