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

Author: tglsfdc

contrib/adminpack/adminpack.c

@@ -8,7 +8,7 @@
  * Author: Andreas Pflug <[email protected]>
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/contrib/adminpack/adminpack.c,v 1.10 2008/01/01 19:45:45 momjian Exp $
+ *	  $PostgreSQL: pgsql/contrib/adminpack/adminpack.c,v 1.11 2008/03/25 22:42:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -23,6 +23,7 @@
 #include "miscadmin.h"
 #include "postmaster/syslogger.h"
 #include "storage/fd.h"
+#include "utils/builtins.h"
 #include "utils/datetime.h"
 
 
@@ -68,11 +69,7 @@ typedef struct
 static char *
 convert_and_check_filename(text *arg, bool logAllowed)
 {
-	int			input_len = VARSIZE(arg) - VARHDRSZ;
-	char	   *filename = palloc(input_len + 1);
-
-	memcpy(filename, VARDATA(arg), input_len);
-	filename[input_len] = '\0';
+	char	   *filename = text_to_cstring(arg);
 
 	canonicalize_path(filename);	/* filename can change length here */
 

contrib/chkpass/chkpass.c

@@ -4,7 +4,7 @@
  * [email protected]
  * http://www.druid.net/darcy/
  *
- * $PostgreSQL: pgsql/contrib/chkpass/chkpass.c,v 1.19 2007/02/27 23:48:05 tgl Exp $
+ * $PostgreSQL: pgsql/contrib/chkpass/chkpass.c,v 1.20 2008/03/25 22:42:41 tgl Exp $
  * best viewed with tabs set to 4
  */
 
@@ -17,6 +17,7 @@
 #endif
 
 #include "fmgr.h"
+#include "utils/builtins.h"
 
 PG_MODULE_MAGIC;
 
@@ -124,15 +125,8 @@ Datum
 chkpass_rout(PG_FUNCTION_ARGS)
 {
 	chkpass    *password = (chkpass *) PG_GETARG_POINTER(0);
-	text	   *result;
-	int			slen;
 
-	slen = strlen(password->password);
-	result = (text *) palloc(VARHDRSZ + slen);
-	SET_VARSIZE(result, VARHDRSZ + slen);
-	memcpy(VARDATA(result), password->password, slen);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_TEXT_P(cstring_to_text(password->password));
 }
 
 
@@ -145,13 +139,10 @@ Datum
 chkpass_eq(PG_FUNCTION_ARGS)
 {
 	chkpass    *a1 = (chkpass *) PG_GETARG_POINTER(0);
-	text	   *a2 = (text *) PG_GETARG_TEXT_P(1);
-	char		str[10];
-	int			sz;
+	text	   *a2 = PG_GETARG_TEXT_PP(1);
+	char		str[9];
 
-	sz = Min(VARSIZE(a2) - VARHDRSZ, 8);
-	memcpy(str, VARDATA(a2), sz);
-	str[sz] = '\0';
+	text_to_cstring_buffer(a2, str, sizeof(str));
 	PG_RETURN_BOOL(strcmp(a1->password, crypt(str, a1->password)) == 0);
 }
 
@@ -160,12 +151,9 @@ Datum
 chkpass_ne(PG_FUNCTION_ARGS)
 {
 	chkpass    *a1 = (chkpass *) PG_GETARG_POINTER(0);
-	text	   *a2 = (text *) PG_GETARG_TEXT_P(1);
-	char		str[10];
-	int			sz;
+	text	   *a2 = PG_GETARG_TEXT_PP(1);
+	char		str[9];
 
-	sz = Min(VARSIZE(a2) - VARHDRSZ, 8);
-	memcpy(str, VARDATA(a2), sz);
-	str[sz] = '\0';
+	text_to_cstring_buffer(a2, str, sizeof(str));
 	PG_RETURN_BOOL(strcmp(a1->password, crypt(str, a1->password)) != 0);
 }