[analyzer] Fix modeling of strnlen to be more conservative. Move tests we can't properly model (yet?) to string-fail.c.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@132955 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 113 insertions, 0 deletions

diff --git a/test/Analysis/string-fail.c b/test/Analysis/string-fail.c
new file mode 100644
index 0000000000..bdd46642c5
--- /dev/null
+++ b/test/Analysis/string-fail.c
@@ -0,0 +1,113 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,cplusplus.experimental.CString,deadcode.experimental.UnreachableCode -analyzer-store=region -Wno-null-dereference -verify %s
+// RUN: %clang_cc1 -analyze -DUSE_BUILTINS -analyzer-checker=core,cplusplus.experimental.CString,deadcode.experimental.UnreachableCode -analyzer-store=region -Wno-null-dereference -verify %s
+// XFAIL: *
+
+// This file is for tests that may eventually go into string.c, or may be
+// deleted outright. At one point these tests passed, but only because we
+// weren't correctly modelling the behavior of the relevant string functions.
+// The tests aren't incorrect, but require the analyzer to be smarter about
+// conjured values than it currently is.
+
+//===----------------------------------------------------------------------===
+// Declarations
+//===----------------------------------------------------------------------===
+
+// Some functions are so similar to each other that they follow the same code
+// path, such as memcpy and __memcpy_chk, or memcmp and bcmp. If VARIANT is
+// defined, make sure to use the variants instead to make sure they are still
+// checked by the analyzer.
+
+// Some functions are implemented as builtins. These should be #defined as
+// BUILTIN(f), which will prepend "__builtin_" if USE_BUILTINS is defined.
+
+// Functions that have variants and are also available as builtins should be
+// declared carefully! See memcpy() for an example.
+
+#ifdef USE_BUILTINS
+# define BUILTIN(f) __builtin_ ## f
+#else /* USE_BUILTINS */
+# define BUILTIN(f) f
+#endif /* USE_BUILTINS */
+
+#define NULL 0
+typedef typeof(sizeof(int)) size_t;
+
+
+//===----------------------------------------------------------------------===
+// strnlen()
+//===----------------------------------------------------------------------===
+
+#define strnlen BUILTIN(strnlen)
+size_t strnlen(const char *s, size_t maxlen);
+
+void strnlen_liveness(const char *x) {
+  if (strnlen(x, 10) < 5)
+    return;
+  if (strnlen(x, 10) < 5)
+    (void)*(char*)0; // no-warning
+}
+
+void strnlen_subregion() {
+  struct two_stringsn { char a[2], b[2]; };
+  extern void use_two_stringsn(struct two_stringsn *);
+
+  struct two_stringsn z;
+  use_two_stringsn(&z);
+
+  size_t a = strnlen(z.a, 10);
+  z.b[0] = 5;
+  size_t b = strnlen(z.a, 10);
+  if (a == 0 && b != 0)
+    (void)*(char*)0; // expected-warning{{never executed}}
+
+  use_two_stringsn(&z);
+
+  size_t c = strnlen(z.a, 10);
+  if (a == 0 && c != 0)
+    (void)*(char*)0; // expected-warning{{null}}
+}
+
+extern void use_stringn(char *);
+void strnlen_argument(char *x) {
+  size_t a = strnlen(x, 10);
+  size_t b = strnlen(x, 10);
+  if (a == 0 && b != 0)
+    (void)*(char*)0; // expected-warning{{never executed}}
+
+  use_stringn(x);
+
+  size_t c = strnlen(x, 10);
+  if (a == 0 && c != 0)
+    (void)*(char*)0; // expected-warning{{null}}  
+}
+
+extern char global_strn[];
+void strnlen_global() {
+  size_t a = strnlen(global_strn, 10);
+  size_t b = strnlen(global_strn, 10);
+  if (a == 0 && b != 0)
+    (void)*(char*)0; // expected-warning{{never executed}}
+
+  // Call a function with unknown effects, which should invalidate globals.
+  use_stringn(0);
+
+  size_t c = strnlen(global_strn, 10);
+  if (a == 0 && c != 0)
+    (void)*(char*)0; // expected-warning{{null}}  
+}
+
+void strnlen_indirect(char *x) {
+  size_t a = strnlen(x, 10);
+  char *p = x;
+  char **p2 = &p;
+  size_t b = strnlen(x, 10);
+  if (a == 0 && b != 0)
+    (void)*(char*)0; // expected-warning{{never executed}}
+
+  extern void use_stringn_ptr(char*const*);
+  use_stringn_ptr(p2);
+
+  size_t c = strnlen(x, 10);
+  if (a == 0 && c != 0)
+    (void)*(char*)0; // expected-warning{{null}}
+}