diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index e8d8e6f828..6d80cc2d64 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -171,6 +171,9 @@ static ProcSignalReason RecoveryConflictReason; static MemoryContext row_description_context = NULL; static StringInfoData row_description_buf; +/* Hook for plugins to get control at start of session */ +session_start_hook_type session_start_hook = NULL; + /* ---------------------------------------------------------------- * decls for routines only used in this file * ---------------------------------------------------------------- @@ -3968,6 +3971,9 @@ PostgresMain(int argc, char *argv[], if (!IsUnderPostmaster) PgStartTime = GetCurrentTimestamp(); + if (session_start_hook) + (*session_start_hook) (); + /* * POSTGRES main processing loop begins here * diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h index ec21f7e45c..f42935f019 100644 --- a/src/include/tcop/tcopprot.h +++ b/src/include/tcop/tcopprot.h @@ -30,6 +30,10 @@ extern PGDLLIMPORT const char *debug_query_string; extern int max_stack_depth; extern int PostAuthDelay; +/* Hook for plugins to get control at start session */ +typedef void (*session_start_hook_type) (void); +extern PGDLLIMPORT session_start_hook_type session_start_hook; + /* GUC-configurable parameters */ typedef enum diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile index b2eaef3bff..abb3203903 100644 --- a/src/test/modules/Makefile +++ b/src/test/modules/Makefile @@ -21,6 +21,7 @@ SUBDIRS = \ test_predtest \ test_rbtree \ test_rls_hooks \ + test_session_hooks \ test_shm_mq \ unsafe_tests \ worker_spi diff --git a/src/test/modules/test_session_hooks/.gitignore b/src/test/modules/test_session_hooks/.gitignore new file mode 100644 index 0000000000..5dcb3ff972 --- /dev/null +++ b/src/test/modules/test_session_hooks/.gitignore @@ -0,0 +1,4 @@ +# Generated subdirectories +/log/ +/results/ +/tmp_check/ diff --git a/src/test/modules/test_session_hooks/Makefile b/src/test/modules/test_session_hooks/Makefile new file mode 100644 index 0000000000..a6fdb0434a --- /dev/null +++ b/src/test/modules/test_session_hooks/Makefile @@ -0,0 +1,23 @@ +# src/test/modules/test_session_hooks/Makefile + +MODULE_big = test_session_hooks +OBJS = test_session_hooks.o $(WIN32RES) +PGFILEDESC = "test_session_hooks - tests for start session hook" + +REGRESS = test_session_hooks +REGRESS_OPTS = --create-role=regress_sess_hook_usr1,regress_sess_hook_usr2 --temp-config=$(top_srcdir)/src/test/modules/test_session_hooks/session_hooks.conf +# Disabled because these tests require extra configuration with +# "shared_preload_libraries=test_session_hooks", which typical +# installcheck users do not have (e.g. buildfarm clients). +NO_INSTALLCHECK = 1 + +ifdef USE_PGXS +PG_CONFIG = pg_config +PGXS := $(shell $(PG_CONFIG) --pgxs) +include $(PGXS) +else +subdir = src/test/modules/test_session_hooks +top_builddir = ../../../.. +include $(top_builddir)/src/Makefile.global +include $(top_srcdir)/contrib/contrib-global.mk +endif diff --git a/src/test/modules/test_session_hooks/README b/src/test/modules/test_session_hooks/README new file mode 100644 index 0000000000..e945ffc45b --- /dev/null +++ b/src/test/modules/test_session_hooks/README @@ -0,0 +1,10 @@ +test_session_hooks +================== + +test_session_hooks is an example of how to use hook for session start. + +This module will insert into a pre-existing table called "session_hook_log" +a log activity which happens at session start. It is possible to control +which user information is logged when using the configuration parameter +"test_session_hooks.username". If set, the hooks will log only information +of the session user matching the parameter value. diff --git a/src/test/modules/test_session_hooks/expected/test_session_hooks.out b/src/test/modules/test_session_hooks/expected/test_session_hooks.out new file mode 100644 index 0000000000..0992b990ba --- /dev/null +++ b/src/test/modules/test_session_hooks/expected/test_session_hooks.out @@ -0,0 +1,34 @@ +-- +-- Tests for start session hook +-- +-- Only activity from role regress_sess_hook_usr2 is logged. +ALTER ROLE regress_sess_hook_usr1 SUPERUSER LOGIN; +ALTER ROLE regress_sess_hook_usr2 SUPERUSER LOGIN; +\set prevdb :DBNAME +\set prevusr :USER +CREATE TABLE session_hook_log(id SERIAL, dbname TEXT, username TEXT, hook_at TEXT); +SELECT * FROM session_hook_log ORDER BY id; + id | dbname | username | hook_at +----+--------+----------+--------- +(0 rows) + +\c :prevdb regress_sess_hook_usr1 +SELECT * FROM session_hook_log ORDER BY id; + id | dbname | username | hook_at +----+--------+----------+--------- +(0 rows) + +\c :prevdb regress_sess_hook_usr2 +SELECT * FROM session_hook_log ORDER BY id; + id | dbname | username | hook_at +----+--------------------+------------------------+--------- + 1 | contrib_regression | regress_sess_hook_usr2 | START +(1 row) + +\c :prevdb :prevusr +SELECT * FROM session_hook_log ORDER BY id; + id | dbname | username | hook_at +----+--------------------+------------------------+--------- + 1 | contrib_regression | regress_sess_hook_usr2 | START +(1 row) + diff --git a/src/test/modules/test_session_hooks/session_hooks.conf b/src/test/modules/test_session_hooks/session_hooks.conf new file mode 100644 index 0000000000..fc62b4adef --- /dev/null +++ b/src/test/modules/test_session_hooks/session_hooks.conf @@ -0,0 +1,2 @@ +shared_preload_libraries = 'test_session_hooks' +test_session_hooks.username = regress_sess_hook_usr2 diff --git a/src/test/modules/test_session_hooks/sql/test_session_hooks.sql b/src/test/modules/test_session_hooks/sql/test_session_hooks.sql new file mode 100644 index 0000000000..01a285e9a5 --- /dev/null +++ b/src/test/modules/test_session_hooks/sql/test_session_hooks.sql @@ -0,0 +1,17 @@ +-- +-- Tests for start session hook +-- + +-- Only activity from role regress_sess_hook_usr2 is logged. +ALTER ROLE regress_sess_hook_usr1 SUPERUSER LOGIN; +ALTER ROLE regress_sess_hook_usr2 SUPERUSER LOGIN; +\set prevdb :DBNAME +\set prevusr :USER +CREATE TABLE session_hook_log(id SERIAL, dbname TEXT, username TEXT, hook_at TEXT); +SELECT * FROM session_hook_log ORDER BY id; +\c :prevdb regress_sess_hook_usr1 +SELECT * FROM session_hook_log ORDER BY id; +\c :prevdb regress_sess_hook_usr2 +SELECT * FROM session_hook_log ORDER BY id; +\c :prevdb :prevusr +SELECT * FROM session_hook_log ORDER BY id; diff --git a/src/test/modules/test_session_hooks/test_session_hooks.c b/src/test/modules/test_session_hooks/test_session_hooks.c new file mode 100644 index 0000000000..0e69ddf954 --- /dev/null +++ b/src/test/modules/test_session_hooks/test_session_hooks.c @@ -0,0 +1,134 @@ +/* ------------------------------------------------------------------------- + * + * test_session_hooks.c + * Code for testing hook for session start. + * + * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/test/modules/test_session_hooks/test_session_hooks.c + * + * ------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "access/parallel.h" +#include "access/xact.h" +#include "access/xlog.h" +#include "commands/dbcommands.h" +#include "executor/spi.h" +#include "lib/stringinfo.h" +#include "miscadmin.h" +#include "tcop/tcopprot.h" +#include "utils/snapmgr.h" +#include "utils/builtins.h" + +PG_MODULE_MAGIC; + +/* Entry point of library loading/unloading */ +void _PG_init(void); +void _PG_fini(void); + +/* GUC variables */ +static char *session_hook_username = "postgres"; + +/* Previous hook on stack */ +static session_start_hook_type prev_session_start_hook = NULL; + +static void +register_session_hook(const char *hook_at) +{ + const char *username; + + StartTransactionCommand(); + SPI_connect(); + PushActiveSnapshot(GetTransactionSnapshot()); + + /* Check the current user validity */ + username = GetUserNameFromId(GetUserId(), false); + + /* Register log just for configured username */ + if (strcmp(username, session_hook_username) == 0) + { + const char *dbname; + int ret; + StringInfoData buf; + + dbname = get_database_name(MyDatabaseId); + + initStringInfo(&buf); + + appendStringInfo(&buf, "INSERT INTO session_hook_log (dbname, username, hook_at) "); + appendStringInfo(&buf, "VALUES (%s, %s, %s);", + quote_literal_cstr(dbname), + quote_literal_cstr(username), + quote_literal_cstr(hook_at)); + + ret = SPI_exec(buf.data, 0); + if (ret != SPI_OK_INSERT) + elog(ERROR, "SPI_execute failed: error code %d", ret); + } + + SPI_finish(); + PopActiveSnapshot(); + CommitTransactionCommand(); +} + +/* sample session start hook function */ +static void +sample_session_start_hook(void) +{ + if (prev_session_start_hook) + prev_session_start_hook(); + + /* nothing to do while in recovery */ + if (RecoveryInProgress()) + return; + + /* consider only normal backends */ + if (MyBackendId == InvalidBackendId) + return; + + /* consider backends connected to a database */ + if (!OidIsValid(MyDatabaseId)) + return; + + /* no parallel workers */ + if (IsParallelWorker()) + return; + + register_session_hook("START"); +} + +/* + * Module load callback + */ +void +_PG_init(void) +{ + /* Save previous hook */ + prev_session_start_hook = session_start_hook; + + /* Set new hook */ + session_start_hook = sample_session_start_hook; + + /* Load GUCs */ + DefineCustomStringVariable("test_session_hooks.username", + "Username to register log on session start", + NULL, + &session_hook_username, + "postgres", + PGC_SIGHUP, + 0, NULL, NULL, NULL); +} + +/* + * Module unload callback + */ +void +_PG_fini(void) +{ + /* Uninstall hook */ + session_start_hook = prev_session_start_hook; +}