amcheck: Fix incorrect use of VARATT_IS_COMPRESSED.

The macro is being applied to a TOAST pointer, not a varlena header.
Therefore the use of VARATT_IS_COMPRESSED() is wrong. We can check
VARATT_EXTERNAL_IS_COMPRESSED(), but then we don't need the length
check that follows.

Report and fix by Kyotaro Horiguchi.

Discussion: http://postgr.es/m/20220517.162719.1671558681467343711.horikyota.ntt@gmail.com

diff --git a/contrib/amcheck/verify_heapam.c b/contrib/amcheck/verify_heapam.c
index c875f3e5a2a559d6818517bd7e041e9685ef15ae..e488f5e234b3ff274f19a7beb68e3cc54ec8181b 100644 (file)
--- a/contrib/amcheck/verify_heapam.c
+++ b/contrib/amcheck/verify_heapam.c
@@ -1385,19 +1385,11 @@ check_tuple_attribute(HeapCheckContext *ctx)
                                   toast_pointer.va_rawsize,
                                   VARLENA_SIZE_LIMIT));
 
-   if (VARATT_IS_COMPRESSED(&toast_pointer))
+   if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
    {
        ToastCompressionId cmid;
        bool        valid = false;
 
-       /* Compression should never expand the attribute */
-       if (VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) > toast_pointer.va_rawsize - VARHDRSZ)
-           report_corruption(ctx,
-                             psprintf("toast value %u external size %u exceeds maximum expected for rawsize %d",
-                                      toast_pointer.va_valueid,
-                                      VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer),
-                                      toast_pointer.va_rawsize));
-
        /* Compressed attributes should have a valid compression method */
        cmid = TOAST_COMPRESS_METHOD(&toast_pointer);
        switch (cmid)