Use wrappers of PG_DETOAST_DATUM_PACKED() more.

This makes almost all core code follow the policy introduced in the
previous commit.  Specific decisions:

- Text search support functions with char* and length arguments, such as
  prsstart and lexize, may receive unaligned strings.  I doubt
  maintainers of non-core text search code will notice.

- Use plain VARDATA() on values detoasted or synthesized earlier in the
  same function.  Use VARDATA_ANY() on varlenas sourced outside the
  function, even if they happen to always have four-byte headers.  As an
  exception, retain the universal practice of using VARDATA() on return
  values of SendFunctionCall().

- Retain PG_GETARG_BYTEA_P() in pageinspect.  (Page images are too large
  for a one-byte header, so this misses no optimization.)  Sites that do
  not call get_page_from_raw() typically need the four-byte alignment.

- For now, do not change btree_gist.  Its use of four-byte headers in
  memory is partly entangled with storage of 4-byte headers inside
  GBT_VARKEY, on disk.

- For now, do not change gtrgm_consistent() or gtrgm_distance().  They
  incorporate the varlena header into a cache, and there are multiple
  credible implementation strategies to consider.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 0ed6a10a443..9fb0e480bf0 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -299,8 +299,8 @@ json_recv(PG_FUNCTION_ARGS)
 JsonLexContext *
 makeJsonLexContext(text *json, bool need_escapes)
 {
-	return makeJsonLexContextCstringLen(VARDATA(json),
-										VARSIZE(json) - VARHDRSZ,
+	return makeJsonLexContextCstringLen(VARDATA_ANY(json),
+										VARSIZE_ANY_EXHDR(json),
 										need_escapes);
 }
 
@@ -1570,7 +1570,7 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 			break;
 		case JSONTYPE_CAST:
 			/* outfuncoid refers to a cast function, not an output function */
-			jsontext = DatumGetTextP(OidFunctionCall1(outfuncoid, val));
+			jsontext = DatumGetTextPP(OidFunctionCall1(outfuncoid, val));
 			outputstr = text_to_cstring(jsontext);
 			appendStringInfoString(result, outputstr);
 			pfree(outputstr);
@@ -2492,7 +2492,7 @@ json_typeof(PG_FUNCTION_ARGS)
 	JsonTokenType tok;
 	char	   *type;
 
-	json = PG_GETARG_TEXT_P(0);
+	json = PG_GETARG_TEXT_PP(0);
 	lex = makeJsonLexContext(json, false);
 
 	/* Lex exactly one token from the input and check its type. */