Catch invalid typlens in a couple of places

Rearrange the logic in record_image_cmp() and record_image_eq() to
error out on unexpected typlens (either not supported there or
completely invalid due to corruption).  Barring corruption, this is
not possible today but it seems more future-proof and robust to fix
this.

Reported-by: Peter Geoghegan 

diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index 5f729342f8d028ae04b60c305fa1abd89002198d..5f3dbc59d5c84d6babf2f8612f2f8699f690dcdb 100644 (file)
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -1442,7 +1442,18 @@ record_image_cmp(FunctionCallInfo fcinfo)
            }
 
            /* Compare the pair of elements */
-           if (att1->attlen == -1)
+           if (att1->attbyval)
+           {
+               if (values1[i1] != values2[i2])
+                   cmpresult = (values1[i1] < values2[i2]) ? -1 : 1;
+           }
+           else if (att1->attlen > 0)
+           {
+               cmpresult = memcmp(DatumGetPointer(values1[i1]),
+                                  DatumGetPointer(values2[i2]),
+                                  att1->attlen);
+           }
+           else if (att1->attlen == -1)
            {
                Size        len1,
                            len2;
@@ -1465,17 +1476,8 @@ record_image_cmp(FunctionCallInfo fcinfo)
                if ((Pointer) arg2val != (Pointer) values2[i2])
                    pfree(arg2val);
            }
-           else if (att1->attbyval)
-           {
-               if (values1[i1] != values2[i2])
-                   cmpresult = (values1[i1] < values2[i2]) ? -1 : 1;
-           }
            else
-           {
-               cmpresult = memcmp(DatumGetPointer(values1[i1]),
-                                  DatumGetPointer(values2[i2]),
-                                  att1->attlen);
-           }
+               elog(ERROR, "unexpected attlen: %d", att1->attlen);
 
            if (cmpresult < 0)
            {
@@ -1671,7 +1673,17 @@ record_image_eq(PG_FUNCTION_ARGS)
            }
 
            /* Compare the pair of elements */
-           if (att1->attlen == -1)
+           if (att1->attbyval)
+           {
+               result = (values1[i1] == values2[i2]);
+           }
+           else if (att1->attlen > 0)
+           {
+               result = (memcmp(DatumGetPointer(values1[i1]),
+                                DatumGetPointer(values2[i2]),
+                                att1->attlen) == 0);
+           }
+           else if (att1->attlen == -1)
            {
                Size        len1,
                            len2;
@@ -1700,16 +1712,9 @@ record_image_eq(PG_FUNCTION_ARGS)
                        pfree(arg2val);
                }
            }
-           else if (att1->attbyval)
-           {
-               result = (values1[i1] == values2[i2]);
-           }
            else
-           {
-               result = (memcmp(DatumGetPointer(values1[i1]),
-                                DatumGetPointer(values2[i2]),
-                                att1->attlen) == 0);
-           }
+               elog(ERROR, "unexpected attlen: %d", att1->attlen);
+
            if (!result)
                break;
        }