Hi
one visitor of p2d2 (Prague PostgreSQL Developer Day) asked if it is
possible to show the current role in psql's prompt. I think it is not
possible, but fortunately (with some limits) almost all necessary work is
done, and the patch is short.
In the assigned patch I implemented a new prompt placeholder %N, that shows
the current role name.
(2023-02-03 15:52:28) postgres=# \set PROMPT1 '%n as %N at '%/%=%#
pavel as pavel at postgres=#set role to admin;
SET
pavel as admin at postgres=>set role to default;
SET
pavel as pavel at postgres=#
Comments, notes are welcome.
Regards
Pavel
From d45b620515387c531ea1d663b87dac6144b0b41e Mon Sep 17 00:00:00 2001
From: "ok...@github.com" <pavel.steh...@gmail.com>
Date: Fri, 3 Feb 2023 15:53:56 +0100
Subject: [PATCH 2/2] implementation of psql prompt placeholder %N
---
src/backend/utils/misc/guc_tables.c | 2 +-
src/bin/psql/common.c | 25 +++++++++++++++++++++++++
src/bin/psql/common.h | 1 +
src/bin/psql/prompt.c | 5 +++++
4 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index b46e3b8c55..3188fd015d 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -4144,7 +4144,7 @@ struct config_string ConfigureNamesString[] =
{"role", PGC_USERSET, UNGROUPED,
gettext_noop("Sets the current role."),
NULL,
- GUC_IS_NAME | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_NOT_WHILE_SEC_REST
+ GUC_IS_NAME | GUC_REPORT | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_NOT_WHILE_SEC_REST
},
&role_string,
"none",
diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index f907f5d4e8..9c82b8253b 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -2310,6 +2310,31 @@ session_username(void)
}
+/*
+ * Return the current user of the current connection.
+ * Replace "none" by session user.
+ */
+const char *
+current_role(void)
+{
+ const char *val;
+
+ if (!pset.db)
+ return NULL;
+
+ val = PQparameterStatus(pset.db, "role");
+ if (val)
+ {
+ if (strncmp(val, "none", 4) == 0 && strlen(val) == 4)
+ return session_username();
+ else
+ return val;
+ }
+ else
+ return PQuser(pset.db);
+}
+
+
/* expand_tilde
*
* substitute '~' with HOME or '~username' with username's home dir
diff --git a/src/bin/psql/common.h b/src/bin/psql/common.h
index cc4c73d097..b7a8182dd2 100644
--- a/src/bin/psql/common.h
+++ b/src/bin/psql/common.h
@@ -37,6 +37,7 @@ extern bool SendQuery(const char *query);
extern bool is_superuser(void);
extern bool standard_strings(void);
extern const char *session_username(void);
+extern const char *current_role(void);
extern void expand_tilde(char **filename);
diff --git a/src/bin/psql/prompt.c b/src/bin/psql/prompt.c
index 969cd9908e..91813e1356 100644
--- a/src/bin/psql/prompt.c
+++ b/src/bin/psql/prompt.c
@@ -165,6 +165,11 @@ get_prompt(promptStatus_t status, ConditionalStack cstack)
if (pset.db)
strlcpy(buf, session_username(), sizeof(buf));
break;
+ /* DB server current user name */
+ case 'N':
+ if (pset.db)
+ strlcpy(buf, current_role(), sizeof(buf));
+ break;
/* backend pid */
case 'p':
if (pset.db)
--
2.39.1
From 153994fd93571964766ca054b0f7fe342ac72a6f Mon Sep 17 00:00:00 2001
From: "ok...@github.com" <pavel.steh...@gmail.com>
Date: Fri, 3 Feb 2023 11:40:41 +0100
Subject: [PATCH 1/2] implementation of BACKEND_PID psql's variable
---
src/bin/psql/command.c | 3 +++
src/bin/psql/help.c | 2 ++
2 files changed, 5 insertions(+)
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index b5201edf55..934dd26c61 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -3783,6 +3783,9 @@ SyncVariables(void)
SetVariable(pset.vars, "PORT", PQport(pset.db));
SetVariable(pset.vars, "ENCODING", pg_encoding_to_char(pset.encoding));
+ snprintf(vbuf, sizeof(vbuf), "%d", PQbackendPID(pset.db));
+ SetVariable(pset.vars, "BACKEND_PID", vbuf);
+
/* this bit should match connection_warnings(): */
/* Try to get full text form of version, might include "devel" etc */
server_version = PQparameterStatus(pset.db, "server_version");
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index e45c4aaca5..61c6edd0ba 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -396,6 +396,8 @@ helpVariables(unsigned short int pager)
HELP0(" AUTOCOMMIT\n"
" if set, successful SQL commands are automatically committed\n");
+ HELP0(" BACKEND_PID\n"
+ " id of server process of the current connection\n");
HELP0(" COMP_KEYWORD_CASE\n"
" determines the case used to complete SQL key words\n"
" [lower, upper, preserve-lower, preserve-upper]\n");
--
2.39.1
