MySQL base64 functions

2006-03-15-mysql-base64-functions.html

@@ -0,0 +1,8 @@
+<!--# set var="title" value="MySQL base64 functions" -->
+<!--# set var="date" value="March 15, 2006" -->
+
+<!--# include file="include/top.html" -->
+
+<p>This one hardly seemed worth a project page. MySQL lacks base64 encode/decode functions, and I needed them, so <a href="files/base64.sql">here</a> they are in procedural SQL. You’ll need MySQL 5.0.19/5.1.8 if you don’t want it to segfault under you when you run them (<a href="http://bugs.mysql.com/bug.php?id=16887">bug #16887</a>).</p>
+
+<!--# include file="include/bottom.html" -->

files/base64.sql

@@ -0,0 +1,173 @@
+-- base64.sql - MySQL base64 encoding/decoding functions
+-- Copyright (C) 2006 Ian Gulliver
+-- 
+-- This program is free software; you can redistribute it and/or modify
+-- it under the terms of version 2 of the GNU General Public License as
+-- published by the Free Software Foundation.
+-- 
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+-- 
+-- You should have received a copy of the GNU General Public License
+-- along with this program; if not, write to the Free Software
+-- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+delimiter |
+
+DROP TABLE IF EXISTS base64_data |
+CREATE TABLE base64_data (c CHAR(1) BINARY, val TINYINT) |
+INSERT INTO base64_data VALUES 
+	('A',0), ('B',1), ('C',2), ('D',3), ('E',4), ('F',5), ('G',6), ('H',7), ('I',8), ('J',9),
+	('K',10), ('L',11), ('M',12), ('N',13), ('O',14), ('P',15), ('Q',16), ('R',17), ('S',18), ('T',19),
+	('U',20), ('V',21), ('W',22), ('X',23), ('Y',24), ('Z',25), ('a',26), ('b',27), ('c',28), ('d',29),
+	('e',30), ('f',31), ('g',32), ('h',33), ('i',34), ('j',35), ('k',36), ('l',37), ('m',38), ('n',39),
+	('o',40), ('p',41), ('q',42), ('r',43), ('s',44), ('t',45), ('u',46), ('v',47), ('w',48), ('x',49),
+	('y',50), ('z',51), ('0',52), ('1',53), ('2',54), ('3',55), ('4',56), ('5',57), ('6',58), ('7',59),
+	('8',60), ('9',61), ('+',62), ('/',63), ('=',0) |
+
+
+DROP FUNCTION IF EXISTS BASE64_DECODE |
+CREATE FUNCTION BASE64_DECODE (input BLOB)
+	RETURNS BLOB
+	CONTAINS SQL
+	DETERMINISTIC
+	SQL SECURITY INVOKER
+BEGIN
+	DECLARE ret BLOB DEFAULT '';
+	DECLARE done TINYINT DEFAULT 0;
+
+	IF input IS NULL THEN
+		RETURN NULL;
+	END IF;
+
+each_block:
+	WHILE NOT done DO BEGIN
+		DECLARE accum_value BIGINT UNSIGNED DEFAULT 0;
+		DECLARE in_count TINYINT DEFAULT 0;
+		DECLARE out_count TINYINT DEFAULT 3;
+
+each_input_char:
+		WHILE in_count < 4 DO BEGIN
+			DECLARE first_char CHAR(1);
+	
+			IF LENGTH(input) = 0 THEN
+				RETURN ret;
+			END IF;
+	
+			SET first_char = SUBSTRING(input,1,1);
+			SET input = SUBSTRING(input,2);
+	
+			BEGIN
+				DECLARE tempval TINYINT UNSIGNED;
+				DECLARE error TINYINT DEFAULT 0;
+				DECLARE base64_getval CURSOR FOR SELECT val FROM base64_data WHERE c = first_char;
+				DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET error = 1;
+	
+				OPEN base64_getval;
+				FETCH base64_getval INTO tempval;
+				CLOSE base64_getval;
+
+				IF error THEN
+					ITERATE each_input_char;
+				END IF;
+
+				SET accum_value = (accum_value << 6) + tempval;
+			END;
+
+			SET in_count = in_count + 1;
+
+			IF first_char = '=' THEN
+				SET done = 1;
+				SET out_count = out_count - 1;
+			END IF;
+		END; END WHILE;
+
+		-- We've now accumulated 24 bits; deaccumulate into bytes
+
+		-- We have to work from the left, so use the third byte position and shift left
+		WHILE out_count > 0 DO BEGIN
+			SET ret = CONCAT(ret,CHAR((accum_value & 0xff0000) >> 16));
+			SET out_count = out_count - 1;
+			SET accum_value = (accum_value << 8) & 0xffffff;
+		END; END WHILE;
+	
+	END; END WHILE;
+
+	RETURN ret;
+END |
+
+DROP FUNCTION IF EXISTS BASE64_ENCODE |
+CREATE FUNCTION BASE64_ENCODE (input BLOB)
+	RETURNS BLOB
+	CONTAINS SQL
+	DETERMINISTIC
+	SQL SECURITY INVOKER
+BEGIN
+	DECLARE ret BLOB DEFAULT '';
+	DECLARE done TINYINT DEFAULT 0;
+
+	IF input IS NULL THEN
+		RETURN NULL;
+	END IF;
+
+each_block:
+	WHILE NOT done DO BEGIN
+		DECLARE accum_value BIGINT UNSIGNED DEFAULT 0;
+		DECLARE in_count TINYINT DEFAULT 0;
+		DECLARE out_count TINYINT;
+
+each_input_char:
+		WHILE in_count < 3 DO BEGIN
+			DECLARE first_char CHAR(1);
+	
+			IF LENGTH(input) = 0 THEN
+				SET done = 1;
+				SET accum_value = accum_value << (8 * (3 - in_count));
+				LEAVE each_input_char;
+			END IF;
+	
+			SET first_char = SUBSTRING(input,1,1);
+			SET input = SUBSTRING(input,2);
+	
+			SET accum_value = (accum_value << 8) + ASCII(first_char);
+
+			SET in_count = in_count + 1;
+		END; END WHILE;
+
+		-- We've now accumulated 24 bits; deaccumulate into base64 characters
+
+		-- We have to work from the left, so use the third byte position and shift left
+		CASE
+			WHEN in_count = 3 THEN SET out_count = 4;
+			WHEN in_count = 2 THEN SET out_count = 3;
+			WHEN in_count = 1 THEN SET out_count = 2;
+			ELSE RETURN ret;
+		END CASE;
+
+		WHILE out_count > 0 DO BEGIN
+			BEGIN
+				DECLARE out_char CHAR(1);
+				DECLARE base64_getval CURSOR FOR SELECT c FROM base64_data WHERE val = (accum_value >> 18);
+
+				OPEN base64_getval;
+				FETCH base64_getval INTO out_char;
+				CLOSE base64_getval;
+
+				SET ret = CONCAT(ret,out_char);
+				SET out_count = out_count - 1;
+				SET accum_value = accum_value << 6 & 0xffffff;
+			END;
+		END; END WHILE;
+
+		CASE
+			WHEN in_count = 2 THEN SET ret = CONCAT(ret,'=');
+			WHEN in_count = 1 THEN SET ret = CONCAT(ret,'==');
+			ELSE BEGIN END;
+		END CASE;
+	
+	END; END WHILE;
+
+	RETURN ret;
+END |

index.html

@@ -40,6 +40,7 @@
 <li>2009-Sep-11: <a href="2009-09-11-confusing-bind-with-cnames.html">Confusing BIND with CNAMEs</a></li>
 <li>2009-Feb-19: <a href="2019-02-19-the-odd-case-of-my-mugging.html">The odd case of my mugging</a></li>
 <li>2009-Feb-03: <a href="2009-02-03-5-packet-tcp-connection.html">5-packet TCP connection?</a></li>
+<li>2006-Mar-15: <a href="2006-03-15-mysql-base64-functions.html">MySQL base64 functions</a></li>
 <li>2006-Mar-03: <a href="2006-03-03-mail-relaying-with-netsuite.html">Mail relaying with NetSuite</a></li>
 <li>2006-Mar-02: <a href="2006-03-02-udev-is-your-friend.html">udev is your friend</a></li>
 <li>2006-Mar-02: <a href="2006-03-02-why-is-my-directory-empty-and-large.html">Why is my directory empty and large?</a></li>

markdown/2006-03-15-mysql-base64-functions.md

@@ -0,0 +1,8 @@
+<!--# set var="title" value="MySQL base64 functions" -->
+<!--# set var="date" value="March 15, 2006" -->
+
+<!--# include file="include/top.html" -->
+
+This one hardly seemed worth a project page. MySQL lacks base64 encode/decode functions, and I needed them, so [here](files/base64.sql) they are in procedural SQL. You’ll need MySQL 5.0.19/5.1.8 if you don’t want it to segfault under you when you run them ([bug #16887](http://bugs.mysql.com/bug.php?id=16887)).
+
+<!--# include file="include/bottom.html" -->

markdown/index.md

@@ -39,6 +39,7 @@
 1. 2009-Sep-11: [Confusing BIND with CNAMEs](2009-09-11-confusing-bind-with-cnames.html)
 1. 2009-Feb-19: [The odd case of my mugging](2019-02-19-the-odd-case-of-my-mugging.html)
 1. 2009-Feb-03: [5-packet TCP connection?](2009-02-03-5-packet-tcp-connection.html)
+1. 2006-Mar-15: [MySQL base64 functions](2006-03-15-mysql-base64-functions.html)
 1. 2006-Mar-03: [Mail relaying with NetSuite](2006-03-03-mail-relaying-with-netsuite.html)
 1. 2006-Mar-02: [udev is your friend](2006-03-02-udev-is-your-friend.html)
 1. 2006-Mar-02: [Why is my directory empty and large?](2006-03-02-why-is-my-directory-empty-and-large.html)