Use x'hex' syntax for null bytes in pdo::quote

Implements x'hex' encoding in pdo::quote for handling strings with null bytes,
 providing a reliable workaround for issue phpGH-13952.
An alternative fix is discussed in PR php#13956

PR php#13956 does something interesting, it avoids the overhead of copying to/from sqlite3_snprintf,
probably speeding up PDO::quote,
but right now I just want to keep things simple.

Author: divinity76

ext/pdo_sqlite/sqlite_driver.c

@@ -226,6 +226,23 @@ static zend_string* sqlite_handle_quoter(pdo_dbh_t *dbh, const zend_string *unqu
 	if (ZSTR_LEN(unquoted) > (INT_MAX - 3) / 2) {
 		return NULL;
 	}
+	if(ZSTR_LEN(unquoted) != 0 && memchr(ZSTR_VAL(unquoted), '\0', ZSTR_LEN(unquoted))) {
+		// x'hex'
+		zend_string *quoted = zend_string_safe_alloc(3 + (2 * ZSTR_LEN(unquoted)), 1, 0, 0);
+		char *outptr = ZSTR_VAL(quoted);
+		const char *inptr = ZSTR_VAL(unquoted);
+		const char *const inendptr = inptr + ZSTR_LEN(unquoted);
+		*outptr++ = 'x';
+		*outptr++ = '\'';
+		while(inptr != inendptr) {
+			const unsigned char c = *inptr++;
+			*outptr++ = "0123456789ABCDEF"[c >> 4];
+			*outptr++ = "0123456789ABCDEF"[c & 0x0F];
+		}
+		*outptr++ = '\'';
+		*outptr = '\0'; // todo: does zend_string_safe_alloc do this for us? i don't know
+		return quoted;
+	}
 	quoted = safe_emalloc(2, ZSTR_LEN(unquoted), 3);
 	/* TODO use %Q format? */
 	sqlite3_snprintf(2*ZSTR_LEN(unquoted) + 3, quoted, "'%q'", ZSTR_VAL(unquoted));

ext/pdo_sqlite/tests/gh13952.phpt

@@ -0,0 +1,77 @@
+--TEST--
+GH-13952 (sqlite PDO::quote silently corrupts strings with null bytes)
+--EXTENSIONS--
+pdo
+pdo_sqlite
+--FILE--
+<?php
+$db = new \PDO('sqlite::memory:', null, null, array(
+    \PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
+    \PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC,
+    \PDO::ATTR_EMULATE_PREPARES => false,
+));
+
+$test_cases = [
+    "",
+    "x",
+    "\x00",
+    "a\x00b",
+    "\x00\x00\x00",
+    "foobar",
+    "foo'''bar",
+    "'foo'''bar'",
+    "'foo'\x00'bar'",
+    "foo\x00\x00\x00bar",
+    "\x00foo\x00\x00\x00bar\x00",
+    "\x00\x00\x00foo",
+    "foo\x00\x00\x00",
+];
+
+foreach($test_cases as $test){
+    $res = $db->query("SELECT " . $db->quote($test))->fetch($db::FETCH_NUM)[0] === $test;
+    if(!$res){
+        throw new Exception("Failed for $test");
+    }
+}
+
+$db->exec('CREATE TABLE test (name TEXT)');
+
+foreach ($test_cases as $test_case) {
+    $quoted = $db->quote($test_case);
+    echo trim(json_encode($test_case), '"'), " -> $quoted\n";
+    $db->exec("INSERT INTO test (name) VALUES (" . $quoted . ")");
+}
+
+$stmt = $db->prepare('SELECT * from test');
+$stmt->execute();
+foreach ($stmt->fetchAll() as $result) {
+    var_dump($result['name']);
+}
+?>
+--EXPECTF--
+-> ''
+x -> 'x'
+\u0000 -> x'00'
+a\u0000b -> x'610062'
+\u0000\u0000\u0000 -> x'000000'
+foobar -> 'foobar'
+foo'''bar -> 'foo''''''bar'
+'foo'''bar' -> '''foo''''''bar'''
+'foo'\u0000'bar' -> x'27666F6F27002762617227'
+foo\u0000\u0000\u0000bar -> x'666F6F000000626172'
+\u0000foo\u0000\u0000\u0000bar\u0000 -> x'00666F6F00000062617200'
+\u0000\u0000\u0000foo -> x'000000666F6F'
+foo\u0000\u0000\u0000 -> x'666F6F000000'
+string(0) ""
+string(1) "x"
+string(1) "%0"
+string(3) "a%0b"
+string(3) "%0%0%0"
+string(6) "foobar"
+string(9) "foo'''bar"
+string(11) "'foo'''bar'"
+string(11) "'foo'%0'bar'"
+string(9) "foo%0%0%0bar"
+string(11) "%0foo%0%0%0bar%0"
+string(6) "%0%0%0foo"
+string(6) "foo%0%0%0"