Fix another oversight in logging of changes in postgresql.conf settings.

We were using GetConfigOption to collect the old value of each setting,
overlooking the possibility that it didn't exist yet.  This does happen
in the case of adding a new entry within a custom variable class, as
exhibited in bug #6097 from Maxim Boguk.

To fix, add a missing_ok parameter to GetConfigOption, but only in 9.1
and HEAD --- it seems possible that some third-party code is using that
function, so changing its API in a minor release would cause problems.
In 9.0, create a near-duplicate function instead.

diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index 58695690500e69c2ddabef9c3842d467af24798d..f6a03e16688ff7ccf4328ed79c9eb65ee26bfee7 100644 (file)
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -813,14 +813,14 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
         * error.
         */
        save_client_min_messages =
-               pstrdup(GetConfigOption("client_min_messages", false));
+               pstrdup(GetConfigOption("client_min_messages", false, false));
        if (client_min_messages < WARNING)
                (void) set_config_option("client_min_messages", "warning",
                                                                 PGC_USERSET, PGC_S_SESSION,
                                                                 GUC_ACTION_LOCAL, true);
 
        save_log_min_messages =
-               pstrdup(GetConfigOption("log_min_messages", false));
+               pstrdup(GetConfigOption("log_min_messages", false, false));
        if (log_min_messages < WARNING)
                (void) set_config_option("log_min_messages", "warning",
                                                                 PGC_SUSET, PGC_S_SESSION,
@@ -835,7 +835,7 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
         * but we cannot do that.  We have to actually set the search_path GUC in
         * case the extension script examines or changes it.
         */
-       save_search_path = pstrdup(GetConfigOption("search_path", false));
+       save_search_path = pstrdup(GetConfigOption("search_path", false, false));
 
        initStringInfo(&pathbuf);
        appendStringInfoString(&pathbuf, quote_identifier(schemaName));

diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index 78907b939dee1383244042c9dbc48aed6ab76d35..3e9b10328d480b47dce5240d74577fdc7b715885 100644 (file)
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -306,9 +306,9 @@ ProcessConfigFile(GucContext context)
                /* In SIGHUP cases in the postmaster, report changes */
                if (context == PGC_SIGHUP && !IsUnderPostmaster)
                {
-                       const char *preval = GetConfigOption(item->name, false);
+                       const char *preval = GetConfigOption(item->name, true, false);
 
-                       /* string variables could be NULL; treat that as empty */
+                       /* If option doesn't exist yet or is NULL, treat as empty string */
                        if (!preval)
                                preval = "";
                        /* must dup, else might have dangling pointer below */
@@ -323,7 +323,7 @@ ProcessConfigFile(GucContext context)
 
                        if (pre_value)
                        {
-                               const char *post_value = GetConfigOption(item->name, false);
+                               const char *post_value = GetConfigOption(item->name, true, false);
 
                                if (!post_value)
                                        post_value = "";

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index f14ee9ebad0d4225603bb70520defc010e65cdbe..1460214293d68e4bc100cc9bf097f418c92da630 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -5838,8 +5838,11 @@ SetConfigOption(const char *name, const char *value,
 
 
 /*
- * Fetch the current value of the option `name'. If the option doesn't exist,
- * throw an ereport and don't return.
+ * Fetch the current value of the option `name', as a string.
+ *
+ * If the option doesn't exist, return NULL if missing_ok is true (NOTE that
+ * this cannot be distinguished from a string variable with a NULL value!),
+ * otherwise throw an ereport and don't return.
  *
  * If restrict_superuser is true, we also enforce that only superusers can
  * see GUC_SUPERUSER_ONLY variables.  This should only be passed as true
@@ -5849,16 +5852,21 @@ SetConfigOption(const char *name, const char *value,
  * valid until the next call to configuration related functions.
  */
 const char *
-GetConfigOption(const char *name, bool restrict_superuser)
+GetConfigOption(const char *name, bool missing_ok, bool restrict_superuser)
 {
        struct config_generic *record;
        static char buffer[256];
 
        record = find_option(name, false, ERROR);
        if (record == NULL)
+       {
+               if (missing_ok)
+                       return NULL;
                ereport(ERROR,
                                (errcode(ERRCODE_UNDEFINED_OBJECT),
-                          errmsg("unrecognized configuration parameter \"%s\"", name)));
+                                errmsg("unrecognized configuration parameter \"%s\"",
+                                               name)));
+       }
        if (restrict_superuser &&
                (record->flags & GUC_SUPERUSER_ONLY) &&
                !superuser())

diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index ee52cd735e33776ad647a57973cd261b7e4b1b62..011f6b7f001a60ce1fcfb732264238f5d355866d 100644 (file)
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -296,7 +296,8 @@ extern void DefineCustomEnumVariable(
 
 extern void EmitWarningsOnPlaceholders(const char *className);
 
-extern const char *GetConfigOption(const char *name, bool restrict_superuser);
+extern const char *GetConfigOption(const char *name, bool missing_ok,
+                               bool restrict_superuser);
 extern const char *GetConfigOptionResetString(const char *name);
 extern void ProcessConfigFile(GucContext context);
 extern void InitializeGUCOptions(void);