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Don't call data type input functions in GUC check hooks

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Instead of calling pg_lsn_in() in check_recovery_target_lsn and
timestamptz_in() in check_recovery_target_time, reorganize the
respective code so that we don't raise any errors in the check hooks.
The previous code tried to use PG_TRY/PG_CATCH to handle errors in a
way that is not safe, so now the code contains no ereport() calls and
can operate safely within the GUC error handling system.

Moreover, since the interpretation of the recovery_target_time string
may depend on the time zone, we cannot do the final processing of that
string until all the GUC processing is done.  Instead,
check_recovery_target_time() now does some parsing for syntax
checking, but the actual conversion to a timestamptz value is done
later in the recovery code that uses it.

Reported-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/flat/20190611061115.njjwkagvxp4qujhp%40alap3.anarazel.de
This commit is contained in:
Peter Eisentraut
2019-06-30 10:15:25 +02:00
parent 666cbae16d
commit 21f428ebde
5 changed files with 85 additions and 74 deletions
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102
src/backend/utils/misc/guc.c
View File

@ -579,7 +579,6 @@ static bool assert_enabled;
static char *recovery_target_timeline_string;
static char *recovery_target_string;
static char *recovery_target_xid_string;
static char *recovery_target_time_string;
static char *recovery_target_name_string;
static char *recovery_target_lsn_string;
@ -11572,20 +11571,20 @@ assign_recovery_target_xid(const char *newval, void *extra)
recoveryTarget = RECOVERY_TARGET_UNSET;
}
/*
* The interpretation of the recovery_target_time string can depend on the
* time zone setting, so we need to wait until after all GUC processing is
* done before we can do the final parsing of the string. This check function
* only does a parsing pass to catch syntax errors, but we store the string
* and parse it again when we need to use it.
*/
static bool
check_recovery_target_time(char **newval, void **extra, GucSource source)
{
if (strcmp(*newval, "") != 0)
{
TimestampTz time;
TimestampTz *myextra;
MemoryContext oldcontext = CurrentMemoryContext;
/* reject some special values */
if (strcmp(*newval, "epoch") == 0 ||
strcmp(*newval, "infinity") == 0 ||
strcmp(*newval, "-infinity") == 0 ||
strcmp(*newval, "now") == 0 ||
if (strcmp(*newval, "now") == 0 ||
strcmp(*newval, "today") == 0 ||
strcmp(*newval, "tomorrow") == 0 ||
strcmp(*newval, "yesterday") == 0)
@ -11593,32 +11592,38 @@ check_recovery_target_time(char **newval, void **extra, GucSource source)
return false;
}
PG_TRY();
/*
* parse timestamp value (see also timestamptz_in())
*/
{
time = DatumGetTimestampTz(DirectFunctionCall3(timestamptz_in,
CStringGetDatum(*newval),
ObjectIdGetDatum(InvalidOid),
Int32GetDatum(-1)));
char *str = *newval;
fsec_t fsec;
struct pg_tm tt,
*tm = &tt;
int tz;
int dtype;
int nf;
int dterr;
char *field[MAXDATEFIELDS];
int ftype[MAXDATEFIELDS];
char workbuf[MAXDATELEN + MAXDATEFIELDS];
TimestampTz timestamp;
dterr = ParseDateTime(str, workbuf, sizeof(workbuf),
field, ftype, MAXDATEFIELDS, &nf);
if (dterr == 0)
dterr = DecodeDateTime(field, ftype, nf, &dtype, tm, &fsec, &tz);
if (dterr != 0)
return false;
if (dtype != DTK_DATE)
return false;
if (tm2timestamp(tm, fsec, &tz, &timestamp) != 0)
{
GUC_check_errdetail("timestamp out of range: \"%s\"", str);
return false;
}
}
PG_CATCH();
{
ErrorData *edata;
/* Save error info */
MemoryContextSwitchTo(oldcontext);
edata = CopyErrorData();
FlushErrorState();
/* Pass the error message */
GUC_check_errdetail("%s", edata->message);
FreeErrorData(edata);
return false;
}
PG_END_TRY();
myextra = (TimestampTz *) guc_malloc(ERROR, sizeof(TimestampTz));
*myextra = time;
*extra = (void *) myextra;
}
return true;
}
@ -11631,10 +11636,7 @@ assign_recovery_target_time(const char *newval, void *extra)
error_multiple_recovery_targets();
if (newval && strcmp(newval, "") != 0)
{
recoveryTarget = RECOVERY_TARGET_TIME;
recoveryTargetTime = *((TimestampTz *) extra);
}
else
recoveryTarget = RECOVERY_TARGET_UNSET;
}
@ -11675,33 +11677,11 @@ check_recovery_target_lsn(char **newval, void **extra, GucSource source)
{
XLogRecPtr lsn;
XLogRecPtr *myextra;
MemoryContext oldcontext = CurrentMemoryContext;
bool have_error = false;
/*
* Convert the LSN string given by the user to XLogRecPtr form.
*/
PG_TRY();
{
lsn = DatumGetLSN(DirectFunctionCall3(pg_lsn_in,
CStringGetDatum(*newval),
ObjectIdGetDatum(InvalidOid),
Int32GetDatum(-1)));
}
PG_CATCH();
{
ErrorData *edata;
/* Save error info */
MemoryContextSwitchTo(oldcontext);
edata = CopyErrorData();
FlushErrorState();
/* Pass the error message */
GUC_check_errdetail("%s", edata->message);
FreeErrorData(edata);
lsn = pg_lsn_in_internal(*newval, &have_error);
if (have_error)
return false;
}
PG_END_TRY();
myextra = (XLogRecPtr *) guc_malloc(ERROR, sizeof(XLogRecPtr));
*myextra = lsn;