Index: src/interfaces/libpq/fe-auth.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/interfaces/libpq/fe-auth.c,v
retrieving revision 1.89
diff -u -r1.89 fe-auth.c
--- src/interfaces/libpq/fe-auth.c	7 Jan 2004 18:56:29 -0000	1.89
+++ src/interfaces/libpq/fe-auth.c	12 Mar 2004 20:07:02 -0000
@@ -590,6 +590,7 @@
 
 		case AUTH_REQ_KRB4:
 #ifdef KRB4
+			pglock_thread();
 			if (pg_krb4_sendauth(PQerrormsg, conn->sock,
 							   (struct sockaddr_in *) & conn->laddr.addr,
 							   (struct sockaddr_in *) & conn->raddr.addr,
@@ -597,8 +598,10 @@
 			{
 				snprintf(PQerrormsg, PQERRORMSG_LENGTH,
 					libpq_gettext("Kerberos 4 authentication failed\n"));
+				pgunlock_thread();
 				return STATUS_ERROR;
 			}
+			pgunlock_thread();
 			break;
 #else
 			snprintf(PQerrormsg, PQERRORMSG_LENGTH,
@@ -722,6 +725,7 @@
 	if (authsvc == 0)
 		return NULL;			/* leave original error message in place */
 
+	pglock_thread();
 #ifdef KRB4
 	if (authsvc == STARTUP_KRB4_MSG)
 		name = pg_krb4_authname(PQerrormsg);
@@ -759,5 +763,6 @@
 
 	if (name && (authn = (char *) malloc(strlen(name) + 1)))
 		strcpy(authn, name);
+	pgunlock_thread();
 	return authn;
 }
Index: src/interfaces/libpq/fe-connect.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/interfaces/libpq/fe-connect.c,v
retrieving revision 1.268
diff -u -r1.268 fe-connect.c
--- src/interfaces/libpq/fe-connect.c	10 Mar 2004 21:12:47 -0000	1.268
+++ src/interfaces/libpq/fe-connect.c	12 Mar 2004 20:07:03 -0000
@@ -3163,4 +3163,34 @@
 
 #undef LINELEN
 }
+/*
+ * To keep the API consistent, the locking stubs are always provided, even
+ * if they are not required.
+ */
+pgthreadlock_t *g_threadlock;
 
+static pgthreadlock_t default_threadlock;
+static void
+default_threadlock(bool acquire)
+{
+#if defined(ENABLE_THREAD_SAFETY)
+       static pthread_mutex_t singlethread_lock = PTHREAD_MUTEX_INITIALIZER;
+       if (acquire)
+               pthread_mutex_lock(&singlethread_lock);
+       else
+               pthread_mutex_unlock(&singlethread_lock);
+#endif
+}
+
+pgthreadlock_t *
+PQregisterThreadLock(pgthreadlock_t *newhandler)
+{
+       pgthreadlock_t *prev;
+
+       prev = g_threadlock;
+       if (newhandler)
+               g_threadlock = newhandler;
+       else
+               g_threadlock = default_threadlock;
+       return prev;
+}
Index: src/interfaces/libpq/libpq-fe.h
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/interfaces/libpq/libpq-fe.h,v
retrieving revision 1.102
diff -u -r1.102 libpq-fe.h
--- src/interfaces/libpq/libpq-fe.h	9 Jan 2004 02:02:43 -0000	1.102
+++ src/interfaces/libpq/libpq-fe.h	12 Mar 2004 20:07:03 -0000
@@ -274,6 +274,22 @@
 					 PQnoticeProcessor proc,
 					 void *arg);
 
+typedef void (pgsigpipehandler_t)(bool enable, void **state);
+
+extern pgsigpipehandler_t *
+PQregisterSigpipeCallback(pgsigpipehandler_t *newhandler);
+
+/*
+ *     Used to set callback that prevents concurrent access to
+ *     non-thread safe functions that libpq needs.
+ *     The default implementation uses a libpq internal mutex.
+ *     Only required for multithreaded apps that use kerberos
+ *     both within their app and for postgresql connections.
+ */
+typedef void (pgthreadlock_t)(bool acquire);
+
+extern pgthreadlock_t * PQregisterThreadLock(pgthreadlock_t *newhandler);
+
 /* === in fe-exec.c === */
 
 /* Simple synchronous query */
Index: src/interfaces/libpq/libpq-int.h
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/interfaces/libpq/libpq-int.h,v
retrieving revision 1.85
diff -u -r1.85 libpq-int.h
--- src/interfaces/libpq/libpq-int.h	5 Mar 2004 01:53:59 -0000	1.85
+++ src/interfaces/libpq/libpq-int.h	12 Mar 2004 20:07:03 -0000
@@ -359,6 +359,16 @@
 extern int pqPacketSend(PGconn *conn, char pack_type,
 			 const void *buf, size_t buf_len);
 
+#ifdef ENABLE_THREAD_SAFETY
+extern pgthreadlock_t *g_threadlock;
+#define pglock_thread() g_threadlock(true);
+#define pgunlock_thread() g_threadlock(false);
+#else
+#define pglock_thread() ((void)0)
+#define pgunlock_thread() ((void)0)
+ #endif
+	 
+
 /* === in fe-exec.c === */
 
 extern void pqSetResultError(PGresult *res, const char *msg);