Fold PQsetenv working state into PGconn, rather than trying to maintain

it in a separate object.  There's no value in keeping the state separate,
and it creates dangling-pointer problems.  Also, remove PQsetenv routines
from public API, until and unless they are redesigned to have a safer
interface.  Since they were never part of the documented API before 7.0,
it's unlikely that anyone is calling them.

doc/src/sgml/libpq.sgml

@@ -629,63 +629,6 @@ int PQbackendPID(const PGconn *conn);
        server host, not the local host!
       </para>
      </listitem>
-
-     <listitem>
-      <para>
-       <function>PQsetenvStart</function>
-       <function>PQsetenvPoll</function>
-       <function>PQsetenvAbort</function>
-       Perform an environment negotiation.
-       <synopsis>
-PGsetenvHandle *PQsetenvStart(PGconn *conn)
-       </synopsis>
-
-       <synopsis>
-PostgresPollingStatusType *PQsetenvPoll(PGsetenvHandle handle)
-       </synopsis>
-       <synopsis>
-void PQsetenvAbort(PGsetenvHandle handle)
-       </synopsis>
-       These two routines can be used to re-perform the environment negotiation
-       that occurs during the opening of a connection to a database
-       server. I have
-       no idea why this might be useful (XXX anyone?) but it might prove useful
-       for users to be able to reconfigure their character encodings 
-       on-the-fly, for example.
-      </para>
-      <para>
-       These functions will not block, subject to the restrictions applied to
-       PQconnectStart and PQconnectPoll.
-      </para>
-      <para>
-       To begin, call handle=PQsetenvStart(conn), where conn is an open connection
-       to the database server. If handle is NULL, then libpq has been unable to
-       allocate a new PGsetenvHandle structure. Otherwise, a valid handle is
-       returned. This handle is intended to be opaque - you may only use it to
-       call other functions in libpq (PQsetenvPoll, for example).
-      </para>
-      <para>
-       Poll the procedure using PQsetenvPoll, in exactly the same way as you would
-       create a connection using PQconnectPoll.
-      </para>
-
-      <para>
-       The procedure may be aborted at any time by calling PQsetenvAbort(handle).
-      </para>
-     </listitem>
-
-     <listitem>
-      <para>
-       <function>PQsetenv</function>
-       Perform an environment negotiation.
-       <synopsis>
-int PQsetenv(PGconn *conn)
-       </synopsis>
-       This function performs the same duties as PQsetenvStart and
-       PQsetenvPoll, but
-       blocks to do so. It returns 1 on success and 0 on failure.
-      </para>
-     </listitem>
     </itemizedlist>
    </para>
   </sect1>

src/interfaces/libpq/libpq-fe.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: libpq-fe.h,v 1.62 2000/03/23 15:00:11 momjian Exp $
+ * $Id: libpq-fe.h,v 1.63 2000/03/24 01:39:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,12 +86,6 @@ extern		"C"
  */
 	typedef struct pg_result PGresult;
 
-/* PGsetenvHandle is an opaque handle which is returned by PQsetenvStart and
- * which should be passed to PQsetenvPoll or PQsetenvAbort in order to refer
- * to the particular process being performed.
- */
-	typedef struct pg_setenv_state *PGsetenvHandle;
-
 /* PGnotify represents the occurrence of a NOTIFY message.
  * Ideally this would be an opaque typedef, but it's so simple that it's
  * unlikely to change.
@@ -231,15 +225,6 @@ extern		"C"
 	/* Override default notice processor */
 	extern PQnoticeProcessor PQsetNoticeProcessor(PGconn *conn, PQnoticeProcessor proc, void *arg);
 
-	/* Passing of environment variables */
-	/* Asynchronous (non-blocking) */
-	extern PGsetenvHandle PQsetenvStart(PGconn *conn);
-	extern PostgresPollingStatusType PQsetenvPoll(PGconn *conn);
-	extern void PQsetenvAbort(PGsetenvHandle handle);
-
-	/* Synchronous (blocking) */
-	extern int PQsetenv(PGconn *conn);
-
 /* === in fe-exec.c === */
 
 	/* Simple synchronous query */

src/interfaces/libpq/libpq-int.h

@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: libpq-int.h,v 1.21 2000/03/14 23:59:23 tgl Exp $
+ * $Id: libpq-int.h,v 1.22 2000/03/24 01:39:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -164,6 +164,17 @@ typedef enum
 	PGASYNC_COPY_OUT			/* Copy Out data transfer in progress */
 } PGAsyncStatusType;
 
+/* PGSetenvStatusType defines the state of the PQSetenv state machine */
+typedef enum
+{
+	SETENV_STATE_OPTION_SEND,	/* About to send an Environment Option */
+	SETENV_STATE_OPTION_WAIT,	/* Waiting for above send to complete  */
+	/* these next two are only used in MULTIBYTE mode */
+	SETENV_STATE_ENCODINGS_SEND, /* About to send an "encodings" query */
+	SETENV_STATE_ENCODINGS_WAIT, /* Waiting for query to complete      */
+	SETENV_STATE_IDLE
+} PGSetenvStatusType;
+
 /* large-object-access data ... allocated only if large-object code is used. */
 typedef struct pgLobjfuncs
 {
@@ -244,8 +255,9 @@ struct pg_conn
 	PGresult   *result;			/* result being constructed */
 	PGresAttValue *curTuple;	/* tuple currently being read */
 
-	/* Handle for setenv request.  Used during connection only. */
-	PGsetenvHandle setenv_handle;
+	/* Status for sending environment info.  Used during PQSetenv only. */
+	PGSetenvStatusType	setenv_state;
+	const struct EnvironmentOptions *next_eo;
 
 #ifdef USE_SSL
 	bool allow_ssl_try;			/* Allowed to try SSL negotiation */