Wrap sprintf()/snprintf() macros to prevent expansion errors.

Previously, FORTIFY_SOURCE used single macros to define these standard
functions for use with clang. This can cause conflicts with other macros used
to call these functions, particularly when those macros expand the number of
arguments to the function. This change wraps our macro definitions, so that
expansion properly takes place for programmer arguments first.

Change-Id: I55929b1fd2a643b9d14a17631c4bcab3b0b712cf

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/fortify_test.cpp b/tests/fortify_test.cpp
index b42c6b781..408991ef7 100644
--- a/tests/fortify_test.cpp
+++ b/tests/fortify_test.cpp
@@ -825,3 +825,21 @@ TEST(TEST_NAME, memcpy_chk_max_int_size) {
   ASSERT_EQ('8',  buf[8]);
   ASSERT_EQ('\0', buf[9]);
 }
+
+// Verify that macro expansion is done properly for sprintf/snprintf (which
+// are defined as macros in stdio.h under clang).
+#define CONTENTS "macro expansion"
+#define BUF_AND_SIZE(A) A, sizeof(A)
+#define BUF_AND_CONTENTS(A) A, CONTENTS
+#define BUF_AND_SIZE_AND_CONTENTS(A) A, sizeof(A), CONTENTS
+TEST(TEST_NAME, s_n_printf_macro_expansion) {
+  char buf[BUFSIZ];
+  snprintf(BUF_AND_SIZE(buf), CONTENTS);
+  EXPECT_STREQ(CONTENTS, buf);
+
+  snprintf(BUF_AND_SIZE_AND_CONTENTS(buf));
+  EXPECT_STREQ(CONTENTS, buf);
+
+  sprintf(BUF_AND_CONTENTS(buf));
+  EXPECT_STREQ(CONTENTS, buf);
+}