#plpsql

This PGSQL function loops through the bytes of a text data type and drops any bytes that don’t conform to UTF8 standard:

CREATE OR REPLACE FUNCTION utf8clean(text) RETURNS TEXT AS $$ DECLARE string ALIAS FOR $1; i INT := 0; bytecount INT; bytes INT[]; byte INT; tmp BYTEA := decode('5c', 'hex');  -- We just need some valid byte to use for set_byte src passed BYTEA;  out TEXT; BEGIN IF $1 is NULL OR octet_length($1) = 0 THEN return $1; END IF;

bytes := ARRAY( SELECT get_byte(convert_to(string, 'UTF8'), x) FROM generate_series(0, octet_length(string) - 1, 1) x );

IF array_length(bytes, 1) IS NULL THEN RETURN $1; END IF;

bytecount := array_length(bytes, 1);

-- Look forward implementation to avoid having to store seen values FOR i IN 0..bytecount LOOP byte := bytes[i];

IF byte = 10 OR byte = 13 OR byte BETWEEN 32 AND 127 THEN -- 1-byte UTF8 IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF; END IF;

IF byte BETWEEN 194 AND 223 THEN -- 2-byte UTF8 IF bytes[i+1] BETWEEN 128 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); END IF; i := i + 1; END IF;

IF byte = 224 THEN -- 3-byte UTF8 IF bytes[i+1] BETWEEN 160 AND 191 AND bytes[i+2] BETWEEN 128 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); passed := passed || set_byte(tmp, 0, bytes[i+2]); END IF; i := i + 2; END IF;

IF byte BETWEEN 225 AND 236 THEN -- 3-byte UTF8 IF bytes[i+1] BETWEEN 128 AND 191 AND bytes[i+2] BETWEEN 128 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); passed := passed || set_byte(tmp, 0, bytes[i+2]); END IF; i := i + 2; END IF;

IF byte = 237 THEN -- 3-byte UTF8 IF bytes[i+1] BETWEEN 128 AND 159 AND bytes[i+2] BETWEEN 128 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); passed := passed || set_byte(tmp, 0, bytes[i+2]); END IF; i := i + 2; END IF;

IF byte BETWEEN 238 AND 239 THEN -- 3-byte UTF8 IF bytes[i+1] BETWEEN 128 AND 191 AND bytes[i+2] BETWEEN 128 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); passed := passed || set_byte(tmp, 0, bytes[i+2]); END IF; i := i + 2; END IF;

IF byte = 240 THEN -- 4-byte UTF8 IF bytes[i+1] BETWEEN 144 AND 191 AND bytes[i+2] BETWEEN 128 AND 191 AND bytes[i+3] BETWEEN 129 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); passed := passed || set_byte(tmp, 0, bytes[i+2]); passed := passed || set_byte(tmp, 0, bytes[i+3]); END IF; i := i + 3; END IF;

IF byte BETWEEN 241 AND 243 THEN -- 4-byte UTF8 IF bytes[i+1] BETWEEN 128 AND 191 AND bytes[i+2] BETWEEN 128 AND 191 AND bytes[i+3] BETWEEN 129 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); passed := passed || set_byte(tmp, 0, bytes[i+2]); passed := passed || set_byte(tmp, 0, bytes[i+3]); END IF; i := i + 3; END IF;

IF byte = 244 THEN -- 4-byte UTF8 IF bytes[i+1] BETWEEN 128 AND 143 AND bytes[i+2] BETWEEN 128 AND 191 AND bytes[i+3] BETWEEN 129 AND 191 THEN IF passed is NULL THEN passed := set_byte(tmp, 0, byte); ELSE passed := passed || set_byte(tmp, 0, byte); END IF;

passed := passed || set_byte(tmp, 0, bytes[i+1]); passed := passed || set_byte(tmp, 0, bytes[i+2]); passed := passed || set_byte(tmp, 0, bytes[i+3]); END IF; i := i + 3; END IF; END LOOP;

out := convert_from(passed, 'UTF8');