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Avoid holding a directory FD open across assorted SRF calls.

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This extends the fixes made in commit 085b6b667 to other SRFs with the
same bug, namely pg_logdir_ls(), pgrowlocks(), pg_timezone_names(),
pg_ls_dir(), and pg_tablespace_databases().

Also adjust various comments and documentation to warn against
expecting to clean up resources during a ValuePerCall SRF's final
call.

Back-patch to all supported branches, since these functions were
all born broken.

Justin Pryzby, with cosmetic tweaks by me

Discussion: https://postgr.es/m/20200308173103.GC1357@telsasoft.com
This commit is contained in:
Tom Lane
2020-03-16 21:05:28 -04:00
parent 113758155c
commit b4570d33aa
10 changed files with 386 additions and 346 deletions
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107
src/backend/utils/adt/datetime.c
View File

@ -4755,12 +4755,12 @@ pg_timezone_abbrevs(PG_FUNCTION_ARGS)
Datum
pg_timezone_names(PG_FUNCTION_ARGS)
{
MemoryContext oldcontext;
FuncCallContext *funcctx;
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
bool randomAccess;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
pg_tzenum *tzenum;
pg_tz *tz;
Datum result;
HeapTuple tuple;
Datum values[4];
bool nulls[4];
int tzoff;
@ -4769,59 +4769,41 @@ pg_timezone_names(PG_FUNCTION_ARGS)
const char *tzn;
Interval *resInterval;
struct pg_tm itm;
MemoryContext oldcontext;
/* stuff done only on the first call of the function */
if (SRF_IS_FIRSTCALL())
{
TupleDesc tupdesc;
/* check to see if caller supports us returning a tuplestore */
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsinfo->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("materialize mode required, but it is not allowed in this context")));
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/* The tupdesc and tuplestore must be created in ecxt_per_query_memory */
oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
/*
* switch to memory context appropriate for multiple function calls
*/
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* initialize timezone scanning code */
tzenum = pg_tzenumerate_start();
funcctx->user_fctx = (void *) tzenum;
randomAccess = (rsinfo->allowedModes & SFRM_Materialize_Random) != 0;
tupstore = tuplestore_begin_heap(randomAccess, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
/*
* build tupdesc for result tuples. This must match this function's
* pg_proc entry!
*/
tupdesc = CreateTemplateTupleDesc(4);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "abbrev",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "utc_offset",
INTERVALOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "is_dst",
BOOLOID, -1, 0);
MemoryContextSwitchTo(oldcontext);
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
MemoryContextSwitchTo(oldcontext);
}
/* stuff done on every call of the function */
funcctx = SRF_PERCALL_SETUP();
tzenum = (pg_tzenum *) funcctx->user_fctx;
/* initialize timezone scanning code */
tzenum = pg_tzenumerate_start();
/* search for another zone to display */
for (;;)
{
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
tz = pg_tzenumerate_next(tzenum);
MemoryContextSwitchTo(oldcontext);
if (!tz)
{
pg_tzenumerate_end(tzenum);
funcctx->user_fctx = NULL;
SRF_RETURN_DONE(funcctx);
}
break;
/* Convert now() to local time in this zone */
if (timestamp2tm(GetCurrentTransactionStartTimestamp(),
@ -4840,25 +4822,22 @@ pg_timezone_names(PG_FUNCTION_ARGS)
if (tzn && strlen(tzn) > 31)
continue;
/* Found a displayable zone */
break;
MemSet(nulls, 0, sizeof(nulls));
values[0] = CStringGetTextDatum(pg_get_timezone_name(tz));
values[1] = CStringGetTextDatum(tzn ? tzn : "");
MemSet(&itm, 0, sizeof(struct pg_tm));
itm.tm_sec = -tzoff;
resInterval = (Interval *) palloc(sizeof(Interval));
tm2interval(&itm, 0, resInterval);
values[2] = IntervalPGetDatum(resInterval);
values[3] = BoolGetDatum(tm.tm_isdst > 0);
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
MemSet(nulls, 0, sizeof(nulls));
values[0] = CStringGetTextDatum(pg_get_timezone_name(tz));
values[1] = CStringGetTextDatum(tzn ? tzn : "");
MemSet(&itm, 0, sizeof(struct pg_tm));
itm.tm_sec = -tzoff;
resInterval = (Interval *) palloc(sizeof(Interval));
tm2interval(&itm, 0, resInterval);
values[2] = IntervalPGetDatum(resInterval);
values[3] = BoolGetDatum(tm.tm_isdst > 0);
tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
pg_tzenumerate_end(tzenum);
return (Datum) 0;
}