Support varlena fields with single-byte headers and unaligned storage.

This commit breaks any code that assumes that the mere act of forming a tuple
(without writing it to disk) does not "toast" any fields.  While all available
regression tests pass, I'm not totally sure that we've fixed every nook and
cranny, especially in contrib.

Greg Stark with some help from Tom Lane

5 files changed, 52 insertions, 9 deletions

diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index 568ac1e5f7..b42dd02672 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -8,7 +8,7 @@
  * Darko Prenosil <Darko.Prenosil@finteh.hr>
  * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
  *
- * $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.62 2007/02/07 00:52:35 petere Exp $
+ * $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.63 2007/04/06 04:21:41 tgl Exp $
  * Copyright (c) 2001-2007, PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  *
@@ -1752,8 +1752,8 @@ get_text_array_contents(ArrayType *array, int *numitems)
 		{
 			values[i] = DatumGetCString(DirectFunctionCall1(textout,
 													  PointerGetDatum(ptr)));
-			ptr = att_addlength(ptr, typlen, PointerGetDatum(ptr));
-			ptr = (char *) att_align(ptr, typalign);
+			ptr = att_addlength_pointer(ptr, typlen, ptr);
+			ptr = (char *) att_align_nominal(ptr, typalign);
 		}
 
 		/* advance bitmap pointer if any */
diff --git a/contrib/hstore/hstore_gist.c b/contrib/hstore/hstore_gist.c
index fbee64be7d..19ed74933f 100644
--- a/contrib/hstore/hstore_gist.c
+++ b/contrib/hstore/hstore_gist.c
@@ -170,7 +170,25 @@ ghstore_compress(PG_FUNCTION_ARGS)
 Datum
 ghstore_decompress(PG_FUNCTION_ARGS)
 {
-	PG_RETURN_DATUM(PG_GETARG_DATUM(0));
+	GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
+	GISTENTRY  *retval;
+	HStore *key;
+
+	key = (HStore *) PG_DETOAST_DATUM(entry->key);
+
+	if (key != (HStore *) DatumGetPointer(entry->key))
+	{
+		/* need to pass back the decompressed item */
+		retval = palloc(sizeof(GISTENTRY));
+		gistentryinit(*retval, PointerGetDatum(key),
+					  entry->rel, entry->page, entry->offset, entry->leafkey);
+		PG_RETURN_POINTER(retval);
+	}
+	else
+	{
+		/* we can return the entry as-is */
+		PG_RETURN_POINTER(entry);
+	}
 }
 
 Datum
diff --git a/contrib/intarray/_int_gist.c b/contrib/intarray/_int_gist.c
index 56eb0c08c2..3c34cb67a7 100644
--- a/contrib/intarray/_int_gist.c
+++ b/contrib/intarray/_int_gist.c
@@ -232,7 +232,16 @@ g_int_decompress(PG_FUNCTION_ARGS)
 
 	CHECKARRVALID(in);
 	if (ARRISVOID(in))
+	{
+		if (in != (ArrayType *) DatumGetPointer(entry->key)) {
+			retval = palloc(sizeof(GISTENTRY));
+			gistentryinit(*retval, PointerGetDatum(in),
+				entry->rel, entry->page, entry->offset, FALSE);
+			PG_RETURN_POINTER(retval);
+		}
+
 		PG_RETURN_POINTER(entry);
+	}
 
 	lenin = ARRNELEMS(in);
 
diff --git a/contrib/pg_trgm/trgm_gist.c b/contrib/pg_trgm/trgm_gist.c
index 476cb1b976..260fe01da4 100644
--- a/contrib/pg_trgm/trgm_gist.c
+++ b/contrib/pg_trgm/trgm_gist.c
@@ -97,7 +97,7 @@ gtrgm_compress(PG_FUNCTION_ARGS)
 	if (entry->leafkey)
 	{							/* trgm */
 		TRGM	   *res;
-		text	   *val = (text *) DatumGetPointer(PG_DETOAST_DATUM(entry->key));
+		text	   *val = DatumGetTextP(entry->key);
 
 		res = generate_trgm(VARDATA(val), VARSIZE(val) - VARHDRSZ);
 		retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
@@ -134,7 +134,25 @@ gtrgm_compress(PG_FUNCTION_ARGS)
 Datum
 gtrgm_decompress(PG_FUNCTION_ARGS)
 {
-	PG_RETURN_DATUM(PG_GETARG_DATUM(0));
+	GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
+	GISTENTRY  *retval;
+	text *key;
+
+	key = DatumGetTextP(entry->key);
+
+	if (key != (text *) DatumGetPointer(entry->key))
+	{
+		/* need to pass back the decompressed item */
+		retval = palloc(sizeof(GISTENTRY));
+		gistentryinit(*retval, PointerGetDatum(key),
+					  entry->rel, entry->page, entry->offset, entry->leafkey);
+		PG_RETURN_POINTER(retval);
+	}
+	else
+	{
+		/* we can return the entry as-is */
+		PG_RETURN_POINTER(entry);
+	}
 }
 
 Datum
diff --git a/contrib/tsearch2/ts_cfg.c b/contrib/tsearch2/ts_cfg.c
index 0dc17703c3..646ffc1481 100644
--- a/contrib/tsearch2/ts_cfg.c
+++ b/contrib/tsearch2/ts_cfg.c
@@ -62,9 +62,7 @@ init_cfg(Oid id, TSCfgInfo * cfg)
 		ts_error(ERROR, "SPI_execp return %d", stat);
 	if (SPI_processed > 0)
 	{
-		prsname = (text *) DatumGetPointer(
-										   SPI_getbinval(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1, &isnull)
-			);
+		prsname = DatumGetTextP(SPI_getbinval(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1, &isnull));
 		oldcontext = MemoryContextSwitchTo(TopMemoryContext);
 		prsname = ptextdup(prsname);
 		MemoryContextSwitchTo(oldcontext);