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Re: minor MERGE cleanups
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* Re: minor MERGE cleanups
@ 2022-04-20 11:45  Alvaro Herrera <[email protected]>
  0 siblings, 0 replies; 2+ messages in thread

From: Alvaro Herrera @ 2022-04-20 11:45 UTC (permalink / raw)
  To: Michael Paquier <[email protected]>; +Cc: Pg Hackers <[email protected]>

On 2022-Apr-20, Michael Paquier wrote:

> On Tue, Apr 19, 2022 at 03:45:22PM +0200, Alvaro Herrera wrote:
> > I expect these fixups in new code should be uncontroversial.
> 
> The whole set looks rather sane to me.

Thank you, I have pushed them.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/






^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* [PATCH v45 2/8] Do not dereference varattrib_4b in VARSIZE_4B.
@ 2026-03-11 13:53  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 2+ messages in thread

From: Antonin Houska @ 2026-03-11 13:53 UTC (permalink / raw)

Since VARSIZE_ANY() may call VARSIZE_4B(), it's possible that the compiler
(when invoked with -Warray-bounds) complains if the argument of VARSIZE_ANY()
is actually smaller than what VARSIZE_4B() expects. This patch adjusts the
VARSIZE_4B() macro so that it does not have to dereference the varattrib_4b
structure. We assume that varlena value always starts with the length word.

The problem does not exist in the tree at the moment since the current users
of VARSIZE_ANY() pass a pointer to a dynamically allocated memory, so the
compiler has no idea about the memory available. However, in an upcoming
patch, it makes sense to pass a pointer to a local variable of "varlena"
type. In such a case, the compiler warning might appear because
sizeof(varlena) is lower than sizeof(varattrib_4b).
---
 src/include/varatt.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/include/varatt.h b/src/include/varatt.h
index 000bdf33b92..31063e5d4f1 100644
--- a/src/include/varatt.h
+++ b/src/include/varatt.h
@@ -207,7 +207,7 @@ typedef struct
 
 /* VARSIZE_4B() should only be used on known-aligned data */
 #define VARSIZE_4B(PTR) \
-	(((const varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
+	(*((const uint32 *) (PTR)) & 0x3FFFFFFF)
 #define VARSIZE_1B(PTR) \
 	(((const varattrib_1b *) (PTR))->va_header & 0x7F)
 #define VARTAG_1B_E(PTR) \
@@ -240,7 +240,7 @@ typedef struct
 
 /* VARSIZE_4B() should only be used on known-aligned data */
 #define VARSIZE_4B(PTR) \
-	((((const varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
+	((*((const uint32 *) (PTR)) >> 2) & 0x3FFFFFFF)
 #define VARSIZE_1B(PTR) \
 	((((const varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
 #define VARTAG_1B_E(PTR) \
-- 
2.47.3


--cldir6umqisr673d
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
	filename="v45-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch"



^ permalink  raw  reply  [nested|flat] 2+ messages in thread


end of thread, other threads:[~2026-03-11 13:53 UTC | newest]

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2022-04-20 11:45 Re: minor MERGE cleanups Alvaro Herrera <[email protected]>
2026-03-11 13:53 [PATCH v45 2/8] Do not dereference varattrib_4b in VARSIZE_4B. Antonin Houska <[email protected]>

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