Index: src/sqlite.h.in
==================================================================
--- src/sqlite.h.in
+++ src/sqlite.h.in
@@ -28,11 +28,11 @@
 ** The name of this file under configuration management is "sqlite.h.in".
 ** The makefile makes some minor changes to this file (such as inserting
 ** the version number) and changes its name to "sqlite3.h" as
 ** part of the build process.
 **
-** @(#) $Id: sqlite.h.in,v 1.257 2007/09/04 12:00:00 drh Exp $
+** @(#) $Id: sqlite.h.in,v 1.258 2007/09/04 12:18:42 drh Exp $
 */
 #ifndef _SQLITE3_H_
 #define _SQLITE3_H_
 #include <stdarg.h>     /* Needed for the definition of va_list */
 
@@ -1701,11 +1701,12 @@
 ** The sqlite3_bind_zeroblob() routine binds a BLOB of length n that
 ** is filled with zeros.  A zeroblob uses a fixed amount of memory
 ** (just an integer to hold it size) while it is being processed.
 ** Zeroblobs are intended to serve as place-holders for BLOBs whose
 ** content is later written using 
-** [sqlite3_blob_open | increment BLOB I/O] routines.
+** [sqlite3_blob_open | increment BLOB I/O] routines.  A negative
+** value for the zeroblob results in a zero-length BLOB.
 **
 ** The sqlite3_bind_*() routines must be called after
 ** [sqlite3_prepare_v2()] (and its variants) or [sqlite3_reset()] and
 ** before [sqlite3_step()].
 ** Bindings are not cleared by the [sqlite3_reset()] routine.
@@ -2056,10 +2057,15 @@
 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
 ** the number of bytes in that string.
 ** The value returned does not include the zero terminator at the end
 ** of the string.  For clarity: the value returned is the number of
 ** bytes in the string, not the number of characters.
+**
+** Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
+** even zero-length strings, are always zero terminated.  The return
+** value from sqlite3_column_blob() for a zero-length blob is an arbitrary
+** pointer, possibly even a NULL pointer.
 **
 ** The sqlite3_column_bytes16() routine is similar to sqlite3_column_bytes()
 ** but leaves the result in UTF-16 instead of UTF-8.  
 ** The zero terminator is not included in this count.
 **

Index: test/zeroblob.test
==================================================================
--- test/zeroblob.test
+++ test/zeroblob.test
@@ -11,11 +11,11 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this file is testing of the zero-filled blob functionality
 # including the sqlite3_bind_zeroblob(), sqlite3_result_zeroblob(),
 # and the built-in zeroblob() SQL function.
 #
-# $Id: zeroblob.test,v 1.8 2007/09/01 16:16:16 danielk1977 Exp $
+# $Id: zeroblob.test,v 1.9 2007/09/04 12:18:42 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
 
 ifcapable !incrblob {
@@ -172,11 +172,17 @@
 do_test zeroblob-6.4 { 
   catchsql {select length(zeroblob(2147483648))} 
 } {1 {string or blob too big}} 
 do_test zeroblob-6.5 { 
   catchsql {select zeroblob(2147483648)} 
-} {1 {string or blob too big}} 
+} {1 {string or blob too big}}
+do_test zeroblob-6.6 {
+  execsql {select hex(zeroblob(-1))}
+} {{}}
+do_test zeroblob-6.7 {
+  execsql {select typeof(zeroblob(-1))}
+} {blob}
 
 # Test bind_zeroblob()
 #
 do_test zeroblob-7.1 {
   set ::STMT [sqlite3_prepare $::DB "SELECT length(?)" -1 DUMMY]