Avoid crashing when restoring a saved GUC session_authorization value

that refers to a now-deleted userid.  Per gripe from Chris Ochs.

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index dfa3f7121edb83c47b0c396d58cea09c86b2a9be..f5ae5a59903bcff2fa10a15498cfe6547ab788a2 100644 (file)
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.98 2004/07/01 00:50:12 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.99 2004/08/11 21:10:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -591,31 +591,37 @@ assign_client_encoding(const char *value, bool doit, GucSource source)
  * lookups.  Hence, the stored form of the value must provide a numeric userid
  * that can be re-used directly.  We store the string in the form of
  * NAMEDATALEN 'x's, followed by T or F to indicate superuserness, followed
- * by the numeric userid --- this cannot conflict with any valid user name,
- * because of the NAMEDATALEN limit on names.
+ * by the numeric userid, followed by a comma, followed by the user name.
+ * This cannot be confused with a plain user name because of the NAMEDATALEN
+ * limit on names, so we can tell whether we're being passed an initial
+ * username or a saved/restored value.
  */
+extern char *session_authorization_string; /* in guc.c */
+
 const char *
 assign_session_authorization(const char *value, bool doit, GucSource source)
 {
    AclId       usesysid = 0;
    bool        is_superuser = false;
+   const char *actual_username = NULL;
    char       *result;
 
    if (strspn(value, "x") == NAMEDATALEN &&
        (value[NAMEDATALEN] == 'T' || value[NAMEDATALEN] == 'F'))
    {
-       /* might be a saved numeric userid */
+       /* might be a saved userid string */
+       AclId       savedsysid;
        char       *endptr;
 
-       usesysid = (AclId) strtoul(value + NAMEDATALEN + 1, &endptr, 10);
+       savedsysid = (AclId) strtoul(value + NAMEDATALEN + 1, &endptr, 10);
 
-       if (endptr != value + NAMEDATALEN + 1 && *endptr == '\0')
+       if (endptr != value + NAMEDATALEN + 1 && *endptr == ',')
        {
-           /* syntactically valid, so use the numeric user ID and flag */
+           /* syntactically valid, so break out the data */
+           usesysid = savedsysid;
            is_superuser = (value[NAMEDATALEN] == 'T');
+           actual_username = endptr + 1;
        }
-       else
-           usesysid = 0;
    }
 
    if (usesysid == 0)
@@ -647,6 +653,7 @@ assign_session_authorization(const char *value, bool doit, GucSource source)
 
        usesysid = ((Form_pg_shadow) GETSTRUCT(userTup))->usesysid;
        is_superuser = ((Form_pg_shadow) GETSTRUCT(userTup))->usesuper;
+       actual_username = value;
 
        ReleaseSysCache(userTup);
    }
@@ -654,15 +661,16 @@ assign_session_authorization(const char *value, bool doit, GucSource source)
    if (doit)
        SetSessionAuthorization(usesysid, is_superuser);
 
-   result = (char *) malloc(NAMEDATALEN + 32);
+   result = (char *) malloc(NAMEDATALEN + 32 + strlen(actual_username));
    if (!result)
        return NULL;
 
    memset(result, 'x', NAMEDATALEN);
 
-   snprintf(result + NAMEDATALEN, 32, "%c%lu",
-            is_superuser ? 'T' : 'F',
-            (unsigned long) usesysid);
+   sprintf(result + NAMEDATALEN, "%c%lu,%s",
+           is_superuser ? 'T' : 'F',
+           (unsigned long) usesysid,
+           actual_username);
 
    return result;
 }
@@ -671,8 +679,19 @@ const char *
 show_session_authorization(void)
 {
    /*
-    * We can't use the stored string; see comments for
+    * Extract the user name from the stored string; see
     * assign_session_authorization
     */
-   return GetUserNameFromId(GetSessionUserId());
+   const char *value = session_authorization_string;
+   AclId       savedsysid;
+   char       *endptr;
+
+   Assert(strspn(value, "x") == NAMEDATALEN &&
+          (value[NAMEDATALEN] == 'T' || value[NAMEDATALEN] == 'F'));
+
+   savedsysid = (AclId) strtoul(value + NAMEDATALEN + 1, &endptr, 10);
+
+   Assert(endptr != value + NAMEDATALEN + 1 && *endptr == ',');
+
+   return endptr + 1;
 }

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 5c4908f27daced140687f95e4e3079db5ae8e456..d015629c3e790428836c3f3b68ddc67cd4cfd284 100644 (file)
--- 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 1.230 2004/08/08 20:17:36 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.231 2004/08/11 21:10:37 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -175,7 +175,6 @@ static char *locale_ctype;
 static char *regex_flavor_string;
 static char *server_encoding_string;
 static char *server_version_string;
-static char *session_authorization_string;
 static char *timezone_string;
 static char *XactIsoLevel_string;
 static char *custom_variable_classes;
@@ -184,6 +183,8 @@ static int  max_index_keys;
 static int max_identifier_length;
 static int block_size;
 static bool integer_datetimes;
+/* should be static, but commands/variable.c needs to get at it */
+char *session_authorization_string;
 
 
 /*