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Enforce superuser permissions checks during ALTER ROLE/DATABASE SET, rather
than during define_custom_variable(). This entails rejecting an ALTER command if the target variable doesn't have a known (non-placeholder) definition, unless the calling user is superuser. When the variable *is* known, we can correctly apply the rule that only superusers can issue ALTER for SUSET parameters. This allows define_custom_variable to apply ALTER's values for SUSET parameters at module load time, secure in the knowledge that only a superuser could have set the ALTER value. This change fixes a longstanding gotcha in the usage of SUSET-level custom parameters; which is a good thing to fix now that plpgsql defines such a parameter.
This commit is contained in:
Tom Lane
@ -10,7 +10,7 @@
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* Written by Peter Eisentraut <peter_e@gmx.net>.
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.549 2010/04/20 11:15:06 rhaas Exp $
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* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.550 2010/04/21 20:54:19 tgl Exp $
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*
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*--------------------------------------------------------------------
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*/
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@ -2864,6 +2864,8 @@ static void ShowGUCConfigOption(const char *name, DestReceiver *dest);
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static void ShowAllGUCConfig(DestReceiver *dest);
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static char *_ShowOption(struct config_generic * record, bool use_units);
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static bool is_newvalue_equal(struct config_generic * record, const char *newvalue);
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static bool validate_option_array_item(const char *name, const char *value,
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bool skipIfNoPermissions);
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/*
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@ -5474,14 +5476,15 @@ flatten_set_variable_args(const char *name, List *args)
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if (args == NIL)
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return NULL;
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/* Else get flags for the variable */
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record = find_option(name, true, ERROR);
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if (record == NULL)
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ereport(ERROR,
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(errcode(ERRCODE_UNDEFINED_OBJECT),
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errmsg("unrecognized configuration parameter \"%s\"", name)));
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flags = record->flags;
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/*
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* Get flags for the variable; if it's not known, use default flags.
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* (Caller might throw error later, but not our business to do so here.)
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*/
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record = find_option(name, false, WARNING);
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if (record)
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flags = record->flags;
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else
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flags = 0;
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/* Complain if list input and non-list variable */
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if ((flags & GUC_LIST_INPUT) == 0 &&
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@ -5870,12 +5873,27 @@ define_custom_variable(struct config_generic * variable)
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else
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phcontext = PGC_SIGHUP;
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break;
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case PGC_S_DATABASE:
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case PGC_S_USER:
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case PGC_S_DATABASE_USER:
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/*
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* The existing value came from an ALTER ROLE/DATABASE SET command.
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* We can assume that at the time the command was issued, we
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* checked that the issuing user was superuser if the variable
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* requires superuser privileges to set. So it's safe to
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* use SUSET context here.
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*/
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phcontext = PGC_SUSET;
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break;
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case PGC_S_CLIENT:
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case PGC_S_SESSION:
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default:
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/*
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* We must assume that the value came from an untrusted user,
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* even if the current_user is a superuser.
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*/
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phcontext = PGC_USERSET;
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break;
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}
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@ -7180,7 +7198,7 @@ ProcessGUCArray(ArrayType *array,
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ArrayType *
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GUCArrayAdd(ArrayType *array, const char *name, const char *value)
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{
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const char *varname;
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struct config_generic *record;
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Datum datum;
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char *newval;
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ArrayType *a;
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@ -7188,15 +7206,15 @@ GUCArrayAdd(ArrayType *array, const char *name, const char *value)
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Assert(name);
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Assert(value);
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/* test if the option is valid */
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set_config_option(name, value,
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superuser() ? PGC_SUSET : PGC_USERSET,
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PGC_S_TEST, GUC_ACTION_SET, false);
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/* test if the option is valid and we're allowed to set it */
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(void) validate_option_array_item(name, value, false);
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/* convert name to canonical spelling, so we can use plain strcmp */
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(void) GetConfigOptionByName(name, &varname);
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name = varname;
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/* normalize name (converts obsolete GUC names to modern spellings) */
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record = find_option(name, false, WARNING);
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if (record)
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name = record->name;
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/* build new item for array */
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newval = palloc(strlen(name) + 1 + strlen(value) + 1);
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sprintf(newval, "%s=%s", name, value);
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datum = CStringGetTextDatum(newval);
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@ -7227,6 +7245,8 @@ GUCArrayAdd(ArrayType *array, const char *name, const char *value)
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if (isnull)
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continue;
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current = TextDatumGetCString(d);
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/* check for match up through and including '=' */
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if (strncmp(current, newval, strlen(name) + 1) == 0)
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{
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index = i;
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@ -7259,21 +7279,20 @@ GUCArrayAdd(ArrayType *array, const char *name, const char *value)
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ArrayType *
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GUCArrayDelete(ArrayType *array, const char *name)
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{
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const char *varname;
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struct config_generic *record;
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ArrayType *newarray;
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int i;
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int index;
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Assert(name);
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/* test if the option is valid */
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set_config_option(name, NULL,
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superuser() ? PGC_SUSET : PGC_USERSET,
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PGC_S_TEST, GUC_ACTION_SET, false);
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/* test if the option is valid and we're allowed to set it */
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(void) validate_option_array_item(name, NULL, false);
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/* convert name to canonical spelling, so we can use plain strcmp */
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(void) GetConfigOptionByName(name, &varname);
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name = varname;
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/* normalize name (converts obsolete GUC names to modern spellings) */
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record = find_option(name, false, WARNING);
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if (record)
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name = record->name;
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/* if array is currently null, then surely nothing to delete */
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if (!array)
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@ -7303,10 +7322,8 @@ GUCArrayDelete(ArrayType *array, const char *name)
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&& val[strlen(name)] == '=')
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continue;
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/* else add it to the output array */
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if (newarray)
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{
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newarray = array_set(newarray, 1, &index,
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d,
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false,
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@ -7314,7 +7331,6 @@ GUCArrayDelete(ArrayType *array, const char *name)
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-1 /* TEXT's typlen */ ,
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false /* TEXT's typbyval */ ,
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'i' /* TEXT's typalign */ );
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}
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else
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newarray = construct_array(&d, 1,
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TEXTOID,
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@ -7326,6 +7342,7 @@ GUCArrayDelete(ArrayType *array, const char *name)
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return newarray;
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}
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/*
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* Given a GUC array, delete all settings from it that our permission
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* level allows: if superuser, delete them all; if regular user, only
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@ -7342,7 +7359,7 @@ GUCArrayReset(ArrayType *array)
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if (!array)
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return NULL;
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/* if we're superuser, we can delete everything */
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/* if we're superuser, we can delete everything, so just do it */
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if (superuser())
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return NULL;
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@ -7355,7 +7372,6 @@ GUCArrayReset(ArrayType *array)
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char *val;
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char *eqsgn;
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bool isnull;
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struct config_generic *gconf;
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d = array_ref(array, 1, &i,
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-1 /* varlenarray */ ,
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@ -7363,7 +7379,6 @@ GUCArrayReset(ArrayType *array)
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false /* TEXT's typbyval */ ,
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'i' /* TEXT's typalign */ ,
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&isnull);
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if (isnull)
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continue;
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val = TextDatumGetCString(d);
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@ -7371,20 +7386,12 @@ GUCArrayReset(ArrayType *array)
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eqsgn = strchr(val, '=');
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*eqsgn = '\0';
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gconf = find_option(val, false, WARNING);
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if (!gconf)
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/* skip if we have permission to delete it */
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if (validate_option_array_item(val, NULL, true))
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continue;
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/* note: superuser-ness was already checked above */
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/* skip entry if OK to delete */
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if (gconf->context == PGC_USERSET)
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continue;
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/* XXX do we need to worry about database owner? */
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/* else add it to the output array */
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if (newarray)
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{
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newarray = array_set(newarray, 1, &index,
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d,
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false,
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@ -7392,7 +7399,6 @@ GUCArrayReset(ArrayType *array)
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-1 /* TEXT's typlen */ ,
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false /* TEXT's typbyval */ ,
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'i' /* TEXT's typalign */ );
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}
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else
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newarray = construct_array(&d, 1,
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TEXTOID,
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@ -7405,6 +7411,89 @@ GUCArrayReset(ArrayType *array)
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return newarray;
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}
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/*
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* Validate a proposed option setting for GUCArrayAdd/Delete/Reset.
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*
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* name is the option name. value is the proposed value for the Add case,
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* or NULL for the Delete/Reset cases. If skipIfNoPermissions is true, it's
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* not an error to have no permissions to set the option.
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*
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* Returns TRUE if OK, FALSE if skipIfNoPermissions is true and user does not
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* have permission to change this option (all other error cases result in an
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* error being thrown).
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*/
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static bool
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validate_option_array_item(const char *name, const char *value,
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bool skipIfNoPermissions)
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{
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struct config_generic *gconf;
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/*
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* There are three cases to consider:
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*
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* name is a known GUC variable. Check the value normally, check
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* permissions normally (ie, allow if variable is USERSET, or if it's
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* SUSET and user is superuser).
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*
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* name is not known, but exists or can be created as a placeholder
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* (implying it has a prefix listed in custom_variable_classes).
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* We allow this case if you're a superuser, otherwise not. Superusers
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* are assumed to know what they're doing. We can't allow it for other
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* users, because when the placeholder is resolved it might turn out to
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* be a SUSET variable; define_custom_variable assumes we checked that.
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*
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* name is not known and can't be created as a placeholder. Throw error,
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* unless skipIfNoPermissions is true, in which case return FALSE.
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* (It's tempting to allow this case to superusers, if the name is
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* qualified but not listed in custom_variable_classes. That would
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* ease restoring of dumps containing ALTER ROLE/DATABASE SET. However,
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* it's not clear that this usage justifies such a loss of error checking.
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* You can always fix custom_variable_classes before you restore.)
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*/
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gconf = find_option(name, true, WARNING);
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if (!gconf)
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{
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/* not known, failed to make a placeholder */
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if (skipIfNoPermissions)
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return false;
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ereport(ERROR,
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(errcode(ERRCODE_UNDEFINED_OBJECT),
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errmsg("unrecognized configuration parameter \"%s\"", name)));
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}
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if (gconf->flags & GUC_CUSTOM_PLACEHOLDER)
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{
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/*
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* We cannot do any meaningful check on the value, so only permissions
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* are useful to check.
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*/
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if (superuser())
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return true;
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if (skipIfNoPermissions)
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return false;
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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errmsg("permission denied to set parameter \"%s\"", name)));
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}
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/* manual permissions check so we can avoid an error being thrown */
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if (gconf->context == PGC_USERSET)
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/* ok */ ;
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else if (gconf->context == PGC_SUSET && superuser())
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/* ok */ ;
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else if (skipIfNoPermissions)
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return false;
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/* if a permissions error should be thrown, let set_config_option do it */
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/* test for permissions and valid option value */
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set_config_option(name, value,
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superuser() ? PGC_SUSET : PGC_USERSET,
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PGC_S_TEST, GUC_ACTION_SET, false);
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return true;
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}
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/*
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* assign_hook and show_hook subroutines
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