Catch invalid typlens in a couple of places

Rearrange the logic in record_image_cmp() and datum_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 <pg@bowt.ie>

diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
index 1568658bc9cfc4f936dd03d7c9f57558bfe8fb8f..73703efe05a3aa42ff3f876d78fe719f18a58161 100644 (file)
--- a/src/backend/utils/adt/datum.c
+++ b/src/backend/utils/adt/datum.c
@@ -265,7 +265,17 @@ datum_image_eq(Datum value1, Datum value2, bool typByVal, int typLen)
 {
        bool            result = true;
 
-       if (typLen == -1)
+       if (typByVal)
+       {
+               result = (value1 == value2);
+       }
+       else if (typLen > 0)
+       {
+               result = (memcmp(DatumGetPointer(value1),
+                                                DatumGetPointer(value2),
+                                                typLen) == 0);
+       }
+       else if (typLen == -1)
        {
                Size            len1,
                                        len2;
@@ -294,16 +304,8 @@ datum_image_eq(Datum value1, Datum value2, bool typByVal, int typLen)
                                pfree(arg2val);
                }
        }
-       else if (typByVal)
-       {
-               result = (value1 == value2);
-       }
        else
-       {
-               result = (memcmp(DatumGetPointer(value1),
-                                                DatumGetPointer(value2),
-                                                typLen) == 0);
-       }
+               elog(ERROR, "unexpected typLen: %d", typLen);
 
        return result;
 }

diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index ea3e40a369429d7b0f2f04fb0a5c062898b2bd65..18496b94c61670adce32d69534102368bc0efa40 100644 (file)
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -1443,7 +1443,18 @@ 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;
@@ -1466,17 +1477,8 @@ 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)
                        {