smatch_points_to_container.c

   1 /*
   2  * Copyright (C) 2022 Oracle.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 #include "ctype.h"
  19 #include "smatch.h"
  20 #include "smatch_slist.h"
  21 #include "smatch_extra.h"
  22
  23 static int my_id;
  24
  25 static char *handle_container_of_assign(struct expression *expr, struct expression **ptr)
  26 {
  27         struct expression *right, *orig;
  28         struct symbol *type;
  29         sval_t sval;
  30         char buf[64];
  31
  32         type = get_type(expr->left);
  33         if (!type || type->type != SYM_PTR)
  34                 return NULL;
  35
  36         right = strip_expr(expr->right);
  37         if (right->type != EXPR_BINOP || right->op != '-')
  38                 return NULL;
  39
  40         if (!get_value(right->right, &sval) ||
  41            sval.value < 0 || sval.value > MTAG_OFFSET_MASK)
  42                 return NULL;
  43
  44         orig = get_assigned_expr(right->left);
  45         if (!orig)
  46                 return NULL;
  47
  48         snprintf(buf, sizeof(buf), "(%lld<~$)", sval.value);
  49         *ptr = orig;
  50         return alloc_string(buf);
  51 }
  52
  53
  54 static void match_assign(struct expression *expr)
  55 {
  56         struct expression *ptr = NULL;
  57         char *container_str, *name;
  58         struct symbol *sym;
  59         char buf[64];
  60
  61         if (expr->op != '=')
  62                 return;
  63
  64         if (is_fake_call(expr->right) || __in_fake_parameter_assign ||
  65             __in_fake_struct_assign)
  66                 return;
  67
  68         container_str = handle_container_of_assign(expr, &ptr);
  69         if (!container_str || !ptr)
  70                 return;
  71         name = expr_to_var_sym(ptr, &sym);
  72         if (!name || !sym)
  73                 goto free;
  74
  75         snprintf(buf, sizeof(buf), "%s %s", name, container_str);
  76         set_state(my_id, buf, sym, alloc_state_expr(expr->left));
  77
  78 free:
  79         free_string(name);
  80         free_string(container_str);
  81 }
  82
  83 static void return_str_hook(struct expression *expr, const char *ret_str)
  84 {
  85         struct expression *call, *arg;
  86         struct symbol *sym;
  87         int offset, param;
  88         char buf[32];
  89         char *name;
  90
  91         if (!expr || expr->type != EXPR_ASSIGNMENT)
  92                 return;
  93         call = expr;
  94         while (call && call->type == EXPR_ASSIGNMENT)
  95                 call = strip_expr(call->right);
  96         if (!call || call->type != EXPR_CALL)
  97                 return;
  98
  99         if (!get_offset_param(ret_str, &offset, &param))
 100                 return;
 101
 102         arg = get_argument_from_call_expr(call->args, param);
 103         arg = strip_expr(arg);
 104         if (!arg)
 105                 return;
 106
 107         name = expr_to_var_sym(arg, &sym);
 108         if (!name || !sym)
 109                 return;
 110
 111         snprintf(buf, sizeof(buf), "%s (%d<~$)", name, offset);
 112         set_state(my_id, buf, sym, alloc_state_expr(expr->left));
 113 }
 114
 115 struct expression *get_stored_container(struct expression *expr, int offset)
 116 {
 117         struct smatch_state *state;
 118         struct symbol *sym;
 119         char buf[64];
 120         char *name;
 121
 122         name = expr_to_var_sym(expr, &sym);
 123         if (!name || !sym)
 124                 return NULL;
 125
 126         snprintf(buf, sizeof(buf), "%s (%d<~$)", name, offset);
 127         free_string(name);
 128         state = get_state(my_id, buf, sym);
 129         if (!state)
 130                 return NULL;
 131         return state->data;
 132 }
 133
 134 void register_points_to_container(int id)
 135 {
 136         my_id = id;
 137
 138         set_dynamic_states(my_id);
 139         add_hook(&match_assign, ASSIGNMENT_HOOK_AFTER);
 140         add_return_string_hook(return_str_hook);
 141         add_modification_hook(my_id, &set_undefined);
 142 }
 143