diff options
Diffstat (limited to 'gcc/c-common.c')
| -rw-r--r-- | gcc/c-common.c | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/gcc/c-common.c b/gcc/c-common.c index 900b5e9..006a831 100644 --- a/gcc/c-common.c +++ b/gcc/c-common.c @@ -230,6 +230,11 @@ int warn_sequence_point; /* Nonzero means to warn about compile-time division by zero. */ int warn_div_by_zero = 1; +/* Warn about NULL being passed to argument slots marked as requiring + non-NULL. */ + +int warn_nonnull; + /* The elements of `ridpointers' are identifier nodes for the reserved type names and storage classes. It is indexed by a RID_... value. */ tree *ridpointers; @@ -344,8 +349,17 @@ static tree handle_deprecated_attribute PARAMS ((tree *, tree, tree, int, bool *)); static tree handle_vector_size_attribute PARAMS ((tree *, tree, tree, int, bool *)); +static tree handle_nonnull_attribute PARAMS ((tree *, tree, tree, int, + bool *)); static tree vector_size_helper PARAMS ((tree, tree)); +static void check_function_nonnull PARAMS ((tree, tree)); +static void check_nonnull_arg PARAMS ((void *, tree, + unsigned HOST_WIDE_INT)); +static bool nonnull_check_p PARAMS ((tree, unsigned HOST_WIDE_INT)); +static bool get_nonnull_operand PARAMS ((tree, + unsigned HOST_WIDE_INT *)); + /* Table of machine-independent attributes common to all C-like languages. */ const struct attribute_spec c_common_attribute_table[] = { @@ -406,6 +420,8 @@ const struct attribute_spec c_common_attribute_table[] = handle_vector_size_attribute }, { "visibility", 1, 1, true, false, false, handle_visibility_attribute }, + { "nonnull", 0, -1, false, true, true, + handle_nonnull_attribute }, { NULL, 0, 0, false, false, false, NULL } }; @@ -5599,3 +5615,280 @@ vector_size_helper (type, bottom) return outer; } + +/* Handle the "nonnull" attribute. */ +static tree +handle_nonnull_attribute (node, name, args, flags, no_add_attrs) + tree *node; + tree name ATTRIBUTE_UNUSED; + tree args; + int flags ATTRIBUTE_UNUSED; + bool *no_add_attrs; +{ + tree type = *node; + unsigned HOST_WIDE_INT attr_arg_num; + + /* If no arguments are specified, all pointer arguments should be + non-null. Veryify a full prototype is given so that the arguments + will have the correct types when we actually check them later. */ + if (! args) + { + if (! TYPE_ARG_TYPES (type)) + { + error ("nonnull attribute without arguments on a non-prototype"); + *no_add_attrs = true; + } + return NULL_TREE; + } + + /* Argument list specified. Verify that each argument number references + a pointer argument. */ + for (attr_arg_num = 1; args; args = TREE_CHAIN (args)) + { + tree argument; + unsigned HOST_WIDE_INT arg_num, ck_num; + + if (! get_nonnull_operand (TREE_VALUE (args), &arg_num)) + { + error ("nonnull argument has invalid operand number (arg %lu)", + (unsigned long) attr_arg_num); + *no_add_attrs = true; + return NULL_TREE; + } + + argument = TYPE_ARG_TYPES (type); + if (argument) + { + for (ck_num = 1; ; ck_num++) + { + if (! argument || ck_num == arg_num) + break; + argument = TREE_CHAIN (argument); + } + + if (! argument + || TREE_CODE (TREE_VALUE (argument)) == VOID_TYPE) + { + error ("nonnull argument with out-of-range operand number (arg %lu, operand %lu)", + (unsigned long) attr_arg_num, (unsigned long) arg_num); + *no_add_attrs = true; + return NULL_TREE; + } + + if (TREE_CODE (TREE_VALUE (argument)) != POINTER_TYPE) + { + error ("nonnull argument references non-pointer operand (arg %lu, operand %lu)", + (unsigned long) attr_arg_num, (unsigned long) arg_num); + *no_add_attrs = true; + return NULL_TREE; + } + } + } + + return NULL_TREE; +} + +/* Check the argument list of a function call for null in argument slots + that are marked as requiring a non-null pointer argument. */ + +static void +check_function_nonnull (attrs, params) + tree attrs; + tree params; +{ + tree a, args, param; + int param_num; + + for (a = attrs; a; a = TREE_CHAIN (a)) + { + if (is_attribute_p ("nonnull", TREE_PURPOSE (a))) + { + args = TREE_VALUE (a); + + /* Walk the argument list. If we encounter an argument number we + should check for non-null, do it. If the attribute has no args, + then every pointer argument is checked (in which case the check + for pointer type is done in check_nonnull_arg). */ + for (param = params, param_num = 1; ; + param_num++, param = TREE_CHAIN (param)) + { + if (! param) + break; + if (! args || nonnull_check_p (args, param_num)) + check_function_arguments_recurse (check_nonnull_arg, NULL, + TREE_VALUE (param), + param_num); + } + } + } +} + +/* Helper for check_function_nonnull; given a list of operands which + must be non-null in ARGS, determine if operand PARAM_NUM should be + checked. */ + +static bool +nonnull_check_p (args, param_num) + tree args; + unsigned HOST_WIDE_INT param_num; +{ + unsigned HOST_WIDE_INT arg_num; + + for (; args; args = TREE_CHAIN (args)) + { + if (! get_nonnull_operand (TREE_VALUE (args), &arg_num)) + abort (); + + if (arg_num == param_num) + return true; + } + return false; +} + +/* Check that the function argument PARAM (which is operand number + PARAM_NUM) is non-null. This is called by check_function_nonnull + via check_function_arguments_recurse. */ + +static void +check_nonnull_arg (ctx, param, param_num) + void *ctx ATTRIBUTE_UNUSED; + tree param; + unsigned HOST_WIDE_INT param_num; +{ + /* Just skip checking the argument if it's not a pointer. This can + happen if the "nonnull" attribute was given without an operand + list (which means to check every pointer argument). */ + + if (TREE_CODE (TREE_TYPE (param)) != POINTER_TYPE) + return; + + if (integer_zerop (param)) + warning ("null argument where non-null required (arg %lu)", + (unsigned long) param_num); +} + +/* Helper for nonnull attribute handling; fetch the operand number + from the attribute argument list. */ + +static bool +get_nonnull_operand (arg_num_expr, valp) + tree arg_num_expr; + unsigned HOST_WIDE_INT *valp; +{ + /* Strip any conversions from the arg number and verify they + are constants. */ + while (TREE_CODE (arg_num_expr) == NOP_EXPR + || TREE_CODE (arg_num_expr) == CONVERT_EXPR + || TREE_CODE (arg_num_expr) == NON_LVALUE_EXPR) + arg_num_expr = TREE_OPERAND (arg_num_expr, 0); + + if (TREE_CODE (arg_num_expr) != INTEGER_CST + || TREE_INT_CST_HIGH (arg_num_expr) != 0) + return false; + + *valp = TREE_INT_CST_LOW (arg_num_expr); + return true; +} + +/* Check for valid arguments being passed to a function. */ +void +check_function_arguments (attrs, params) + tree attrs; + tree params; +{ + /* Check for null being passed in a pointer argument that must be + non-null. We also need to do this if format checking is enabled. */ + + if (warn_nonnull) + check_function_nonnull (attrs, params); + + /* Check for errors in format strings. */ + + if (warn_format) + check_function_format (NULL, attrs, params); +} + +/* Generic argument checking recursion routine. PARAM is the argument to + be checked. PARAM_NUM is the number of the argument. CALLBACK is invoked + once the argument is resolved. CTX is context for the callback. */ +void +check_function_arguments_recurse (callback, ctx, param, param_num) + void (*callback) PARAMS ((void *, tree, unsigned HOST_WIDE_INT)); + void *ctx; + tree param; + unsigned HOST_WIDE_INT param_num; +{ + if (TREE_CODE (param) == NOP_EXPR) + { + /* Strip coercion. */ + check_function_arguments_recurse (callback, ctx, + TREE_OPERAND (param, 0), param_num); + return; + } + + if (TREE_CODE (param) == CALL_EXPR) + { + tree type = TREE_TYPE (TREE_TYPE (TREE_OPERAND (param, 0))); + tree attrs; + bool found_format_arg = false; + + /* See if this is a call to a known internationalization function + that modifies a format arg. Such a function may have multiple + format_arg attributes (for example, ngettext). */ + + for (attrs = TYPE_ATTRIBUTES (type); + attrs; + attrs = TREE_CHAIN (attrs)) + if (is_attribute_p ("format_arg", TREE_PURPOSE (attrs))) + { + tree inner_args; + tree format_num_expr; + int format_num; + int i; + + /* Extract the argument number, which was previously checked + to be valid. */ + format_num_expr = TREE_VALUE (TREE_VALUE (attrs)); + while (TREE_CODE (format_num_expr) == NOP_EXPR + || TREE_CODE (format_num_expr) == CONVERT_EXPR + || TREE_CODE (format_num_expr) == NON_LVALUE_EXPR) + format_num_expr = TREE_OPERAND (format_num_expr, 0); + + if (TREE_CODE (format_num_expr) != INTEGER_CST + || TREE_INT_CST_HIGH (format_num_expr) != 0) + abort (); + + format_num = TREE_INT_CST_LOW (format_num_expr); + + for (inner_args = TREE_OPERAND (param, 1), i = 1; + inner_args != 0; + inner_args = TREE_CHAIN (inner_args), i++) + if (i == format_num) + { + check_function_arguments_recurse (callback, ctx, + TREE_VALUE (inner_args), + param_num); + found_format_arg = true; + break; + } + } + + /* If we found a format_arg attribute and did a recursive check, + we are done with checking this argument. Otherwise, we continue + and this will be considered a non-literal. */ + if (found_format_arg) + return; + } + + if (TREE_CODE (param) == COND_EXPR) + { + /* Check both halves of the conditional expression. */ + check_function_arguments_recurse (callback, ctx, + TREE_OPERAND (param, 1), param_num); + check_function_arguments_recurse (callback, ctx, + TREE_OPERAND (param, 2), param_num); + return; + } + + (*callback) (ctx, param, param_num); +} |