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/NEWS b/NEWS
index 32712a85ca..dc4862c291 100644
--- a/NEWS
+++ b/NEWS
@@ -21,6 +21,10 @@ PHP                                                                        NEWS
 - OpenSSL:
   . Bump minimal OpenSSL version to 1.0.2. (Jakub Zelenka)
 
+- PDO:
+  . Fixed bug #40913 (PDO_MYSQL: PDO::PARAM_LOB does not bind to a stream for
+    fetching a BLOB). (Nikita)
+
 - PSpell:
   . Convert resource<pspell> to object \PSpell. (Sara)
   . Convert resource<pspell config> to object \PSPellConfig. (Sara)