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, 7 insertions, 14 deletions

diff --git a/src/backend/libpq/be-fsstubs.c b/src/backend/libpq/be-fsstubs.c
index e2477a1dd14..a7d746ae58c 100644
--- a/src/backend/libpq/be-fsstubs.c
+++ b/src/backend/libpq/be-fsstubs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.88 2008/03/22 01:55:14 ishii Exp $
+ *	  $PostgreSQL: pgsql/src/backend/libpq/be-fsstubs.c,v 1.89 2008/03/25 22:42:43 tgl Exp $
  *
  * NOTES
  *	  This should be moved to a more appropriate place.  It is here
@@ -47,6 +47,7 @@
 #include "miscadmin.h"
 #include "storage/fd.h"
 #include "storage/large_object.h"
+#include "utils/builtins.h"
 #include "utils/memutils.h"
 
 
@@ -320,7 +321,7 @@ lowrite(PG_FUNCTION_ARGS)
 Datum
 lo_import(PG_FUNCTION_ARGS)
 {
-	text	   *filename = PG_GETARG_TEXT_P(0);
+	text	   *filename = PG_GETARG_TEXT_PP(0);
 
 	PG_RETURN_OID(lo_import_internal(filename, InvalidOid));
 }
@@ -332,7 +333,7 @@ lo_import(PG_FUNCTION_ARGS)
 Datum
 lo_import_with_oid(PG_FUNCTION_ARGS)
 {
-	text	   *filename = PG_GETARG_TEXT_P(0);
+	text	   *filename = PG_GETARG_TEXT_PP(0);
 	Oid		   oid = PG_GETARG_OID(1);
 
 	PG_RETURN_OID(lo_import_internal(filename, oid));
@@ -362,11 +363,7 @@ lo_import_internal(text *filename, Oid lobjOid)
 	/*
 	 * open the file to be read in
 	 */
-	nbytes = VARSIZE(filename) - VARHDRSZ;
-	if (nbytes >= MAXPGPATH)
-		nbytes = MAXPGPATH - 1;
-	memcpy(fnamebuf, VARDATA(filename), nbytes);
-	fnamebuf[nbytes] = '\0';
+	text_to_cstring_buffer(filename, fnamebuf, sizeof(fnamebuf));
 	fd = PathNameOpenFile(fnamebuf, O_RDONLY | PG_BINARY, 0666);
 	if (fd < 0)
 		ereport(ERROR,
@@ -410,7 +407,7 @@ Datum
 lo_export(PG_FUNCTION_ARGS)
 {
 	Oid			lobjId = PG_GETARG_OID(0);
-	text	   *filename = PG_GETARG_TEXT_P(1);
+	text	   *filename = PG_GETARG_TEXT_PP(1);
 	File		fd;
 	int			nbytes,
 				tmp;
@@ -441,11 +438,7 @@ lo_export(PG_FUNCTION_ARGS)
 	 * 022. This code used to drop it all the way to 0, but creating
 	 * world-writable export files doesn't seem wise.
 	 */
-	nbytes = VARSIZE(filename) - VARHDRSZ;
-	if (nbytes >= MAXPGPATH)
-		nbytes = MAXPGPATH - 1;
-	memcpy(fnamebuf, VARDATA(filename), nbytes);
-	fnamebuf[nbytes] = '\0';
+	text_to_cstring_buffer(filename, fnamebuf, sizeof(fnamebuf));
 	oumask = umask((mode_t) 0022);
 	fd = PathNameOpenFile(fnamebuf, O_CREAT | O_WRONLY | O_TRUNC | PG_BINARY, 0666);
 	umask(oumask);