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, 5 insertions, 0 deletions

diff --git a/Zend/zend_ptr_stack.h b/Zend/zend_ptr_stack.h
index cc062de872..9f6fc13161 100644
--- a/Zend/zend_ptr_stack.h
+++ b/Zend/zend_ptr_stack.h
@@ -111,6 +111,11 @@ static zend_always_inline void *zend_ptr_stack_pop(zend_ptr_stack *stack)
 	return *(--stack->top_element);
 }
 
+static inline void *zend_ptr_stack_top(zend_ptr_stack *stack)
+{
+    return stack->elements[stack->top - 1];
+}
+
 #endif /* ZEND_PTR_STACK_H */
 
 /*