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, 9 insertions, 1 deletions

diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 5dbc00fce53..f719b492c14 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -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/include/utils/builtins.h,v 1.309 2008/03/23 00:24:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.310 2008/03/25 22:42:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -617,6 +617,14 @@ extern Datum varchartypmodout(PG_FUNCTION_ARGS);
 extern Datum varchar(PG_FUNCTION_ARGS);
 
 /* varlena.c */
+extern text *cstring_to_text(const char *s);
+extern text *cstring_to_text_with_len(const char *s, int len);
+extern char *text_to_cstring(const text *t);
+extern void text_to_cstring_buffer(const text *src, char *dst, size_t dst_len);
+
+#define CStringGetTextDatum(s) PointerGetDatum(cstring_to_text(s))
+#define TextDatumGetCString(d) text_to_cstring((text *) DatumGetPointer(d))
+
 extern Datum textin(PG_FUNCTION_ARGS);
 extern Datum textout(PG_FUNCTION_ARGS);
 extern Datum textrecv(PG_FUNCTION_ARGS);