From e6c16ea038104ef15b087ff9fca23d9b2406e65e Mon Sep 17 00:00:00 2001 From: marxin Date: Mon, 10 Oct 2016 12:13:12 +0200 Subject: [PATCH] Enhance c_getstr API gcc/ChangeLog: 2016-10-10 Martin Liska * fold-const.c (c_getstr): Guard string termination, or validate that requested length is within a string constant. * fold-const.h (c_getstr): Set default value for the new arg. --- gcc/fold-const.c | 44 +++++++++++++++++++++++++++++++++++--------- gcc/fold-const.h | 3 ++- 2 files changed, 37 insertions(+), 10 deletions(-) diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 02aa484..eb53e84 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -14440,24 +14440,50 @@ 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. + If the string constant is properly zero-terminated, the constant is returned. + Otherwise, if REQ_LENGTH is a non-negative number, the constant + is returned if the string length is greater or equal to REQ_LENGTH. + If STRLEN is a valid pointer, length (including terminatinch character) + of returned string is stored to the argument. */ const char * -c_getstr (tree src) +c_getstr (tree src, HOST_WIDE_INT req_length, 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); + } - return TREE_STRING_POINTER (src) + tree_to_uhwi (offset_node); + unsigned HOST_WIDE_INT string_length = TREE_STRING_LENGTH (src); + const char *string = TREE_STRING_POINTER (src); + if (offset > string_length) + return NULL; + + /* If the string is properly '\0' character terminated, return it. */ + if ((string_length > 0 && string[string_length - 1] == 0) + || (req_length != -1 + && (unsigned HOST_WIDE_INT)req_length <= string_length - offset)) + { + if (strlen) + *strlen = string_length - offset; + return string + offset; + } + else + return NULL; } #if CHECKING_P diff --git a/gcc/fold-const.h b/gcc/fold-const.h index 637e46b..bbf831a 100644 --- a/gcc/fold-const.h +++ b/gcc/fold-const.h @@ -182,7 +182,8 @@ 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 src, HOST_WIDE_INT req_length = -1, + 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