From bee44f0dedc86b1c354e21dd87dad6313147dcc3 Mon Sep 17 00:00:00 2001 From: marxin Date: Thu, 13 Oct 2016 10:20:12 +0200 Subject: [PATCH 1/4] Support only \0-terminated string in c_getstr and return strlen gcc/ChangeLog: 2016-10-13 Martin Liska * fold-const.c (c_getstr): Support of properly \0-terminated string constants. New argument is added. * fold-const.h: New argument is added. --- gcc/fold-const.c | 38 +++++++++++++++++++++++++++++--------- gcc/fold-const.h | 2 +- 2 files changed, 30 insertions(+), 10 deletions(-) diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 02aa484..57a9243 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -14440,24 +14440,44 @@ fold_build_pointer_plus_hwi_loc (location_t loc, tree ptr, HOST_WIDE_INT off) } /* Return a char pointer for a C string if it is a string constant - or sum of string constant and integer constant. */ + or sum of string constant and integer constant. We only support + string constants properly terminated with '\0' character. + If STRLEN is a valid pointer, length (including terminating character) + of returned string is stored to the argument. */ const char * -c_getstr (tree src) +c_getstr (tree src, unsigned HOST_WIDE_INT *strlen) { tree offset_node; + if (strlen) + *strlen = 0; + src = string_constant (src, &offset_node); if (src == 0) - return 0; + return NULL; - if (offset_node == 0) - return TREE_STRING_POINTER (src); - else if (!tree_fits_uhwi_p (offset_node) - || compare_tree_int (offset_node, TREE_STRING_LENGTH (src) - 1) > 0) - return 0; + unsigned HOST_WIDE_INT offset = 0; + if (offset_node != NULL_TREE) + { + if (!tree_fits_uhwi_p (offset_node)) + return NULL; + else + offset = tree_to_uhwi (offset_node); + } + + unsigned HOST_WIDE_INT string_length = TREE_STRING_LENGTH (src); + const char *string = TREE_STRING_POINTER (src); + + /* Support only properly null-terminated strings. */ + if (string_length == 0 + || string[string_length - 1] != '\0' + || offset > string_length) + return NULL; - return TREE_STRING_POINTER (src) + tree_to_uhwi (offset_node); + if (strlen) + *strlen = string_length - offset; + return string + offset; } #if CHECKING_P diff --git a/gcc/fold-const.h b/gcc/fold-const.h index 637e46b..bc22c88 100644 --- a/gcc/fold-const.h +++ b/gcc/fold-const.h @@ -182,7 +182,7 @@ extern bool expr_not_equal_to (tree t, const wide_int &); extern tree const_unop (enum tree_code, tree, tree); extern tree const_binop (enum tree_code, tree, tree, tree); extern bool negate_mathfn_p (combined_fn); -extern const char *c_getstr (tree); +extern const char *c_getstr (tree, unsigned HOST_WIDE_INT *strlen = NULL); /* Return OFF converted to a pointer offset type suitable as offset for POINTER_PLUS_EXPR. Use location LOC for this conversion. */ -- 2.9.2