From 474da67ef9ec3658e4da9deb5373353532b2a840 Mon Sep 17 00:00:00 2001 From: Martin Sebor Date: Wed, 14 Dec 2016 17:23:16 +0000 Subject: PR c/78673 - sprintf missing attribute nonnull on destination argument PR c/78673 - sprintf missing attribute nonnull on destination argument PR c/17308 - nonnull attribute not as useful as it could be gcc/ChangeLog: PR c/17308 * builtin-attrs.def (ATTR_NONNULL_1_1, ATTR_NONNULL_1_2): Defined. (ATTR_NONNULL_1_3, ATTR_NONNULL_1_4, ATTR_NONNULL_1_5): Same. (ATTR_NOTHROW_NONNULL_1_1, ATTR_NOTHROW_NONNULL_1_2): Same. (ATTR_NOTHROW_NONNULL_1_3, ATTR_NOTHROW_NONNULL_1_4): Same. (ATTR_NOTHROW_NONNULL_1_5): Same. (ATTR_NONNULL_1_FORMAT_PRINTF_1_2): Same. (ATTR_NONNULL_1_FORMAT_PRINTF_2_0): Same. (ATTR_NONNULL_1_FORMAT_PRINTF_2_3): Same. (ATTR_NONNULL_1_FORMAT_PRINTF_3_0): Same. (ATTR_NONNULL_1_FORMAT_PRINTF_3_4): Same. (ATTR_NONNULL_1_FORMAT_PRINTF_4_0): Same. (ATTR_NONNULL_1_FORMAT_PRINTF_4_5): Same. * builtins.c (validate_arg): Add argument. Treat null pointers passed to nonnull arguments as invalid. (validate_arglist): Same. * builtins.def (fprintf, fprintf_unlocked): Add nonnull attribute. (printf, printf_unlocked, sprintf. vfprintf, vsprintf): Same. (__sprintf_chk, __vsprintf_chk, __fprintf_chk, __vfprintf_chk): Same. * calls.c (get_nonnull_ags, maybe_warn_null_arg): New functions. (initialize_argument_information): Diagnose null pointers passed to arguments declared nonnull. * calls.h (get_nonnull_args): Declared. gcc/c-family/ChangeLog: PR c/17308 * c-common.c (check_nonnull_arg): Disable when optimization is enabled. gcc/testsuite/ChangeLog: PR c/17308 * gcc.dg/builtins-nonnull.c: New test. * gcc.dg/nonnull-4.c: New test. From-SVN: r243661 --- gcc/calls.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) (limited to 'gcc/calls.c') diff --git a/gcc/calls.c b/gcc/calls.c index bc3cbd5..8466427 100644 --- a/gcc/calls.c +++ b/gcc/calls.c @@ -1501,6 +1501,91 @@ maybe_complain_about_tail_call (tree call_expr, const char *reason) error_at (EXPR_LOCATION (call_expr), "cannot tail-call: %s", reason); } +/* Return a bitmap with a bit set corresponding to each argument in + a function call expression CALLEXPR declared with attribute nonnull, + or null if none of the function's argument are nonnull. The caller + must free the bitmap. */ + +bitmap +get_nonnull_args (const_tree callexpr) +{ + tree fn = CALL_EXPR_FN (callexpr); + if (!fn || TREE_CODE (fn) != ADDR_EXPR) + return NULL; + + tree fndecl = TREE_OPERAND (fn, 0); + tree fntype = TREE_TYPE (fndecl); + tree attrs = TYPE_ATTRIBUTES (fntype); + if (!attrs) + return NULL; + + bitmap argmap = NULL; + + /* A function declaration can specify multiple attribute nonnull, + each with zero or more arguments. The loop below creates a bitmap + representing a union of all the arguments. An empty (but non-null) + bitmap means that all arguments have been declaraed nonnull. */ + for ( ; attrs; attrs = TREE_CHAIN (attrs)) + { + attrs = lookup_attribute ("nonnull", attrs); + if (!attrs) + break; + + if (!argmap) + argmap = BITMAP_ALLOC (NULL); + + if (!TREE_VALUE (attrs)) + { + /* Clear the bitmap in case a previous attribute nonnull + set it and this one overrides it for all arguments. */ + bitmap_clear (argmap); + return argmap; + } + + /* Iterate over the indices of the format arguments declared nonnull + and set a bit for each. */ + for (tree idx = TREE_VALUE (attrs); idx; idx = TREE_CHAIN (idx)) + { + unsigned int val = TREE_INT_CST_LOW (TREE_VALUE (idx)) - 1; + bitmap_set_bit (argmap, val); + } + } + + return argmap; +} + +/* In a call EXP to a function FNDECL some of whose arguments may have + been declared with attribute nonnull as described by NONNULLARGS, + check actual argument ARG at the zero-based position ARGPOS for + equality to null and issue a warning if it is not expected to be. */ + +static void +maybe_warn_null_arg (tree fndecl, tree exp, tree arg, + unsigned argpos, bitmap nonnullargs) +{ + if (!optimize + || !nonnullargs + || TREE_CODE (TREE_TYPE (arg)) != POINTER_TYPE + || !integer_zerop (arg) + || (!bitmap_empty_p (nonnullargs) + && !bitmap_bit_p (nonnullargs, argpos))) + return; + + ++argpos; + + location_t exploc EXPR_LOCATION (exp); + + if (warning_at (exploc, OPT_Wnonnull, + "argument %u null where non-null expected", argpos)) + { + if (DECL_IS_BUILTIN (fndecl)) + inform (exploc, "in a call to built-in function %qD", fndecl); + else + inform (DECL_SOURCE_LOCATION (fndecl), + "in a call to function %qD declared here", fndecl); + } +} + /* Fill in ARGS_SIZE and ARGS array based on the parameters found in CALL_EXPR EXP. @@ -1684,6 +1769,9 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED, /* Array for up to the two attribute alloc_size arguments. */ tree alloc_args[] = { NULL_TREE, NULL_TREE }; + /* Get a bitmap of pointer argument numbers declared attribute nonnull. */ + bitmap nonnullargs = get_nonnull_args (exp); + /* I counts args in order (to be) pushed; ARGPOS counts in order written. */ for (argpos = 0; argpos < num_actuals; i--, argpos++) { @@ -1915,6 +2003,11 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED, if (args[i].locate.size.var) ADD_PARM_SIZE (*args_size, args[i].locate.size.var); + /* Check pointer argument for equality to NULL that is being passed + to arguments declared with attribute nonnull and warn. */ + maybe_warn_null_arg (fndecl, exp, args[i].tree_value, argpos, + nonnullargs); + /* Increment ARGS_SO_FAR, which has info about which arg-registers have been used, etc. */ @@ -1935,6 +2028,8 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED, alloc_size. */ maybe_warn_alloc_args_overflow (fndecl, exp, alloc_args, alloc_idx); } + + BITMAP_FREE (nonnullargs); } /* Update ARGS_SIZE to contain the total size for the argument block. -- cgit v1.1