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C front-end: use proper index type for argv and envp access #6819

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merged 1 commit into from
Apr 21, 2022
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C front-end: use proper index type for argv and envp access #6819

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21 changes: 15 additions & 6 deletions src/ansi-c/ansi_c_entry_point.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -302,6 +302,7 @@ bool generate_ansi_c_start_function(
}

const symbolt &argv_symbol=ns.lookup("argv'");
const array_typet &argv_array_type = to_array_type(argv_symbol.type);

{
// Assume argc is at least zero. Note that we don't assume it's
Expand Down Expand Up @@ -405,10 +406,12 @@ bool generate_ansi_c_start_function(
{
// assign argv[argc] to NULL
const null_pointer_exprt null(
to_pointer_type(to_array_type(argv_symbol.type).element_type()));
to_pointer_type(argv_array_type.element_type()));

index_exprt index_expr(
argv_symbol.symbol_expr(), argc_symbol.symbol_expr());
argv_symbol.symbol_expr(),
typecast_exprt::conditional_cast(
argc_symbol.symbol_expr(), argv_array_type.index_type()));

init_code.add(code_frontend_assignt(index_expr, null));
// disable bounds check on that one
Expand All @@ -419,14 +422,17 @@ bool generate_ansi_c_start_function(
if(parameters.size()==3)
{
const symbolt &envp_symbol=ns.lookup("envp'");
const array_typet &envp_array_type = to_array_type(envp_symbol.type);
const symbolt &envp_size_symbol=ns.lookup("envp_size'");

// assume envp[envp_size] is NULL
null_pointer_exprt null(
to_pointer_type(to_array_type(envp_symbol.type).element_type()));
to_pointer_type(envp_array_type.element_type()));

index_exprt index_expr(
envp_symbol.symbol_expr(), envp_size_symbol.symbol_expr());
envp_symbol.symbol_expr(),
typecast_exprt::conditional_cast(
envp_size_symbol.symbol_expr(), envp_array_type.index_type()));

equal_exprt is_null(std::move(index_expr), std::move(null));

Expand All @@ -452,7 +458,8 @@ bool generate_ansi_c_start_function(

{
index_exprt index_expr(
argv_symbol.symbol_expr(), from_integer(0, c_index_type()));
argv_symbol.symbol_expr(),
from_integer(0, argv_array_type.index_type()));
// disable bounds check on that one
index_expr.add_source_location().add_pragma("disable:bounds-check");

Expand All @@ -467,9 +474,11 @@ bool generate_ansi_c_start_function(
if(parameters.size()==3)
{
const symbolt &envp_symbol=ns.lookup("envp'");
const array_typet &envp_array_type = to_array_type(envp_symbol.type);

index_exprt index_expr(
envp_symbol.symbol_expr(), from_integer(0, c_index_type()));
envp_symbol.symbol_expr(),
from_integer(0, envp_array_type.index_type()));

const pointer_typet &pointer_type =
to_pointer_type(parameters[2].type());
Expand Down