ext/readline: readline_info fix usage when the buffer is not initialised

 rl_initialise is only called when readline() is used so the global
 buffer might not be initialised yet.

Author: devnexen

Diff for: ext/readline/readline.c

@@ -187,8 +187,10 @@ PHP_FUNCTION(readline_info)
 					RETURN_THROWS();
 				}
 #ifndef PHP_WIN32
-				if (strlen(oldstr) < Z_STRLEN_P(value)) {
+				if (!oldstr || strlen(oldstr) < Z_STRLEN_P(value)) {
 					rl_extend_line_buffer(Z_STRLEN_P(value) + 1);
+				} else if (!rl_line_buffer) {
+					rl_line_buffer = malloc(Z_STRLEN_P(value) + 1);
 				}
 				memcpy(rl_line_buffer, Z_STRVAL_P(value), Z_STRLEN_P(value) + 1);
 				rl_end = Z_STRLEN_P(value);

Diff for: ext/readline/tests/readline_info_002.phpt

@@ -0,0 +1,31 @@
+--TEST--
+readline_info(): using line_buffer before rl_line_buffer is initialised.
+--EXTENSIONS--
+readline
+--SKIPIF--
+<?php if (READLINE_LIB == "libedit") die("skip readline only");
+if (getenv('SKIP_REPEAT')) die("skip readline has global state");
+?>
+--FILE--
+<?php
+
+$name = tempnam('/tmp', 'readline.tmp');
+
+var_dump(readline_info('line_buffer'));
+readline_info('line_buffer', 'abcdef');
+var_dump(readline_info('line_buffer'));
+readline_add_history('123');
+readline_write_history($name);
+readline_info('line_buffer', 'abcdefghijkl');
+var_dump(readline_info('line_buffer'));
+
+var_dump(file_get_contents($name));
+
+unlink($name);
+?>
+--EXPECTF--
+string(0) ""
+string(6) "abcdef"
+string(12) "abcdefghijkl"
+string(4) "123
+"