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argc/argv modelling: argument string must remain in scope #8174

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Merged
merged 1 commit into from
Feb 2, 2024
Merged

argc/argv modelling: argument string must remain in scope #8174

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4 changes: 4 additions & 0 deletions regression/goto-instrument/argc-argv1/main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,11 @@
int main(int argc, char* argv[])
{
if(argc>=2)
{
assert(argv[1]!=0);
// we can access at least one character (might be a string-terminating zero)
char first_char = *argv[1];
}

return 0;
}
10 changes: 7 additions & 3 deletions src/goto-instrument/dump_c.cpp
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Expand Up @@ -208,10 +208,14 @@ void dump_ct::operator()(std::ostream &os)

// we don't want to dump in full all definitions; in particular
// do not dump anonymous types that are defined in system headers
if((!tag_added || symbol.is_type) &&
system_symbols.is_symbol_internal_symbol(symbol, system_headers) &&
symbol.name!=goto_functions.entry_point())
if(
(!tag_added || symbol.is_type) &&
system_symbols.is_symbol_internal_symbol(symbol, system_headers) &&
symbol.name != goto_functions.entry_point() &&
symbol.name != CPROVER_PREFIX "arg_string") // model for argc/argv
{
continue;
}

bool inserted=symbols_sorted.insert(name_str).second;
CHECK_RETURN(inserted);
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15 changes: 10 additions & 5 deletions src/goto-instrument/model_argc_argv.cpp
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Expand Up @@ -85,20 +85,22 @@ bool model_argc_argv(
std::ostringstream oss;
oss << "int ARGC;\n"
<< "char *ARGV[1];\n"
<< "extern char " CPROVER_PREFIX "arg_string[4096];\n"
<< "void " << goto_model.goto_functions.entry_point() << "()\n"
<< "{\n"
<< " unsigned next=0u;\n"
<< " " CPROVER_PREFIX "assume(ARGC>=1);\n"
<< " " CPROVER_PREFIX "assume(ARGC<=" << max_argc << ");\n"
<< " char arg_string[4096];\n"
<< " " CPROVER_PREFIX "input(\"arg_string\", &arg_string[0]);\n"
<< " " CPROVER_PREFIX "input(\"arg_string\", \n"
<< " &" CPROVER_PREFIX "arg_string[0]);\n"
<< " for(int i=0; i<ARGC && i<" << max_argc << "; ++i)\n"
<< " {\n"
<< " unsigned len;\n"
<< " " CPROVER_PREFIX "assume(len<4096);\n"
<< " " CPROVER_PREFIX "assume(next+len<4096);\n"
<< " " CPROVER_PREFIX "assume(arg_string[next+len]==0);\n"
<< " ARGV[i]=&(arg_string[next]);\n"
<< " " CPROVER_PREFIX "assume(\n"
<< " " CPROVER_PREFIX "arg_string[next+len]==0);\n"
<< " ARGV[i]=&(" CPROVER_PREFIX "arg_string[next]);\n"
<< " next+=len+1;\n"
<< " }\n"
<< "}";
Expand All @@ -124,8 +126,11 @@ bool model_argc_argv(
// add __CPROVER_assume if necessary (it might exist already)
if(
symbol_pair.first == CPROVER_PREFIX "assume" ||
symbol_pair.first == CPROVER_PREFIX "input")
symbol_pair.first == CPROVER_PREFIX "input" ||
symbol_pair.first == CPROVER_PREFIX "arg_string")
{
goto_model.symbol_table.add(symbol_pair.second);
}
else if(symbol_pair.first == goto_model.goto_functions.entry_point())
{
value = symbol_pair.second.value;
Expand Down