Don't allow data_directory to be set in postgresql.auto.conf by ALTER SYSTEM.

data_directory could be set both in postgresql.conf and postgresql.auto.conf so far.
This could cause some problematic situations like circular definition. To avoid such
situations, this commit forbids a user to set data_directory in postgresql.auto.conf.

Backpatch this to 9.4 where ALTER SYSTEM command was introduced.

Amit Kapila, reviewed by Abhijit Menon-Sen, with minor adjustments by me.

diff --git a/doc/src/sgml/ref/alter_system.sgml b/doc/src/sgml/ref/alter_system.sgml
index 081b3722a0b4951056c47efc29e53ba1a69b1d47..d11f6beeed79ed608b538fcf2b7029958ea7ccac 100644 (file)
--- a/doc/src/sgml/ref/alter_system.sgml
+++ b/doc/src/sgml/ref/alter_system.sgml
@@ -76,6 +76,16 @@ ALTER SYSTEM SET <replaceable class="PARAMETER">configuration_parameter</replace
   </variablelist>
  </refsect1>
 
+ <refsect1>
+  <title>Notes</title>
+
+  <para>
+    This command can't be used to set <xref linkend="guc-data-directory">
+    and any parameters (e.g., <link linkend="runtime-config-preset">preset options</>)
+    that are not allowed in <filename>postgresql.conf</>.
+  </para>
+ </refsect1>
+  
  <refsect1>
   <title>Examples</title>
 

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1d094f00c61062876986edbd53a54a2b77d9609a..8ca065b7feeb51a28b8bb49c7f78903c2f22d8e0 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3095,10 +3095,14 @@ static struct config_string ConfigureNamesString[] =
        },
 
        {
+               /*
+                * Can't be set by ALTER SYSTEM as it can lead to recursive definition
+                * of data_directory.
+                */
                {"data_directory", PGC_POSTMASTER, FILE_LOCATIONS,
                        gettext_noop("Sets the server's data directory."),
                        NULL,
-                       GUC_SUPERUSER_ONLY
+                       GUC_SUPERUSER_ONLY | GUC_DISALLOW_IN_AUTO_FILE
                },
                &data_directory,
                NULL,
@@ -6735,12 +6739,17 @@ AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
                                (errcode(ERRCODE_UNDEFINED_OBJECT),
                           errmsg("unrecognized configuration parameter \"%s\"", name)));
 
+       /*
+        * Don't allow the parameters which can't be set in configuration
+        * files to be set in PG_AUTOCONF_FILENAME file.
+        */
        if ((record->context == PGC_INTERNAL) ||
-               (record->flags & GUC_DISALLOW_IN_FILE))
-               ereport(ERROR,
-                               (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
-                                errmsg("parameter \"%s\" cannot be changed",
-                                               name)));
+               (record->flags & GUC_DISALLOW_IN_FILE) ||
+               (record->flags & GUC_DISALLOW_IN_AUTO_FILE))
+                ereport(ERROR,
+                                (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+                                 errmsg("parameter \"%s\" cannot be changed",
+                                                name)));
 
        if (!validate_conf_option(record, name, value, PGC_S_FILE,
                                                          ERROR, true, NULL,

diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index c15a5bbb7b3493059524deb8db1dd6c8fd41244d..1493d2cb79cbcde4fccf29a02efa2523d938a52a 100644 (file)
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -195,6 +195,7 @@ typedef enum
 #define GUC_UNIT_TIME                  0x7000  /* mask for MS, S, MIN */
 
 #define GUC_NOT_WHILE_SEC_REST 0x8000  /* can't set if security restricted */
+#define GUC_DISALLOW_IN_AUTO_FILE      0x00010000      /* can't set in PG_AUTOCONF_FILENAME */
 
 /* GUC vars that are actually declared in guc.c, rather than elsewhere */
 extern bool log_duration;