From ed91252bc252e926595abf7886a9c2aac0e91801 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 26 May 2008 18:54:36 +0000 Subject: [PATCH] Fix an old corner-case bug in set_config_option: push_old_value has to be called before, not after, calling the assign_hook if any. This is because push_old_value might fail (due to palloc out-of-memory), and in that case there would be no stack entry to tell transaction abort to undo the GUC assignment. Of course the actual assignment to the GUC variable hasn't happened yet --- but the assign_hook might have altered subsidiary state. Without a stack entry we won't call it again to make it undo such actions. So this is necessary to make the world safe for assign_hooks with side effects. Per a discussion a couple weeks ago with Magnus. Back-patch to 8.0. 7.x did not have the problem because it did not have allocatable stacks of GUC values. --- src/backend/utils/misc/guc.c | 186 +++++++++++++++++------------------ 1 file changed, 88 insertions(+), 98 deletions(-) diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 1dbffbfb482..bca9e3fc384 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -10,7 +10,7 @@ * Written by Peter Eisentraut . * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.432 2008/01/30 18:35:55 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.432.2.1 2008/05/26 18:54:36 tgl Exp $ * *-------------------------------------------------------------------- */ @@ -4370,6 +4370,10 @@ set_config_option(const char *name, const char *value, source = conf->gen.reset_source; } + /* Save old value to support transaction abort */ + if (changeVal && !makeDefault) + push_old_value(&conf->gen, action); + if (conf->assign_hook) if (!(*conf->assign_hook) (newval, changeVal, source)) { @@ -4380,32 +4384,26 @@ set_config_option(const char *name, const char *value, return false; } - if (changeVal || makeDefault) + if (changeVal) { - /* Save old value to support transaction abort */ - if (!makeDefault) - push_old_value(&conf->gen, action); - if (changeVal) - { - *conf->variable = newval; - conf->gen.source = source; - } - if (makeDefault) - { - GucStack *stack; + *conf->variable = newval; + conf->gen.source = source; + } + if (makeDefault) + { + GucStack *stack; - if (conf->gen.reset_source <= source) + if (conf->gen.reset_source <= source) + { + conf->reset_val = newval; + conf->gen.reset_source = source; + } + for (stack = conf->gen.stack; stack; stack = stack->prev) + { + if (stack->source <= source) { - conf->reset_val = newval; - conf->gen.reset_source = source; - } - for (stack = conf->gen.stack; stack; stack = stack->prev) - { - if (stack->source <= source) - { - stack->prior.boolval = newval; - stack->source = source; - } + stack->prior.boolval = newval; + stack->source = source; } } } @@ -4447,6 +4445,10 @@ set_config_option(const char *name, const char *value, source = conf->gen.reset_source; } + /* Save old value to support transaction abort */ + if (changeVal && !makeDefault) + push_old_value(&conf->gen, action); + if (conf->assign_hook) if (!(*conf->assign_hook) (newval, changeVal, source)) { @@ -4457,32 +4459,26 @@ set_config_option(const char *name, const char *value, return false; } - if (changeVal || makeDefault) + if (changeVal) { - /* Save old value to support transaction abort */ - if (!makeDefault) - push_old_value(&conf->gen, action); - if (changeVal) - { - *conf->variable = newval; - conf->gen.source = source; - } - if (makeDefault) - { - GucStack *stack; + *conf->variable = newval; + conf->gen.source = source; + } + if (makeDefault) + { + GucStack *stack; - if (conf->gen.reset_source <= source) + if (conf->gen.reset_source <= source) + { + conf->reset_val = newval; + conf->gen.reset_source = source; + } + for (stack = conf->gen.stack; stack; stack = stack->prev) + { + if (stack->source <= source) { - conf->reset_val = newval; - conf->gen.reset_source = source; - } - for (stack = conf->gen.stack; stack; stack = stack->prev) - { - if (stack->source <= source) - { - stack->prior.intval = newval; - stack->source = source; - } + stack->prior.intval = newval; + stack->source = source; } } } @@ -4521,6 +4517,10 @@ set_config_option(const char *name, const char *value, source = conf->gen.reset_source; } + /* Save old value to support transaction abort */ + if (changeVal && !makeDefault) + push_old_value(&conf->gen, action); + if (conf->assign_hook) if (!(*conf->assign_hook) (newval, changeVal, source)) { @@ -4531,32 +4531,26 @@ set_config_option(const char *name, const char *value, return false; } - if (changeVal || makeDefault) + if (changeVal) { - /* Save old value to support transaction abort */ - if (!makeDefault) - push_old_value(&conf->gen, action); - if (changeVal) - { - *conf->variable = newval; - conf->gen.source = source; - } - if (makeDefault) - { - GucStack *stack; + *conf->variable = newval; + conf->gen.source = source; + } + if (makeDefault) + { + GucStack *stack; - if (conf->gen.reset_source <= source) + if (conf->gen.reset_source <= source) + { + conf->reset_val = newval; + conf->gen.reset_source = source; + } + for (stack = conf->gen.stack; stack; stack = stack->prev) + { + if (stack->source <= source) { - conf->reset_val = newval; - conf->gen.reset_source = source; - } - for (stack = conf->gen.stack; stack; stack = stack->prev) - { - if (stack->source <= source) - { - stack->prior.realval = newval; - stack->source = source; - } + stack->prior.realval = newval; + stack->source = source; } } } @@ -4610,6 +4604,10 @@ set_config_option(const char *name, const char *value, source = conf->gen.reset_source; } + /* Save old value to support transaction abort */ + if (changeVal && !makeDefault) + push_old_value(&conf->gen, action); + if (conf->assign_hook && newval) { const char *hookresult; @@ -4647,40 +4645,32 @@ set_config_option(const char *name, const char *value, } } - if (changeVal || makeDefault) + if (changeVal) { - /* Save old value to support transaction abort */ - if (!makeDefault) - push_old_value(&conf->gen, action); - if (changeVal) - { - set_string_field(conf, conf->variable, newval); - conf->gen.source = source; - } - if (makeDefault) - { - GucStack *stack; + set_string_field(conf, conf->variable, newval); + conf->gen.source = source; + } + if (makeDefault) + { + GucStack *stack; - if (conf->gen.reset_source <= source) + if (conf->gen.reset_source <= source) + { + set_string_field(conf, &conf->reset_val, newval); + conf->gen.reset_source = source; + } + for (stack = conf->gen.stack; stack; stack = stack->prev) + { + if (stack->source <= source) { - set_string_field(conf, &conf->reset_val, newval); - conf->gen.reset_source = source; + set_string_field(conf, &stack->prior.stringval, + newval); + stack->source = source; } - for (stack = conf->gen.stack; stack; stack = stack->prev) - { - if (stack->source <= source) - { - set_string_field(conf, &stack->prior.stringval, - newval); - stack->source = source; - } - } - /* Perhaps we didn't install newval anywhere */ - if (newval && !string_field_used(conf, newval)) - free(newval); } } - else if (newval) + /* Perhaps we didn't install newval anywhere */ + if (newval && !string_field_used(conf, newval)) free(newval); break; }