Hi
>>
>>
>> But afaict there's no problem with using pqParseInput3() and
>> PQexecFinish() even if the message isn't handled as part of the
>> transaction. Some other messages that pqParseInput3 handles which are
>> not part of the transaction are 'N' (Notice) and 'K' (secret key).
>>
>
> I have to recheck it
>
here is new version based on usage of PQexecFinish
Regards
Pavel
>
> Regards
>
> Pavel
>
>
From 4567473ebd7fec9dc836793e8e80244b22e5c96b Mon Sep 17 00:00:00 2001
From: "ok...@github.com" <pavel.steh...@gmail.com>
Date: Mon, 24 Jul 2023 20:18:16 +0200
Subject: [PATCH 2/2] Implementation of %N prompt placeholder
It is based on forcing reporting feature"role" GUC to client.
---
doc/src/sgml/ref/psql-ref.sgml | 19 +++++++++++++++++-
src/bin/psql/command.c | 13 +++++++++++++
src/bin/psql/prompt.c | 35 ++++++++++++++++++++++++++++++++++
src/bin/psql/settings.h | 1 +
src/bin/psql/startup.c | 32 +++++++++++++++++++++++++++++++
5 files changed, 99 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index 182e58353f..b5da83013e 100644
--- a/doc/src/sgml/ref/psql-ref.sgml
+++ b/doc/src/sgml/ref/psql-ref.sgml
@@ -4567,7 +4567,24 @@ testdb=> <userinput>INSERT INTO my_table VALUES (:'content');</userinput>
<listitem><para>The port number at which the database server is listening.</para></listitem>
</varlistentry>
- <varlistentry id="app-psql-prompting-n">
+ <varlistentry id="app-psql-prompting-n-uc">
+ <term><literal>%N</literal></term>
+ <listitem>
+ <para>
+ The database role name. This value is specified by command
+ <command>SET ROLE</command>. Until execution of this command
+ the value is set to the database session user name.
+ </para>
+
+ <para>
+ This substitution requires <productname>PostgreSQL</productname>
+ version 16 and up. When you use older version, the empty string
+ is used instead.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry id="app-psql-prompting-n-lc">
<term><literal>%n</literal></term>
<listitem>
<para>
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 1300869d79..bf67febc11 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -3861,6 +3861,7 @@ SyncVariables(void)
{
char vbuf[32];
const char *server_version;
+ PGresult *result;
/* get stuff from connection */
pset.encoding = PQclientEncoding(pset.db);
@@ -3890,6 +3891,18 @@ SyncVariables(void)
/* send stuff to it, too */
PQsetErrorVerbosity(pset.db, pset.verbosity);
PQsetErrorContextVisibility(pset.db, pset.show_context);
+
+ /* link role GUC when it is needed for prompt */
+ if (pset.prompt_shows_role)
+ result = PQlinkParameterStatus(pset.db, "role");
+ else
+ result = PQunlinkParameterStatus(pset.db, "role");
+
+ if (PQresultStatus(result) != PGRES_COMMAND_OK)
+ pg_log_info("cannot set REPORT flag on configuration variable \"role\": %s",
+ PQerrorMessage(pset.db));
+
+ PQclear(result);
}
/*
diff --git a/src/bin/psql/prompt.c b/src/bin/psql/prompt.c
index 969cd9908e..b0f5158c59 100644
--- a/src/bin/psql/prompt.c
+++ b/src/bin/psql/prompt.c
@@ -165,6 +165,41 @@ get_prompt(promptStatus_t status, ConditionalStack cstack)
if (pset.db)
strlcpy(buf, session_username(), sizeof(buf));
break;
+ /* DB server user role */
+ case 'N':
+ if (pset.db)
+ {
+ int minServerMajor;
+ int serverMajor;
+ const char *rolename = NULL;
+
+ /*
+ * This feature requires GUC "role" to be marked
+ * as GUC_REPORT. Without it is hard to specify fallback
+ * result. Returning empty value can be messy, returning
+ * PQuser like session_username can be messy too.
+ * Exec query is not too practical too, because it doesn't
+ * work when session is not in transactional state, and
+ * CURRENT_ROLE returns different result when role is not
+ * explicitly specified by SET ROLE.
+ */
+ minServerMajor = 1600;
+ serverMajor = PQserverVersion(pset.db) / 100;
+ if (serverMajor >= minServerMajor)
+ {
+ rolename = PQparameterStatus(pset.db, "role");
+
+ /* fallback when role is not set yet */
+ if (rolename && strcmp(rolename, "none") == 0)
+ rolename = session_username();
+ }
+
+ if (rolename)
+ strlcpy(buf, rolename, sizeof(buf));
+ else
+ buf[0] = '\0';
+ }
+ break;
/* backend pid */
case 'p':
if (pset.db)
diff --git a/src/bin/psql/settings.h b/src/bin/psql/settings.h
index 1106954236..cb7c12bd1d 100644
--- a/src/bin/psql/settings.h
+++ b/src/bin/psql/settings.h
@@ -154,6 +154,7 @@ typedef struct _psqlSettings
PGVerbosity verbosity; /* current error verbosity level */
bool show_all_results;
PGContextVisibility show_context; /* current context display level */
+ bool prompt_shows_role;
} PsqlSettings;
extern PsqlSettings pset;
diff --git a/src/bin/psql/startup.c b/src/bin/psql/startup.c
index 5a28b6f713..0dac396525 100644
--- a/src/bin/psql/startup.c
+++ b/src/bin/psql/startup.c
@@ -1094,10 +1094,40 @@ histcontrol_hook(const char *newval)
return true;
}
+static void
+prompt_needs_role_parameter_status(void)
+{
+ PGresult *result;
+
+ if (!pset.db)
+ return;
+
+ pset.prompt_shows_role = false;
+
+ if (pset.prompt1 && strstr(pset.prompt1, "%N"))
+ pset.prompt_shows_role = true;
+ else if (pset.prompt2 && strstr(pset.prompt2, "%N"))
+ pset.prompt_shows_role = true;
+ else if (pset.prompt3 && strstr(pset.prompt3, "%N"))
+ pset.prompt_shows_role = true;
+
+ if (pset.prompt_shows_role)
+ result = PQlinkParameterStatus(pset.db, "role");
+ else
+ result = PQunlinkParameterStatus(pset.db, "role");
+
+ if (PQresultStatus(result) != PGRES_COMMAND_OK)
+ pg_log_info("cannot set REPORT flag on configuration variable \"role\": %s",
+ PQerrorMessage(pset.db));
+
+ PQclear(result);
+}
+
static bool
prompt1_hook(const char *newval)
{
pset.prompt1 = newval ? newval : "";
+ prompt_needs_role_parameter_status();
return true;
}
@@ -1105,6 +1135,7 @@ static bool
prompt2_hook(const char *newval)
{
pset.prompt2 = newval ? newval : "";
+ prompt_needs_role_parameter_status();
return true;
}
@@ -1112,6 +1143,7 @@ static bool
prompt3_hook(const char *newval)
{
pset.prompt3 = newval ? newval : "";
+ prompt_needs_role_parameter_status();
return true;
}
--
2.41.0
From 3d1d739ef973e9e58bd930c02657abd42c38d732 Mon Sep 17 00:00:00 2001
From: "ok...@github.com" <pavel.steh...@gmail.com>
Date: Mon, 24 Jul 2023 20:13:17 +0200
Subject: [PATCH 1/2] Protocol ReportGUC message
This patch implements dynamic reporting changes of GUC to client side.
The flags per GUC can be changed by functions SetGUCOptionFlag and UsetGUCOptionFlag.
---
doc/src/sgml/protocol.sgml | 37 +++++++++++++++++++++++++++++
src/backend/tcop/postgres.c | 32 +++++++++++++++++++++++++
src/backend/utils/misc/guc.c | 31 ++++++++++++++++++++++++
src/include/libpq/protocol.h | 1 +
src/include/utils/guc.h | 2 ++
src/interfaces/libpq/exports.txt | 2 ++
src/interfaces/libpq/fe-exec.c | 36 +++++++++++++++++++++++++++-
src/interfaces/libpq/fe-protocol3.c | 1 -
src/interfaces/libpq/fe-trace.c | 12 ++++++++++
src/interfaces/libpq/libpq-fe.h | 3 +++
src/interfaces/libpq/libpq-int.h | 4 +++-
11 files changed, 158 insertions(+), 3 deletions(-)
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index b11d9a6ba3..fe6c4042fd 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -5401,6 +5401,43 @@ psql "dbname=postgres replication=database" -c "IDENTIFY_SYSTEM;"
</listitem>
</varlistentry>
+ <varlistentry id="protocol-message-formats-ReportGUC">
+ <term>ReportGUC (F)</term>
+ <listitem>
+ <variablelist>
+ <varlistentry>
+ <term>Byte1('r')</term>
+ <listitem>
+ <para>
+ Identifies the message type. ReportGUC is sent by
+ frontend when the changes of specified GUC option
+ should be (or should not be) reported to state parameter.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Byte1</term>
+ <listitem>
+ <para>
+ 't' when reporting should be enables, 'f' if reporting should be
+ disabled.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>String</term>
+ <listitem>
+ <para>
+ The name of GUC option.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="protocol-message-formats-RowDescription">
<term>RowDescription (B)</term>
<listitem>
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index e4756f8be2..0e4ddbf8ee 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -451,6 +451,11 @@ SocketBackend(StringInfo inBuf)
doing_extended_query_message = false;
break;
+ case PqMsg_ReportGUC:
+ maxmsglen = PQ_SMALL_MESSAGE_LIMIT;
+ doing_extended_query_message = false;
+ break;
+
default:
/*
@@ -4835,6 +4840,33 @@ PostgresMain(const char *dbname, const char *username)
send_ready_for_query = true;
break;
+ case PqMsg_ReportGUC:
+ {
+ const char *name;
+ const char *status;
+ int is_set;
+
+ is_set = pq_getmsgbyte(&input_message);
+ name = pq_getmsgstring(&input_message);
+ pq_getmsgend(&input_message);
+
+ if (is_set == 't')
+ {
+ SetGUCOptionFlag(name, GUC_REPORT);
+ status = "SET REPORT_GUC";
+ }
+ else
+ {
+ UnsetGUCOptionFlag(name, GUC_REPORT);
+ status = "UNSET REPORT_GUC";
+ }
+
+ pq_puttextmessage(PqMsg_CommandComplete, status);
+
+ valgrind_report_error_query("ReportGUC message");
+ }
+ break;
+
/*
* 'X' means that the frontend is closing down the socket. EOF
* means unexpected loss of frontend connection. Either way,
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 84e7ad4d90..4a1e968255 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2532,6 +2532,37 @@ BeginReportingGUCOptions(void)
}
}
+/*
+ * Allow to set / unset dynamicaly flags to GUC variables
+ */
+void
+SetGUCOptionFlag(const char *name, int flag)
+{
+ struct config_generic *conf;
+
+ /* only GUC_REPORT flag is supported now */
+ Assert(flag == GUC_REPORT);
+
+ conf = find_option(name, false, true, ERROR);
+ conf->flags |= flag;
+
+ if (flag == GUC_REPORT)
+ /* force transmit value of related option to client Parameter Status */
+ ReportGUCOption(conf);
+}
+
+void
+UnsetGUCOptionFlag(const char *name, int flag)
+{
+ struct config_generic *conf;
+
+ /* only GUC_REPORT flag is supported now */
+ Assert(flag == GUC_REPORT);
+
+ conf = find_option(name, false, true, ERROR);
+ conf->flags &= ~flag;
+}
+
/*
* ReportChangedGUCOptions: report recently-changed GUC_REPORT variables
*
diff --git a/src/include/libpq/protocol.h b/src/include/libpq/protocol.h
index cc46f4b586..bd2c368b54 100644
--- a/src/include/libpq/protocol.h
+++ b/src/include/libpq/protocol.h
@@ -27,6 +27,7 @@
#define PqMsg_Sync 'S'
#define PqMsg_Terminate 'X'
#define PqMsg_CopyFail 'f'
+#define PqMsg_ReportGUC 'r'
#define PqMsg_GSSResponse 'p'
#define PqMsg_PasswordMessage 'p'
#define PqMsg_SASLInitialResponse 'p'
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index e89083ee0e..c200ca9b34 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -370,6 +370,8 @@ extern void ResetAllOptions(void);
extern void AtStart_GUC(void);
extern int NewGUCNestLevel(void);
extern void AtEOXact_GUC(bool isCommit, int nestLevel);
+extern void SetGUCOptionFlag(const char *name, int flag);
+extern void UnsetGUCOptionFlag(const char *name, int flag);
extern void BeginReportingGUCOptions(void);
extern void ReportChangedGUCOptions(void);
extern void ParseLongOption(const char *string, char **name, char **value);
diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt
index 850734ac96..7e101368d5 100644
--- a/src/interfaces/libpq/exports.txt
+++ b/src/interfaces/libpq/exports.txt
@@ -191,3 +191,5 @@ PQclosePrepared 188
PQclosePortal 189
PQsendClosePrepared 190
PQsendClosePortal 191
+PQlinkParameterStatus 192
+PQunlinkParameterStatus 193
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index 974d462d4b..c34a826fb1 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -1069,6 +1069,33 @@ pqSaveMessageField(PGresult *res, char code, const char *value)
res->errFields = pfield;
}
+/*
+ * Add GUC_REPORT flag to specified setting and wait for synchronization
+ * with state parameters.
+ */
+PGresult *
+PQlinkParameterStatus(PGconn *conn, const char *paramName)
+{
+ if (!PQexecStart(conn))
+ return NULL;
+ if (!PQsendTypedCommand(conn, PqMsg_ReportGUC, 't', paramName))
+ return NULL;
+ return PQexecFinish(conn);
+}
+
+/*
+ * Remove GUC_REPORT flag from specified setting.
+ */
+PGresult *
+PQunlinkParameterStatus(PGconn *conn, const char *paramName)
+{
+ if (!PQexecStart(conn))
+ return NULL;
+ if (!PQsendTypedCommand(conn, PqMsg_ReportGUC, 'f', paramName))
+ return NULL;
+ return PQexecFinish(conn);
+}
+
/*
* pqSaveParameterStatus - remember parameter status sent by backend
*/
@@ -2543,11 +2570,14 @@ PQsendClosePortal(PGconn *conn, const char *portal)
*
* Available options for "command" are
* PqMsg_Close for Close; or
- * PqMsg_Describe for Describe.
+ * PqMsg_Describe for Describe; or
+ * PqMsg_ReportGUC for (un)set GUC_REPORT flag.
*
* Available options for "type" are
* 'S' to run a command on a prepared statement; or
* 'P' to run a command on a portal.
+ * 't' to set GUC_REPORT flag
+ * 'f' to unset GUC_REPORT flag
*
* Returns 1 on success and 0 on failure.
*/
@@ -2591,6 +2621,10 @@ PQsendTypedCommand(PGconn *conn, char command, char type, const char *target)
{
entry->queryclass = PGQUERY_DESCRIBE;
}
+ else if (command == PqMsg_ReportGUC)
+ {
+ entry->queryclass = PGQUERY_SETTING;
+ }
else
{
libpq_append_conn_error(conn, "unknown command type provided");
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 5613c56b14..90d4e17e6f 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -2003,7 +2003,6 @@ pqEndcopy3(PGconn *conn)
return 1;
}
-
/*
* PQfn - Send a function call to the POSTGRES backend.
*
diff --git a/src/interfaces/libpq/fe-trace.c b/src/interfaces/libpq/fe-trace.c
index b18e3deab6..2a439080e1 100644
--- a/src/interfaces/libpq/fe-trace.c
+++ b/src/interfaces/libpq/fe-trace.c
@@ -522,6 +522,15 @@ pqTraceOutputZ(FILE *f, const char *message, int *cursor)
pqTraceOutputByte1(f, message, cursor);
}
+/* ReportGUC */
+static void
+pqTraceOutputr(FILE *f, const char *message, int *cursor)
+{
+ fprintf(f, "ReportGUC\t");
+ pqTraceOutputByte1(f, message, cursor);
+ pqTraceOutputString(f, message, cursor, false);
+}
+
/*
* Print the given message to the trace output stream.
*/
@@ -644,6 +653,9 @@ pqTraceOutputMessage(PGconn *conn, const char *message, bool toServer)
case PqMsg_AuthenticationRequest:
pqTraceOutputR(conn->Pfdebug, message, &logCursor);
break;
+ case PqMsg_ReportGUC:
+ pqTraceOutputr(conn->Pfdebug, message, &logCursor);
+ break;
case PqMsg_PortalSuspended:
fprintf(conn->Pfdebug, "PortalSuspended");
/* No message content */
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
index 97762d56f5..ba3ad7e0aa 100644
--- a/src/interfaces/libpq/libpq-fe.h
+++ b/src/interfaces/libpq/libpq-fe.h
@@ -593,6 +593,9 @@ extern unsigned char *PQescapeBytea(const unsigned char *from, size_t from_lengt
size_t *to_length);
+/* Control of dynamic propagation settings to state parameters */
+extern PGresult *PQlinkParameterStatus(PGconn *conn, const char *paramName);
+extern PGresult *PQunlinkParameterStatus(PGconn *conn, const char *paramName);
/* === in fe-print.c === */
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index c745facfec..081e228f2b 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -322,7 +322,8 @@ typedef enum
PGQUERY_PREPARE, /* Parse only (PQprepare) */
PGQUERY_DESCRIBE, /* Describe Statement or Portal */
PGQUERY_SYNC, /* Sync (at end of a pipeline) */
- PGQUERY_CLOSE /* Close Statement or Portal */
+ PGQUERY_CLOSE, /* Close Statement or Portal */
+ PGQUERY_SETTING /* setting GUC_REPORT flag */
} PGQueryClass;
/*
@@ -718,6 +719,7 @@ extern PGresult *pqFunctionCall3(PGconn *conn, Oid fnid,
int *result_buf, int *actual_result_len,
int result_is_int,
const PQArgBlock *args, int nargs);
+extern int pqSendReportGUCMessage(PGconn *conn, const char *paramName, bool create_flag);
/* === in fe-misc.c === */
--
2.41.0
