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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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45
proc/slabinfo.c
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@@ -47,6 +47,13 @@
#define STACKS_INCR 128 // amount reap stack allocations grow
/* ---------------------------------------------------------------------------- +
this #define will be used to help ensure that our Item_table is synchronized |
with all the enumerators found in the associated header file. It is intended |
to only be defined locally (and temporarily) at some point prior to release! | */
// #define ITEMTABLE_DEBUG //-------------------------------------------------- |
// ---------------------------------------------------------------------------- +
/*
Because 'select' could, at most, return only node[0] values and since 'reap' |
would be forced to duplicate global slabs stuff in every node results stack, |
@@ -134,7 +141,7 @@ struct slabinfo_info {
// ___ Results 'Set' Support ||||||||||||||||||||||||||||||||||||||||||||||||||
#define setNAME(e) set_slabinfo_ ## e
#define setNAME(e) set_ ## e
#define setDECL(e) static void setNAME(e) \
(struct slabinfo_result *R, struct slabs_hist *S, struct slabs_node *N)
@@ -144,8 +151,8 @@ struct slabinfo_info {
// delta assignment
#define HST_set(e,t,x) setDECL(e) { (void)N; R->result. t = (signed long)S->new. x - S->old. x; }
setDECL(noop) { (void)R; (void)S; (void)N; }
setDECL(extra) { (void)S; (void)N; R->result.ul_int = 0; }
setDECL(SLABINFO_noop) { (void)R; (void)S; (void)N; }
setDECL(SLABINFO_extra) { (void)S; (void)N; R->result.ul_int = 0; }
NOD_set(SLAB_NAME, str, name)
NOD_set(SLAB_NUM_OBJS, u_int, nr_objs)
@@ -234,7 +241,11 @@ srtDECL(noop) { \
// ___ Controlling Table ||||||||||||||||||||||||||||||||||||||||||||||||||||||
typedef void (*SET_t)(struct slabinfo_result *, struct slabs_hist *, struct slabs_node *);
#ifdef ITEMTABLE_DEBUG
#define RS(e) (SET_t)setNAME(e), e, STRINGIFY(e)
#else
#define RS(e) (SET_t)setNAME(e)
#endif
typedef int (*QSR_t)(const void *, const void *, void *);
#define QS(t) (QSR_t)srtNAME(t)
@@ -248,13 +259,17 @@ typedef int (*QSR_t)(const void *, const void *, void *);
* those *enum slabinfo_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
QSR_t sortfunc; // sort cmp func for a specific type
char *type2str; // the result type as a string value
} Item_table[] = {
/* setsfunc sortfunc type2str
------------------------------ ----------- ---------- */
{ RS(noop), QS(noop), TS_noop },
{ RS(extra), QS(ul_int), TS_noop },
{ RS(SLABINFO_noop), QS(noop), TS_noop },
{ RS(SLABINFO_extra), QS(ul_int), TS_noop },
{ RS(SLAB_NAME), QS(str), TS(str) },
{ RS(SLAB_NUM_OBJS), QS(u_int), TS(u_int) },
@@ -292,9 +307,6 @@ static struct {
{ RS(SLABS_DELTA_PAGES_TOTAL), QS(noop), TS(s_int) },
{ RS(SLABS_DELTA_SIZE_ACTIVE), QS(noop), TS(s_int) },
{ RS(SLABS_DELTA_SIZE_TOTAL), QS(noop), TS(s_int) },
// dummy entry corresponding to SLABINFO_logical_end ...
{ NULL, NULL, NULL }
};
/* please note,
@@ -732,6 +744,23 @@ PROCPS_EXPORT int procps_slabinfo_new (
{
struct slabinfo_info *p;
#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 != SLABINFO_logical_end) {
fprintf(stderr, "%s: SLABINFO_logical_end is %d, expected %d\n"
, __FILE__, SLABINFO_logical_end, i);
failed = 1;
}
if (failed) _Exit(EXIT_FAILURE);
#endif
if (info == NULL || *info != NULL)
return -EINVAL;
if (!(p = calloc(1, sizeof(struct slabinfo_info))))