agora inbox for [email protected]
help / color / mirror / Atom feedFrom: Antonin Houska <[email protected]>
Subject: [PATCH 2/5] Add va_header field to the varattrib_4b union.
Date: Wed, 11 Mar 2026 14:53:19 +0100
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. With the new field,
VARSIZE_4B() can check the size w/o dereferencing varattrib_4b pointer.
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 | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/src/include/varatt.h b/src/include/varatt.h
index 000bdf33b92..c54d5160c22 100644
--- a/src/include/varatt.h
+++ b/src/include/varatt.h
@@ -137,6 +137,10 @@ typedef union
* compression method; see va_extinfo */
char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
} va_compressed;
+ uint32 va_header; /* Without this, compiler might raise warning
+ * (-Warray-bounds) if the argument of
+ * VARSIZE_ANY() is smaller than
+ * varattrib_4b */
} varattrib_4b;
typedef struct
@@ -207,7 +211,7 @@ 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 +244,7 @@ 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
--=-=-=
Content-Type: text/plain
Content-Disposition: attachment;
filename=v41-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch
view thread (2+ messages)
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected]
Subject: Re: [PATCH 2/5] Add va_header field to the varattrib_4b union.
In-Reply-To: <no-message-id-78628@localhost>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox