Fix lexing of nested heredoc strings in token_get_all()

This fixes bug #60097.

Before two global variables CG(heredoc) and CG(heredoc_len) were used to
track the current heredoc label. In order to support nested heredoc
strings the *previous* heredoc label was assigned as the token value of
T_START_HEREDOC and the language_parser.y assigned that to CG(heredoc).

This created a dependency of the lexer on the parser. Thus the
token_get_all() function, which accesses the lexer directly without
also running the parser, was not able to tokenize nested heredoc strings
(and leaked memory). Same applies for the source-code highlighting
functions.

The new approach is to maintain a heredoc_label_stack in the lexer, which
contains all active heredoc labels.

As it is no longer required, T_START_HEREDOC and T_END_HEREDOC now don't
carry a token value anymore.

In order to make the work with zend_ptr_stack in this context more
convenient I added a new function zend_ptr_stack_top(), which retrieves the
top element of the stack (similar to zend_stack_top()).

1 files changed, 0 insertions, 3 deletions

diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index c3c35eb5fc..0533bf8c18 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -6708,9 +6708,6 @@ again:
 		case T_OPEN_TAG_WITH_ECHO:
 			retval = T_ECHO;
 			break;
-		case T_END_HEREDOC:
-			efree(Z_STRVAL(zendlval->u.constant));
-			break;
 	}
 
 	INIT_PZVAL(&zendlval->u.constant);