Some security checks that we've found an external value completely

when fetching toasted values.

Jan

diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index e9b071d0c0c9a0ff86ed105a1b966434dc8384eb..8abadaa7355eb5c75bbfed4ae9f071e47ef5af21 100644 (file)
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.6 2000/07/06 18:22:45 wieck Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.7 2000/07/11 12:32:03 wieck Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -929,9 +929,17 @@ toast_fetch_datum(varattrib *attr)
    Datum                   chunk;
    bool                    isnull;
 
+   char                   *chunks_found;
+   char                   *chunks_expected;
+
    ressize = attr->va_content.va_external.va_extsize;
     numchunks = (ressize / TOAST_MAX_CHUNK_SIZE) + 1;
 
+   chunks_found    = palloc(numchunks);
+   chunks_expected = palloc(numchunks);
+   memset(chunks_found,    0, numchunks);
+   memset(chunks_expected, 1, numchunks);
+
    result = (varattrib *)palloc(ressize + VARHDRSZ);
    VARATT_SIZEP(result) = ressize + VARHDRSZ;
    if (VARATT_IS_COMPRESSED(attr))
@@ -971,7 +979,7 @@ toast_fetch_datum(varattrib *attr)
        heap_fetch(toastrel, SnapshotAny, &toasttup, &buffer);
        pfree(indexRes);
 
-       if (!toasttup.t_data)
+       if (toasttup.t_data == NULL)
            continue;
        ttup = &toasttup;
 
@@ -982,6 +990,20 @@ toast_fetch_datum(varattrib *attr)
        residx = (int32)heap_getattr(ttup, 2, toasttupDesc, &isnull);
        chunk = heap_getattr(ttup, 3, toasttupDesc, &isnull);
 
+       /* ----------
+        * Some checks on the data we've found
+        * ----------
+        */
+       if (residx * TOAST_MAX_CHUNK_SIZE + VARATT_SIZE(chunk) - VARHDRSZ
+                       > ressize)
+           elog(ERROR, "chunk data exceeds original data size for "
+                       "toast value %d", 
+                       attr->va_content.va_external.va_valueid);
+       if (chunks_found[residx]++ > 0)
+           elog(ERROR, "chunk %d for toast value %d appears multiple times",
+                       residx,
+                       attr->va_content.va_external.va_valueid);
+
        /* ----------
         * Copy the data into our result
         * ----------
@@ -993,6 +1015,16 @@ toast_fetch_datum(varattrib *attr)
        ReleaseBuffer(buffer);
    }
 
+   /* ----------
+    * Final checks that we successfully fetched the datum
+    * ----------
+    */
+   if (memcmp(chunks_found, chunks_expected, numchunks) != 0)
+       elog(ERROR, "not all toast chunks found for value %d",
+                       attr->va_content.va_external.va_valueid);
+   pfree(chunks_expected);
+   pfree(chunks_found);
+
    /* ----------
     * End scan and close relations
     * ----------