Fix handling of escape sequences in postgres_fdw.application_name

postgres_fdw.application_name relies on MyProcPort to define the data
that should be added to escape sequences %u (user name) or %d (database
name).  However this code could be run in processes that lack a
MyProcPort, like an autovacuum process, causing crashes.

The code generating the application name is made more flexible with this
commit, so as it now generates no data for %u and %d if MyProcPort is
missing, and a simple "unknown" if MyProcPort exists, but the expected
fields are not set.

Reported-by: Alexander Lakhin
Author: Kyotaro Horiguchi, Michael Paquier
Reviewed-by: Hayato Kuroda, Masahiko Sawada
Discussion: https://postgr.es/m/17789-8b31c5a4672b74d9@postgresql.org
Backpatch-through: 15
This commit is contained in:
Michael Paquier 2023-02-21 20:01:43 +09:00
parent 038f586d5f
commit 8427ce4c37

View File

@ -485,8 +485,6 @@ process_pgfdw_appname(const char *appname)
const char *p;
StringInfoData buf;
Assert(MyProcPort != NULL);
initStringInfo(&buf);
for (p = appname; *p != '\0'; p++)
@ -522,13 +520,29 @@ process_pgfdw_appname(const char *appname)
appendStringInfoString(&buf, cluster_name);
break;
case 'd':
appendStringInfoString(&buf, MyProcPort->database_name);
if (MyProcPort)
{
const char *dbname = MyProcPort->database_name;
if (dbname)
appendStringInfoString(&buf, dbname);
else
appendStringInfoString(&buf, "[unknown]");
}
break;
case 'p':
appendStringInfo(&buf, "%d", MyProcPid);
break;
case 'u':
appendStringInfoString(&buf, MyProcPort->user_name);
if (MyProcPort)
{
const char *username = MyProcPort->user_name;
if (username)
appendStringInfoString(&buf, username);
else
appendStringInfoString(&buf, "[unknown]");
}
break;
default:
/* format error - ignore it */