Make local copy of client hostnames in backend status array.

The other strings, application_name and query string, were snapshotted to
local memory in pgstat_read_current_status(), but we forgot to do that for
client hostnames. As a result, the client hostname would appear to change in
the local copy, if the client disconnected.

Backpatch to all supported versions.

Author: Edmund Horner
Reviewed-by: Michael Paquier
Discussion: https://www.postgresql.org/message-id/CAMyN-kA7aOJzBmrYFdXcc7Z0NmW%2B5jBaf_m%3D_-77uRNyKC9r%3DA%40mail.gmail.com

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 437c91faa234a175297d32d7c60d0e9648db83a1..c562c0c04347188b0e7a49e0e1511c8c01121bbb 100644 (file)
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2786,6 +2786,7 @@ pgstat_read_current_status(void)
        PgBackendStatus *localtable;
        PgBackendStatus *localentry;
        char       *localappname,
+                          *localclienthostname,
                           *localactivity;
        int                     i;
 
@@ -2801,6 +2802,9 @@ pgstat_read_current_status(void)
        localappname = (char *)
                MemoryContextAlloc(pgStatLocalContext,
                                                   NAMEDATALEN * MaxBackends);
+       localclienthostname = (char *)
+               MemoryContextAlloc(pgStatLocalContext,
+                                                  NAMEDATALEN * MaxBackends);
        localactivity = (char *)
                MemoryContextAlloc(pgStatLocalContext,
                                                   pgstat_track_activity_query_size * MaxBackends);
@@ -2832,6 +2836,8 @@ pgstat_read_current_status(void)
                                 */
                                strcpy(localappname, (char *) beentry->st_appname);
                                localentry->st_appname = localappname;
+                               strcpy(localclienthostname, (char *) beentry->st_clienthostname);
+                               localentry->st_clienthostname = localclienthostname;
                                strcpy(localactivity, (char *) beentry->st_activity);
                                localentry->st_activity = localactivity;
                        }
@@ -2850,6 +2856,7 @@ pgstat_read_current_status(void)
                {
                        localentry++;
                        localappname += NAMEDATALEN;
+                       localclienthostname += NAMEDATALEN;
                        localactivity += pgstat_track_activity_query_size;
                        localNumBackends++;
                }