Remove server and libpq support for old FE/BE protocol version 2.

Protocol version 3 was introduced in PostgreSQL 7.4. There shouldn't be
many clients or servers left out there without version 3 support. But as
a courtesy, I kept just enough of the old protocol support that we can
still send the "unsupported protocol version" error in v2 format, so that
old clients can display the message properly. Likewise, libpq still
understands v2 ErrorResponse messages when establishing a connection.

The impetus to do this now is that I'm working on a patch to COPY
FROM, to always prefetch some data. We cannot do that safely with the
old protocol, because it requires parsing the input one byte at a time
to detect the end-of-copy marker.

Reviewed-by: Tom Lane, Alvaro Herrera, John Naylor
Discussion: https://www.postgresql.org/message-id/9ec25819-0a8a-d51a-17dc-4150bb3cca3b%40iki.fi

5 files changed, 7 insertions, 39 deletions

diff --git a/src/include/commands/copyfrom_internal.h b/src/include/commands/copyfrom_internal.h
index e37942df391..705f5b615be 100644
--- a/src/include/commands/copyfrom_internal.h
+++ b/src/include/commands/copyfrom_internal.h
@@ -24,8 +24,7 @@
 typedef enum CopySource
 {
 	COPY_FILE,					/* from file (or a piped program) */
-	COPY_OLD_FE,				/* from frontend (2.0 protocol) */
-	COPY_NEW_FE,				/* from frontend (3.0 protocol) */
+	COPY_FRONTEND,				/* from frontend */
 	COPY_CALLBACK				/* from callback function */
 } CopySource;
 
diff --git a/src/include/libpq/libpq.h b/src/include/libpq/libpq.h
index e4e5c215655..b20deeb5550 100644
--- a/src/include/libpq/libpq.h
+++ b/src/include/libpq/libpq.h
@@ -29,8 +29,6 @@ typedef struct
 	bool		(*is_send_pending) (void);
 	int			(*putmessage) (char msgtype, const char *s, size_t len);
 	void		(*putmessage_noblock) (char msgtype, const char *s, size_t len);
-	void		(*startcopyout) (void);
-	void		(*endcopyout) (bool errorAbort);
 } PQcommMethods;
 
 extern const PGDLLIMPORT PQcommMethods *PqCommMethods;
@@ -43,8 +41,6 @@ extern const PGDLLIMPORT PQcommMethods *PqCommMethods;
 	(PqCommMethods->putmessage(msgtype, s, len))
 #define pq_putmessage_noblock(msgtype, s, len) \
 	(PqCommMethods->putmessage_noblock(msgtype, s, len))
-#define pq_startcopyout() (PqCommMethods->startcopyout())
-#define pq_endcopyout(errorAbort) (PqCommMethods->endcopyout(errorAbort))
 
 /*
  * External functions.
@@ -67,7 +63,6 @@ extern void TouchSocketFiles(void);
 extern void RemoveSocketFiles(void);
 extern void pq_init(void);
 extern int	pq_getbytes(char *s, size_t len);
-extern int	pq_getstring(StringInfo s);
 extern void pq_startmsgread(void);
 extern void pq_endmsgread(void);
 extern bool pq_is_reading_msg(void);
@@ -75,7 +70,7 @@ extern int	pq_getmessage(StringInfo s, int maxlen);
 extern int	pq_getbyte(void);
 extern int	pq_peekbyte(void);
 extern int	pq_getbyte_if_available(unsigned char *c);
-extern int	pq_putbytes(const char *s, size_t len);
+extern int	pq_putmessage_v2(char msgtype, const char *s, size_t len);
 
 /*
  * prototypes for functions in be-secure.c
diff --git a/src/include/libpq/pqcomm.h b/src/include/libpq/pqcomm.h
index a86b895b268..be9d9705744 100644
--- a/src/include/libpq/pqcomm.h
+++ b/src/include/libpq/pqcomm.h
@@ -114,9 +114,12 @@ is_unixsock_path(const char *path)
 #define PG_PROTOCOL_MINOR(v)	((v) & 0x0000ffff)
 #define PG_PROTOCOL(m,n)	(((m) << 16) | (n))
 
-/* The earliest and latest frontend/backend protocol version supported. */
+/*
+ * The earliest and latest frontend/backend protocol version supported.
+ * (Only protocol version 3 is currently supported)
+ */
 
-#define PG_PROTOCOL_EARLIEST	PG_PROTOCOL(2,0)
+#define PG_PROTOCOL_EARLIEST	PG_PROTOCOL(3,0)
 #define PG_PROTOCOL_LATEST		PG_PROTOCOL(3,0)
 
 typedef uint32 ProtocolVersion; /* FE/BE protocol version number */
@@ -132,32 +135,6 @@ typedef ProtocolVersion MsgType;
 
 typedef uint32 PacketLen;
 
-
-/*
- * Old-style startup packet layout with fixed-width fields.  This is used in
- * protocol 1.0 and 2.0, but not in later versions.  Note that the fields
- * in this layout are '\0' terminated only if there is room.
- */
-
-#define SM_DATABASE		64
-#define SM_USER			32
-/* We append database name if db_user_namespace true. */
-#define SM_DATABASE_USER (SM_DATABASE+SM_USER+1)	/* +1 for @ */
-#define SM_OPTIONS		64
-#define SM_UNUSED		64
-#define SM_TTY			64
-
-typedef struct StartupPacket
-{
-	ProtocolVersion protoVersion;	/* Protocol version */
-	char		database[SM_DATABASE];	/* Database name */
-	/* Db_user_namespace appends dbname */
-	char		user[SM_USER];	/* User name */
-	char		options[SM_OPTIONS];	/* Optional additional args */
-	char		unused[SM_UNUSED];	/* Unused */
-	char		tty[SM_TTY];	/* Tty for debug output */
-} StartupPacket;
-
 extern bool Db_user_namespace;
 
 /*
diff --git a/src/include/tcop/fastpath.h b/src/include/tcop/fastpath.h
index b67c44fe69e..c4d7a47dd72 100644
--- a/src/include/tcop/fastpath.h
+++ b/src/include/tcop/fastpath.h
@@ -15,7 +15,6 @@
 
 #include "lib/stringinfo.h"
 
-extern int	GetOldFunctionMessage(StringInfo buf);
 extern void HandleFunctionRequest(StringInfo msgBuf);
 
 #endif							/* FASTPATH_H */
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index 3c0e57621fc..b59651289e4 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -207,7 +207,6 @@ extern int	errhidecontext(bool hide_ctx);
 
 extern int	errbacktrace(void);
 
-extern int	errfunction(const char *funcname);
 extern int	errposition(int cursorpos);
 
 extern int	internalerrposition(int cursorpos);
@@ -367,7 +366,6 @@ typedef struct ErrorData
 	int			elevel;			/* error level */
 	bool		output_to_server;	/* will report to server log? */
 	bool		output_to_client;	/* will report to client? */
-	bool		show_funcname;	/* true to force funcname inclusion */
 	bool		hide_stmt;		/* true to prevent STATEMENT: inclusion */
 	bool		hide_ctx;		/* true to prevent CONTEXT: inclusion */
 	const char *filename;		/* __FILE__ of ereport() call */