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Remove partial, broken support for NULL pointers when fetching attributes.

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Previously, fastgetattr() and heap_getattr() tested their fourth argument
against a null pointer, but any attempt to use them with a literal-NULL
fourth argument evaluated to *(void *)0, resulting in a compiler error.
Remove these NULL tests to avoid leading future readers of this code to
believe that this has a chance of working.  Also clean up related legacy
code in nocachegetattr(), heap_getsysattr(), and nocache_index_getattr().

The new coding standard is that any code which calls a getattr-type
function or macro which takes an isnull argument MUST pass a valid
boolean pointer.  Per discussion with Bruce Momjian, Tom Lane, Alvaro
Herrera.
This commit is contained in:
Robert Haas
2010-01-10 04:26:36 +00:00
parent 8b9fa7a93a
commit 84b6d5f359
5 changed files with 36 additions and 109 deletions
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74
src/backend/access/common/heaptuple.c
View File

@ -50,7 +50,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.129 2010/01/02 16:57:33 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.130 2010/01/10 04:26:36 rhaas Exp $
*
*-------------------------------------------------------------------------
*/
@ -323,8 +323,7 @@ heap_attisnull(HeapTuple tup, int attnum)
Datum
nocachegetattr(HeapTuple tuple,
int attnum,
TupleDesc tupleDesc,
bool *isnull)
TupleDesc tupleDesc)
{
HeapTupleHeader tup = tuple->t_data;
Form_pg_attribute *att = tupleDesc->attrs;
@ -333,8 +332,6 @@ nocachegetattr(HeapTuple tuple,
bool slow = false; /* do we have to walk attrs? */
int off; /* current offset within data */
(void) isnull; /* not used */
/* ----------------
* Three cases:
*
@ -344,68 +341,32 @@ nocachegetattr(HeapTuple tuple,
* ----------------
*/
#ifdef IN_MACRO
/* This is handled in the macro */
Assert(attnum > 0);
if (isnull)
*isnull = false;
#endif
attnum--;
if (HeapTupleNoNulls(tuple))
{
#ifdef IN_MACRO
/* This is handled in the macro */
if (att[attnum]->attcacheoff >= 0)
{
return fetchatt(att[attnum],
(char *) tup + tup->t_hoff +
att[attnum]->attcacheoff);
}
#endif
}
else
if (!HeapTupleNoNulls(tuple))
{
/*
* there's a null somewhere in the tuple
*
* check to see if desired att is null
* check to see if any preceding bits are null...
*/
int byte = attnum >> 3;
int finalbit = attnum & 0x07;
#ifdef IN_MACRO
/* This is handled in the macro */
if (att_isnull(attnum, bp))
/* check for nulls "before" final bit of last byte */
if ((~bp[byte]) & ((1 << finalbit) - 1))
slow = true;
else
{
if (isnull)
*isnull = true;
return (Datum) NULL;
}
#endif
/* check for nulls in any "earlier" bytes */
int i;
/*
* Now check to see if any preceding bits are null...
*/
{
int byte = attnum >> 3;
int finalbit = attnum & 0x07;
/* check for nulls "before" final bit of last byte */
if ((~bp[byte]) & ((1 << finalbit) - 1))
slow = true;
else
for (i = 0; i < byte; i++)
{
/* check for nulls in any "earlier" bytes */
int i;
for (i = 0; i < byte; i++)
if (bp[i] != 0xFF)
{
if (bp[i] != 0xFF)
{
slow = true;
break;
}
slow = true;
break;
}
}
}
@ -567,8 +528,7 @@ heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
Assert(tup);
/* Currently, no sys attribute ever reads as NULL. */
if (isnull)
*isnull = false;
*isnull = false;
switch (attnum)
{