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Diagnose incompatible OpenLDAP versions during build and test.
With OpenLDAP versions 2.4.24 through 2.4.31, inclusive, PostgreSQL backends can crash at exit. Raise a warning during "configure" based on the compile-time OpenLDAP version number, and test the crash scenario in the dblink test suite. Back-patch to 9.0 (all supported versions).
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‎configure

Lines changed: 77 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -13663,6 +13663,17 @@ fi
1366313663

1366413664
fi
1366513665

13666+
# PGAC_LDAP_SAFE
13667+
# --------------
13668+
# PostgreSQL sometimes loads libldap_r and plain libldap into the same
13669+
# process. Check for OpenLDAP versions known not to tolerate doing so; assume
13670+
# non-OpenLDAP implementations are safe. The dblink test suite exercises the
13671+
# hazardous interaction directly.
13672+
13673+
13674+
13675+
13676+
1366613677
if test "$with_ldap" = yes ; then
1366713678
if test "$PORTNAME" != "win32"; then
1366813679

@@ -13820,6 +13831,72 @@ fi
1382013831

1382113832
done
1382213833

13834+
{ $as_echo "$as_me:$LINENO: checking for compatible LDAP implementation" >&5
13835+
$as_echo_n "checking for compatible LDAP implementation... " >&6; }
13836+
if test "${pgac_cv_ldap_safe+set}" = set; then
13837+
$as_echo_n "(cached) " >&6
13838+
else
13839+
cat >conftest.$ac_ext <<_ACEOF
13840+
/* confdefs.h. */
13841+
_ACEOF
13842+
cat confdefs.h >>conftest.$ac_ext
13843+
cat >>conftest.$ac_ext <<_ACEOF
13844+
/* end confdefs.h. */
13845+
#include <ldap.h>
13846+
#if !defined(LDAP_VENDOR_VERSION) || \
13847+
(defined(LDAP_API_FEATURE_X_OPENLDAP) && \
13848+
LDAP_VENDOR_VERSION >= 20424 && LDAP_VENDOR_VERSION <= 20431)
13849+
choke me
13850+
#endif
13851+
int
13852+
main ()
13853+
{
13854+
13855+
;
13856+
return 0;
13857+
}
13858+
_ACEOF
13859+
rm -f conftest.$ac_objext
13860+
if { (ac_try="$ac_compile"
13861+
case "(($ac_try" in
13862+
*\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
13863+
*) ac_try_echo=$ac_try;;
13864+
esac
13865+
eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
13866+
$as_echo "$ac_try_echo") >&5
13867+
(eval "$ac_compile") 2>conftest.er1
13868+
ac_status=$?
13869+
grep -v '^ *+' conftest.er1 >conftest.err
13870+
rm -f conftest.er1
13871+
cat conftest.err >&5
13872+
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
13873+
(exit $ac_status); } && {
13874+
test -z "$ac_c_werror_flag" ||
13875+
test ! -s conftest.err
13876+
} && test -s conftest.$ac_objext; then
13877+
pgac_cv_ldap_safe=yes
13878+
else
13879+
$as_echo "$as_me: failed program was:" >&5
13880+
sed 's/^/| /' conftest.$ac_ext >&5
13881+
13882+
pgac_cv_ldap_safe=no
13883+
fi
13884+
13885+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
13886+
fi
13887+
{ $as_echo "$as_me:$LINENO: result: $pgac_cv_ldap_safe" >&5
13888+
$as_echo "$pgac_cv_ldap_safe" >&6; }
13889+
13890+
if test "$pgac_cv_ldap_safe" != yes; then
13891+
{ $as_echo "$as_me:$LINENO: WARNING:
13892+
*** With OpenLDAP versions 2.4.24 through 2.4.31, inclusive, each backend
13893+
*** process that loads libpq (via WAL receiver, dblink, or postgres_fdw) and
13894+
*** also uses LDAP will crash on exit." >&5
13895+
$as_echo "$as_me: WARNING:
13896+
*** With OpenLDAP versions 2.4.24 through 2.4.31, inclusive, each backend
13897+
*** process that loads libpq (via WAL receiver, dblink, or postgres_fdw) and
13898+
*** also uses LDAP will crash on exit." >&2;}
13899+
fi
1382313900
else
1382413901

1382513902
for ac_header in winldap.h

‎configure.in

Lines changed: 29 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1067,10 +1067,39 @@ if test "$with_libxslt" = yes ; then
10671067
AC_CHECK_HEADER(libxslt/xslt.h, [], [AC_MSG_ERROR([header file <libxslt/xslt.h> is required for XSLT support])])
10681068
fi
10691069

1070+
# PGAC_LDAP_SAFE
1071+
# --------------
1072+
# PostgreSQL sometimes loads libldap_r and plain libldap into the same
1073+
# process. Check for OpenLDAP versions known not to tolerate doing so; assume
1074+
# non-OpenLDAP implementations are safe. The dblink test suite exercises the
1075+
# hazardous interaction directly.
1076+
1077+
AC_DEFUN([PGAC_LDAP_SAFE],
1078+
[AC_CACHE_CHECK([for compatible LDAP implementation], [pgac_cv_ldap_safe],
1079+
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
1080+
[#include <ldap.h>
1081+
#if !defined(LDAP_VENDOR_VERSION) || \
1082+
(defined(LDAP_API_FEATURE_X_OPENLDAP) && \
1083+
LDAP_VENDOR_VERSION >= 20424 && LDAP_VENDOR_VERSION <= 20431)
1084+
choke me
1085+
#endif], [])],
1086+
[pgac_cv_ldap_safe=yes],
1087+
[pgac_cv_ldap_safe=no])])
1088+
1089+
if test "$pgac_cv_ldap_safe" != yes; then
1090+
AC_MSG_WARN([
1091+
*** With OpenLDAP versions 2.4.24 through 2.4.31, inclusive, each backend
1092+
*** process that loads libpq (via WAL receiver, dblink, or postgres_fdw) and
1093+
*** also uses LDAP will crash on exit.])
1094+
fi])
1095+
1096+
1097+
10701098
if test "$with_ldap" = yes ; then
10711099
if test "$PORTNAME" != "win32"; then
10721100
AC_CHECK_HEADERS(ldap.h, [],
10731101
[AC_MSG_ERROR([header file <ldap.h> is required for LDAP])])
1102+
PGAC_LDAP_SAFE
10741103
else
10751104
AC_CHECK_HEADERS(winldap.h, [],
10761105
[AC_MSG_ERROR([header file <winldap.h> is required for LDAP])],

‎contrib/dblink/Makefile

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,9 @@ SHLIB_PREREQS = submake-libpq
99
EXTENSION = dblink
1010
DATA = dblink--1.0.sql dblink--unpackaged--1.0.sql
1111

12-
REGRESS = dblink
12+
REGRESS = paths dblink
13+
REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
14+
EXTRA_CLEAN = sql/paths.sql expected/paths.out
1315

1416
# the db name is hard-coded in the tests
1517
override USE_MODULE_DB =

‎contrib/dblink/expected/.gitignore

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1 @@
1+
/paths.out

‎contrib/dblink/expected/dblink.out

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -105,6 +105,33 @@ SELECT *
105105
FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
106106
WHERE t.a > 7;
107107
ERROR: connection not available
108+
-- The first-level connection's backend will crash on exit given OpenLDAP
109+
-- [2.4.24, 2.4.31]. We won't see evidence of any crash until the victim
110+
-- process terminates and the postmaster responds. If process termination
111+
-- entails writing a core dump, that can take awhile. Wait for the process to
112+
-- vanish. At that point, the postmaster has called waitpid() on the crashed
113+
-- process, and it will accept no new connections until it has reinitialized
114+
-- the cluster. (We can't exploit pg_stat_activity, because the crash happens
115+
-- after the backend updates shared memory to reflect its impending exit.)
116+
DO $pl$
117+
DECLARE
118+
detail text;
119+
BEGIN
120+
PERFORM wait_pid(crash_pid)
121+
FROM dblink('dbname=contrib_regression', $$
122+
SELECT pg_backend_pid() FROM dblink(
123+
'service=test_ldap dbname=contrib_regression',
124+
-- This string concatenation is a hack to shoehorn a
125+
-- set_pgservicefile call into the SQL statement.
126+
'SELECT 1' || set_pgservicefile('pg_service.conf')
127+
) t(c int)
128+
$$) AS t(crash_pid int);
129+
EXCEPTION WHEN OTHERS THEN
130+
GET STACKED DIAGNOSTICS detail = PG_EXCEPTION_DETAIL;
131+
-- Expected error in a non-LDAP build.
132+
IF NOT detail LIKE 'syntax error in service file%' THEN RAISE; END IF;
133+
END
134+
$pl$;
108135
-- create a persistent connection
109136
SELECT dblink_connect('dbname=contrib_regression');
110137
dblink_connect

‎contrib/dblink/input/paths.source

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
-- Initialization that requires path substitution.
2+
3+
CREATE FUNCTION putenv(text)
4+
RETURNS void
5+
AS '@libdir@/regress@DLSUFFIX@', 'regress_putenv'
6+
LANGUAGE C STRICT;
7+
8+
CREATE FUNCTION wait_pid(int)
9+
RETURNS void
10+
AS '@libdir@/regress@DLSUFFIX@'
11+
LANGUAGE C STRICT;
12+
13+
CREATE FUNCTION set_pgservicefile(text) RETURNS void LANGUAGE SQL
14+
AS $$SELECT putenv('PGSERVICEFILE=@abs_srcdir@/' || $1)$$;

‎contrib/dblink/output/paths.source

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
1+
-- Initialization that requires path substitution.
2+
CREATE FUNCTION putenv(text)
3+
RETURNS void
4+
AS '@libdir@/regress@DLSUFFIX@', 'regress_putenv'
5+
LANGUAGE C STRICT;
6+
CREATE FUNCTION wait_pid(int)
7+
RETURNS void
8+
AS '@libdir@/regress@DLSUFFIX@'
9+
LANGUAGE C STRICT;
10+
CREATE FUNCTION set_pgservicefile(text) RETURNS void LANGUAGE SQL
11+
AS $$SELECT putenv('PGSERVICEFILE=@abs_srcdir@/' || $1)$$;

‎contrib/dblink/pg_service.conf

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,7 @@
1+
# pg_service.conf for minimally exercising libpq use of LDAP.
2+
3+
# Having failed to reach an LDAP server, libpq essentially ignores the
4+
# "service=test_ldap" in its connection string. Contact the "discard"
5+
# service; the test works whether or not it answers.
6+
[test_ldap]
7+
ldap://127.0.0.1:9/base?attribute?one?filter

‎contrib/dblink/sql/.gitignore

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1 @@
1+
/paths.sql

‎contrib/dblink/sql/dblink.sql

Lines changed: 28 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -65,6 +65,34 @@ SELECT *
6565
FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
6666
WHERE t.a > 7;
6767

68+
-- The first-level connection's backend will crash on exit given OpenLDAP
69+
-- [2.4.24, 2.4.31]. We won't see evidence of any crash until the victim
70+
-- process terminates and the postmaster responds. If process termination
71+
-- entails writing a core dump, that can take awhile. Wait for the process to
72+
-- vanish. At that point, the postmaster has called waitpid() on the crashed
73+
-- process, and it will accept no new connections until it has reinitialized
74+
-- the cluster. (We can't exploit pg_stat_activity, because the crash happens
75+
-- after the backend updates shared memory to reflect its impending exit.)
76+
DO $pl$
77+
DECLARE
78+
detail text;
79+
BEGIN
80+
PERFORM wait_pid(crash_pid)
81+
FROM dblink('dbname=contrib_regression', $$
82+
SELECT pg_backend_pid() FROM dblink(
83+
'service=test_ldap dbname=contrib_regression',
84+
-- This string concatenation is a hack to shoehorn a
85+
-- set_pgservicefile call into the SQL statement.
86+
'SELECT 1' || set_pgservicefile('pg_service.conf')
87+
) t(c int)
88+
$$) AS t(crash_pid int);
89+
EXCEPTION WHEN OTHERS THEN
90+
GET STACKED DIAGNOSTICS detail = PG_EXCEPTION_DETAIL;
91+
-- Expected error in a non-LDAP build.
92+
IF NOT detail LIKE 'syntax error in service file%' THEN RAISE; END IF;
93+
END
94+
$pl$;
95+
6896
-- create a persistent connection
6997
SELECT dblink_connect('dbname=contrib_regression');
7098

‎src/test/regress/regress.c

Lines changed: 46 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
66

77
#include <float.h>
88
#include <math.h>
9+
#include <signal.h>
910

1011
#include "access/transam.h"
1112
#include "access/xact.h"
@@ -14,8 +15,10 @@
1415
#include "commands/trigger.h"
1516
#include "executor/executor.h"
1617
#include "executor/spi.h"
18+
#include "miscadmin.h"
1719
#include "utils/builtins.h"
1820
#include "utils/geo_decls.h"
21+
#include "utils/memutils.h"
1922
#include "utils/rel.h"
2023

2124

@@ -35,6 +38,8 @@ extern char *reverse_name(char *string);
3538
extern int oldstyle_length(int n, text *t);
3639
extern Datum int44in(PG_FUNCTION_ARGS);
3740
extern Datum int44out(PG_FUNCTION_ARGS);
41+
extern Datum regress_putenv(PG_FUNCTION_ARGS);
42+
extern Datum wait_pid(PG_FUNCTION_ARGS);
3843

3944
#ifdef PG_MODULE_MAGIC
4045
PG_MODULE_MAGIC;
@@ -737,3 +742,44 @@ int44out(PG_FUNCTION_ARGS)
737742
*--walk = '\0';
738743
PG_RETURN_CSTRING(result);
739744
}
745+
746+
PG_FUNCTION_INFO_V1(regress_putenv);
747+
748+
Datum
749+
regress_putenv(PG_FUNCTION_ARGS)
750+
{
751+
MemoryContext oldcontext;
752+
char *envbuf;
753+
754+
if (!superuser())
755+
elog(ERROR, "must be superuser to change environment variables");
756+
757+
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
758+
envbuf = text_to_cstring((text *) PG_GETARG_POINTER(0));
759+
MemoryContextSwitchTo(oldcontext);
760+
761+
if (putenv(envbuf) != 0)
762+
elog(ERROR, "could not set environment variable: %m");
763+
764+
PG_RETURN_VOID();
765+
}
766+
767+
/* Sleep until no process has a given PID. */
768+
PG_FUNCTION_INFO_V1(wait_pid);
769+
770+
Datum
771+
wait_pid(PG_FUNCTION_ARGS)
772+
{
773+
int pid = PG_GETARG_INT32(0);
774+
775+
if (!superuser())
776+
elog(ERROR, "must be superuser to check PID liveness");
777+
778+
while (kill(pid, 0) == 0)
779+
pg_usleep(50000);
780+
781+
if (errno != ESRCH)
782+
elog(ERROR, "could not check PID %d liveness: %m", pid);
783+
784+
PG_RETURN_VOID();
785+
}

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