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Fix parsing of MS GUID with mixed endianness.

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It turns out that MS SQL Server is using its own representation for GUID
with a mixed endianness. In this blind patch we attempt to parse the binary
vector in the right way when building our internal representation of an
UUID, before making a string out of it for Postgres, which doesn't use the
same mixed-endianness format.

Fixes #910. Maybe?
This commit is contained in:
Dimitri Fontaine 2019-02-18 19:37:42 +01:00
parent 7c146c46b9
commit fbdc95ede6
1 changed files with 31 additions and 1 deletions
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32
src/utils/transforms.lisp
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@ -350,10 +350,40 @@
(t
date-string-or-integer)))))))
;;;
;;; MS SQL Server GUID binary representation is a mix of endianness, as
;;; documented at
;;; https://dba.stackexchange.com/questions/121869/sql-server-uniqueidentifier-guid-internal-representation
;;; and
;;; https://en.wikipedia.org/wiki/Globally_unique_identifier#Binary_encoding.
;;;
;;; "Other systems, notably Microsoft's marshalling of UUIDs in their
;;; COM/OLE libraries, use a mixed-endian format, whereby the first three
;;; components of the UUID are little-endian, and the last two are
;;; big-endian."
;;;
;;; So here we steal some code from the UUID lib and make it compatible with
;;; this strange mix of endianness for SQL Server.
;;;
(defmacro arr-to-bytes-rev (from to array)
"Helper macro used in byte-array-to-uuid."
`(loop for i from ,to downto ,from
with res = 0
do (setf (ldb (byte 8 (* 8 (- i ,from))) res) (aref ,array i))
finally (return res)))
(defun sql-server-uniqueidentifier-to-uuid (id)
(declare (type (or null (array (unsigned-byte 8) (16))) id))
(when id
(format nil "~a" (uuid:byte-array-to-uuid id))))
(let ((uuid
(make-instance 'uuid:uuid
:time-low (arr-to-bytes-rev 0 3 id)
:time-mid (arr-to-bytes-rev 4 5 id)
:time-high (arr-to-bytes-rev 6 7 id)
:clock-seq-var (aref id 8)
:clock-seq-low (aref id 9)
:node (uuid::arr-to-bytes 10 15 id))))
(princ-to-string uuid)))))
(defun unix-timestamp-to-timestamptz (unixtime-string)
"Takes a unix timestamp (seconds since beginning of 1970) and converts it