Rewrite PDO result binding

Instead of requiring the type to be determined in advance by the
describer function and then requiring get_col to return a buffer
of appropriate type, allow get_col to return an arbitrary zval.
See UPGRADING.INTERNALS for a more detailed description of the
change.

This makes the result fetching simpler, more efficient and more
flexible. The general possibility already existed via the special
PDO_PARAM_ZVAL type, but the usage was very inconvenient and/or
inefficient. Now it's possible to easily implement behavior like
"return int if it fits, otherwise string" and to avoid any kind
of complex management of temporary buffers.

This also fixes bug #40913 (our second highest voted bug of all
time, for some reason). PARAM_LOB result bindings will now
consistently return a stream resource, independently of the used
database driver.

I've tried my best to update all PDO drivers for this change, but
some of the changes may be broken, as I cannot test or even build
some of these drivers (in particular PDO dblib and PDO oci).
Fixes are appreciated -- a working CI setup would be even more
appreciated ;)

1 files changed, 4 insertions, 0 deletions

diff --git a/UPGRADING b/UPGRADING
index 8625303aac..9b80b702a3 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -42,6 +42,10 @@ PHP 8.1 UPGRADE NOTES
 - PDO:
   . PDO::ATTR_STRINGIFY_FETCHES now also stringifies values of type bool to
     "0" or "1". Previously booleans were not stringified.
+  . Calling bindColumn() with PDO::PARAM_LOB (and assuming stringification is
+    not enabled) will now consistently bind a stream result, as documented.
+    Previously the result would be either a stream or a string depending on the
+    used database driver and the time the binding is performed.
 
 - PDO MySQL:
   . Integers and floats in result sets will now be returned using native PHP