Simplify and standardize conversions between TEXT datums and ordinary C

strings.  This patch introduces four support functions cstring_to_text,
cstring_to_text_with_len, text_to_cstring, and text_to_cstring_buffer, and
two macros CStringGetTextDatum and TextDatumGetCString.  A number of
existing macros that provided variants on these themes were removed.

Most of the places that need to make such conversions now require just one
function or macro call, in place of the multiple notational layers that used
to be needed.  There are no longer any direct calls of textout or textin,
and we got most of the places that were using handmade conversions via
memcpy (there may be a few still lurking, though).

This commit doesn't make any serious effort to eliminate transient memory
leaks caused by detoasting toasted text objects before they reach
text_to_cstring.  We changed PG_GETARG_TEXT_P to PG_GETARG_TEXT_PP in a few
places where it was easy, but much more could be done.

Brendan Jurd and Tom Lane

1 files changed, 11 insertions, 35 deletions

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 3990f1d863e..1b6a58f6616 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.294 2008/03/10 02:13:22 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.295 2008/03/25 22:42:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -6380,7 +6380,6 @@ Datum
 pg_start_backup(PG_FUNCTION_ARGS)
 {
 	text	   *backupid = PG_GETARG_TEXT_P(0);
-	text	   *result;
 	char	   *backupidstr;
 	XLogRecPtr	checkpointloc;
 	XLogRecPtr	startpoint;
@@ -6410,8 +6409,7 @@ pg_start_backup(PG_FUNCTION_ARGS)
 				 errhint("archive_command must be defined before "
 						 "online backups can be made safely.")));
 
-	backupidstr = DatumGetCString(DirectFunctionCall1(textout,
-												 PointerGetDatum(backupid)));
+	backupidstr = text_to_cstring(backupid);
 
 	/*
 	 * Mark backup active in shared memory.  We must do full-page WAL writes
@@ -6531,9 +6529,7 @@ pg_start_backup(PG_FUNCTION_ARGS)
 	 */
 	snprintf(xlogfilename, sizeof(xlogfilename), "%X/%X",
 			 startpoint.xlogid, startpoint.xrecoff);
-	result = DatumGetTextP(DirectFunctionCall1(textin,
-											 CStringGetDatum(xlogfilename)));
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
 }
 
 /*
@@ -6547,7 +6543,6 @@ pg_start_backup(PG_FUNCTION_ARGS)
 Datum
 pg_stop_backup(PG_FUNCTION_ARGS)
 {
-	text	   *result;
 	XLogRecPtr	startpoint;
 	XLogRecPtr	stoppoint;
 	pg_time_t	stamp_time;
@@ -6669,9 +6664,7 @@ pg_stop_backup(PG_FUNCTION_ARGS)
 	 */
 	snprintf(stopxlogfilename, sizeof(stopxlogfilename), "%X/%X",
 			 stoppoint.xlogid, stoppoint.xrecoff);
-	result = DatumGetTextP(DirectFunctionCall1(textin,
-										 CStringGetDatum(stopxlogfilename)));
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_TEXT_P(cstring_to_text(stopxlogfilename));
 }
 
 /*
@@ -6680,7 +6673,6 @@ pg_stop_backup(PG_FUNCTION_ARGS)
 Datum
 pg_switch_xlog(PG_FUNCTION_ARGS)
 {
-	text	   *result;
 	XLogRecPtr	switchpoint;
 	char		location[MAXFNAMELEN];
 
@@ -6696,9 +6688,7 @@ pg_switch_xlog(PG_FUNCTION_ARGS)
 	 */
 	snprintf(location, sizeof(location), "%X/%X",
 			 switchpoint.xlogid, switchpoint.xrecoff);
-	result = DatumGetTextP(DirectFunctionCall1(textin,
-											   CStringGetDatum(location)));
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_TEXT_P(cstring_to_text(location));
 }
 
 /*
@@ -6711,7 +6701,6 @@ pg_switch_xlog(PG_FUNCTION_ARGS)
 Datum
 pg_current_xlog_location(PG_FUNCTION_ARGS)
 {
-	text	   *result;
 	char		location[MAXFNAMELEN];
 
 	/* Make sure we have an up-to-date local LogwrtResult */
@@ -6726,10 +6715,7 @@ pg_current_xlog_location(PG_FUNCTION_ARGS)
 
 	snprintf(location, sizeof(location), "%X/%X",
 			 LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff);
-
-	result = DatumGetTextP(DirectFunctionCall1(textin,
-											   CStringGetDatum(location)));
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_TEXT_P(cstring_to_text(location));
 }
 
 /*
@@ -6740,7 +6726,6 @@ pg_current_xlog_location(PG_FUNCTION_ARGS)
 Datum
 pg_current_xlog_insert_location(PG_FUNCTION_ARGS)
 {
-	text	   *result;
 	XLogCtlInsert *Insert = &XLogCtl->Insert;
 	XLogRecPtr	current_recptr;
 	char		location[MAXFNAMELEN];
@@ -6754,10 +6739,7 @@ pg_current_xlog_insert_location(PG_FUNCTION_ARGS)
 
 	snprintf(location, sizeof(location), "%X/%X",
 			 current_recptr.xlogid, current_recptr.xrecoff);
-
-	result = DatumGetTextP(DirectFunctionCall1(textin,
-											   CStringGetDatum(location)));
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_TEXT_P(cstring_to_text(location));
 }
 
 /*
@@ -6789,8 +6771,7 @@ pg_xlogfile_name_offset(PG_FUNCTION_ARGS)
 	/*
 	 * Read input and parse
 	 */
-	locationstr = DatumGetCString(DirectFunctionCall1(textout,
-												 PointerGetDatum(location)));
+	locationstr = text_to_cstring(location);
 
 	if (sscanf(locationstr, "%X/%X", &uxlogid, &uxrecoff) != 2)
 		ereport(ERROR,
@@ -6819,8 +6800,7 @@ pg_xlogfile_name_offset(PG_FUNCTION_ARGS)
 	XLByteToPrevSeg(locationpoint, xlogid, xlogseg);
 	XLogFileName(xlogfilename, ThisTimeLineID, xlogid, xlogseg);
 
-	values[0] = DirectFunctionCall1(textin,
-									CStringGetDatum(xlogfilename));
+	values[0] = CStringGetTextDatum(xlogfilename);
 	isnull[0] = false;
 
 	/*
@@ -6849,7 +6829,6 @@ Datum
 pg_xlogfile_name(PG_FUNCTION_ARGS)
 {
 	text	   *location = PG_GETARG_TEXT_P(0);
-	text	   *result;
 	char	   *locationstr;
 	unsigned int uxlogid;
 	unsigned int uxrecoff;
@@ -6858,8 +6837,7 @@ pg_xlogfile_name(PG_FUNCTION_ARGS)
 	XLogRecPtr	locationpoint;
 	char		xlogfilename[MAXFNAMELEN];
 
-	locationstr = DatumGetCString(DirectFunctionCall1(textout,
-												 PointerGetDatum(location)));
+	locationstr = text_to_cstring(location);
 
 	if (sscanf(locationstr, "%X/%X", &uxlogid, &uxrecoff) != 2)
 		ereport(ERROR,
@@ -6873,9 +6851,7 @@ pg_xlogfile_name(PG_FUNCTION_ARGS)
 	XLByteToPrevSeg(locationpoint, xlogid, xlogseg);
 	XLogFileName(xlogfilename, ThisTimeLineID, xlogid, xlogseg);
 
-	result = DatumGetTextP(DirectFunctionCall1(textin,
-											 CStringGetDatum(xlogfilename)));
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
 }
 
 /*