Handle gcc.StringCst on the right-hand-side of an assignment

Author: davidmalcolm

libcpychecker/absinterp.py

@@ -1549,6 +1549,8 @@ def eval_rvalue(self, expr, loc):
             return ConcreteValue(expr.type, loc, expr.constant)
         if isinstance(expr, gcc.RealCst):
             return ConcreteValue(expr.type, loc, expr.constant)
+        if isinstance(expr, gcc.StringCst):
+            return AbstractValue(expr.type, loc)
         if isinstance(expr, gcc.SsaName):
             region = self.var_region(expr.var)
             check_isinstance(region, Region)
@@ -2579,6 +2581,8 @@ def eval_rhs(self, stmt):
             return self.eval_rvalue(rhs[0], stmt.loc)
         elif stmt.exprcode == gcc.RealCst:
             return self.eval_rvalue(rhs[0], stmt.loc)
+        elif stmt.exprcode == gcc.StringCst:
+            return self.eval_rvalue(rhs[0], stmt.loc)
         elif stmt.exprcode == gcc.AddrExpr:
             return self.eval_rvalue(rhs[0], stmt.loc)
         elif stmt.exprcode == gcc.NopExpr:

tests/cpychecker/absinterp/assignment-from-string-const/input.c

@@ -0,0 +1,35 @@
+/*
+   Copyright 2014 David Malcolm <dmalcolm@redhat.com>
+   Copyright 2014 Red Hat, Inc.
+
+   This is free software: you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see
+   <http://www.gnu.org/licenses/>.
+*/
+
+#include <Python.h>
+
+char test_string(const char *src)
+{
+    char buf[256]="";
+    strncpy(buf, src, 256);
+    return buf[0];
+}
+
+/*
+  PEP-7
+Local variables:
+c-basic-offset: 4
+indent-tabs-mode: nil
+End:
+*/

tests/cpychecker/absinterp/assignment-from-string-const/script.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+#   Copyright 2011 David Malcolm <dmalcolm@redhat.com>
+#   Copyright 2011 Red Hat, Inc.
+#
+#   This is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#   General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see
+#   <http://www.gnu.org/licenses/>.
+
+from libcpychecker import main
+
+main(verify_refcounting=True,
+     dump_traces=True)

tests/cpychecker/absinterp/assignment-from-string-const/stdout.txt

@@ -0,0 +1,8 @@
+Trace 0:
+  Transitions:
+    'returning'
+  Return value:
+    repr(): UnknownValue(gcctype=gcc.PointerType(dereference=<gcc.ArrayType object at 0xdeadbeef>), loc=gcc.Location(file='tests/cpychecker/absinterp/assignment-from-string-const/input.c', line=25))
+    str(): unknown char[256] * from tests/cpychecker/absinterp/assignment-from-string-const/input.c:25
+  Exception:
+    (struct PyObject *)0 from tests/cpychecker/absinterp/assignment-from-string-const/input.c:23